Citation
Photodetachment of gas-phase halogen molecular anions and the enolate anion of acetophenone

Material Information

Title:
Photodetachment of gas-phase halogen molecular anions and the enolate anion of acetophenone
Creator:
Daubach, Ronald O., 1952-
Publication Date:
Language:
English
Physical Description:
x, 212 leaves : ill. ; 28 cm.

Subjects

Subjects / Keywords:
Anions ( jstor )
Chlorine ( jstor )
Electron affinity ( jstor )
Electrons ( jstor )
Ions ( jstor )
Lasers ( jstor )
Magnetic fields ( jstor )
Photodetachment ( jstor )
Signals ( jstor )
Wavelengths ( jstor )
Acetophenone ( lcsh )
Anions ( lcsh )
Chemistry thesis Ph. D
Dissertations, Academic -- Chemistry -- UF
Ion cyclotron resonance spectrometry ( lcsh )
Genre:
bibliography ( marcgt )
non-fiction ( marcgt )

Notes

Thesis:
Thesis (Ph. D.)--University of Florida, 1983.
Bibliography:
Bibliography: leaves 205-211.
General Note:
Typescript.
General Note:
Vita.
Statement of Responsibility:
by Ronald O. Daubach.

Record Information

Source Institution:
University of Florida
Holding Location:
University of Florida
Rights Management:
Copyright [name of dissertation author]. Permission granted to the University of Florida to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.
Resource Identifier:
020034714 ( ALEPH )
12130357 ( OCLC )

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PHOTODETACHMENT OF GAS-PHASE HALOGEN MOLECULAR
ANIONS AND THE ENOLATE ANION OF
ACETOPHENONE















by

Ronald 0. Daubach


A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL
n r- r] a r I I i T i r r^ f 'r', ~ \ | Ah r- r n "TrIri

































Copyright 1983


by
Ronald 0.


Daubach















ACKNOWLEDGEMENTS

The author thanks Dr. John R. Eyler for his instruction,


assistance, and direction in this research effort.


In addition,


the patience and concern of Dr. Eyler in all stages of this research

and manuscript preparation are gratefully acknowledged.


The stimulation provided by fellow graduate students wa


valuable.


Particular thanks are extended to Dr. L. Morgenthaler,


R. J. Doyle,and D.


A. Atherton.


The design of the microcomputer


interface was initially generated by Dr. Ed


Voigtman


without


whose assistance no subsequent progress would have been possible.


The construction of the apparatus used in thi


work involved


the efforts of many.


The professional workmanship of Mr


Art Grant,


Mr. Ed Whitehead, Mr. Rudy Strohschein


Mr. James Chambleeand


Mr. Robert Dugan is thankfully commended.

The author thanks Ms. Constance Miller for the patient and

careful preparation of this dissertation.


impetus to accomplish when the desire lagged was provided


by the love, concern,and devotion of Joni Meno Daubach which is

deeply appreciated.

Funding for this research has been provided by the Division


















TABLE OF CONTENTS


Page
I I


ACKNOWLEDGEMENTS.


LIST OF TABLES.

LIST OF FIGURES


* 4 4 * S a a a S

* . S C * S S a S a .t a ft C C l


ABSTRACT.


CHAPTER I


INTRODUCTION.


Historica
Negativ
Electron
Experimen
Theoretic
Outline o


* a C S C S C S 9 0 S 5 1


1 and Scientif
e Ions
Affinity a
tal Techniques
a] Techniques.
f Dissertation


ic Interest


* S S 0 S S S S C S S S
* C S S S S S S C S
S S S S S S S S C S S
* a C C P 5 C 9 5 C S
* S S S S C S C S S S S


CHAPTER II


THEORY OF ION CYCLOTRON RESONANCE


Ion Motion in Static Fields
Ion Motion in an RF Electric Field
Ion Detection . .


* 5
* S S


* S
* S S


CHAPTER II


EXPERIMENTAL APPARATUS.


Trappi
Vacuum
Optica
Pulsed
Microc
Mi
Mi
Mi


ng Cell .
Apparatus.
1 Apparatus
Electronic
computer
crocomputer
crocomputer
crocomputer


Ii

S


S S S S S S 5 31


* C S P 5 C P 5 5 0 5 5 5 ft 5
S* S C C C a C C S S S
and Modifications .
Interface Hardware. .
Software. .


Run Time Operation. .
Derivation of the Expression for the
detachment Cross-Section .


Photo-












12 Results. .
f Franck-Condon Factors
ular Anion-Formation of Br


of
Res
ord
1 R


BrZ
ul s
e Mo
esul


lecular Anion
ts S S


* S S
* S S S S P
* S S S 4


CHAPTER IV


PHOTODETACHMENT STUDY OF THE ENOLATE ANION


OF ACETOPHENONE


Formation of the Enolate Anion .
Analysis of the Acetophenone Enolate Anion
Resul ts. . *


CHAPTER V


SUMMARY.


S S S C S U S S S S P 5 5 S 4 S a S 4 1


APPENDIX I


APPENDIX II

APPENDIX III

APPENDIX IV


APPENDI


ON-BOARD MICROCOMPUTER HARDWARE MODIFICATION


MICROCOMPUTER CONTROL REGISTERS.


MICROCOMPUTER PROGRAMS

SAMPLE PREPARATION


NUMERICAL VALUES OF THE RKR POTENTIALS AND
THE FRANCK-CONDON OVERLAP PROGRAM OUTPUT


REFERENCES a

BIOGRAPHICAL SKETCH


S 0
tio
Mo
tac
s o


fC
n o
lec
hme
fB
noc
fB


nt


rC














LIST OF TABLES


Page


Tabl

1


Laser Dyes and Observed Lasing Wavelength Regions.


Grating Characteristi


as a Function of


Wavelength for a 1200 line/mm Grating


Autocollimation

Factors in the Relative


for a Range of


Value


Errors in the Cross-Section
and f Equal to 1.0 and 0.75.


Variation of ICR Operating Parameters During Studies
to Maximize Formation of the Nitrite Ion from


Nitromethane


82


Empirical Electron Affinities for NO2 in eV


Spectroscopic Constants Used in th


Determination


of the Rydberg-Klein-Rees Potential Curve for Cl2.

Spectroscopic Constants Used in the Determination
of the Rydberg-Klein-Rees Potential Curve for Clo


Correlation of the Observed Peaks


) in
cvn


the Cl Photodetachment Spectrum with '^"
Calculated Transitions Energies (Tcaic) and
Franck-Condon Factors. . . .


Adiabatic Electron Affinity Values for Chlorine
Determined from the Assignment of the Photo-


detachment Spectrum Structure.


121


Comparison of Literature Values for the Electron
Affinity of Chlorine . . .


Experimental Wavelengths1(x) and Term Values (T )
and First Differences (A) for the Observed exp


Photoreduction of Bromine


Molecular Negative Ions.















LIST OF FIGURES


Figure


Page


Trochoidal


Trajectory of a Charged Particle


in Uniform and Static Crossed Electri
Magnetic Fields. . .


Trapped Ion Cyclotron Resonance Cell Schematic


Time-Dependent Radii for Non-Resonant Particl


GLC Circuit Emulation of ICR Detection

Trapped Ion Cyclotron Resonance Cell


Schematic Diagram of the Digital Pulse Electronics


Vacuum


tern Schematic.


Dye Laser Apparatus and Orientation.


A Typical Pulsed ICR Experiment Pul


Sequence


Operator/Microcomputer Interaction Flowchart


Main Program Branch Flowchart.


Baseline MO Data Flowchart


Resonant Baseline Data Flowchart


Laser Status Flowchart -

Microcomputer RAM Memory Map


* . S 0

* a S a * S


Negative Ion Mass Spectrum of Nitromethane


Negative Ion Mass Spectrum for a Chlorine/
Nitromethane Mixture . .












Figure


Page


Photodetachment of Cl

Photoproduction of Cl


C1G Photodetachment Cross
of Wavelength. . *


action as a Function


Rydberg-Klein-Rees Potential Energy Curves for
Cl 2 ard C] 2 l 5 5 5 5 C 5

The Negative Ion Mass Spectrum of a Mixture of


Chlorine/Bromine and Nitromethane.


Photodetachment Spectrum of Br2-

Negative Ion Mass Spectrum with BrCl

Acetophenone Signal Intensity.

Photoreduction of the Enolate Anion.


C .125


I S a

I C S S I


* S S S S P

* C S 5 9 C


Photodetachment of Acetophenone as a Function of


Wavelength at 150 ms Delay

Photodetachment of Acetophenone
Wavelength at 200 ms Delay

Photodetachment of Acetophenone
Wavelength at 250 ms Delay


as a Function of


as a Function of
148















Abstract of Dissertation Presented to the Graduate Council of
the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy



PHOTODETACHMENT OF GAS-PHASE HALOGEN MOLECULAR
ANIONS AND THE ENOLATE ANION OF
ACETOPHENONE

By


Ronald 0


Daubach


December 1983


Chairman: Dr. Jo
Major Department:


ihn R. Eyler
Chemistry


The photodetachment of electrons from negative


molecular ions has been investigated.


halogen


An ion cyclotron resonance


mass spectrometer was employed for the generation,


detection of the ions.


containment and


Photoprocesses were induced by means of an


integrated, tunable dye laser system.

Structure was observed in the photodetachment spectra of chlorine


and bromine molecular anions.


This


structure was correlated to


vibronic fine


structure of the photodetachment transition.


adiabatic electron affinity value for chlorine of


2.36


+0.27


eV was obtained


The absence of structure in the bromine photodetach-










anion of bromine monochloride was generated but was of low signal


intensity.


The photodetachment spectrum of the enolate anion of


acetophenone exhibited behavior which supported previous

explanations of the source of the structure in the cross-section near

threshold.
















CHAPTER


INTRODUCTION


Historical and Scientific Interest in Negative Ions

The study of negative ions in the gas phase has elicited

increasing interest since Wildt ascertained the importance of H- to

the explanation of the anomalous infrared opacity of the solar


pectrum (1). This

affinity continuum


insight was founded upon the investigation of the


associated with the radiative attachment of an


electron to an atom by Gerlach and Gromann (2)


Wildt further proposed


that the radiative behavior of diatomic negative ions of neutral


diatomics of established astrophysical importance such as H


NH, OH,and CH might be of


analysis.


significance in stellar radiation spectral


Subsequent study of negative ions for astrophysical


applications has been largely concerned with defining the wavelengtn


dependence of the interaction of


Following the recognition of the


plasmas, an awareness of negative


chemistry


eight with the selected ions (3)


mport of negative ions in stellar

ions evolved in atmospheric


, flame chemistry, gas laser plasma chemistry, and radiation


chemistry and biology.

Consideration of the behavior of negative ions in the atmosphere


e a,- -% 1


S
W% fl t~ t** S fl ~ *t ~ C **% ,-~ C .C ,, -4-. ~- t, -' ,- 4- L~ C 1 *. 4 .-. 4










concentration extending from 60 to 450 kilometers above the earth's


surface.


Fluctuations, either local or temporal,


in the free electron


concentration in thi


region have profound effects on the


reflectivity to radiofrequencies exhibited by the region.


Consequently,


the formation and destruction of negative ions with the concomitant

loss or gain of free electrons must be characterized to account for

the observed radiofrequency reflectivity.


Negative ion chemistry in the lower atmosphere


stratosphere


(15-60 kilometers) and the troposphere


0-15 kilometers)


, is pertinent


to air pollution chemistry and had been suggested as a


ink for


chlorofluorocarbons released into the atmosphere.


Recent


tudies


have discredited this suggestion as the reactions of the hydrated

negative ions which predominate at the lower altitudes with


chlorofluorocarbons have been shown to proceed

The study of ions in flames is of current


been of interest


transport in flames (


composition of flames i


lowly (6).

interest (7) and has


Moreau's early studies of negative ion


* The complexity of the negative ion

s illustrated by the number of negative ions


in significant concentration


a simp


clean, methane-oxygen


flame in which no fewer than twelve negative


identified


ions have been


Not only the characterization of flames by the study


of the ion distribution, which remains an active area of research (10),


but also the


use of flames in spectroscopy rely upon the clarification










knowledge of electron-neutral interactions and negative ion formation.

Typically, short wavelength lasers have employed some variation


of a fast-risetime, high-energy electron discharge pumping scheme


The excited neutral


and positive ions formed during discharge have


been included in models of laser performance


A recent


investigation has extended consideration to negative ions produced by


the attachment of secondary electrons to F2 and NF3


the alternate


sources of fluorine in XeF laser ga


mobility of Cl-


mixtures (14)


in Xe, a factor in evaluating the


mixtures, has been investigated


15) and it ha


In addition, the

Cl excimer


been suggested that the


molecular bromine anion contributes to XeBr*


excimer formation in


electron discharge pumped mixtures through reaction with Xe+ (16)


Negative ions are of interest in radiation and nuclear chemistry.

Biologically active free radicals, excited states,and negative ions


are generated by radiation incident on biological matter (17).


development of nuclear pumped lasers and gas-core reactors employing


as the fuel /medium requires


that the negative ion formation of


compound of relatively large electron affinity be


evaluated (18).


Electron Affinity


ectron affinity of the corresponding neutral is the most


fundamental property associated with a negative


The electron


affinity i


defined


as the change


in the tota


energy of the system


upon the addition of an electron.


The change


in the system energy










Negative electron affinities are associated with unstable systems which


may, however, exhibit resonance


related to the formation of a


transient negative ion state (19)


For an atomic negative ion


affinity is complete.


given definition of electron


A complication arises for molecular negative ions


due to the change in the nuclear configuration associated with the


addition of the el

are conceivable.

neutral and ground


ectron.


Two distinct types of electron affinities


The energy difference associated with the ground state

state ion both with zero internal energy and both


at their respective equilibrium geometries i


adiabatic electron affinity.


referred to as the


A more readily observable energy


difference, the vertical electron affinitycorresponds to the change

in energy between the neutral and negative ion ground electronic states


at the equilibrium nuclear configuration of the neutral.


In general,


the term vertical electron affinity is used for all values of observed

electron affinities for which either the negative ion or the neutral


possess


internal


excitation.


Herein


les the basic problem in the


interpretation of experimental measurements of molecular


ectron


affinities, the difficulty encountered in the evaluation of the internal


energy of the initial and final states. In g

techniques measure vertical electron affiniti


ower limits to the adiabati


general, experimental


which provide upper or


or thermodynamic electron affinity


based upon some estimate of the


internal excitation.


Several reviews











Experimental Technigcues


Two types of charge transfer techniques have proven usefu


in the


study of electron affinities


exothermi


charge transfer (CT) and


endothermic charge transfer (ECT)


Exothermic charge transfer yield


limits on a molecular electron affinity by observation of the direction

of spontaneous charge transfer between negative ions and target


neutra


[lore accurate values of the


imits for the electron affinity


may be surmised if the

can be estimated (24).


exothermicity of the charge transfer reaction

Endothermic charge transfer employs the


energy of translation to induce a nominally endothermic charge transfer


(25)


This technique enabi


the energy dependence of the cross


section above threshold to be determined


Collisional ionization is


a related scheme in which both of the initial reactant


are neutrals.


Collision-induced, ion-pair formation lends itself to the evaluation


of the product negative ion


electron affinity provided the positive


ion's ionization potential


is independently known (26)


These


techniques are limited by the residual uncertainties


in the distribution


of the e


xcess


energy between translation and internal modes and the


detailed distribution of the internal energy for systems with more

than one degree of internal freedom.

A variety of photodetachment techniques for obtaining electron


affinities have been developed.

variable (28) frequency photoelec


These include fixed (27) and


spectrometry and variabi


^f *_f r *









length-tuning-range lasers of excellent monochromaticity has greatly


assisted the application of photodetachment schemes.


The major


characteristic distinguishing the different photodetachment techniques


is the detailed means by which the process


is instigated and detected.


The fixed frequency photoelectric experiment employs an argon ion

(Art) laser (488.0 nm) to eject electrons from a beam of negative ions.

The photoelectrons are energy analyzed over a defined angular collection


aperture to obtain the photoelectron spectrum.


Variable frequency


photoelectron spectrometry measures the production of photoelectrons


as a function of the irradiation wavelength.


Beam and drift tube photo-


detachment employ either neutral beam or residual ion beam detection


rather than direct analysis of the ejected electrons.


The important


advantage of a drift tube experiment is the reasonable assurance that

an ion has a thermal internal energy distribution prior to photo-

excitation.


Ion cyclotron resonance


ICR) techniques for the study of photo-


induced processes of ions merge the advantage of drift tube thermaliza-


tion with controlled


, low energy, electron-impact production of


negative ions to minimi


ion internal excitation


31-32).


The pulsed


ICR technique is capable of characterizing effects of ion internal

excitation by varying the time available for the collisional de-excitation

prior to photoexcitation (33).


Theoretical Techniques










of a photodetachment spectrum.


and evaluating cross-


classified


Means of estimating electron affinities


section behavior have been developed and may be


as semiempirical, ab initio,and collision theory techniques.


Semiempirical results deal solely with the prediction of electron


affinities.


Pritchard (34) gave a very complete historical summary


of semiempirical estimation of electron affinities based on observed


lattice energies and thermodynamic arguments.


Person (35) suggested a


semiempirical scheme based upon the charge-transfer frequency of


donor-acceptor complexes (36


and its relation to the vertical electron


affinity of the acceptor and derived good results for several


diatomic halogen molecules.


Recently


a means of estimating molecular


electron affinities from the constituent atoms electron affinities and

positions in the Periodic Table has been proposed (37).

Theoretical determinations of electron affinities have employed


either direct or indirect schemes


38).


Indirect methods consist of


individual calculations for the potential energy of the neutral and


negative ion states.


The potential energy curves generated are then


used to obtain values for the adiabati


affinities


and vertical electron


These methods are constrained by the necessity of very


high precision in the individual state energies since the


electron


affinities are given as the difference of two large values, yet are


quite small with respect to the total energies of either state.


addition, it i


not trivial to insure that the calculations for both










normally of the order of the correlation energy (39),the energy

associated with the assumption of an average potential due to all of


the electrons with the exception of the electron whos


calculated.


energy state is


This average potential is an assumption basic to a]]


Hartree-Fock schemes and limits the value of this particular scheme


for electron affinity determination.


CI accounts for correlation effects


including a number of electronic configurations into the energy


calculations (40).


Generally, the validity of any indirect method


depends upon the system as well as the technique.

Several variations of a direct method for calculating potential

energy differences between electronic states at a selected nuclear


configuration have recently been developed (38).


These techniques


eliminate


the inaccuracies of the indirect procedures.


The method


begins with a calculation of the neutral potential energy curve.


operator simulating the addition or removal of an electron i

applied to a specific point on the potential energy surface.


determines the ion energy.


then

This


For vertical and adiabatic electron


affinity


estimation, this method appears promising.


It is feasible,


although computationally extensive, to generate the detailed anion


potential


surfaces necessary to predict spectral behavior for the


transitions.

Photodetachment spectral analysis consists of modeling the energy


dependence of the cross-section at threshold.


The rigorous mathematical










system applicable to diatomics is well documented (43).


The details


of the theory and derivation will not be of significance here; however


the results will be applied in analysis of the observed spectra


behavior.

Outline of the Dissertation

This dissertation presents a description of photodetachment


studi


executed on molecular negative ions.


These investigations were


carried out using a pulsed ion cyclotron resonance mass spectrometer


combined with a pulsed, flashlamp-pumped dye laser.


A data collection


and analysis system was interfaced to the experiment to simplify and


accelerate data reduction.


Chapter II describes the theory of


cyclotron resonance as it pertains to ion containment and detection.

Chapter III addresses the details of the experimental procedure and


set-up.


Chapter IV presents the results for the diatomic halogen


anions investigated


Cl2


, Br2


and BrCI


Chapter V presents the


results for the enolate anion of acetophenone.


A summary of the results


and assessment of the technique for the study of molecular anions is

put forward in Chapter VI.

Appendix I documents alterations made to the microcomputer to


enhance its data handling performance.


Appendix II itemizes the


control registers for the software data collection and analysis.

Appendix III contains the microcomputer programs written to implement


the data collection.


Append i


x IV describes the sample preparations















CHAPTER II
THEORY OF ION CYCLOTRON RESONANCE


The study of photo-induced processes of ga


phase ions


necessitates a well-defined region of observation and the minimization


of non photo-induced ion losses.


In addition, a sensitive method of


sufficient resolution is required for the detection of ions of


varying mass-to-charge ratios.


The classical motion of a charged


particle in electric and magnetic fields I


applied to the


spatial


restriction and the detection of ions.


Ion Motion in Static Fields


An isolated, charged particle in motion located in a magnetic


field interacts with the field classically.


This interaction of


charged particle and magnetic field constrains the particle motion in


the plane perpendicular to the field.


For a uniform and static


magnetic field, the interaction of the particle and the field results


in the gyration of the particle about the magnetic field


The field-induced motion i


rotation


ines


characterized by the frequency of the


, t, given as (44)


= qB/m


where a is the charge nn the article. m is the narticlp mass. B is










velocity perpendicular to the field,


,must be nonzero for this


interaction, significantly


, the frequency of


gyration is independent


of the actual magnitude of the velocity component.


Therefore,


of identical charge-to-mass ratios circulate about the magnetic field


lines


at a single natural


cyclotron frequency regard]


ess


of the


distribution of velocity components,


The component,


remains


significant since the radiu


gyration


, retains a functional


dependence on vo.


- qB (2


The motion of a charged particle in the presence of uniform and


static electric and magnetic fields, E and B


respectively


governed by the


Lorentz force


l aw,


= q(E + v x B)


where v is the particle velocity.


This equation is readily soluble


for the a


assumed field conditions


for the equations of motion of the


parti


44).


For the


simplifi


d field conditions


in which E and B


are mutually perpendicular,


the equations of motion dictate a


trochoidal


path,


superposition of the cyclotron motion and the


drift of the center of the cyclotron orbit perpendicular to both


field


(Figure


The separation of the


complex trajectory of the


particle into the cyclotron and drift


components


is a useful


j~~~e. 1- S S S
,,.',r'.z..urlflfl rfl~fl rnr% %ntI.,,.n .5.. .-..-.---~- -- .1




























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WiI mi3


\N










Three-dimensional ion containment is not accomplished with the


simple


field conditions thus far treated.


In neither of the


cases


considered has the motion of the particle

field lines been restricted. Also, the


parallel to the magnetic


transverse electric field


induces a particle drift producing a channel for ion loss perpendicular


to both the electric and magnetic fields.


Consequently, a configuration


of fields


iminating these ion loss channels must be


selected.


The trapped ion cell developed by Mclver produces an electro-


static potential for which the equipotential lines


ose on themselves


in the plane perpendicular to the magnetic field in addition to

forming an electrostatic potential well parallel to the magnetic


field axis (46). The c

are indicated in Figure


magnetic field for subsequent disc

electrically independent plates.


ell geometry and definition of coordinate axes


which also indicates the direction of the


The cell consists of


For effective negative ion trapping,


the upper (U),


ower (L


and end (E) plates are held at +1.0 volt,


while the trapping (T) plate potential


are -1.5 volts.


In the


case


of positive ion trapping, the polarity of each plate potential


is reversed.


solution of Laplace'


Equation for a cell identical


to that shown in Figure


has provided an expression for the three-


dimensional potential produced in the cell interior (47).


analyti


approximation to this expression valid near the center of


the cell yields a quadrupolar


electric field
































a)
C-)
C-
'Wro
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r r- 4~J
4~Jt4~ C
roew
Er4-)
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0(0 0)
(nor'- 2
-Cl-ta
-


* 4%
w
4-)
(oc
-w
00-
a
S...
W


=0)

wet,
-


- S tLJ r-'
a)- 4-
~ U
Wrt~ a)
W04-~C
U

C.r-0OW
o
VlV4-~ Or- C
WWOW4-'ets
0 C~We- U
a,-~ 0) -~
C(~woD-w
Os- Uu~
L4-JW
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0W4-~-C

(0r
0
04- 4-4-)
0 >y- ro S...
C S.- ~W
o 'n~ar oJ~ n
00)
C 2 tO 0)r- -p
~00)0 C
wCw U.-w-
o 0 Di- a.c a

OEWWa -o
S.- 0C s-S.-
1-04-) tO4-'.--J 0)
















eJ
w^~~ ~-D Z^ ZZ


D)


WJ - v-
^~^~-^D i -r -m -j L


I


-j


-j










where a is the cell width, VT is the trapping plate potential, V0 is


the upper and


ower plate potential and


related to the actual dimension


of the cell.


are constants


The restriction of ion


motion is evident when the guiding center motion is evaluated for the

approximately quadrupolar cell potential.


The expression for the drift velocity of the guiding center


xB/B2


With the magnetic field direction


velocity in component form becomes


as defined (Figure


= Ey/B =[2x(VT- V)/aBy



= -Ex/B =[-2c(VT- Vo)/a2Blx


Clearly, the drift velocity vector in any plane of constant


the drift


z l


(6)

es


in the plane and is perpendicular to the electric field vector, E.


Since E is everywhere perpendicular to the equipotential


ines,


ion drift occurs along the


losed equipotential lines of the


electro-


static


field.


The frequency of the drift along the elliptical


equipotential lines is derived from the solution of the equations of

motion in the quadrupolar field as (47)

o- 2(VT-Vo) ()x)









potential lines at frequency

loss of ions.


The remaining component of the


eliminates the mechanism of drift


electric field, Ez, is of the


form (47)


=-Kz k


where


= 2(VT


- VO /a


Substitution of this expression into the


z-component of the Lorentz


force law (2) yields the equation for simple harmonic motion of a

charged particle along the magnetic field lines


=-t-2z


where mT


: (qK/m)1


Oscillatory motion along the


axis is imposed


upon


ons whose initial total energy


kinetic and potential, is less


than the trapping potential well.


A side-effect of the electrostatic


restriction of the ions in the z-direction is a shift in the observed


cyclotron frequency from the natural cyclotron frequency, fr.


effective


cyclotron frequency, w ,


is (47)


= (w-mT2)


= {w2-C[2(VT- Vo)]2}


(10)


Clearly, alteration


of the trapping potentials results in a shift


of the cyclotron frequency unles

alteration of the magnetic field


compensated with an appropriate

strength.










Natural cyclotron frequency,


w/2n


153.6 kHz


Radiu


of cyclotron orbit


Drift frequency,


t 214 Hz


Drift velocity, Vd


0.27 m/sec


Trapping frequency, aT/2n

Observed cyclotron frequency, Wc/2ir


24.4 kHz

152 kHz


where v


=V =v
x y


Is 2


x 102 m/


sec.


The motion of the ion proceeds as


follows.


during the period of one complete oscillation of the guiding


center along the magnetic field line (T T


~ 40 ps) the ion will have


completed six rotations about the guiding center (Tm


6us) and the


guiding center will have drifted along an electrostatic equipotential

line and perpendicular to the magnetic field axis a distance of

approximately 0.01 mm.


Ion Motion in an RF Electric Field


An rf


electric field takes the form


Ei(t)


= EI sin vit)


for a field linearly polarized in the x-direction.


A linearly


polarized rf field may be decomposed into counterrotating circularly

polarized fields


E 1(t)


sin (wit) 1 + I cos (wit) j


-ii


'-4 I I









Restricting consideration to the circularly polarized component of


the same sense as the ion motion


~E~jt)


48), the force equation in


component form becomes


qE1
--%6-


sin (wit) + w u


cos (wlt)


c


Transforming and solving these equations yields the velocity components

driven by the rf electric field in a static magnetic field


Ux(t)


2m(l-2c )


[cos (%ct)


- cos (wlt)]


-qE1
2m(l -c )


[sin (wct)


- sin (wlt)]


The time dependent expression for the energy of the motion, E (49),

attributable to the combined rf electric and static magnetic field is


- qu.E


q[Et2
= .... T{[coS(amct)


- cos(wit) ] sin(wit)


-[sin(wact)


Equating the instantaneous kineti


- sin(wlt)] cos(wit) }.


energy, dE/dt, to the spontaneous


power absorption, A(t), and simplifyingthe trigonometric terms
1 I n H \


qE1
2m










This general


expression


for instantaneous power absorption may be


evaluated for the conditions of ion resonance and extended rf


irradiation to determine


the average power absorption per resonant ion.


Substituting into the expression


for the kinetic energy


E:v


yields the particle kinetic energy due to rf excitation


2


- c)'


2c)


instanteous power absorption is then readily converted to the


average power absorption, A(w1)


over the period of irradiation


A(w1)


Sq2E12
4m(w1-wc)


(18)


Finally


, the behavior of these quantities at resonance (w1


) can be


evaluated


q2E12t


A(t)


= (dE/dt)


q2E12t2


E


A(w)
*C


2


The rf electric field directly influences the cyclotron motion of the


ion about the magnetic field lines.


The nature of the


interaction


becomes evident when the


time dependent radius of the cyclotron motion










At resonance (ul=w ) Equation 20 reduces


2BI-t


The radius of gyration of an ion in resonance


increases


linearly with the


irradiation time and with the electric field amplitude.


At higher


magnetic field


the resonant ion radius i


smaller for the same rf


irradiation conditions.


The radius of a nonresonant ion is seen to


be varying with time but is bounded as a result of the phase mismatch


between


the resonant frequency of the


ion and the driving rf


field


(Figure 3).


motion of a collection of ion


with a distribution of


velociti

motion (


has been determined from the equations for


In the trapped ion cell,


ingle particle


ions are formed through the


interaction of


a pulsed electron beam directed along the


z-axis


with


a sample gas in thermal equilibrium.


Assuming that there is no


gradient of electron energy along the electron beam (generally invalid)


and that the electron pulse is


long with respect to the period for


simple harmonic motion along the


z-axi


(generally true)


then the


ions can be assumed to be uniformly di


tributed along the


The uniform distribution of guiding centers along the


z-axi


z-axi


drifts


along equipotential


cross


field lines


-section is assumed the


If an electron beam of circular


initial distribution of guiding centers


circular in the xy-plane.


The geometry of the initial


stribution
































Time-Dependent Radii


For ( 2 ) i
r +-T and rmln


for Non-Resonant Particles.


Hz


is equal


rmax is equal to
to r- For (-))


is equal


equal


cE
to an d r


(to ,c4max
or--.


Figure 3.






24




















-
N
N
/
/
I






r

I

N

/
/
/
/
N- -
N-
- -









at the drift frequency,


This produces an oscillation of the


population of guiding centers between a circular distribution and an

elliptical distribution at twice the drift frequency, which for the


numerical example above corresponds to 428 Hz.


However, the duration


of the electron beam pu


ms, i


longer than the period of the


guiding center drift oscillation,


-2.3


ms,and the ion


will be


uniformly distributed along the elliptical orbits if ion formation is


constant during the electron beam pulse.


Therefore, ions formed at


any instant exhibit a shifting population distribution but the total

collection of ions is uniformly distributed along elliptical drift

lines.


Ion Detection


Power absorption by an ion from an amplitude limited rf

electric field is the basis of ion cyclotron resonance detection.

Obviously the means for generating a suitably stable rf field and a


means of detecting absorption of the field are required


Both of these


functions can be accomplished with a marginal oscillator detector.

Marginal oscillator circuit applications in ion cyclotron

resonance detection (50) are completely analogous to their earlier

application in nuclear magnetic resonance (nmr) detection (51).

Consequently, ion cyclotron resonance marginal oscillators have evolved


with few modifications from nmr marginal oscillators.


1fornafinnc nf tho hicir mnvmnrni l ncr-illfnvr rirriiif coni fn irLan+










operation


as required for ion detection


Second


, a gated amplifier


serves


to pulse the circuit output with the application of an


externally derived gate pulse.

The analysis of marginal oscillator detection can be carried out


in terms of the gated, limited feedback oscillator (Figure 4).


parallel


GLC (conductance-inductance-capacitance) tank circuit


of the oscillator has a resonant frequency


= (LC)-


where L is the circuit inductance and C is the circuit;and cell


capacitanc

circuit.


e.


The conductance, G, represents resistive losses in the


The limiter supplies a constant amplitude signal,


VO, to the resonant circuit through the feedback resistor, Rf.


resonance, oC


= (w [)l


, hence the admittance is a pure conductance


and the voltage across G


, V6, becomes


+ Rf


where V0


1 + GRf


is the rms voltage level from the limiter and VG is the rms


voltage level across the resonant circuit.


An infinitesimal change


in conductance directly affects the rms voltage level of the


resonant


circuit


VoRf


(1 + GRf)2


VGRf


(24)


l + GRf


AVG
AG








































o CO
'4 <- 0
o
.- 4-
a*s Cr04**-)
4U 4- 04-

rU U) C W3+-

+4-J(J4


0 0) (C r-
C-f 01C4-0 Q

*f.4-Jc-o4-JO
+'>0 Wa'-10C

ED -> 0WV1O

WU4-> LS.- Cu
=3 1 Q f 0)
ar- 4-LW 0

0SC -Ct") Con3


Ott) aeUCo

-i 0rC C >,
CD>> +j _j r- 0



0)
L

a)


U-










28

























L
0
4-)
U
OJ
4-a
C)
C


























Sm.-
C)
C)
4-) 4-
'F-
2 -
'I.-
-S E
cc










0

0



'4-










expression for the instantaneous power absorption of a resonant


Equation 19


is equated to Equation


and solved for AVG


_ q2E12t ( Rf )


4mvG


1 + GRf


The criterion for maximum power transfer is


- Rf


as would be anticipated.


This solution is extended to n ions and


the average value of AVG for such an ensemble is


2E2
nq'Ei'


4miGV


Equation


1 + GRf


contains the important aspects of the detection process.


First, signal intensity i


resonant ions.


a direct measure of the number of


Implicit is the assumption that the ion-field


interaction is not interrupted by particle collisions, reactive or


nonreactive, or by loss of ions due to containment leaks.


In practice,


short with respect to ion loss mechanism characteristic times and


expression is valid.


related to the mass of the


Second, the signal intensity is inversely

ion. This complicating behavior must be


considered in pulsed ICR mass spectrometry analyses


Third


average voltage level change as derived has an ambiguous dependence


on the rf field strength.


An alternate expression clarifies this










Thus, the voltage change due to absorption is linearly related to the

voltage across the circuit and inversely proportional to the square


of the plate separation, a


across which the rf field is applied.


In practical pulsed ICR, the transient voltage level change is


integrated


over the period of the rf irradiation.


The resulting


amplitude may be sampled and held for display or transfer.


Integration alters the dependence of the


signal on the irradiation


period so that the integrator output level is now described by


nq2Ei2t2
8mVG


(I + GRf)


2nq2Vt2 Rf

= 2ma (I + GR f


when the instantaneous change in the voltage level is linear over


the period of integration.


negative sign in the numerator of


Equations 26-30 is removed by inversion of the signal voltage


level


in the post-detection electronics.















CHAPTER III
EXPERIMENTAL APPARATUS

The pulsed ion cyclotron resonance experiments presented in this

dissertation required the interfacing of electronic, optical, and


vaccum components.


The central component of any ion cyclotron


resonance experiment is the ion cell


required, properly timed pul


The electronics apply


and excitations to the ion cell and


detect the influence of the contained ions on an applied rf field.

The vacuum system provides a suitable environment at the cell for


the production, maintenance, and detection of ions.


Since the


experiments described involve radiative transitions of ions, a suit-


radiation source must be coupled to the ion containment region


through the vacuum hardware and ion cell.


In addition, the


radiation source must be controlled by an appropriate trigger so


to operate synchronously with the potential


and excitations employed


in the ion detection process.


Trapping Cell

The trapped ion analyzer cell (Figure 5) requires si


potentials in conjunction with the uniform,


produce an effective ion trap. The


tatic magnetic field to


dc potential polarities are




































5-
W4-~O
4-' O&
wa woe
4~)
- C) ra 5-F-r- D~Wr-r
Ci 4-'
rOL-~0rd
rOC
Ww.rr-n'r3n Ci
ou~ WuOa-rna
a cc C)

Ci
CL-C
.naa$-w 3H-ocn,
C)
r Q sg... 0 r tO
C rt~4-iD-4-)4- (Ar~r- C
0r(tI C r r 0

EWrV) 4..)
OWOS- 0 00
~4-)L-OWZ4-

C) WW~CrD)CO~
Wr-4-) C)
c~-~ Ci C~C C)r cnW~C
OrOOnfl-
-CE Ci
ttr 0.W (I) a
WUcflWtfl .rE
070 n U C) 5- cr.C C) S- w
a C) +~w
recowrOat roE0
Lr- WCr ac tn-C
H-fl C4-' a ta*~ 0~U in


Lfl

Ci
5-
=
0)







33






N
+
r
/
4~)



-o
a
LU


L
0
>4-)
-(0
r
~
a
C) 4J(fl
E 'no
rrj -
7-

LC
-o cu.~
L CL
(5








.-0 C)
0
7-
z
C).-
4-at
U
a
'-4 C)
S..
C) CM0
0~3
-~
CM












/
I

/




C
L 0>
c n WLC)










symmetric.


Absolute voltage levels of on


volt for the end, upper


ower plates with trapping plate potentials of one and one-half volts


are sufficient for effective


The cell dc potential


trapping.

are taken from the regulated five-volt


power supply of the digital pulse electronics


53) (Figure 6).


Q, ten-turn variable resistance connected across the +5 volt and


volt busses defines the dc level.


The dc lines are buffered to


the appropriate cell plates to insure that the dc power supply


oading


is minimal.

Filament and grid dc potentials are also produced in the digital


pulse electronic


package (53)


. The voltage range is 0 to -100 volts


for each.


The filament current is provided by a Kepco 1000-0.2 (M)


Filament Power Supply (54


The electron current through the cell i


positively biased collector plate


monitored at a


Current-to-vol tage conversion


and amplification produce a measurement suitable for display on an


oscilloscope.


A collector output voltage of 1 volt corresponds to


an electron current of


microamp.


Typica


electron currents are on


the order of 0.01 microamps.

Vacuum Apparatus


The vacuum apparatus is illustrated


schematically in Figure 7


The main vacuum can and low vacuum and high vacuum manifolds are


constructed of stain]


ess


steel.


A variety of gasket material
































a)
0) (Ar-
cn~C- 0

0~4-~
co a
04-' 0
5-. 'C.)
(A
UU-oc
0.) Wr-~
r0.WrO
LU cnr- E
0)4-
WL a)
q-c
--C L.4-'

~ o~E
3c0
1 5-
'a a >~4-

cn..c>w
r-U1
o wra
0)-CU

-o
U, C*-
4-era
00 U)
(/) (a
E4-'4--
(auq-w
S.-WOL
a)c I to
roC-~
r00U)
CU..- C
s-ac
00) 'I-

4-'CW(a
(O~r->C
E Wr
0) r-r-4-)
-C- (A
UWUW
cnOtfl


C
L
4-,
a
0
C-)
-o
a
rd
C
C
* I-
4-,
U
a)

0
C-)

C
0
*

U
a)
4-)
0)
-o


(a


U
C
'a
a)
-c
4~34~~
C
ow
4-SE
a

cc-


























N
Lu
a


OLi~


IOJaUO3 'Q 6ui~wi2
aslnd IOi,!b!



































Wa)
-Cu
-o

wOO

~0
Ct,

r- aS-A-'
& OW

EQ C
0) r .4-) r
..c..c C

cacti

wuS.~rd
4-) *r-O.

>~, C ~A
'n=w
U (I)
ECdS~ro
-C
a


a)
4-i
Co
4-)
10
-(a
*r-D~)
C-)
c04-

Or-
4JQ
S.-
-04-i
00
(4-u
* I..-
c-c,
(oc
Ecu

Ecn

on,
raa)
(4-
-Co
0)
.1~ 0)
CCv)


CO-^ r0 E< -0









38
















-
Co 1~~
0)
(A E
w (A
0) 4-' 'A U)
W 02 Cl) U
:3 Cd '0 (0
Ut '0 to 3: a
0) 0 0) 'v-
a r 0
o 0) 0) a 0 *r-)
S.-. 0.
L 3: -c
Cd '0 3: 4-' 0) 0)
N S... C) U S.-
U 0) C 0)
a A (A Dl C a
C 0 (0 (0 0 (0
0 CD -J S '-~ I-


S S S
I-i ~-J S C








0)

(0

01 (.4~
-C C)
0
'0 -
3: '0
U
t/1
a 4- N- -o
o E 0 N- I-
) 0 0
N-
:3 4-'
a C~) :3 C
Ott U (0 0)
r 8
0 (A (U r -
0 to
J N-4--) N- 0
4- N-
a U N-
-cc) '0 C (0 4--
0~' (0 0
r0 E 0-
E 0) 3: ~-' E
Ci-' :3 E C U)
u a.
xa u z -
U (U U I C C
ar Cd 0 0
,- 4-) 4w.) r
*
1:3 W U)
ocr Dl 3: 'V U U
0 C C 0) (0 (0
i~ - -J


S S
cn 0 0 IW CD










ionization gauge joints. In addition, valves B and G contain polyimide

0-rings and valve C a Viton A seal. Two-inch oil diffusion pumps


(A) (CVC Model PM-120)


55) with appropriate backing pumps maintain


the vacuum of the two independent vacuum manifolds


The ultimate


pressure attained in the high vacuum manifold i


(1-3)


x 10


Torr


measured at the Bayard-Alpert ionization gauge (I)


inlet manifold


Pressure of the


determined with a cold cathode discharge gauge


Typical inlet manifold pressures are (0.1-1.0)


x 10


Torr.


sample is leaked from the inlet manifold to the main vacuum can through


sapphire seal


eak val


F) (56).


The titanium sublimation pump


(55) maintains the vacuum in the high vacuum manifold during periods

of inactivity.

The location of the trapped ion cell (N) and the V-3400 low


impedance electromagnet (57) pole faces (M) are shown for clarity.


antireflectivity-coated optical gl


window (L) was mounted on the


end of the main vacuum can by modifying a standard flange.


Optical Apparatus


A standard Candela dye


assembly, CL-100 flashlamp, a dye


*system comprised of an ED-100U head

cavity with antireflectivity-coated


optical windows, and a variable high voltage


kV maximum)


power supply was employed


in the photo-experiments (58)


ED-100U


head produces a high energy discharge through the Xe flashlamp of


t hco PI -lflf f1,'chlamnk 2ernrmk1i, inr.n en-.^l/.^n-. ^-*^^^-


J .- -


I










Circuitry wa


constructed to transform a


ms TTL level pulse into


the 150 volt


, 1.5 ps sparkgap firing pulse to permit synchronous


control by a TTL pulse sequence (59).

The dye reservoir volume and circulation speed are sufficient

to insure that the dye cavity is flushed with fresh dye for each


laser shot.

dye solutions


minimi


A Micropump Model 10-85-316-865 pump


60).


irculates the


Dye lines of polypropylene tubing are employed to


dye degradation due to leaching of impuriti


lines (61).


A Pall liquid filtration


from the


system was added to the dye


circulation


tern to remove particles which scatter light and


reduce the efficiency of the dye laser (62).

Dye solutions were made up to a total volume of two liters in


100% ethanol obtained from chemical stores


The procedure for mixing


the dye solutionswas to start with an initially highly concentrated

solution and dilute the solution with ethanol until the output was


maximized.

of 10-4 to


resulted in dye solution concentrations on the order


10- molar.


Laser


dyes which were used in the photo-


experiments,as well as dyes which were tested but did not lase


with sufficient intensity or lased onl


wavelength range, are listed in Table 1


over a very restricted

Nomenclature for the dyes


is that of Exciton,


study (63)


the primary supplier of dy


The position of the dye


used in this


laser cavity relative to the


main vacuum can and subsidiary optical components is illustrated in










Table 1.


Laser Dyes and Observed Lasing Wavelength Regions


Observed Useful Wavelength Range


LD 423


No activity


LD 440


No activity


LD 450


No activity


LD 460


445-465


LD 47


Extremely weak


LD 480


470-485


LD 490


470-510


Coumarin 540


510-550


Fluorol 555


No activity


Rhodamine 6G


575-605































3
ow
v-c
t4-~
9-
E30
Cr0
S.-
0) -3 C
(I) *" CI C 0
OW Or-
o O4JW4JflV4~)W.CcDC
W-~r- D~r- (0 0) 0 > 4-<~ 0)

to -o >~*- & to a ~ 3 Lg
.4-) 4-'4-'-acLn(o 00)
CW.rCJOrdEO
WC>0J>UOE>~eOjt0>~C~)
-4-)rr5r- U
S- U 4-. ..C 0 U CC in 0 *.- ,-
04- WflCtonC~J.rL>r-
OW~rCr0W
auuo
CCOO4-~ r0EEO
cfl4-)S~OCLW
e4-~ (0--Q.C COCUOW.C
vwa ~ao*r-S-
CO **CI~ ~ Leo to
4-'O -'~cCQ)+JtocflW ti-C
US-*r>tnc
LECLL. LWO~ OJ'wtoW
Cr
au 33Wcc)
a Q.OOU)0'rOLfl

L-WeOC C43O4-~----4-~L
*r-O
wE ro~c 3 o~Ofla-.----c 5-. ES-
*r-0JLL
to Etot eo04-----c E+~w'.-
~aWrWCr4- wL4-)aE
4.)4-4~) U W'r 0) >0)
0)01(0
>).C >) 0) 0 r to S- 0) a~ C
CI- 0>cUt~ ron-at n,-w

a

0)
5-

a)
* I...-






43










Lu


0
(5






a:
-J 4
IL









cc
4



a-
-e
4-
4-
(1) -4-
cn - -
















C)
-A-










resonator.


All gratings used were blazed at 500 nm.


Either a 1200


line/mm PTR (64) or Bausch and Lomb grating (65) was employed for


these studio


The general characteristics of these gratings are


presented in Table


In a few studies a 600 line/mm grating obtained


from Edmund Scientific (66) was also used


The grating


selected


was mounted on a Burleigh SG-l0l Star Gimbal Mount and SG-305 Mount


Base


67).


assembly was fixed to a rotating base driven by a


motor-turned lead screw/lever arm assembly.

At the ion cell, the laser cavity optical element was a copper

mirror attached physically to and contacting electrically the end


plate of the trapped ion cell.


Visual inspection of thi


mirror


indicated that it was of low quality and the


condition.


surface was in poor


Replacement of the copper mirrorwith a reconditioned 90%


reflecting A1 mirror did not markedly improve the laser output.

Wavelength selection is determined solely by the dispersive


cavity


element, the diffraction grating.


Since the grating drive


was uncalibrated


, a beamsplitter on the optical axis split a fraction


of the incident light to a monochromator for spectral analysis.

An American Instrument Company Model 1-8401 monochromator (68) and


and Instruments


A J-Y H20 0.5 meter monochromator


(69) were used.


Both were periodically calibrated versus Hg lines and the 632.8 nm

line of a HeNe laser.

Following wavelength determination at a particular grating angle,





















4'
a
C 0
4~3 U,
4-
L WW 0
CD tflDE r4 0 0 0-i cfl
cj Cr)
E Cl) *r- .4-'
S >OE 0 0 0 0 0 c-i
C C a
0) w
C (0
0)
C .4~3


CM (A
(A
~0
(0 a
S
A
-c c-i
(0 a
-c L
4-' (A
C
0) C 'ci- N-. 0 -4-'
0 ("J Cr) tO 03 C'J
0) C'J CM CM Cr)
(A r-4 r-t r-4 (0
ra L
w
a S.-
4-
o C
C
C
o S.- C
(0 (0
4-' I-
U =
C 0
= C a
Li. CC
tO -a
0)
U) CA
(0
~0
U)
o 0) ~0
-o 0)
4-' -4-'
In (0
-a -
5-0 =
we- 0) (~)
r 0~ LO .1
0(0 0-i S
eOE C 0 Cr) N. 'ci- o
CC r-4 CM CM

00 0 a
U S.-
0-jo 4-) o
4-3
C,- SI- (I,
S.-
Cd 0)
S-a a.
C13*- to
-ow
CM LW










output and was read from an


oscilloscope or transferred through


properly buffered inputs


to a data collection


tern.


simplicity of the optical arrangement did not


lead to fast and


simple alignment


ince one element of the


laser cavity wa


contained inside the vacuum can and was not stationary with respect


to the remaining


laser cavity components


use of a Spectra Physics


155 HeNe Laser (71


Alignment was aided by


which could be directed


first to align the vacuum can


laser cavity element relative to the


oscillator cavity and then redirected to align the grating with respect


to the


oscillator cavity.


The dye


laser head and high voltage power


in separate rf shield cages.


This


upply werecontained


shielding eliminated rf inter-


ference with the marginal


oscillator detector circuitry.


Pulsed Electronics


A pulsed ion cyclotron resonance experiment requires a sequence


of control


pulses of variable delay and


in some


instan


ces,


variable


width to govern the timing of ion formation,


ion detection


removal


from the cell


and when desired


, ion irradiation.


A digital


synchronously-timed control


system has


generation of the requisite pulses


(53


been constructed for the

) (Figure 9).


A typical


sequence 1


initiated by two internal


pulses


that are required to reset and clamp the counters and flip-flops


(precondition Dulse) and serve as thp


7prn timp rofnronrc


(c-tn rt-




























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detect, quench, and


pulses are of variable delay and variabi


width


consequently each Dul


has two assigned timing circuits.


emaining pulses, sample, integrator reset, and free are of variable

delay but constant width and each requires only a single timing


circuit.


Delay timers for all pulses are referenced to the


us start


pulse.


Pulse width timers begin counting at the end of their


corresponding pulse delay.


The delay timers may be collectively


operated at one of three available clock frequencies.


Clock frequencies


of 10 kHz


, 1 kHz, and 100 Hz may be


selected to yield minimum pul


delays of 0.1 I ms, 1 ms, and 10 ms, respectively


The pulse width timers


are operated from a set clock frequency of 10 kHz and produce a minimum


width pulse of 0.1 ms.


Each pulse delay and width is


selected by


three-decade thumbwheel switches.


The grid pulse i


start pulse.


the first working pulse generated following the


The grid pulse is amplified so that low is 0 volts and


high i


+10 volts.


This pulse i


mixed with a variable dc level and


applied to the grid separating the rhenium filament from the electron.


beam entrance slit in the si

variable dc grid potential i


de plate of the trapped ion cell


set to be 5 volts more negative


than


the variable dc filament potential and the electrons

filament, do not pass through the grid into the cell


emitted at the

During the grid


pulse the potential of the grid is 5 volts more positive than the
filament potential and electrons are accelerated into the cell.










The detect pulse serves several functions.


First, it controls


the marginal oscillator rf output to the lower plate of the cell


through the gated amplifier in the


imiter feedback circuit of the


marginal oscillator as described by Mclver (46).


Second, in


combination with a variable length, inverted pulse from a one-shot

which itself is triggered by the rising edge of the detect pulse,

the detect pulse produces an integrate pulse during which the integrator


is active.


The logical


*1AND ing of the detect pul


and inverted


one-shot pulse eliminates the initial spike observed'in the marginal


oscillator output due to mismatchin

compensation circuitry (53), The fa

triggers a one-shot which produces a


sample/hold circuit.


g in the marginal oscillator

lling edge of the detect pulse


ms sample pulse to activate the


Ion detection is a concerted action of the


marginal oscillator, integrator,and sample/hold circuits.


The detect


pulse gates on the marginal oscillator and integrator and the ions


are irradiated


, the power absorption is determined and i


converted to


a voltage level at the integrator output


At the end of the detect


(and integrate) pulse the


ms sample pulse i


generated and the


sample/hold circuit samples its input which is the output of the


integrator.


Finally, an independently generated integrator reset


pulse resets the integrator prior to the next pulse sequence.

To insure that only ions produced during a single grid pulse are


present during a detect, a quench pul


is applied to the upper









pulse is used


as a gate for an external gateable rf


oscillator whose output is then applied to the upper cell plate for

excitation of ions which are nonresonant at the selected magnetic


field and marginal oscillator frequency.


This excitation serves


purposes.


At low voltage levels


excitation increases the ion


translational energy while trapping remains efficient.


At high voltage


level


excitation ejects the


The free pulse 1


resonant ion from the cell (72).


a one millisecond width


, variable delay pulse


designed as a general, external trigger pulse.


The free pulse operates


on TTL logic levels.


It has been used as the synchronou


trigger


for the flashlamp-pumped dye laser sparkgap discharge circuitry.

Initiation of a complete pulse sequence can be accomplished in


three different modes.


operation.


single


The single cycl


cycle, fixed rate,or automatic


mode results in one complete pulse


sequence occurring whenever a front panel pushbutton is depressed.

Fixed rate mode causes the complete pulse sequence to be repeated at


a selected time interval which ranges from 20 millisecond


to 5


seconds in a 1-


sequence.


The automatic mode


starts a pul


sequence 175 milliseconds after the quench pul


terminating the


proceeding sequence.

A typical pulsed ion cyclotron resonance (PICR) experiment


proceeds in the following manner.


With no resonant ions, the previously


set digital pulse sequence is performed to obtain a zero


evel










capacitor is charged and the trigger pulse, normally the free pulse


or a microcomputer-generated pul


se, i


activated to fire the laser


immediately prior to ion detection.


The digital pulse sequence is


repeated for the required number of laser shots.


Marginal


oscillator and photodetector data are recorded for each


aser shot


The laser trigger is deactivated and with the ions still resonant the


sequence repeats until sufficient marginal oscillator level and


photodetector level measurements have been obtained.


Finally, the


ions are tuned off resonance and the marginal oscillator zero level


data is recorded for several pul


sequences.


This scheme allows for


the correction of zero baseline and resonant ion baseline drifts.


Microcomputer


The resonant absorption of the output of the marginal oscillator

is detected as a change in the analog voltage level of the marginal


oscillator frequency envelope.


To convert thi


analog signal to a


digital signal suitable for analysis by a digital microcomputer a


data conversion/collection


stem has been developed.


The system is


comprised of a microcomputer and an analog to digital


as well


(A/D) converter


as input signal conditioning elements and programmable


data routing component


The microcomputer architecture is addressed


to the degree to which it has influenced the interface design and


operation.


The description of the interface i


s functional and non-


cnori-fr


\iAI t-h ronirrl


f-n chin rrocinnnl-inn


Tho nnonarinn cfwetom









of the data conversion/collection


stem delineates its limitations


and suggests refinement


to attain


key-on operation.


Experimenta


data was analyzed manually to verify the system performance.


Microcomputer and Modifications


A KIM-1 microcomputer served as the control element for the data


conversion/collection system (73).


The KIM-I


, a single-board, 6502-


processor-based microcomputer, has integrated input/output hardware,

hex keypad, system ROM (read-only memory) and 1K (1024 words) of RAM


(random-access memory)


The structure of the input/output hardware as


to the available control and data lines requires further mention.

The KIM-I can respond to an external event in a programmed fashion.

This implies that the microcomputer acknowledge and correctly identify


an external event.


Recognition of an external event requires a


combination of hardware and software.


The level of the interrupt


request line (IRQ) is altered synchronously with the external event

and interrupts the processor upon completion of a logical machine


step.


Critical status registers are preserved by the IRQ software


residing in ROM.


Control i


transferred to a program located through


the interrupt request vectors (IV) which have been preprogrammed


by user code to select the correct response to the externa


event.


Once the external event has been correctly handled the critical
registers are restored and operation is resumed from the point of

interrupt.










microcomputer from the external device or vice versa.


This transfer


takes place a


cross


15input/output lines, divided into two ports,


peripheral A data, PAD and peripheral B data, PBD.


The 6502


architecture and operating system treat these ports as memory


locations which can be written to or read.


The direction of the data


transfer is established by the status of the control ports, peripheral

A data direction register, PADD, and peripheral B data direction


register


PBDD.


These registers are interpreted as collections of


status bits which correspond directly to the PAD or PBD bits


status bit value of 0 indicates that the corresponding peripheral


device bit i


to be read as an input, while a status bit set to


indicates that the bit is written to by the microprocessor.


combinations of inputs and outputs are permissible and buffering in

both directions has been implemented on board.

A general appreciation of the input/output structure of the


microcomputer is necessary for interfacing,


In this case it is also


necessary to be aware of the memory (RAM) architecture, due to the
on-board modifications dictated by the limited memory available on


the standard


stem.


, 8-bit RAM words of the 6502 processor


are constructed from eight 1-bit

address lines of all eight chips


x 1024-location, memory chips. Th

are tied together so that the same


address is


selected at each chip.


The 1K of memory supplied by the


KIM-1 is insufficient for complex control and data manipulation









Microcomputer Interface Hardware

The limitations of the KIM-i microcomputer's input/output


architecture place constraints on interface design.


The KIM-I is


restricted to digital input/output with a maximum of 8 bits transferred


per input/output operation.


Consequently, external analog


signals


to be transferred to the microcomputer memory must be converted to


digital format.


The KIM-1 is a TTL level microcomputer which requires


that valid TTL levels be provided


as inputs


These constraints are


easily attended to; thus the interface design, although dependent on

the KIM-I input/output architecture and implementation, is more


stringently defined by the nature of the external signal


For a typical pulsed ion cyclotron resonance (PICR) experiment


the values to be measured


zero baseline, the marginal oscillator


output in the absence of resonant ions; ion baseline, the marginal

oscillator output in the presence of resonant ions; laser level,

the marginal oscillator output after laser irradiation of the

resonant ions; laser energy values, the output of the photodetector


with and without laser irradiation.


analog voltage level and two separate channel


Each of these signals is an


to the A/D converter


are required for the marginal oscillator and photodetector outputs.


Since the A/D has a single analog


nput these signal


are multiplexed


to that input under software control


function


The sequence of control


resulting in the input of converted marginal oscillator










The KIM-i will be in


a no operation (NOP) loop which can only


be exited via an interrupt request or a keypad interrupt.


transfers control to


An IRQ


programs addressed by the interrupt vectors


which contain either system start-up or program-defined values.


What-


ever the actual program location accessed, the scheme of the interrupt

service requires a resetting of the interrupt vectors in preparation

for an ensuing interrupt and the updating of running counters which

identify the type and count of marginal oscillator and photodetector


data on line.


The transfer of the marginal oscillator or photodetector


voltage via the A/D to the KIM is controlled through the microcomputer

PAD (PAO-PA7) via four 3-bit, 8-bidirectional-channel multiplexers


MUX)


PAO-PA3 are always configured as KIM-i outputs.


PAO controls


MUX inhibit lines and PA1-PA3 constitute a 3-bit


, binary word which


selects the MUX channels


The input to a MUX i


transferred to the out-


put on an inhibit low with the transfer direction determined by the


PADD status bits.


PA6 serves


as the channel select line for the 1-bit,


2-channel (A/D input) MUX

the status of the select


A clocked latch intervenes to preserve


ines of the 2-channel MUX until it i


reselected.


PBO i


used


as the software generated clock


ine for the


clocked logic.


(PBO replaced PA4 which was defective on the KIM-1


used)


A logical one on the


2-channel MUX


elect line transfers the


photodetector level to the A/D input, a logical zero


selects the MO


level










output is read into the KIM-i in three 4-bit parts through the four


8-bidirectional-channel MUX s.

PBO and PA5-PA7 as KIM-I1 inputs.


The data direction registers configure

PAl-PA3 select the A/D channels.


Channel one selects the least significant four bits of the conversion,

channel two the next four significant bits, and channel three the four


most significant bits.


The conversion result is recombined and


stored by the A/D read software.


The interface provides a pulse to the laser trigger electronic


for program-defined counter states.


In a preliminary version of the


software a latch was set (1) during the read sequence prior to that


for which the laser was to be fired.


The latch output was AND'ed


with the free pul


aser trigger pu


laser triggering by


of the ensuing pul


sequence to provide the


The latch input was then reset

successive pulse sequences. This


0) to prevent


technique i


cumbersome and a simplified


scheme has been implemented in which the


trigger pulse is generated by software immediately after the interrupt


is received.


This scheme results in nontrivial simplification


of the software.


The IRQ is provided by the free pul


for automatic triggering


and by an debounced pushbutton for manual triggering


are conditioned by a pair of Schmitt triggers


one-shot pul


Both inputs


which feed into a


generator to produce a sharp, clean IRQ pulse at the


microprocessor.










as the peak detector reset and, consequently, must occur after the


photodetector read is completed.


For certainty, the


positioned to occur immediately prior to the quench pu


Microcomputer Software


Programs are coded in 6502 machine language.


The architecture


of the 6502 processor minimizes the volume of code, since operations

are frequently performed on a single specialized memory location,


the accumulator.


Addressing codes are varied and specialized to


transfer rapidly and efficiently


selected data to and from the


accumulator.

The software is designed to reduce the need for operator attention


during a complete measurement sequence.


The microcomputer is no


longer merely a data router/interface controller.


Data analysis


codes


are included to perform simple data reduction.


The zero baseline


average code averages the results of thirty-two (hex 20) zero baseline


measurements.


The ion baseline average code deri


the average of


eight ion baseline values symmetric about a laser shot sequence.

Zero baseline correction of the ion baseline and laser level is


coded.


Similar functions, zero baseline measurement and correction


of signal


evels, are coded for the photodetector output.


Full double


preci si on


16-bit


- 16-bit) division i


implemented.


Vectored


storage of intermediate results(raw data) to temporary storage areas

and the relocation of reduced data prior to overlay of the










eight ion MO and photodetector measurements


and sixteen


laser MO


and photodetector measurements)


reduced from four hundred bytes


sixty-four bytes


Flowcharts outline the data conversion/collection and analysis


software (Figures 10-14)

expanded RAM is provided


A memory map


showing the allocation of the


(Figure


Time Operation


Due to memory


limitations some critical


registers are not set by


the initialization routine,


these registers require keypad


initialization.


The status register (hex address


OOF1) must be set to


00 to clear the interrupt request flag.


No maskable interrupt


can be acknowledged until


the flag is cleared.


Certain


system


interrupts are non-maskable and always


acknowledged.


The interrupt


vector


hex address


17FE) and interrupt vector high


(IVH,


address


KIM-i


17FF) are manually


set to DO and 08 respectively


thus configured to acknowledge an


The


IRQ and to respond by


calling the main control


program


Figure


The status and interrupt


vector registers must be reset for


each complete measurement sequence.


Three memory


locations


addresses OF,


, and 11)


contain the


running sum of zero baseline values.


These registers must also be


zeroed at the


start of a complete measurement sequence.


remaining


registers require initialization prior to the first complete measure-


mpnt ccniionro


liii, I lILa V LI .4 I *ItZ ~ LX


I|r 1
































Figure 10.


Operator/Microcomputer
This flowchart described


attention.


Programs are


Interaction Flowchart.
s the required operator


loaded from


cassette tape and operation initializations


are performed.


Initial


interrupt vector values


are set and the microcomputer enters an NOP


loop until


interrupted.


An end-of-experiment


test determines the experiment


then analyzes and stores
form.


the data


,atus and
in final












Tape


In.


p


Final


Store


Calculate


Average


..ero


Bat; C


Operator


Promp t


Datn Analysis


61





Manual!
Load




i tialize \

?gisters
____/___T^^1

Values






Is Y
RQ = Z e


N



ta l Ze ro^yc ^ ^^ -._....-... ... -
































Figure 11.


Main Program Branch Flowchart.
The program flow about the primary


decision is shown.


Primary decision


is the nature of the data to be
obtained at the next interrupt.
test value of 0 corresponds to
baseline data for the marginal


oscillator (B).


Test value 1


corresponds to ion baseline data
for the marginal oscillator and


the photodetector (C).


Test value


2 corresponds to laser MO and photo-
detector data.



















Test


Generate


Laser


Pulse


Decrement


La ser


Shot


Counter


Store


MO Data


Store


aser


r ata


Read


Data


Read


Laser Data


Chan































Figure 12. Baseline MO Data Flowchart.
The functions required for baseline
data collection are indicated.
A single decision is made to
determine when ions should be tuned
into resonance which when true
prompts the operator.















CL


65




B


inge IV
to
D





t Zero
'unters





Read
) Data




iculate
running
Sum



ecrement
Zero
Counters





Counter ^-----RTI^


Se
Co


Ca


R


(


Change


D<
































Figure 13.


Resonant Baseline Data Flowchart.
The procedure for taking baseline MO
values with resonant ions while
simultaneously taking zero photo-


detector values is diagrammed.


Data


overlap occurs for each four sets of
measurements after the first eight
baseline measurements are stored.














C
In
Vect


67







Change
terrupt
tor toJ)



4t 100
)unters

i

elect
10 Data



ReadStore
--( I00
)0 Data Data




I ected7

N


ver Iay
)0 Data
:orage



Ir


M


Select


Laser Data


e


s.f


C(


I0































Figure 14.


Laser Status Flowchart.


Determination of a laser firing
is necessary for subsequent data
reduction and memory overlap


decision.


In addition, the last


laser shot of a sequence must be
identified to reduce the data to
final form.














Laser
Fired


69













Store
average 100
MO Data


Store O
average 10
hoto Data


Laser


Counter


Change IV


Calculate
Average
100 MO Data


Increment


Flag


Calculate


Average
100 Photo Dat


Decrement
ID Flag
Set PIRQ


Change IV
to
(D


Set 0/2
Counter
































Figure 15.


Microcomputer RAM Memory Map.
The major divisions indicate blocks
of four pages, natural machine divisions


of memory.


The beginning and ending hex


address for each logical software unit


is provided.


Note that the A/D subroutine


is dispersed throughout the available
memory.













0800

0852

0869

088E

08B7




08DO




OAOO


OA50


OA9A



OBOO



OB81

OB90

OBBI

OBE7


- 0851

- 0868

- 088D

- 08B4

- 08CE




- 09FO




- 0A45


- 0A91


- OAFC



- OB80



- OB8F

- OBBO

- OBE3

- OBFF


Initialization Subroutine

Obtain Data and A/D Delay Subroutine

MUX Select Photodetector Subroutine

MUX Select MO Subroutine

A/D Read Subroutine (Part II)




Main Control Program




A/D Read Subroutine (Part I)


Four Channel Storage Subroutine


Data Analysis and Storage Subroutine



Double Precision Divide Subroutine



A/D Read Subroutine (Part IV)

Triple Precision Average Subroutine

Laser Trigger Subroutine

A/D Read Subroutine (Part III)









address 42 should be set to 02 and following the fourth complete


sequence set to 03.


The initialization routine resides at hex


address 0800.


To run the initialization routine, 0800 i


keyed to


the address display and GO is keyed.


The remaining critical registers


are set and the microcomputer enters the nc operation


NOP) loop


until interrupted by an IRQ or keypad interrupt (Figure 10)


function of each register is given in Appendix II.

The first IRQ enters the main control program at A (Figure 11).

The initial value of the ID register (hex address 0000) is 0,


consequently the B branch (Figures HI and I is taken.


The interrupt


vectors are altered to point to D to protect the zero baseline


counters which are subsequently set.


The zero MO level i


read and


the result summed into the initially zeroed registers OF, 10 and 11.


The zero baseline counters are decremented.


If less than one half


of the zero baseline readings have been taken there i


a simple


return


from interrupt (RTI), returning the KIM-1 to the NOP loop.


Subsequent


interrupts enter the main control program at D until one half of the


zero baseline measurements have been accumulated.


Then, interrupt


vectors are changed to point to A, the ID register is incremented
and a programmable interrupt request (PIRQ) flag set, prior to an RTI.


As before the RTI returns the system to the wait loop


however


since


PIRQ is the test value of the loop, the system will "fall through"


the loop.


The test of the total zero baseline counter will be










operator prompt to tune the ions into resonance


and charge the laser


capacitor "084E' is entered in the address field of the display

and GO is depressed to clear the interrupt flag and to return the


KIM to the wait loop.


The next IRQ enters the main control program at A.


register contains 01 and branch C is selected.


The ID


The interrupt vectors


are changed to point to E to protect the ion baseline counters.


100 level counters are set and MO level i


read exactly as before.


The two byte result is stored via the y-indexed address mode.


appropriate value for the y-register is loaded from OC.


address is located in OD.


the MO level


The base


The PHOTO level is read and stored as for


, however, the base address is first incremented by hex


10 so that the two types of data are mapped into different memory


locations.


The base address is restored to its original value after


the PHOTO read/store in preparation for the next cycle.


The program


requests eight two-byte MO levels and eight two-byte PHOTO level
per laser shot for the determination of the respective averages.

Once the averages have been evaluated and stored, the first four


of each type may be over written.


evel


"AND'ing the y-register value


with hex OF prior to saving its value in OC accomplishes the overlay.


If the


) level counter is nonzero a simple return from


interrupt is taken.


If the counter is zero


the software determines


if the


aser has been fired.


If not


, the interrupt vectors are









read


as before and stored.


The laser counter is decremented and ID


register decremented (01).


the (100/2) level counter i


Interrupt vectors are set to E so that

reset and a new sequence of 100 level


taken


If the laser has fired


, average


00 MO and 100 PHOTO level


calculated and stored.


If the laser counter is nonzero, the interrupt


vectors and ID register are set to fire the laser on the ensuing


interrupt.


For a zero laser counter, the interrupt vectors and


0/2)


level counter are reset to read the required zero baseline level


commencing with the next interrupt.


The ID register is set to zero


and PIRQ set (01) to initiate an operator prompt.


The display


"0000


xx" requests the operator to tune the ions off resonance.


When


the (0/2) counter tests zero, an RTI occurs and since PIRQ is set a


test of the total zero (0) counter is made.


The total zero counter


will be zero and the zero baseline average is determined.

Data analysis consists of the evaluation of


MOLNL
MOLL


- MOLBASE
- MOLBASE


LSRL


= PDLL


- PDLNL


(32)


where MOL represents a marginal oscillator


evel, PDL a photodetector


evel


, L refers to a laser shot sequence with


ons, NL refers to an ion


resonance sequence with no laser shot and BASE refers to no resonant


ions or laser shot.


Thus F-i is the inverse of the fractional remainder









of data are stored for each laser shot and a prompt is generated to


signa


that the data collection system is prepared for a new sequence.


Implementation of the division in Equation 31 requires a 16


bit by 16-bit divide routine and a


bit shift routine to format pro-


perly


the data for storage.


These routines have been coded and


incorporated into the analysis loop.

Programs are listed in Appendix i1. Memory addresses, machine

codes and mnemonic codes are included to facilitate use, alteration,


adaptation and relocation of the various subroutines.


Comments have


been included to simplify the reading of the code.


Derivation of the Expression for the


Photodetachment Cross-Section


The probability of photodetaching a negative ion of photo-


detachment cross-section o (x) at wavelength


of the incident


radiation field of photon flux p(x) in time t is given by the expression


RCA)


- exp [-kt f p(x)


oCx) cIA


(33)


where k is a constant related to the interaction region (74).


a pulsed radiation


ource with pulse duration t and energy per pul


E the number of photons per pul


_- xEx/hc.


quantity is directly related to the photon flux provided a, the


radiation beam cross-sectional area, is known









If N


represents the number of anions detected prior to irradiation


and N the number of anions detected following irradiation


then N and


No are related by


No-N


=-fN


Pht)


(36)


where f represents the probability that every detected anion is in the


radiation field.


Substituting for P


) and rearranging and taking the


logarithm of each side yields


kt f p(A)


a(X) dx


N-N


If the bandwidth of the source is narrow and constant with respect

to the wavelength, then


kt f p(X) o (x) dA


= Ckt p(A)


where C represents the effect of the constant bandwidth, and p(A)


ando(X) are assumed to be


slowly varying with respect to wavelength.


Using the


simplification and substituting for


an expression for


the photodetachment cross-section containing only experimentally


observable quantities i


k' a(A)


s~btai ned_

1-fNo


XE~


(39)


where


= Ck/hca.


Rearranging th


argument of the logarithm


term, the cross-section expression becomes
r 1.. "









Clearly this expression exhibits the correct limiting dependence on f,


f approaches one, indicating that all ions are within the


radiation field, the argument of the logarithm becomes No/N.


Finally,


( ) can be written


a'(A)


IfTT


(41)


where


is the fractional decrease in the ion signal upon irradiation,


(N, N)/NO.


standard error analysis yields the expression for the relative


error for k'o(x),


W2[k


/ \2
*~A


W2(N)/N2


Cln(f/f-A)] 2


^2 F, 2


where W(x) represents the random error of variable


The influen


of each of the factors involved in the error terms is indicated in Table


for a range of


relative


values.


errors in Table


The magnitudes of the coefficients of the

do not completely characterize the errors.


The relative


errors themsel


must also be considered.


0o W(N)A


W(f)/f and W(E )/E2 are constant for a constant amplitude ion signal


with a constant S/N ratio.


The relative error associated with N,


W(N)/N increases with decreasing N, that is, for a constant


N ratio


*1 n I- n - a A 4 ~ ~ .4 I- -% 4- 4 a 1 - .4 4- a a ~.J a 1 . a - .~ .4. I...




















































LU










signal-to-noise ratio of 100, the squared relative error is 10


fore, the error contribution due to the No


the tabulated value of ABC.


There-


measurement is 10- times


The error in the N measurement is tabulated


(column E, Tabi


3) for the same initial signal-to-noise ratio.


ABCE


represents the squared relative error.

the N relative error term. Furthermc


ABCE will always be greater than


ire, ABCE exhibits a minimum near


equal to 0.6.


A reasonable value for W(f)/f i


0.05 (33)


This large


relative error is combined with its coefficient and summed with the

other large error source, N measurement, to determine the optimum ion


attenuation.


This occurs at an approximate


of 0.3.


W(N)/N and


W(Ex)/Ex can be estimated to be 6x104 and 0.03 respectively.


At the


optimum A for an ion signal-to-noise ratio of 100 and for the relative
errors as described and f equal to 1, the predicted relative error in


the cross-section i


0.08


The error at a given


most sensitive


to changes in W(Ex)Ex and W(f)/f.


If W(E)/Ex were doubled, the cross-


section relative error would increase to 0.095


, similarly doubling


W(f)/f results in a relative


error of 0.13.


Departure from the optimum


value results in


error at


dramatic changes in the cross-section relative


least for deviations less than +0


To optimize the photo-induced experiments


(No) and the signal-to-noise ratio must be optimized.


, the signal intensity


Increased apparent


intensity without increased signal-to-noise will not improve the


relative


errors.


Ex should be accurately variable with a constant















CHAPTER IV
EXPERIMENTAL RESULTS AND DISCUSSION
OF THE HALOGEN ANION STUDIES


The ions discussed in this chapter are those


for which


observabi


ion intensities could be produced.


and Br2


were


generated with sufficient intensities to assure reasonable


ignal-to-


noise ratios for the photo-excitation studies


BrCl


was observed


optimized, but under no operating conditions was the


adequate


Chlorine Molecular Anion
Formation of CIL-


signal quality


The generation of C1


- was not straightforward


Four means of


producing the chlorine molecular anion were attempted


procedures were successful


Direct attachment of low-energy electrons


to chlorine molecules was attempted over the nominal


electron


energy range,


0 to


IOeV


chlorine sample pressures at the


cell


vacuum can ranging from


10-4 to


IxlO-7


Torr


No molecular


chlorine anion was observed for any combination of these parameters.


At all


experimental


condition


, dissociative attachment yie


Hiding


was seen to occur exclusively.


Dissociative attachment of


and the instrumental


parameters pertinent to its formation were


to undertake photo-excitation measurements.









energies were varied to cover a]] combinations of these parameters.


The observed dissociative attachment generated CI-


only;


no Cl2


detected.


A charge transfer to chlorine from a suitable precursor


anion was investigated.


Nitrite ion, NO2


, was readily produced from


nitromethane, CH3NO2.

the interaction of NO2


Electron transfer was expected to occur for


with a species of greater


lectron affinity.


Optimization of the nitrite ion intensity


, followed by the addition


of chlorine yielded C1


photo-excitation study.


-atl


evels acceptable for pursuing the


Finally, C1


was produced in low-energy


0 ev) electron impact with a sample of chlorotrifluoroethylene


(C2F3CI)


The C12


- signal intensity was not as strong as that


observed from the charge transfer process.


The means selected for


- generation in the ensuing photo-excitation study was the electron


transfer from nitrite ion to molecular chlorine.

Prior to undertaking the discussion of the photo-excitation


study of the chlorine molecular anion


, the precursor anion's negative


ion mass spectrum and generation will be analyzed.


The nitrite


ion intensity was optimized with respect to all ICR and sample


parameters.


The range of the parameters and the resolution of the


variation of each parameter are presented in Tabi


The negative


ion mass spectrum of nitromethane contained a single peak at a mass-


to-charge (m/e) ratio of 46 amu/e.


The signal-to-noi


ratio at the


optimized system settings was approximately 40 to 1 (Figure 16).
*3 -.1 a -











Tabi


Variation of ICR Operating Parameters During Studies to
Maximize Formation of the Nitrite Ion from Nitromethane.


Parameter


Range


Resolution


Electron Energy

Sample Pressure


- 18 eV


4x10~7


- 1x104 mm Hg


lx10-7


- ix10~5


mm Hg


Grid Pulse


8 ms


- 25 ms


5 ms


Detect Delay


- 300 ms


Detect Widthc

Marginal Oscillator
Level


5 ms


Not varied


- I00 mV


10 mV


aA true estimate of the electron energy is obtained by subtracting
the trapping plate potential of 1.50 v.


bThe background sample pressure was 2-4


x 10-7 mm Hg.


CDetect width and marginal oscillator level are related, however, over
the range of marginal oscillator levels attempted detect width did
not require change.



































S
a)
C
10
-cw
cuD-
EE
Oro
s-tn
-I-,
~ S

4-E

Eu)
=0
S-v-i
4-,
(JO

a
(flu,


In
(0
3
Ca)'
CEO
&4-' I
o In
-(0(0
Wr E
a)



Ow a)


I 0(0
o 0
- .01.0


(flu, 'ci-
(0r>< W-~
rd ru4-
S Wv-4~ a) 0

0
Ororo
- S- ~
to I-rd
WulW3 S-
>11~S-
*~dfl>., *W
4-' E In o~u~ Cfl
r0 InS-ES-
a)wwaJ 10
cuc S.- con
zH- D-WcP 0

S
1.0

a)
Sh~
=
0~'
* I...-
LL













electron energy for peak nitrite ion intensity was 0.83 eV.


Nitrite


ion generation from nitromethane was deemed to be a suitable, clean

choice as the precursor for the molecular anion of chlorine.

The chlorine molecular anion was generated and its signal

intensity optimized in a manner that simplified the tuning procedure.


Nitrite ions were detected and the intensity of the


signal was


maximized for a nitromethane pressure between 5x10-6 and 1x105 Torr.

Chlorine was leaked to the cell through the second inlet manifold


and jeweled leak valve.


The NO2


signal intensity was monitored as


the chlorine was addedA.


The nitrite ion intensity fell off rapidly


with the introduction of chlorine. When the NO2

decreased to less than 10% of its peak value,


intensity had

the chlorine pressure


at the


cell was stabilized.


The magnetic field was set to bring the


ion into resonance and once thi


delay was increased until the Cl


signal was located the detect

peak intensity had dropped to


approximately


0% of the initially observed


evel.


At this detect


delay, the magnetic field was altered to bring the C1


- anion into


resonance.


In some instances


, scans of the magnetic field about


the nominal resonant magnetic field for C1


proved necessary to locate


the ion.


The C12


signal was maximized with respect to the ratio


of components inlet to the ion cell region, the total sample
pressure at the ion cell, and al] of the tuning parameters of the


spectrometer.
4, t 6


A negative ion mass spectrum for a chlorine/nitro-


#































C
0)0
.aL
-p4-,
U
(4-a)
0-
u-J
a)
S.-
z
05-
(AL-
Wo
S.-'---
a
U-)
WI
-o
a-4
E)C
(OC\J
(A


AC
(0
a)
a
I C
C\j*r
-U,

a)
wL-
..CL)
F-a


U)4~)

3
0

a)
t~t/~
~ro

5-
Wo
Ec
r .1-


4-)
4-)

~*- rOfl
L-EEr
Or~ dJr
(I~
CC '0
EO ~4Jr
-4.C OW
S-
-4-30W4a
O& E W4-)
a) Oflo
aOL a)
Cflr4&
a)
U) U) C~-C~
a) (A
SW CLAr
D) "- C

Cr00
5- r U) 4~) -
~Cr0r0W
Wtnu~ -a
>0 -~
*,- rrJC'd >)fl54
a~wo
cO 05-3W
a)W4-' a)
W~a COW
rF-- W*r-V

C

-4

a)
5-
:3
a)
*
Lu
























































-4-I


'("4
0
2~


























0)
Ga
r1 C
L
Cow s-w
-c S.-r-r-
0-c wa,
wnoa
S.- 04-v
4-C) O*r
o(ntj, 5-
~ C) D~)
(no U
I CC)
row c\Jw~c
C) S-C u~4-~
OrO~C)
5-4-
S-v 120
*
r~Wtfl.CC
S a~z4-J~,-
C) C
.CO Crr-
&
awe
4- E4-' Wfl t-0
o E
wo~w
'awE .cO
4-'~Cq)u1
01--CrC
C)
a a
t~n
C)-tt4J
(01- *i- C.r-
5.-CE
to -I-' 0'3 12r-
S>C0 (A-
Wa)
4-)S CLW
a
Wa)' O.r-
-cc- U)U-I-~
CroOc
w~a
wwawa
to =
0)1-I
E4-' CM- Ew
r r" i- a *.-
1-ro oI-i---

C
-4
C)
1-
a)
Lt.






















CI
NO


0d2


- a -









It was difficult to maintain stable C1L


- signal


level


total


pressure at the


ionization gauge drifted markedly.


This


variation was


the result of the fluctuation of the chlorine delivery


or the nitromethane delivery with equal


frequency.


After the sampi


pressures were continuously monitored and adjusted for periods of up


to three hours,


the drift was reduced and


lowly varying C1


2 signals


were obtained.


There are discrepancy


between the results of the molecular


chlorine anion formation behavior observed in this


studies.


tudy and previous


- has been generated by electron attachment at total


pressures as


low as 4x107


Torr at electron energies of 1


to 2


(75).


The resultant Cl


- ions exhibited lifetimes up to one second in


the cell


of an


ion cyclotron resonance mass spectrometer.


This


Lifetime


significantly


longer than those observed in this study;


however,


may be attributed to the relatively high pressures used in thi


investigation


(total


pressure on the order of 10 Torr).


Generation


of C1


2 from carbon tetrachloride has been reported with an appearance


potential


eV in a time-of-flight ma


pectrometer (76).


inability to generate C1


from CCI4


in this


study could not be


attributed to a single instrumental


parameter


, but i


likely the result


of some combination of

trapping imperfections


lectron energy distribution aberrations,


and relative detection sensitivity


A number of investigations have been performed on NO2


nnc c 4 hi


LIl


- due to its


..+fmncnhri, 4rr mnnvrt-nn z-.mnA +"th rhanrn n'f n/M/v, nr n n'f "it-c nhnlfn-




Full Text
9
system applicable to diatomics is well documented (43). The details
of the theory and derivation will not be of significance here; however,
the results will be applied in analysis of the observed spectral
behavior.
Outline of the Dissertation
This dissertation presents a description of photodetachment
studies executed on molecular negative ions. These investigations were
carried out using a pulsed ion cyclotron resonance mass spectrometer
combined with a pulsed, flashlamp-pumped dye laser. A data collection
and analysis system was interfaced to the experiment to simplify and
accelerate data reduction. Chapter II describes the theory of ion
cyclotron resonance as it pertains to ion containment and detection.
Chapter III addresses the details of the experimental procedure and
set-up. Chapter IV presents the results for the diatomic halogen
anions investigated, Cl^-, Br^-, and BrCl". Chapter V presents the
results for the enolate anion of acetophenone. A summary of the results
and assessment of the technique for the study of molecular anions is
put forward in Chapter VI.
Appendix I documents alterations made to the microcomputer to
enhance its data handling performance. Appendix II itemizes the
control registers for the software data collection and analysis.
Appendix III contains the microcomputer programs written to implement
the data collection. Appendix IV describes the sample preparations
and handling techniques for the parent compounds. Appendix V
contains the calculated potential energy curves and Franck-Condon
analysis for Cl^ ~ Cl.


Appendix Va. Potential Energy Curves (con't)
R
0, 4458 502 340
01
2.4483113960
0 1
0-, 4507 727 580
0 1
b 453 2 34 1 2 00
01
3,4 55 6 0 54 3 20
3 1
3-. 458 1568 44 0
0 1
'. 46061 820 60
0 1
0 o 461 0 79:? 6 90
C 1
0, 4655409 3 10
0 1
3.468 0 0229 30
3 1
3,4704536550
0 1
. 4 72. 9 2 5 0 1 70
01
3 i 4 7 5 3 36? 790
0 1
0 47734 774 1 0
0 1
2.46) 509 l 3 30
0 1
3,4627704650
0 1
3, 4? 52 31 8270
31
3.4376931900
0 1
J 4931545520
3 1
3. 49 26 159 1 40
0 1
3,495 2 77?760
0 1
3,4975386330
3 1
¡.5003300 0 00
0 1
PE
O .? 1 7 067943 0
0.2 1 6 7 687 9? 0
0,2 1 6 5C 30 24D
0.2162261 6 30
0.2 1594.17260
0?156611650
0.215378921D
0.2150973990
0,2 1 4 31 69770
3.2145380050
0.2!42608079
0.2 1 3 9 356 34 9
0. 2 13 71 29090
0.2 1 344 27 38 0
0.2131754C10
0,2129111 1 id
3,2126500590
0,212 3924?1O
0.2121 38.35 2D
0.2118879930
0.21 16414690
0.21 1398891 0
0. 211 1 6 03540
05
O <- 3 O O c O O O o O O O o o O O O O O < 3 <
>n tn ji ji oi u* ji oi ji oi u o; yi ui o; ji ji ji u ji i


Appendix Va. Potential Energy Curves (con't)
R PE
0
4 4 : 4 8 r B 30
0 1
3e 9 -1 24 75 220
24
0 .
44 1 9 0 08 4P
3 1
Co 90 2 7859780
04

4 43X1749 10
0 1
0*9842308270
04
*\
~ c
444 7 7 49 4 60
3 l
3 98558446.30
04
3.
446 1 519 990
01
3*9868492 83 0
3 4

4 4 7 5 6 9 0 1 > in
0 1
3.9880276350
34
J >
44 j9151 3 40
3 1
0.5 89 1213 700
04
\
45 "> 4031 570
0 1
C. 990 1343 1 20
34
* .
45 1 -320? 090
3 1
3 9910 6 7 2 6 uO
0 4
r- .
453 2 572 320
0 1
0 .95 1 92 30 1 30
04
d.
4546543l60
C l
3. 992 70381 1 0
04
Do
45o0 7 13 570
0 1
0.9934118940
0 4
0. 4574^84200
3 1
Oo 994 0494 730
04
D ,
45790 54 7 70
3 1
0. 99 461 673 00
34
Dj
4603225750
0 1
0.995 1 218220
3 4
o
46 1 7395 7 80
31
0.95 556 38790
C l
J c
46 3. 1 56( 3 10
3 1
Oo 9 09 53 80 020
0 4
0-.
4645735830
0 1
0o9v62552650
C 4

465990 73 60
0 1
0.5565147120
04
J o
4674077800
0 1
0.9967183530
04
Oo
468824841O
01
0.9968681360
0 4
*>

4732418940
3 1
0.9969661530
04
Do
47 1658 3 470
0 1
0o95701413CD
/
D.
47 3 0 7 50 990
3 1
0. 997 01 41 6C0
C 4
4 74 4 9 30 5 30
3 1
0.9969679556
04
"S
J >
4759101350
0 1
0.9968773 5** 0
04
*\ _

4773271570
3 1
0. 996 7442 730
C 4
) o
4787442 10D
3 1
0.9965703590
34
Oo
4631612630
3 1
0.9963573850
34
1.
4015783150
3 1
3.9961070510
04
0-,
4829953680
0 1
0.9C 58?10260
04
Do
48 44 124210
31
0.9955C05460
04
j.;
4 85 8294730
0 1
0.995 14 34 150
C 4
Oo
4872465260
0 1
3.994 76 5 C 04 3
04
D .
486 6 6 35 7 90
3 1
3.9943522 520
04
Oo
493 3 8 36 3 t 13
0 1
0.99 391 16640
04
0 0
491 49 76 840
01
0.99X4447150
0 4
-
49914737D
3 1
0.592 552 8460
34
Oo
4943317890
0 1
0.5^24374630
04
y
4 957 4884 20
01
0.9913999570
34
'o
4071658950
3 l
0. oc- l 34 1 6 600
C 4
o*
4985829470
0 1
0.5V07638900
04


Appendix I LI. Microcomputer Programs (continued)
Multiplexer Select Marginal Oscillator Subroutine
Address Label Op Code Mnemonic Comment
088E
08B4
MUX MO
EA
EA
A9 5F
8D 03 17
8D 01 17
8D 02 17
A9 IF
8D 00 17
CE 00 17
A9 5E
8D 02 17
A9 5F
8D 02 17
EE 00 17
A9 00
85 40
60
NOP
NOP
LDA #5F
STA 1703
STA 1701
STA 1702
LDA #1F
STA 1700
DEC 1700
LDA #5E
STA 1702
LDA #5F
STA 1702
INC 1700
LDA #00
STA 40
RTS
_ Configure PADD's & PAD'S
Drop inhibit
- Toggle clock line PBO
Raise inhibit
|_ Set 'Type of Data' Flag
<_n
LO


Clearly this expression exhibits the correct limiting dependence on f,
for as f approaches one, indicating that all ions are within the
radiation field, the argument of the logarithm becomes Nq/N. Finally,
k'a(A) can be written as
k' a(a) =
In
f-A
A E,
(41)
where a is the fractional decrease in the ion signal upon irradiation,
A standard error analysis yields the expression for the relative
error for k'0(A),
w2rk'c(x)i |
"n/N0\ 2 W2(Nn)/N02 /
UY
w2(n)/n2
[k'o(x)]2 '
\f-Aj
In (f/f-A)
2 \
kf-V
"ln(f/f-A)J
. w;(f)./f; + m +
f-A J jfn (f/f-Aj 2 + x2 E-2
(42)
where W(x) represents the random error of variable x. The influence
of each of the factors involved in the error terms is indicated in Tabl
3 for a range of a values. The magnitudes of the coefficients of the
relative errors in Table 3 do not completely characterize the errors.
The relative errors themselves must also be considered. N W(n)/N ,
o oo
W(f)/f and W(Ex)/Ea are constant for a constant amplitude ion signal
with a constant S/N ratio. The relative error associated with N,
W(N)/N increases with decreasing N, that is, for a constant S/N ratio
increased ion attenuation leads to increased relative error in the
determination of the residual ion concentration. ABC represents the
coefficient sguared for the relative error of N For an ion


Figure 1. Trochoidal Trajectory of a Charged Particle in Uniform
and Static Crossed Electric and Magnetic Fields. A
nonzero component of particle velocity in the y-direction
is presumed in the generation of the trochoidal path.


Table 3. Factors in the Relative Errors in the Cross-Section for a Range of A Values and f Equal to
1.0 and 0.75
A
B
C
D
E
ABC
BD
A
(N/N0)2
{1n[f/(f-A)]}-2
1.0 0.75
1.0 0.75
t A/ (f-A )] 2
1.0 0.75
w2(n)/n2
1.0
0.75
1.0
0.75
.99
lxlO-4
0.05
104
9801
1
0.05

490
.9
lxlO"2
0.19
--
100
--
81.0
--
lxlO-2
0.19
15.4
--
.8
4xl0'2
0.39
--
25
--
16.0
--
2.5xl0-3
0.39
--
6.24
--
.7
9xl0-2
0.69
0.14
11.1
400
5.44
196
l.llxlO-3
0.69
3.24
3.75
27.4
.6
0.16
1.19
0.39
6.25
44.4
2.25
16.0
6.25xl04
1.19
2.77
2.68
6.24
.5
0.25
2.08
0.83
4.00
16.0
1.00
4.00
-4
4x10
2.08
3.33
2.08
3.32
.4
0.36
3.83
1.72
2.78
8.16
0.44
1.31
2.78xl0-4
3.83
5.04
1.69
2.25
.3
0.49
7.86
3.83
2.04
4.94
0.18
0.44
2.04xl0~4
7.86
9.26
1.41
1.69
.2
0.64
20.08
10.4
1.56
3.31
0.06
0.13
1.56xl0-4
20.08
22.02
1.20
1.35
. 1
0.81
90.01
48.8
1.23
2.37
0.01
0.02
1.23xl0-4
90.01
93.15
0.90
0.98


Table 2. Grating Characteristics as a Function of Wavelength for a 1200 line/mm Grating
in Autocol1imation
x(nm)
Littrow Angle, 3(deg)
Angular Dispersion (yrad/nm)
Inverse
Linear Dispersion*
nm/mm
300
10.4
1224
0.41
400
13.9
1237
0.40
500
17.5
1264
0.40
600
21.1
1286
0.39
700
24.8
1320
0.39
*Linear dispersion is calculated based upon an intracavity single-pass pathlength of
two meters.


Figure 9. A Typical Pulsed ICR Experiment Pulse Sequence.
Breaks in the line indicate variability. The
pulses are: precondition, PC; start, S; grid, G;
C2i free, F; detect, D; quench, Q. Not shown
are the integrate, sample and integrate reset
pulses. The integrate pulse coincides with D
and the sample pulse is a 2ms pulse triggered
at the falling edge of D. The integrate reset
pulse is generated prior to detection.


211
104. J. L. Dunham, Phys. Rev. 41, 721 (1932).
105. A. C. hurley, Introducti on to the Electron Theory of Sina 11
Molecules (Academic, New York, 1976), p. 1.
106. 0. Klein, Z. Physik. 76, 226 (1932).
107. R. N. Zare and J. K. Cashion, UCRL-10881 (1963).
108. J. W. Cooley, Math, of Computation 15, 363 (1961).
109. A. E. Douglas and A. R. Hoy, Canadian J. Phys. 53, 1965 (1975).
110. B. Rosen, Spectroscopic Data Relative to Diatomic Molecules
(Pergamon, New York, 1970), p. 121.
111. J. A. Coxon, Mol. Spectros. 1, 177 (1973).
112. M. V. Kurepa, D. S. Babic, and D. S. Belie, Chem. Phys. 59, 125
(1981).
113. J. A. Ayala, W. E. Wentworth, and E. C. M. Chen, J. Phys. Chem.
85^, 768 (1981).
114. M. Allan and S. F. Wong, J. Chem. Phys. M, 1687 (1981).
115. K. Lacmann and D. D. Herschbach, Chem. Phys. Lett. 6, 106 (1970).
116. W. A. Chupka, J. Berkowitz, and D. Gutman, J. Chem. Phys. 55,
2724 (1971).
117. H. C. Mattraw, C. F. Pachucki, and N. J. Hawkins, J. Chem. Phys.
22, 1117 (1954).
118. H. G. Vesper and G. K. Rollesfson, J. Am. Chem. Soc. 56, 620
(1934).
119. R. N. Compton and L. G. Christophorou, Phys. Rev. 154, 110
(1967).
120. J. A. Stockdale, R. N. Compton, and P. W. Reinhardt, Phys. Rev.
184, 81 (1969).
121. A. H. Zimmermann, K. J. Reed, and J. I. Brauman, J. Am. Chem.
Soc. _99, 7203 (1977).
122. R. L. Jackson, A. H. Zimmermann, and J. I. Brauman, J. Chem.
Phys. 71, 2088 (1979).


Appendix 111. Microcomputer Programs (continued)
Main Program (continued)
Address
0911
091F
0921
092E
0931
Label
Op Code
Mnemonic
Comment
C6 02
DEC 02
H
Decrements total and half
C6 03
DEC 03
-
total counters
F0 02
BEQ 02

If half total taken, skip
58
CLI
-
return from interrupt and
40
RTL
_
alter Interrupt Vectors (IV
s)
E6 19
INC 19
Increment Int. Req. Flag
A9 DO
LDA #D0
8D FE 17
STA 17FE
Change Interrupt Vectors to
A9 08
LDA #08
ID
8D FF 17
STA 17 FF
E6 00
INC 00
Increment ID Flag
58
CLI
40
RTI
A9 2E
LDA #2E
8D FE 17
STA 17FE
Change Interrupt Vectors to
A9 09
LDA #09
100 Data
8D FF 17
STA 17FF
A5 04
LDA 04

4A
LSR
Sets Counter to one half of
100
85 05
STA 05
_
r
per Laser Shot
20 52 08
JSR 0852
Jumps to Obt & Del
A4 OC
LDY OC

Loads Y-register
A5 1C
91 OD
LDA 1C
STAy OD
I
F
Stores LSB of 100 MO Data
AIV 1 S


of data are stored for each laser shot and a prompt is generated to
signal that the data collection system is prepared for a new sequence.
Implementation of the division in Equation 31 requires a 16
bit by 16-bit divide routine and a 12-bit shift routine to format pro
perly the data for storage. These routines have been coded and
incorporated into the analysis loop.
Programs are listed in Appendix III. Memory addresses, machine
codes and mnemonic codes are included to facilitate use, alteration,
adaptation and relocation of the various subroutines. Comments have
been included to simplify the reading of the code.
Derivation of the Expression for the
Photodetachment Cross-Section
The probability of photodetaching a negative ion of photo
detachment cross-sectiono (a) at wavelength A of the incident
radiation field of photon flux p(a) in time t is given by the expressi
P(a) = 1 exp [-kt / p(a) o (a) da 1 (33)
where k is a constant related to the interaction region (74). For
a pulsed radiation source with pulse duration t and energy per pulse,
E the number of photons per pulse is
A
nA = xEA/hc. (34)
This quantity is directly related to the photon flux provided a, the
radiation beam cross-sectional area, is known
p(a ) = A EA/hcat.
(35)


49
detect, quench, and pulses are of variable delay and variable width
and consequently each pulse has two assigned timing circuits. The
emaining pulses, sample, integrator reset, and free are of variable
delay but constant width and each requires only a single timing
circuit. Delay timers for all pulses are referenced to the 25 ys start
pulse. Pulse width timers begin counting at the end of their
corresponding pulse delay. The delay timers may be collectively
operated at one of three available clock frequencies. Clock frequencies
of 10 kHz, 1 kHz, and 100 Hz may be selected to yield minimum pulse
delays of 0.1 ms, 1 ms, and 10 ms, respectively. The pulse width timers
are operated from a set clock frequency of 10 kHz and produce a minimum
width pulse of 0.1 ms. Each pulse delay and width is selected by
three-decade thumbwheel switches.
The grid pulse is the first working pulse generated following the
start pulse. The grid pulse is amplified so that low is 0 volts and
high is +10 volts. This pulse is mixed with a variable dc level and
applied to the grid separating the rhenium filament from the electron,
beam entrance slit in the side plate of the trapped ion cell. The
variable dc grid potential is set to be 5 volts more negative than
the variable dc filament potential and the electrons, emitted at the
filament, do not pass through the grid into the cell. During the grid
pulse the potential of the grid is 5 volts more positive than the
filament potential and electrons are accelerated into the cell.


122
Table 10. Comparison of Literature Values for the Electron
Affinity of Chlorine.
Electron Affinity
(eV) Technique
Reference
9 OC _L 0.27
2.36 032
Photodetachment
Present Work
2.32 0.1
Endothermic Charge Transfer
79
2.5 0.5
Chemionization
115
2.52 0.17
Dissociative Electron Capture
76
2.35 0.15
Exothermic Charge Transfer
78
2.38 0.1
Endothermic Charge Transfer
116


Three-dimensional ion containment is not accomplished with the
simple field conditions thus far treated. In neither of the cases
considered has the motion of the particle parallel to the magnetic
field lines been restricted. Also, the transverse electric field
induces a particle drift producing a channel for ion loss perpendicular
to both the electric and magnetic fields. Consequently, a configuration
of fields eliminating these ion loss channels must be selected.
The trapped ion cell developed by Mclver produces an electro
static potential for which the equipotential lines close on themselves
in the plane perpendicular to the magnetic field in addition to
forming an electrostatic potential well parallel to the magnetic
field axis (46). The cell geometry and definition of coordinate axes
are indicated in Figure 2, which also indicates the direction of the
magnetic field for subsequent discussion. The cell consists of six
electrically independent plates. For effective negative ion trapping,
the upper (U), lower (L), and end (E) plates are held at +1.0 volt,
while the trapping (T) plate potentials are -1.5 volts. In the case
of positive ion trapping, the polarity of each plate potential
is reversed. The solution of Laplace's Equation for a cell identical
to that shown in Figure 2 has provided an expression for the three-
dimensional potential produced in the cell interior (47). An
analytic approximation to this expression valid near the center of
the cell yields a quadrupolar electric field


Appendix
Vb. Molecular Chlorine
and Molecular
Chlori ne
Anion
Franck-
Condon
Overlap
Factors (con
't)
v*,v**
T(cm1)
Q
Lambda
QT**3
QT**4
RC
R**2C
Phase
2 1 H
22622. 52
0. 06 37 0 02
4420.374
3.13069
1 2
0.22750
16
2.33 70
5.46 42
_
l 1 19
r 123 10-0l
3923. 153
3.20330
1 2
0.51960
16
2.4240
5.e7 02

14,19
-25271.70
j 19330 Cl
3556.995
0.31213
1 2
0.78960
16
2.4153
5,8331
-
1 3. 19
-25056. 70
C.4317D-02
3953 .949
0.67910
1 1
3.17020
1 6
2.4058
5* 782 l
4-
l l 9
-2*04 *.70
C.26390-02
4025.003
0.40470
l 1
0.10053
l 6
2.4066
5.7990
Â¥
17,19
-24635. 70
0, 1 5 780-01
4059.153
0.23603
1 2
0.58140
16
2.3966
5,7447
-
1 3. 19
-24425.70
0* 1 l 100-01
4 093.3 77
0,1619D
1 2
0.39540
16
2.3888
5,7043
Â¥
19,19
-24226.70
0 8989D- 04
4127.677
0. 1 2780
l 0
0.3 0960
14
2.3642
5.5457

21, 19
-24026.70
0, 7960 0-02
4162.036
0.11040
12
0.26530
1 6
2.3792
5.6636

2 I l 9
-23029.70
0.14170-0l
4 196. 443
0. 1 91 73
12
0.45680
16
2.3718
5.6250
4-
22, 1 9
-2*635.7 0
337210-02
4230.ee7
0.49130
1 1
0.11610
16
2. 3641
5.5634

23, 19
-23444.70
0. 1590^-0?
4265.356
0.2 3490
1 1
0.48030
15
2.3640
5. 59 78
-
24, 19
-23256.70
0l1080-0l
4299.835
0. 14940
1 2
0.34750
16
2.3554
5.5491
4-
23, 19
-23071.70
0.37990-02
4334.314
0.10013
12
0.24930
16
2.3407
5. 5130
-
1 3, ? )
-25932.39
0.19500-01
3855.182
3.3430D
1 2
0.88 170
16
2.4359
5. 93 3 0
Â¥
14,20
-25714.39
C.3001D-02
3888.8 74
0.5 10 23
1 1
0. 1 3 12 0
16
2.4246
5.8712
-
15,2C
-25455.35
Oo 45490-0?
3921.663
0.75420
1 1
0.19230
16
2.4264
5.8929

16, 20
-25267.39
0. 17330-0l
3954.541
0.20030
l 2
0.70080
16
2.4164
5.0394
4-
17, 20
-25070.39
0.34300-02
3967.497
0.1 3300
1 2
0.33340
16
2.4077
5.7930
-
l 0 ,20
- 24872.39
0. 27060-03
4020.522
0. 4 16 40
1C
0.10360
15
2.4176
5.8702

19,20
-24665.39
0. 1 1 500-01
4053.606
0.17260
1 2
0.42580
16
2.3982
5. 75-> 2
4
2 ) 20
-24465.39
C. 12580-0l
4 086. 7.38
0.18430
1 2
0.45090
16
2.3904
5.7124
-
21,20
-24272,39
0.98230-03
4119.907
0. 1 4053
l 1
0.34100
15
2.3792
5.64 77
4-
22, 2C
-24078.35
0.49350-0?
4153.101
0.63090
1 1
0.16550
16
2.3814
5. 6756
4-
2 3, 20
-23887.39
Oc 13 160-01
4186.309
0. 1 7940
l 2
0.4 286D
16
2.3737
5.6342
-
24,2 0
-23695,39
0. 47 770-0 .2
42ic.5 1 0
3.63590
1 1
9.15070
16
2.366?
5 59 4 p
4-
25, 20
-23514.35
0. 10120-02
4252.713
0.13160
1 1
0.30940
1 5
2.3663
5.6 1 39
4-
204


I certify that I have read this study and that in my opinion
it conforms to acceptable standards of scholarly presentation and is
full adequate, in scope and quality, as a dissertation for the
degree of Doctor of Philosophy.
Thomas L. Bailey
Professor of Physics
This dissertation was submitted to the Graduate Faculty of the
Department of Chemistry in the College of Liberal Arts and Sciences and
to the Graduate Council, and was accepted as partial fulfillment of the
requirements for the degree of Doctor of Philosophy.
December 1983
Dean for Graduate Studies and Research


CO
CT)


Read
100 Data
Overlay
100 Data
Storage
Y


Appendix III. Microcomputer Programs (continued)
Triple Precision Average Subroutine
Address
Label
Op Code
Mnemonic
Comment
0B90
46 28
BO OA
LSR 18
BCS OA
D-
Test for Finish
46 17
LSR 17
]
66 16
ROR 16
Divide by two
66 15
ROR 15
r
18
4C 90 OB
CLC
JMP 0B90
3-
Repeat Division
A5 15
LDA 15
OBAO
85 1C
STA 1C
A5 16
LDA 16
85 IB
STA IB
A9 00
LDA #00
Store result and initialize
85 15
STA 15
the Average Registers
85 16
STA 16
85 17
STA 17
85 18
STA 18
OBBO
60
RTS


Appendix
Vb. Molecular Chlorine
and Molecular
Chlorine
Ani on
Franck-Condon Overlap
Factors (con
11)
v*,v**
T(cnf2)
Q
Lambda
QT**3
QT**4
RC
R**2C Phase
1 ? 1^
-J'dcU 52
- C 1 *4 1 r' o 1
.- .' i
0.2 73 -ID
l 7
j 5 9 0 7 0
1 6
2 l 4 1
5.3? 58
4-
, 1 /
- 2 6 ; 6 c 7 r
, 7"550-r'P
3 4 Sbo 9 0 7
Ocl6970
l 2
J .4652 0
16
2.5?58
6.3960

1 i 5
-2~ 3 r*97 j
, Hc'.ii;-vl
3538*6 1 9
0.78610
1
C.??2S0
1 7
2.5139
0.3455
-
2, 15
-oOQ.S,7 0
, 656.2 n- oi
3560.571
0*14560
1 3
0.40560
1 7
2.509 3
6. 2 96 7
M'-
-27834*70
o 56 050-6i
3592.638
0. 122 30
1 3
D. 34 1 90
1 7
2.4956
6. 24 75
-
.IS
-27536.70
C 1 4 ? 1 ') 0
7524.930
0.29320
1 2
C.82270
16
2.4350
6.152P

5 15
-? 73*17 0
C. 2^580-02
3667.417
0.46160
1 1
J l 2 6 2 0
16
2.4893
6.2068

6 1 o
-P7QC9,70
O 36 3 0 0-01
369Q,o 78
0.56330
l 2
0.15260
1 7
2.4757
6.1300
-
7,10
-2636 0.7 0
C c 3061 o-oi
1722.911
C 5 7 8 0 D
12
015540
1 7
2.466l
6. 08 0c
4-
^ i :
-26624*70
Jo 4? 05")- 3 2
37 55. 91 1
0 e 7 9 3 7 D
l 1
0*2! 130
16
2.4542
6. 0172
-
0,10
-2 6 301 *70
~ 6 0 76 0-0?
i7o9o D70
9.11170
1 2
0.25400
16
2. 454 3
6 D 3 0 5
-
1 5 lr-
-26161*70
0* 2* 6 7' 0 1
3 >32 2 3 62
0.44170
1 2
0.11 560
l 7
24442
5.5746
4-
11*10
-?:i ->3 4*7 3
" o 14 300-0 1
3855.838
Oe 25320
l 2
066960
1 6
2.4350
5.5271
-
12, 10
-.26 7 1 0,7 0
>,*2080-0r
3389.4 31
C.13950
09
0.35870
1 3
2.3309
5.2768
f
D ?
-2 D 3 9. 30
> C*14 53^-01
3443.599
0.35560
l 2
C 1 0330
l 7
2.5453
6.4800
l ?c
-28 7 ft J?, 3 9
6. 5 3 66 0-0 1
34 74o 347
0.12790
1 3
0. 36630
17
2*5351
6.4275
-
?, 2 *
-2652 Gw 3 9
Ck72150-01
3505.?ei
0.16750
1 3
D. 4 7 79 0
1 7
2.5250
6.3757
4-
3, PC
- 2 P 2 7 7 o 3 9
0.33290-01
3536.395
0.75270
l 2
0 *2 l 29 0
17
2.5146
6.3217
-
- 2 0
-2*029*39
C 0 70 610-0 4
75O7.6 84
0*15550
1 C
0. 4 3590
1 4
24644
6*0233
4-
s, 2:
-2 7764. * 0
0* 22 2 3 0- 01
3 599.1 44
3 4 7250
1 2
0 l 3 1 30
1 7
2.4999
6*25 1
4-
t PC
- 27 6 4 2*IP
Do 35 2 70-0 l
3630.767
C,73700
12
0.203CJ
1 7
2 .4896
6. 1978
-
7.2 0
-3 73 0 3o 3 0
0 . 2 9 7 D ?
3662.549
016350
1 2
D.46110
16
2.4783
6. 13 7 6
4-
1 2 ?
-P7067.30
; 39900-0?
36v4t483
0,79130
l 1
L/ 2 14 2 0
lb
2.4789
6. 15 15
4-
0 2c
-263
'O 251 DO- 21
3726.562
J a 4 65 OD
1 2
0.1 3 01 0
i 7
2.4665
0.0844
-
1 '',20
-2o60*.!9
: o 1 t 4 0 D D 1
776ft.779
? 3 ^ 8 7 0
l 2
: .3 2 1 40
1 6
2.4567
6.0333
4-
11*2'
- PC 37 7.3C
>;c 02 00 CO
8791o126
Ool6550
09
''43 66 0
l 3
2. 340 2
5. 3 1 86
-
12,20
- ? f- 1 c 3 3 5
: 13530-D1
3623.5
o; .24200
1 2
0.6 3 280
16
p. 4 4 53
5 o v6 1 3
-


85
electron energy for peak nitrite ion intensity was 0.83 eV. Nitrite
ion generation from nitromethane was deemed to be a suitable, clean
choice as the precursor for the molecular anion of chlorine.
The chlorine molecular anion was generated and its signal
intensity optimized in a manner that simplified the tuning procedure.
Nitrite ions were detected and the intensity of the signal was
maximized for a nitromethane pressure between 5x10 and 1x10 Torr.
Chlorine was leaked to the cell through the second inlet manifold
and jeweled leak valve. The NC^" signal intensity was monitored as
the chlorine was added.. The nitrite ion intensity fell off rapidly
with the introduction of chlorine. When the NC^' intensity had
decreased to less than 10% of its peak value, the chlorine pressure
at the cell was stabilized. The magnetic field was set to bring the
Cl ion into resonance and once this signal was located the detect
pulse delay was increased unti 1 the Cl" peak intensity had dropped to
approximately 20% of the initially observed level. At this detect
delay, the magnetic field was altered to bring the C^" anion into
resonance. In some instances, scans of the magnetic field about
the nominal resonant magnetic field for Cl2_ proved necessary to locate
the ion. The Cl2 signal was maximized with respect to the ratio
of components inlet to the ion cell region, the total sample
pressure at the ion cell, and all of the tuning parameters of the
spectrometer. A negative ion mass spectrum for a chlorine/nitro-
methane mixture (pressure ratio determined at the ionization gauge
on the main vacuum manifold) is reproduced in Figure 17. The time
dependences of the predominant negative ions, NO2, Cl2, and Cl",
are indicated in the time-scanned spectra (Figure 18).


INTENSITY
eei


118
The interpretation of these results is complicated by the fact
that no long progressions are present. From the (V*,V**) transitions
(16,6), (15,6), (14,6), and (13,6) an average first difference
of 219 cm ^ is obtained as compared to an average first difference
of 215 cm ^ from the calculated term values. The average second
difference from the experimentally determined term values is 4.5 cm"\
but a positive and negative value are generated indicating that the
wavelengths are not accurately enough determined to justify
assigning any significance to this value.
Calculated Franck-Condon factors are not expected to predict
the intensity pattern of the spectrum. This is due to the fact that
the initial level populations cannot be controlled and only broad
estimates of the energy available for internal excitation of the
anion are known. For the accepted values of the electron affinities
of nitrogen dioxide and of chlorine 2.38 + 0.06 eV and 2.52 + 0.17 eV,
respectively, the maximum available energy for internal excitation
from the electron transfer process alone is 0.37 eV (2985 cm^)
which could account for anion excitation up to V** = 12.
One means for determining the internal energy of the molecular
anion is through the observation of endothermic reactions of the
anion (75). If the amount of endothermicity can be gauged, a limit on
the anion's internal excitation may be set. This was attempted
using the Cl^ -CH^OH reaction. The experiment was complicated by the
fact that there were only two gas inlets to the cell region. For Cl^
formation, both inlets were already used. Consequently, a sample


130
bromine Using andwgxe, 323.2 cm 1 and 1.07 cm respectively
(88d), this expression indicates that levels up to v' equal twenty
must be involved in the transition.
No identifiable structure which can be associated with ground
state anion excitation appears in the spectrum. This is due to the
fact that high vibrational levels of the anion will produce closely
spaced lines which remain unresolved here. From the correlation of
the Cl2" photoreduction spectrum with the term values generated by
the FC overlap factor calculation it is apparent that the process for
formation of C^" from NO2 (Equation 43) populates. Cl2 vibrational
levels at least up to v ' = 16. This corresponds to 3752 cm* of
vibrational excitation of Cl 2". The nominal difference between the
accepted electron affinities for nitrogen dioxide and chlorine can
account for only one-third of this excitation. The excess
excitation may result from two effects. First, for a vertical
attachment process between the neutral and anion potential curves,
highly excited vibrational levels of the anion are expected to be
populated due to the large difference between the equilibrium bond
lengths of the two states (88b). Second, electron-impact., vibrational
excitation of chlorine neutral molecules may be competing with
dissociative attachment. Then, attachment may occur to vibrationally
hot neutrals with more favorable Franck-Condon overlap factors, but
with a range of final state internal excitation (114). Assuming
3752 cm"1 of excitation of Br2', an estimated v' of 23 is obtained.
This corresponds to a vibrational energy spacing for the anion of
approximately 108 cm ^. This spacing would be observable under the
resolution used here only under fortuitous circumstances. The


94
cross section for this reaction dropped sharply indicating that
it was exothermic. The reverse reaction was not observed ; however,
a competing reaction
ci2_ + no2 N02C1 + Cl' (44)
has been reported (78).
The generation of Cl2 from chlorotrifluoroethylene was also
observed. This behavior has been reported, but the mechanism for the
formation was not determined (92). Investigation of this source of
Cl2 included a search for precursor and intermediate ions, however
none were identified. The original investigators' conclusion that
a pyrolytic reaction was occurring on a hot filament surface is
a reasonable explanation of this behavior and is not contradicted
by this study.
Halogens are known to be highly reactive, corrosive compounds.
Reactions with pump oils, ion gauge cathodes, gaskets, etc. have
hindered measurements of halogen properties. There is also
empirical evidence confirmed by the experience of this study that
passivation of the system is required prior to obtaining stable
halogen ion signals (93, 94). This passivation time may be hours
or days depending upon the vacuum containment system geometry,
surface area and surface condition. Of particular significance is
the effect of chlorine reactions at the surface of an electron
filament which may alter the work function of the filament material
and change the characteristics of the electron beam. This effect
is pronounced for low-energy electrons and has been observed to


Appendix III. Microcomputer Programs (continued)
Main Program (continued)
Address
Label
Op Code
Mnemonic
Comment
EA
NOP
EA
NOP
EA
NOP
EA
NOP
C6 07
DEC 07
Decrement Laser Counter
09F0
A9 IF
LDA #1F .
r
8D FE 17
STA 17F6
L Change IV s to 100 Data
A9 09
LDA #09
8D FF 17
STA 17FF _J
1
C6 00
DEC 00
Decrement ID Flag
58
CLI
09FD
40
RTI
CT>
CT>


Figure 15. Microcomputer RAM Memory Map.
The major divisions indicate blocks
of four pages, natural machine divisions
of memory. The beginning and ending hex
address for each logical software unit
is provided. Note that the A/D subroutine
is dispersed throughout the available
memory.


Figure 3. Time-Dependent Radii for Non-Resonant Particles
For <7S£) = 1 HZ rmax Is el r + T and rrain is etlual t0 r'f- For (T7)
2 HZ cE3* 15 e<|Ua t0 r + a"d r" iS
equal to r-£p.


CHAPTER I
INTRODUCTION
Historical and Scientific Interest in Negative Ions
The study of negative ions in the gas phase has elicited
increasing interest since Wildt ascertained the importance of H" to
the explanation of the anomalous infrared opacity of the solar
spectrum (1). This insight was founded upon the investigation of the
"affinity continuum" associated with the radiative attachment of an
electron to an atom by Gerlach and Gromann (2). Wildt further proposed
that the radiative behavior of diatomic negative ions of neutral
diatomics of established astrophysical importance such as H,,, 0^,
NH, OH,and CH might be of significance in stellar radiation spectral
analysis. Subsequent study of negative ions for astrophysical
applications has been largely concerned with defining the wavelengtn
dependence of the interaction of light with the selected ions (3).
Following the recognition of the import of negative ions in stellar
plasmas, an awareness of negative ions evolved in atmospheric
chemistry, flame chemistry, gas laser plasma chemistry, and radiation
chemistry and biology.
Consideration of the behavior of negative ions in the atmosphere
is essential in accounting for effects such as the reflection of radio
waves at the lower ionosphere (4) and the fate of atmospheric
pollutants (5). The ionosphere is a region of high free electron


6
length-tuning-range lasers of excellent monochromaticity has greatly
assisted the application of photodetachment schemes. The major
characteristic distinguishing the different photodetachment techniques
is the detailed means by which the process is instigated and detected.
The fixed frequency photoelectric experiment employs an argon ion
(Ar+) laser (488.0 nm) to eject electrons from a beam of negative ions.
The photoelectrons are energy analyzed over a defined angular collection
aperture to obtain the photoelectron spectrum. Variable frequency
photoelectron spectrometry measures the production of photoelectrons
as a function of the irradiation wavelength. Beam and drift tube photo
detachment employ either neutral beam or residual ion beam detection
rather than direct analysis of the ejected electrons. The important
advantage of a drift tube experiment is the reasonable assurance that
an ion has a thermal internal energy distribution prior to photo-
excitation.
Ion cyclotron resonance (ICR) techniques for the study of photo-
induced processes of ions merge the advantage of drift tube thermaliza-
tion with controlled, low energy, electron-impact production of
negative ions to minimize ion internal excitation (31-32). The pulsed
ICR technique is capable of characterizing effects of ion internal
excitation by varying the time available for the collisional de-excitation
prior to photoexcitation (33).
Theoretical Techniques
Evaluation of the experimental measurement of electron affinities
has been hampered by the absence of reliable, theoretical predictions
of the electron affinity and by the inability to predict the features



Appendix III. Microcomputer Programs (continued)
Twelve Significant
Bit Shift
Subroutines
Address Label
Op Code
Mnemonic
Comment
03C2 Begin
A5 03
LDA D3
Shifts the output of the
DO 13
BNE 13
Double Precision Divide
03C6 D2
A5 D2
LDA D2
Routine into the standard
30 IE
BMI IE
two byte format
A9 00
LDA #00
85 D9
STA D9
06 D4
RSL D4
26 D5
ROL D5
26 D2
ROL D2
E6 D8
INC D8
4C 06 03
JMP 03C6
D3
A9 07
LDA #07
85 D9
STA D9
46 D3
LSR D3
66 D2
ROR D2
66 D5
ROR D5
E6 D8
INC D8
4C C2 03
JMP 03C2
STO
18
CLC
A5 D8
LDA D8
65 D9
ADC D9
85 D8
STA D8
A5 D5
LDA D5
29 FO
AND #F0
05 08
ORA D8
85 D5
STA D5
60
RTS


Appendix Vb. Molecular Chlorine and Molecular
v*,v**
T(cm"1)
Q
Lambda
, i'
- 2 T 0.' l
, 1 '-AH- ; .<
56 72. 4 1 9
l If.
- ?* r. 7 J. o i
4 ;7;fi-A'
*707.410
* '
- ? 7 1 5 0 1

l 7r56f>- 0 1
3742.654
* 1 f
->*4 .8 5 1
- .
4 a 7j' J 1
37 70 1 46
4. 1 r
-2-22 C. 31

5 ; 3 5 13 ,961
i f-
- * > - 7 5 a 1
c
43')- ** 1
3*49. 854
6* 1 o
-2 ) 7.3 1.. o 1
>
1 5- 0 1
3 886 0 6 0
7*1'
-2CA04, ) i
. ,
4 6 77 6-0**
302?,490
1 '
-7 i59o 0 1

i /1 7D- : i
*959 140
-.It
- 2 6 02 5 0 1
o
30309-01
39 .003
1 If
-?47 >5.0 l
'J
2 0609-0 1
40 33. 0 70
1 1 t
-24568o91
o
if' 50-c :
4070.334
2* 1 t
-24344,01
o,
60 3 8!'-02
4107.787
>, 17
- ?7 Afv l o 7 ? >
. }
l 768 )-02
3611.161
1*17
-2 74 J4,; ?
- 1
9C 899-OP
3644 *989
1 7
- 2 7 1 in, 9 2
,
31 63 9-01
3 6 79 .C5 1
% 17
-?.r 2 9*9 p
- *
56 65 9- 01
3713.342
4. 17
-26601,92
*> a
j7 7 0 )-01
"*7*7.35f.
17
-26436.92
. o
27139-01
3782.569
6*17
-26
o
97700-03
3817.534
7. 1 7
-25s55. 9?
' ,
1 0809-^|
385? .6 85
'3*17
-?"719.9?
o
7 '*520- : l
38 38o 0 37
0* 1 7
-2 54 66c, 5?
a
22 1 5.0C 1
3 5?.59 1
',17
-26256.02
C1.
1 6 779-02
3959.311
1.17
-25029.92
' a
6 769- OP
3995.218
2, 1 7
-24 6 J 5 9?
?'
2281D- 0 1
4031.295
", It
-2 *3 147.52 ^
o
32 979- 0?
35 52. 71 l
i i e
0
. o
15 59 9- 0 1
3 5 .85. 4 4 8
?* 18
- 276 36,52
c
4 V 4 6'' 0 1
*''"19.401
1* 1 J
2 T 3 J 5 5 7
J 0
L '4 8 50 C l
3 6 61o 5 65
4 l H
-2 7 1 3 7-, 5 ?
' 0
40 14 9-21
*6 84 Q 3 6
1 b
-? r .2. 52
.
4 6 5 3 9-02
?. 7 1 3 6 C 7
~ 1 H
O60< ?
./ o
6 8 -p
*7 52.2 7.3
7. 14
-26 4 1 1,5?
J o
3 297.)-0 1
3786.227
5, 16
- 2 1 75.52
. 0
25239-01
3 2C o 36 4
c f 1 fy
-?594 5 ?
c
? 3 5 7 9 0 ?
3 9 64 ,6 7t
* 1 4
- 3 ; 7 12,52
ft
7 : 4 0 r 0 3
3 i' ,16 7
l 1
vt?#rV
c
7 >839- : 1
1923. 797
Chlorine
An i on
Franck-
Condon
Overlap
Factors (con't)
QT**3
QT**4
RC
R**2C
Phase
Oc 1 04 7 J
t 1
0.2 8*32 9
1 5
? 4 8 J >
t. 16 4 3

0.8756.)
1 1
3.2 380
If
.4713
D.1098
-
0 a 3 34 > 9
1 2
0 .39479
16
2.4623
c. 06d4

C. 74950
l 2
0.1 9 34)
1 7
? .4542
6 02 39
-
0 l 4 7 o
1 3
0.2744)
l 7
24453
5. 9Or 3
0. 666 20
l 2
0.22500
l 7
2.4375
5. 94 02
-
0.71 6
1 2
0.81410
16
2.420
5. 69 7 2

0.7 7=10 0
09
0.19 76D
14
23905
5.6623
-
0.21229
1 2
0.53599
16
2.4167
5.8428
-
0.47480
I 2
0.11860
1 7
2.4083
5. 6000

0o 3 l 4 1 o
1 2
0 .7 787 D
16
2.40 0 3
5. 7559
-
0.246^9
1 1
0.6 065D
15
2.3896
5.7013
? .871 10
1 1
0.21210
1 6
2.3394
5 7 1 33
f
C 2 9 0 5 9
1 l
0 *60 449
1 6
2.4983
6. 23 3 3
0*20420
1 2
0.56029
1 6
2.4871
6.1871
-
0 .6 -*52 0
1 2
0.1727D
l 7
?.4781
6. 1420
f
0.11060
1 3
0.2 9809
1 7
2.469 3
6. 05 75

0.10960
1 3
C.2924D
1 7
24605
6. 054 1
*
0.50140
l 2
J l 3 25 D
17
2 4 5 1 6
6. 00 88
-
0. 1 7560
1 1
0. 4 6 009
15
24366
5.5255
.
0.13390
1 ?
0.49030
l 6
2.4392
5. 95?7
*
Do 5 26 1 0
1 2
0l3530
17
2.430 0
5.5054
-
' .36:660
1 2
0.93489
16
2.4215
53626

C *270 2D
1 1
0.6 8 26 0
1 5
2.4097
o. 7976

0. 1 09 49
1 2
0.2 7 380
16
2.4105
5.8142
-
0. 3 48 ?D
1 2
C.3 6 260
1 6
2.4016
5. 7684
Co 73539
1 1
C.20 70 D
16
2.5 t 24
6. 3135
0. 4 2500
l 2
0.11850
1 7
2.5029
f2655
-
0.10440
1 3
0.28369
1 7
2.4936
6.218b
4-
0 1 3.3 2 0
1 3
0.36489
l 7
2.484a
6.1726
-
0.8 3? 30
1 2
p. 2 1 770
1 7
2.4752
c1264

0 9 C *5 0 D
l 1
0 2 4 34 0
l 6
2.46 35
6.0637
-
C 1 30 o0
1 2
0. 3 4 809
1 6
2.4629
6.070 l
-
0 o 5 650 0
1 2
0.14920
1 7
24524
6.0150
f
Oc 4 f>2 5 0
l 2
0.11349
1 7
2.4434
5.9691
-
0 w 4 1 1f9
1 1
:. i o e s o
1 6
2.4313
* 5:31
*
..1198 9
1 2
0.30810
1 6
2.432?
Da 5 1 9C
f-
J-. 3 >4 49
l 2
0. 1 0 05 9
1 7
I.4 226
5.66 5 d
-


50
The detect pulse serves several functions. First, it controls
the marginal oscillator rf output to the lower plate of the cell
through the gated amplifier in the limiter feedback circuit of the
marginal oscillator as described by Mclver (46). Second, in
combination with a variable length, inverted pulse from a one-shot
which itself is triggered by the rising edge of the detect pulse,
the detect pulse produces an integrate pulse during which the integrator
is active. The logical 'ANDing of the detect pulse and inverted
one-shot pulse eliminates the initial spike observed in the marginal
oscillator output due to mismatching in the marginal oscillator
compensation circuitry (53), The falling edge of the detect pulse
triggers a one-shot which produces a 2 ms sample pulse to activate the
sample/hold circuit. Ion detection is a concerted action of the
marginal oscillator, integrator, and sample/hold circuits. The detect
pulse gates on the marginal oscillator and integrator and the ions
are irradiated, the power absorption is determined and is converted to
a voltage level at the integrator output. At the end of the detect
(and integrate) pulse the 2 ms sample pulse is generated and the
sample/hold circuit samples its input which is the output of the
integrator. Finally, an independently generated integrator reset
pulse resets the integrator prior to the next pulse sequence.
To insure that only ions produced during a single grid pulse are
present during a detect, a quench pulse is applied to the upper
plate to eject all ions from the cell prior to repetition of the
pulse sequence. A pulse of either polarity will perturb the trapping
field and remove the ions from the cell.


npfjcnu i A
vu. nuiecuiar
uniorme and
mo 1 ecu 1 a
v*,V**
T(cm-1)
Q
Lambda
ip
f ?
c w i 7 : i
<* 1 v 7 5 J .
7 1 ?
- 4 7
'*'J 0 )- 0 l
4 M ; c 4 2
i 1 ^
-? 7 7 4 Pvt 7
>; o 11-0?
4 ? f'45
ip
- ? M 1 5.' 7
JO ^rO' 01
4 3 26 O 0 6 *
i:, i 2
- v> H H S i- 7
M : >. 2- 0 1
43M 54"
11.12
-'7. fc^e.t 7
- 2 7 91 '-?5
4417.321
i i r
- 2 * 4 J. 4 o 5 7
- oo l 7f.- ; >
44 57* 3 66
v,l3
-2r>60 7o 1 1 >
: O 105 30-?4
3 74.9 G 1
l 1 l
-? 5"0. 1 1
2 2 1 8 0- 0*1
3913.573
Ml
- 1 4 l 90- 0 2
395 30 l 77
7,13
- 2 5 3 4 £ l 1
C V **> 7 ; 3 0 '
39 92.795
4,17
- ? 4 7 9 7 1 l
,o l 5 y90 G1
4 0 32 o 7 2 3
5,13
-3455 2.1 1
. O 3 ? 5 0- 0 1
4 3 7? 97 0
6, 1 3
-2471C.l1
? 4f?c;cn_'>i
4 1 13.513
7, l 3
- *071,1 l
:3 5i 4 oo i
4 1 54. 355
3. 1 3
-2 3 J5, 1 1
3 3 74 ?n-0 1
4 1 954 92
9.13
- 2 ** 6 7 2 1 1
: t c 04f- oi
4 2 36 .9 09
10, 1 3
-?337?. 1 l
o, l Of. 40- 0 3
4? 7b.6 0 4
1 1 1 .3
- ?. 3 1 4 5 o 1 1
31 ? ? i D -: i
4320.567
13, 13
- 7 ? 1 1 l
- 27 OoO- 0 l
4 3 62. 791
3,14
-2 6 7,5 ? J
jo f 7 39 0-0
30 04 063
1.14
- 2 i 0 >0.53
66 9 0*" -0 ?
7341.643
_ l 4
- ? 3 7 7 6 5 3
rO 36 96D-0 2
36 79.4 99
3.14
-?55255 3
j o 1 .? 5 3 CO 0 1
39 17.64 7
4,14
-25277,53
3, 29400- 01
3956.083
">14
-2 5 0 3 2.5.3
' .,4 759 D- ? 1
7094.002
',14
-2 4 79 C.5 3
.-b795O-0!
4032759
f % 14
-2455 l o53
"c 7 4 9 D C 1
4073.066
3.14
-2- 3 1 5,5 3
, i o c o o ; i
4112.595
.14
- 24 On 2. 5 3
0, 1 5 360 0?
4l 5? .386
i:, 14
- 2 3.9 5 2 5 7
Oa 1 3 660- 0 l
4192.428
11,14
- 2 35 2 5 7
j 2 6 *60-01
423?.710
12,14
- 2 '401,53
", 21 130-01
4273.225
3. 10
-f: 7 5 1- 75 t
<. 1 9 no-.^
7 7.36.66 7
1 13
? d 5 0 4 6 ->
r 1 a ?? :o- 0 7
37 72.655
? 1 4
-2-2 50, -.5
-o 4-' ?o C ?
3b J9, 401
3. 1 r
-?:><; 9 5,7 0
? 24 75 0- -1
3646.17*
4.15
-25751.95
, 45600 Cl
3883.217
5,15
- 7 5 5 0 b 5 5
rM.; 50- o 1
3920.516
Ml'
2*526 4*6 5
;,42440-01
39 5b '"'6 5
' 1 c
-250?5. .j5
v 1 3 5 00- 01
3*95,369
3.15
-2 4 769 n -<5
c 6 0-04
4 0 3 7. c QQ
. 15
-24556 a 55
-a 1 4 .40- 01
4<; 72.164
M, 1 c
-74 n < 5
c ? 4 jo : i
4 1 1 Oo 6 85
1 1 1 c
-2 4 09 9,35
. ?* 36.0-C 1
4145.40-
12,15
-?3375.6?
",221 6 O- y>
4 1 r< 6 ,33?
jOr.or O < ' O O o O o O O O O O O o fO O O j O O O
Chlorine Anion Franck-Condon Overlap Factors (con't)
QT**3
QT**4
RC
R**2C
Phase
, h 1 1 9
1
. 1 1 J l O
1 7
2 3 7 C 1
5. 6 2 71

0 5 82 39
1 "
J 1 4 91 J
1 7
3 36 4 .
5 59 7 1
-
: a 7 51 i;>
1 2
M4 740
1 7
2 35 6 b
5 5 6 . j

v.,4 1f or
1 2
0 > 5 9 3 0
16
2.3507
5 5 2 l
-
0. l ?e>9
1 2
0.2 8970
16
2.3435
6 c 4 9 r-
3.2 7-7 J
0 c
0.63040
l 2
2.3912
5. 92 1 5
f
2 3 l l 2 3 r
l 2
0.25120
l c
2.3318
5.4401
-
'.2 84 10
0<
0. 7 3 310
1 3
2.4338
6.9252
4
0.3659O
1
0.94 52 D
l 4
?.4 265
5. 8fl- 7
-
1 25 70
l 1
0.5811 D
15
2.4174
58452

: 6 > 6 80
1 1
0.2246D
1 6
2.4C >4
5. 30f C
-
0.24390
l 2
0 6 0 4 b D
l 0
2.4 0 l 7
6. 76 9C
4
j.46230
1 2
J. t l 840
l 7
?3940
5.7321

0 6 55?0
1 2
0l6970
1 7
2.3865
5. 69 59
4
0.71680
l 2
0.17250
17
P.3792
5.66 0 3
-
0.4 6 0 70
1 2
0. 1 1 170
17
2.3713
5.6247
4
0.13200
l 2
0.31160
1 6
2 364 ?
5.0807
-
Oc 17460
1 0
0.31450
1 4
2.3697
5.6 * 6 8
-
0.15160
1 2
0.35080
1 6
2. 35 26
5.5371
4
0 5 3 0 5 0 0
l 2
07 4 70 0
16
2.3455
5.50 1 3
-
0.10770
1 0
0. 2 7 260
1 4
2.4492
6 OC ? 4
4
0.11 800
1 1
0.30720
1 5
2.44C7
5.V567
-
0.0 3 7C0
1 1
0.1 6320
16
?4324
5 9lQ0
4
0. 2 1 C10
1 2
0. 5 36 30
1 6
2.424 7
5.3784
-
0 0 4 746 0
1 ?
0.12000
17
2.4164
5. 83 96
4
:75270
1 2
0. 1 8940
1 7
2.4036
5.801*
-
3.62560
1 2
0.20 340
1 7
2.4 009
5.7642
4
0.55490
1 2
3.13620
l 7
2.39 32
5.7263
-
C 1 f 690
1 2
0. 39 120
1 6
2.395?
5.6 9 c. _
4
0.2146Q
1 0
0.51660
l 4
2.39 1 4
5. 74 54
4
Co 185 40
1 2
0. 4 4 21 O
l b
2.373b
5 # b 31 1
-
v374:0
1 2
0. 9 8 37 0
16
2.3661
5.5986
4
C 0 2 7 1 8 0
1 2
0 .53520
l 5
?3590
5.563o
-
Oo 3 45 00
1 0
0.92 330
1 4
24647
tm07f 7
4
0. 3.7 >2 0
1 l
0.99900
1 5
2.456:
6. 035^
-
j. 1 54^0
1 2
0 4 0 b 5 0
16
2.4475
6 9 9 1 7
4
0 .4 ?*oa
1 2
:.i 1 130
1 7
2.4392
5.96 C d
-
0.77370
1 2
0.20050
1 7
2.4311
5.9107
4
Oo 036 90
1 P
C. 2 3 90 0
1 7
2.4231
5,8713
-
: c 6 84 ao
1 2
1 7 290
1 7
2.4151
5 d3 2 :
4
0.21179
1 2
j .5 2 97 0
16
2.4067
r'. 7 8 99
-
: 0 7 7150
0 9
0.19130
1 4
2 -,264
5.9347
-
: ? : 7; j
1 2
0.5 1 060
16
2.3940
5 7 7 7 7
4
0 0 4 ? 3'0
l 2
: .1 0 30 0
l 7
7.39 70
5596 I
-
0 ? 35 9.0
1 2
0 0 9 6 9 0
1 C
2. 3795
r 6 r.
4
0.7:ic 0
l 1
3.72010
1 5
2 J 7 0 3
5o 6 1 £:
-


90
It was difficult to maintain stable Cl^- signal levels. The
total pressure at the ionization gauge drifted markedly. This
variation was the result of the fluctuation of the chlorine delivery
or the nitromethane delivery with equal frequency. After the sample
pressures were continuously monitored and adjusted for periods of up
to three hours, the drift was reduced and slowly varying Cl^" signals
were obtained.
There are discrepancies between the results of the molecular
chlorine anion formation behavior observed in this study and previous
studies. Cl2 has been generated by electron attachment at total
pressures as low as 4x10 ^ Torr at electron energies of 1 to 2 eV
(75). The resultant Clions exhibited lifetimes up to one second in
the cell of an ion cyclotron resonance mass spectrometer. This lifetime
is significantly longer than those observed in this study; however,
this may be attributed to the relatively high pressures used in this
-5
investigation (total pressure on the order of 10 Torr). Generation
of Cl2 from carbon tetrachloride has been reported with an appearance
potential of 2.3 eV in a time-of-flight mass spectrometer (76). The
inability to generate Cl2 from CC1^ in this study could not be
attributed to a single instrumental parameter, but is likely the result
of some combination of electron energy distribution aberrations,
trapping imperfections, and relative detection sensitivity.
A number of investigations have been performed on NC^- due to its
possible atmospheric importance and the chance of overlap of its photo
detachment spectrum with the solar radiation spectrum (77-84, 85, 86).


55
Microcomputer Interface Hardware
The limitations of the KIM-1 microcomputer's input/output
architecture place constraints on interface design. The KIM-1 is
restricted to digital input/output with a maximum of 8 bits transferred
per input/output operation. Consequently, external analog signals
to be transferred to the microcomputer memory must be converted to
digital format. The KIM-1 is a TTL level microcomputer which requires
that valid TTL levels be provided as inputs. These constraints are
easily attended to; thus the interface design, although dependent on
the KIM-1 input/output architecture and implementation, is more
stringently defined by the nature of the external signals.
For a typical pulsed ion cyclotron resonance (PICR) experiment
the values to be measured are zero baseline, the marginal oscillator
output in the absence of resonant ions; ion baseline, the marginal
oscillator output in the presence of resonant ions; laser level,
the marginal oscillator output after laser irradiation of the
resonant ions; laser energy values, the output of the photodetector
with and without laser irradiation. Each of these signals is an
analog voltage level and two separate channels to the A/D converter
are required for the marginal oscillator and photodetector outputs.
Since the A/D has a single analog input these signals are multiplexed
to that input under software control. The sequence of control
functions resulting in the input of converted marginal oscillator
and photodetector levels may be summarized for a general, two-channel
read.


Initialize
Registers
Calculate
Average Zero
Base]ine


52
capacitor is charged and the trigger pulse, normally the free pulse
or a microcomputer-generated pulse, is activated to fire the laser
immediately prior to ion detection. The digital pulse sequence is
repeated for the required number of laser shots. Marginal
oscillator and photodetector data are recorded for each laser shot.
The laser trigger is deactivated and with the ions still resonant the
pulse sequence repeats until sufficient marginal oscillator level and
photodetector level measurements have been obtained. Finally, the
ions are tuned off resonance and the marginal osci llator zero level
data is recorded for several pulse sequences. This scheme allows for
the correction of zero baseline and resonant ion baseline drifts.
Microcomputer
The resonant absorption of the output of the marginal oscillator
is detected as a change in the analog voltage level of the marginal
oscillator frequency envelope. To convert this analog signal to a
digital signal suitable for analysis by a digital microcomputer a
data conversion/collection system has been developed. The system is
comprised of a microcomputer and an analog to digital (A/D) converter
as well as input signal conditioning elements and programmable
data routing components. The microcomputer architecture is addressed
to the degree to which it has influenced the interface design and
operation. The description of the interface is functional and non
specific with regard to chip designation. The operating system
software is summarized by functional unit as it would be encountered
in the course of normal operation. Analysis of the current status


Appendix Va. Potential Energy Curves (con't)
R PE
0,20 746 17630
0 1
0.5 2 0 l 6- 2 9 5 4 >
0 4
0.2031638590
01
0,5186504049
7 4
0 ?0 0 1
0. 5 9906' 994')
C 4
0,8005801410
0 1
0.4594004940
0 4
j. 2 1 O 9 47 380
01
0.4 896629940
0 3
0.211 01400 ID
: i
0.4 79 35 0 45 40
04
0.21 1 7 382 12 0
0 1
0 ,-4 6,99629540
04
'.2124876630
0 1
0. 460 OC 04 94 0
04
O.2132026550
0 1
0.44 9 9629940
7 4
0. 2 1 39 4255 00
: i
0 o 4 3 9 3804640
0 4
. 314 69 06 6 3D
0 1
0,4 29 6629 9 40
04
0.2154443910
0 1
0.4194004640
09
.9 2162051 17)
01
0.4 0 9 06 2 9 94 D
04
'c 2 16 9 732 700
0 t
0.3 9965 04 940
0 4
0. 21 7 7492 060
0 1
0.78 3 16 29 9 40
Z ~~
0.213 5337 1 70
0 1
0.377600494D
04
0-. 2193270 1 7 0
0 1
0.7f 6 96 29940
04
0. 220 1 297370
01
0,35 6 25 04Q4D
r\
-.32 09426 2 V0
0 1
0,34 5 468 9 94 0
4
0. 22 1 ''662 1 2 0
0 1
0 o 7 34 600 49 40
0 4
o 2 226 0 12 6 5D
0 1
0.3236629940
C ;i
Oc 223 44 82 7 8D
0 l
0. 3l 265 0 4 940
04
0,2243090190
0 1
0,30 1 5629 c,4)
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22 5 1 335490
01
0.29 0 40 4 94 0
04
0 226 0 732 040
0 1
0 7 7 9 1 6 2 5 4 o
04
0. 226 9791 750
0 1
0.8- 7 450 4 940
<7 /,
. 2 279 02 7 6 ID
0 1
0.2564629940
04
0 2238 454 260
0 1
0,86500 04940
Q i.
% 2293083190
01
0.233 4 62994 o
/> /.
Oo 27079481 ID
0 1
C. 2?1 85 04 040
5 4
C: 231 8055 JoO
0 1
0,2 1 2 16 .29 9 40
04
* .2 323 434 5 20
01
0. 1 9.340 0494D
04
0.2330 1 14 070
0 1
0.1 36 56 299 40
04
0. 2350 1 27 380
0 1
0.1 74 65 04 94 0
0 4
0. 23 6 1 81 3 950
0 1
0. 1 62 662 9 640
04
0, 237 332 1 07 0
4 1
0.15060 4940
0 4
23356 Ct 24
0 1
0,138'+629940
04
J 2 398 44 04 5Q
0 1
0.12625'4940
04
0.2411913110
0 1
0.113962004D
04
.'. 24261 39520
:i
0. 1 0 1 60 0 4 94 0
04
0;244l279640
0 1
0,39162 99380
0 3
0. 245 7529 970
0 1
0,7< 650 +v 3 8)
-7
R
PE
Oo
24 75 194 1 40
0 1
Oo
2494753070
0 1
O
251 69 87 460
01
Oc
2543436530
0 l
Oo
257 6033 900
0 1
z
260 2744 450
0 1
0 o
266 3027 75D
0 l
Oc
272470723D
01
o.
2750770360
0 l
0,
278 8242 04D
0 1
0 o
2817 541560
01
0 o
284 2652 790
0 1
0,
2865115330
0 1
Oc
288571 7390
01
J o
2904926 17D
0 1
Oo
2923045740
01
0 .
29402870 ID
o i
0,
2956303360
0 l
0.
297271 0530
01
.} o
2 333 0963 50
0 1
c,
3003 036280
0 1
0 .
30 1 7 588 2 50
0 1
0 0
3C .3 1 796 040
0 1
Oc
3045701520
0 1
0 .
3059338830
0 l
0 ,
3 0 7 2 7 36 6 7 O
0 1
0.
3035 920 2 10
0 1
J o
30989 11 3 ID
0 1
0 ,
311 1729 2 1 D
0 1
3 1 2 4 3 9 0 9 50
01
0 o
3 l 3 6 9 1 1 7 0 D
0 1
Oo
31 49305 1 1 O
01
0 .
31 61 58344D
0 1
Oo
31 73757850
0 l
0,
31 85838490
01
Oo
31 97834 66D
0 1
0, 3209754910
0 1
0.
322 1607 1 30
01
0 *
3233396650
0 l
0 o
3245136270
0 1
>
3256826 350
0 1
0-)
326 .84 7ci 86 n
0 1
0.6406299360 O
0 5 1 4 0 0 4 9 3 30 0^
0 3 8 6 6 2 9 9 3 3 0 0 3
03 6 85 04 93 SO 0 3
0 1 2 9 6 2 ra 9 3RD 03
0.649 1 1 1 8 770 02
OcO
0.6491118770 "0
0.1296299380 03
0.26850 4 9 38D 0 3
0.3866299380 0 7
0. 5 140 0 49 8 30 C 3
0.6406259330 03
0.766504933 ') 0
0.8Q1 62 9 93 3 0 3
0.
1016004940
Z
0.
1139629940
:4
0 ,
1262504940
c ^
0 .
1334629940
j i
0.
1^060 04 940
>j -4
0 c
la 26629940
z u
0.
1746504940
Q4
0 .
1 86. 56 2 98 40
0.1984004940 Ci
0.21016 29 940 0-*
0.22 1 86 049 40 4
0.233462994> 04
0.2 4 5 0C C 4 c- 40 0 4
0.3564639940 04
0. 26 7 8 50 4.94 0 04
0.2 7916 29940 04
0.29040:4940 04
0.3015629940 04
0.3126504940 04
0.3236629940 04
0.334600494D 04
0.3454629940 04
0.356250494) 04
0.3669629940 04
0.3 7 7 6 0 0 4 o 4 D 0 1
0. 3681 62 9940 0^
0.30686'4=40 '4
oo
o


in ion intensity were 10-15 mj for wavelengths correspondng to a
maximum in the absorption spectrum of the ion.
In addition to observing the decrease in Cl2_ signal intensity
upon irradiation, fragment/product ions were sought. In the case of
Cl, the ion cyclotron resonance mass spectrometer could be tuned
to the ion at a detect delay time at which the Cl signal was measurabl
The detect aperture was then returned to the time at which the Cl2
reduction was observed; however, the Cl resonance conditions were
not altered. Subsequently, photo-produced Cl or Cl generated
from some photo-produced intermediate could be measured. A photo-
induced spectrum of Cl is presented in Figure 20. Other product
ions were sought as well. CH3N02C1~, N02cr, NOCI ~, CH3CT, and
CH^Cl were possible product ions that were sought at each peak of
Cl2" photodestruction. Since these ions were not present in the
original negative ion mass spectrum of the nitromethane/chlorine
mixture, the procedure for determining their presence was more
involved than those for Cl. While photoreduction of the Cl2"
signal intensity was taking place, a slow, magnetic field scan over
0.050 Tesla and centered at a possible product anion's nominal,
resonant magnetic field strength was conducted. These measurements
were performed for each postulated anion at each wavelength where
a significant reduction in the Cl2' intensity was observed. None
of the proposed product anions with the exception of Cl was
observed.
The energy range covered in the photo-excitation experiments
was limited to 0.39 eV (3170 cm ^). The short wavelength limits


TIME (ms)
INTENSITY


INTENSITY
001


REFERENCES
1. R. Wildt, Astrophys. J. 89, 295 (1939).
2. W. Gerlach and F. Gromann, Z. Phys. 18, 239 (1923).
3. L. M. Branscomb and B.E.F. Pagel, Roy. Astronomical Soc. (London)
Monthly Notices, 1_18, 258 (1959).
4. Ya. L. Al'pert, Radio Wave Propagation and the Ionosphere
(Consultants' Bureau, New York, 1963), p. ITT
5. E. E. Ferguson, Kinetics of Ion-Molecule Reactions, edited by P.
Ausloos, NATO Adv. Study Inst. Series B (Plenum, New York,
1979).
6. E. E. Ferguson, F. C. Fehsenfeld and D. L. Albritton, Gas Phase
Ion Chemistry, edited by M. T. Bowers (Academic, New York,
1979), p. 45.
7. a. A. N. Hayhurst and N. R. Telford, Combustion and Flame 28,
67 (1977).
b. A. N. Hayhurst, D. B. Kittleson, and N. R. Telford,
Combustion and Flame 28, 123 (1977).
c. A. N Hayhurst and D. B. Kittleson, Combustion and Flame 31,
37 (1978).
8. G. Moreau, Compt. Rend. 148, 342 (1909).
9. D. K. Bohme, Kinetics of Ion-Molecule Reactions, edited by P.
Ausloos, NATO Adv. Study Inst. Series B (Plenum,
New York, 1979), p. 323.
10. G. S. Aravin and E. S. Semenov, Combustion, Explosions and
Shock Waves T5_, 589 (1979).
11. Ch. K. Rhodes, Excimer Lasers, Topics in Applied Physics,
(Springer-Verlag, Berlin, 1979) Vol. 30.
12- a. S. K. Searles and C. A. Hart, Appl. Phys. Lett. 27_, 243 (1975).
b. R. Burnham, D. Harris, and N. Djeu, Appl. Phys. Lett. 28,
86 (1976).
205


72
address 42 should be set to 02 and following the fourth complete
sequence set to 03. The initialization routine resides at hex
address 0800. To run the initialization routine, 0800 is keyed to
the address display and GO is keyed. The remaining critical registers
are set and the microcomputer enters the nc operation (NOP) loop
until interrupted by an IRQ or keypad interrupt (Figure 10). The
function of each register is given in Appendix II.
The first IRQ enters the main control program at A (Figure 11).
The initial value of the ID register (hex address 0000) is 0,
consequently the B branch (Figures 11 and 12) is taken. The interrupt
vectors are altered to point to D to protect the zero baseline
counters which are subsequently set. The zero M0 level is read and
the result summed into the initially zeroed registers OF, 10 and 11.
The zero baseline counters are decremented. If less than one half
of the zero baseline readings have been taken there is a simple return
from interrupt (RTI), returning the KIM-1 to the NOP loop. Subsequent
interrupts enter the main control program at D until one half of the
zero baseline measurements have been accumulated. Then, interrupt
vectors are changed to point to A, the ID register is incremented
and a programmable interrupt request (PIRQ) flag set, prior to an RTI.
As before the RTI returns the system to the wait loop, however, since
PIRQ is the test value of the loop, the system will "fall through"
the loop. The test of the total zero baseline counter will be
negative at this point. A branch to the read-only memory (ROM)
operating system is taken which displays "0001 xx". This is the


Figure 12. Baseline MO Data Flowchart.
The functions required for baseline
data collection are indicated.
A single decision is made to
determine when ions should be tuned
into resonance which when true
prompts the operator.


Appendix III. Microcomputer Programs (continued)
Main Program (continued)
Address Label Op Code Mnemonic
Comment
A9 10
LDA #10
64 OD
ADC OD
09B9
85 OD
STA OD
A9 02
LDA #02
85 40
STA 40
E6 12
INC 12
09C1
A5 12
LDA 12
C9 01
CMP #01
FO C6
BEQ C6
C6 12
DEC 12
C6 12
DEC 12
A5 OD
LDA OD
E9 20
SBC #20
85 OD
STA OD
09D1
A5 07
LDA 07
DO 03
BNE 03
4C 73 09
JMP 0973
4C 69 09
JMP 0969
09DB
20 B1 OB
JSR 0BB1
20 52 08
JSR 0852
09E1
20 50 OA
JSR 0A50
20 58 08
JSR 0858
20 50 OA
JSR 0A50
Alters Base Address to that
for Photo Data 100
{- Sets Laser/ICR Flag to Laser
Sets Laser/M0 Avg. Flag to
Laser
Returns to Avg. Laser
IF Resets Laser/MO Avg. Flag to 0
Checks for final laser shot
Sets up for final four 100's
Jump to change IVs to ID
Jump to Laser Trigger Subr.
Obtain and store laser MO and
Photo data


18
potential lines at frequency n eliminates the mechanism of drift
loss of ions.
The remaining component of the electric field, E is of the
form (47)
= -Kz k (8)
where
K = 2(Vr VQ)e/a2.
Substitution of this expression into the z-component of the Lorentz
force law (2) yields the equation for simple harmonic motion of a
charged particle along the magnetic field lines
vz = -y
(9)
where w-p = (qK/m)2. Oscillatory motion along the z axis is imposed
upon ions whose initial total energy, kinetic and potential, is less
than the trapping potential well. A side-effect of the electrostatic
restriction of the ions in the z-directi on is a shift in the observed
cyclotron frequency from the natural cyclotron frequency, to. The
effective cyclotron frequency, uj is (47)
aB
no)
Clearly, alteration of the trapping potentials results in a shift
of the cyclotron frequency unless compensated with an appropriate
alteration of the magnetic field strength.
Typical values of the ion motion parameters for an ion of mass
number 70 and unit negative charge in a magnetic field of 0.70 Telsa
with the standard plate potentials are


Appendix Va. Potential Energy Curves (con't)
R
PE
, 241 8 3 89 26")
: i
C-, 51 5 46 -38760
04
1 74 3 30
0 1
7 5 7 9 1 6 71 2 50
3 4
3 2538267 3 3
3 1
0 09r. 1 70 2 8 039
0*
' 251 6. 373 7 4 0
Cl
0 0 4i; 74250
04
3 3252 3 4 94 3 30
3 l
O. l CO 6 3 33 8 60
05
0 25 3 3o37 90 )
0 1
3.1.' 2 8 356 370
C 5
. 2553 251 £30
3 1
0. 1C 63165 689
05
2 c 25 5 7 365i6 o
3 l
3 l 1 3 5 3 70'- j.O
f, c:
J j
3 t 261 2 4 78 7 7 3
01
3.1 1 P 73 52 83 0
35
.2^7 392 3 30
: i
3 o 1 2 3 763 7 9 70
V ~J
3,26 pi 70* 11 )
0 1
C ,12 6 6 5 5 P, 5 0 0
3 -
3o 25 36 319 530
0 1
0.13341 C8559
05
jo 27 1 3 9 3 3 2 5 3
3 1
3.1380251590
05
3 27355463? 3
0 1
-.1424555c19
9S
i 2 7 6 3 1 60 4 90
01
0. 1 4 66 2122 99
05
J ~ 77.6 4 7?. i 10
3 1
3o 1 0 096 90 270
05
Cc 2 3 053 87 77''
0 1
J 1 0533 44 3:1
* r.
23 7 4 3 01 3 60
3 1
1539 1 35460
05
3 33 5 86 14 9-3 0
3 1
jol' 268 9 2 8 7''
35
288 32286.30
3 !
0.1652384*5'''
03
J 25 3 7843 220
0 1
i. l 6 56 8 23 2 30
3 5
C 2 5'3 2 455 34 =
0 1
Jo 172982425 '
3 5
295 7 065 460
: i
3 1 761 40661 >
05
3 . 79 3 l 68 030
3 1
0. 17 0 1592969
0 rj
3j 300 625- 70 )
0 1
J .1 34 34 76 >
0 7
7.377 051 0 320
: i
2. 184 7 8 70 959
-\r
3 305552394O
0 1
0, 18 7 40 13 88 9
0 5
3 3 7 3 0 1 37 5 70
C 1
0.18 986 78110
35
'5 3 1 7 4751 190
0 1
3. 1 = 224 756 .89
: a
O' 31 3 5364310
0 1
0 1 94*555680
0 8
7..31 3978 4 30
3 1
0. 1 5 66 C3 91 OO
06
Jo 3 1 7 8 592 05!)
3 1
3.19?6053620
0 5
0. 32)3205670
0 1
0.2 C 0496 3 4 3 16
-> rr
?. 3 2 7 3 15 2 90
3 1
0.2) 22 773 1.20
05
3 32524329 1 0
C 1
0.20 39527 510
05
i. 327 7046530
31
0.2055261520
35
35 33 3 166 7 150
3 1
0.207001004D
0 5
Do 3326273 779
0 1
0.2 3 3 3607860
0 8
' 33508374 30
3 1
3.2056639600
05
."o 337550 1 C-O
3 1
3.21 086 6949-0
05
3 3 4 0 C 11464 7)
01
0.2 1 1 5.941 48 0
05
, 3424 728.260
: i
3.21 3 01 75C30
05
R
PE
0.-> 344 5 .3-4 1 3 30
0 1
0.2 135 7 35 1 O''
? 347 39555 3D
0 1
0.2148542230
0 34 38569 t 20
: i
3.215 66 3 2 1 46
0- 35 2 3 1 82 74 0
0 1
0 O 2 1 64C 36 O'-9
3.354 7796 360
0 1
0.21 7 0 78461 ..
3 357240998(3
3 1
3,2176507550
0. 35570236 10
3 1
0.2182*34030
3.367i637230
31
0.2187392420
O'364625C350
0 1
3.21=1810360
% 3670864470
01
0.2155714690
Do 36 95 4 78 390
3 1
0.2 1 5513 1 5 30
0, 372 0 091 7 1 3
0 1
0.220 20 86 C p >
3.37 44705 3 30
0 1
3. 22)460253 3
Oo 3769 31895 )
0 l
0.22067057 70
3, 375 39 3? 570
01
C.22 0341753 0
1.3819546l90
0 1
3. 22 357603 7 1
0:. 384 3 156 8 1 0
0 1
0.2213755660
3o 3867 7 734 4
0 1
0.221 14240 C
)o 3892387360
3 1
3, 22 1 1785220
Oo. 351 7 000630
0 1
3.221 18 58 4 8 0
0.39416143 00
0 1
0.22 1 l 662 C60
3 3 3966 227 920
0 l
0.2?i1213620
Oo 3990841 540
01
0.2213530076
3.40 1 5455160
0 1
3,220=62764'
0,404 0 36^ 78 3
0 1
0 o ? ? 0 f? 5 ? 1 4 >
3. 40 6.4682 400
01
0*220 72 2756 =
3. 403 9 296 C 20
3 1
0.2205 75 90 CO
Oc. 4 1 1 3 509650
0 1
0*223 41 29 7 33
4138523270
01
C.223235272o
0,41531 36390
0 1
0.^230440320
0,41 8 7 750 5 1 3
0 1
0.21984042=0
0.421 2 364 l 30
0 1
0.21 5 62 55 83 o
3, 4236 977750
0 1
0.2 1 94C 35600
o94261591570
01
0.2191663733
0o 4 28 62 04 990
0 1
0. 216923573.3
0,4310318610
0 1
3.2 1 66 742 79=
3, 43354322.30
01
0.213413153"'
0,436 3 045860
0 l
0.21315 3 5 =0
0, 438465548L)
0 1
3.21 7 8 5 7 =7,3
1.4 4 39 273 1 OO
3 1
0.217619071O
3,4 433386 72 3
0 1
0.2173449043


53
of the data conversion/collection system delineates its limitations
and suggests refinements to attain 'key-on' operation. Experimental
data was analyzed manually to verify the system performance.
Microcomputer and Modifications
A KIM-1 microcomputer served as the control element for the data
conversion/collection system (73). The KIM-1, a single-board, 6502-
processor-based microcomputer, has integrated input/output hardware,
hex keypad, system ROM (read-only memory) and IK (1024 words) of RAM
(random-access memory). The structure of the input/output hardware as
to the available control and data lines requires further mention.
The KIM-1 can respond to an external event in a programmed fashion.
This implies that the microcomputer acknowledge and correctly identify
an external event. Recognition of ari external event requires a
combination of hardware and software. The level of the interrupt
request line (IRQ) is altered synchronously with the external event
and interrupts the processor upon completion of a logical machine
step. Critical status registers are preserved by the IRQ software
residing in ROM. Control is transferred to a program located through
the interrupt request vectors (IV) which have been preprogrammed
by user code to select the correct response to the external event.
Once the external event has been correctly handled the critical
registers are restored and operation is resumed from the point of
interrupt.
An interrupt request is an externally generated request for
service. The servicing of the interrupt involves data transfer to the


182
equilibrium mixture was being inlet to the ion generation
region (117). A 50-50 mixture of bromine and chlorine was made up
in the standard manner. The sample was then irradiated for 2 hours.
As noted in the main text, no improvement in the BrCl" signal
intensity was observed.


51
The >2 pulse is used as a gate for an external gateable rf
oscillator whose output is then applied to the upper cell plate for
excitation of ions which are nonresonant at the selected magnetic
field and marginal oscillator frequency. This excitation serves two
purposes. At low voltage levels excitation increases the ion
translational energy while trapping remains efficient. At high voltage
levels (2 excitation ejects the nip resonant ion from the cell (72).
The free pulse is a one millisecond width, variable delay pulse
designed as a general, external trigger pulse. The free pulse operates
on TTL logic levels. It has been used as the synchronous trigger
for the flashlamp-pumped dye laser sparkgap discharge circuitry.
Initiation of a complete pulse sequence can be accomplished in
three different modes: single cycle, fixed rate,or automatic
operation. The single cycle mode results in one complete pulse
sequence occurring whenever a front panel pushbutton is depressed.
Fixed rate mode causes the complete pulse sequence to be repeated at
a selected time interval which ranges from 20 milliseconds to 5
seconds in a 1-2-5 sequence. The automatic mode starts a pulse
sequence 175 milliseconds after the quench pulse terminating the
preceeding sequence.
A typical pulsed ion cyclotron resonance (PICR) experiment
proceeds in the following manner. With no resonant ions, the previously
set digital pulse sequence is performed to obtain a zero level
for the marginal oscillator signal. Ions are then tuned into
resonance by an appropriate adjustment of the magnetic field.
Marginal oscillator and photodetector levels are recorded. The laser


Figure 26. Acetophenone Signal Intensity.
The optimum acetophenone signal was
obtained with OH as the precursor
for the spectrometer conditions:
sample pressure, 2.0x10"* Torr,
(1/10 mixture of acetophenone to
H?0), electron energy, 7.42 eV,
detect delay, 170 msec, and detect
width of 3.0 msec.


109
R2(V)
S(V,K) = V/ (V- U (R ) dR (51)
RX(V) R
The potential derivatives with respect to V and K of the simplified
form of the action integral are
f = § = h (R2-Rx) (52)
9 = § = h These equations may be evaluated for R1 and the classical
turning points.
Rl,2 (V) = + (54)
Both f and g are determined as functions of V from the complex
form of the Klein action integral
f (V) = (8n2v)~h
r
/
o
dl
J V-E(I,o)
(55)
g (v) =
( 8 ji p
2)%
r
o
B y (I) d I
7v-e(i,0)
(56)
where BV(I) = BeCe('h") + and other constants are defined as
usual. The method evaluates numerically the f(V) and g(V) and
determines the classical turning points.


Figure 17. Negative Ion Mass Spectrum for a Chiorine/Nitromethane Mixture.
The mass range is 10 to 100 amu. Total sample pressure of the
1 to 2 chlorine/nitromethane mixture was 2x10^ Torr. Electron
energy was 2.5 eV. Detect delay time was 70 ms. The Cl2 peak
is weak at this detect delay, but increases with increasing
detect delay.


Relative Cross-Section (Arb. Units)


13


LIST OF FIGURES
Figure Page
1 Trochoidal Trajectory of a Charged Particle
in Uniform and Static Crossed Electric and
Magnetic Fields 13
2 Trapped Ion Cyclotron Resonance Cell Schematic ... 16
3 Time-Dependent Radii for Non-Resonant Particles. . 24
4 GLC Circuit Emulation of ICR Detection 28
5 Trapped Ion Cyclotron Resonance Cell 33
6 Schematic Diagram of the Digital Pulse Electronics 36
7 Vacuum System Schematic 38
8 Dye Laser Apparatus and Orientation 43
9 A Typical Pulsed ICR Experiment Pulse Sequence ... 48
10 Operator/Microcomputer Interaction Flowchart .... 61
11 Main Program Branch Flowchart 63
12 Baseline MO Data Flowchart 65
13 Resonant Baseline Data Flowchart 67
14 Laser Status Flowchart 69
15 Microcomputer RAM Memory Map 71
16 Negative Ion Mass Spectrum of Nitromethane 84
17 Negative Ion Mass Spectrum for a Chlorine/
Nitromethane Mixture 87
18 Time-Dependent Mass Spectra of the Major Peaks
of a Chlorine/Nitromethane Mixture 89
vi i


Figure 11. Main Program Branch Flowchart.
The program flow about the primary
decision is shown. Primary decision
is the nature of the data to be
obtained at the next interrupt. A
test value of 0 corresponds to
baseline data for the marginal
oscillator (B). Test value 1
corresponds to ion baseline data
for the marginal oscillator and
the photodetector (C). Test value
2 corresponds to laser MO and photo
detector data.


Figure 24. Photodetachment Spectrum of BrI.
The optimized BrZ signal photo
detachment was observed from 470
nm to 500 nm. The structure apparent
in the cross-section is not explained
by the expected cross-section behavior
near threshold.


Figure 5. Trapped Ion Cyclotron Resonance Cell.
Six dc plate potentials produce the
necessary electrostatic potential at
the cell interior. Upper and lower
plates both have multiple roles. The
upper plate is used for o>2 excitation
and quenching of ions. The lower plate
is the marginal oscillator input/detect
plate. The grid, filament and collector
comprise the electron beam generation
system.


56
The KIM-1 will be in a no operation (NOP) loop which can only
be exited via an interrupt request or a keypad interrupt. An IRQ
transfers control to programs addressed by the interrupt vectors,
which contain either system start-up or program-defined values. What
ever the actual program location accessed, the scheme of the interrupt
service requires a resetting of the interrupt vectors in preparation
for an ensuing interrupt and the updating of running counters which
identify the type and count of marginal oscillator and photodetector
data on line. The transfer of the marginal oscillator or photodetector
voltage via the A/D to the KIM is controlled through the microcomputer
PAD (PA0-PA7) via four 3-bit, 8-bidirectional-channel multiplexers
(MUX). PA0-PA3 are always configured as KIM-1 outputs. PAO controls
MUX inhibit lines and PA1-PA3 constitute a 3-bit, binary word which
selects the MUX channels. The input to a MUX is transferred to the out
put on an inhibit low with the transfer direction determined by the
PADD status bits. PA6 serves as the channel select line for the 1-bit,
2-channel (A/D input) MUX. A clocked latch intervenes to preserve
the status of the select lines of the 2-channel MUX until it is
reselected. PBO is used as the software generated clock line for the
clocked logic. (PBO replaced PA4 which was defective on the KIM-1
used). A logical one on the 2-channel MUX select line transfers the
photodetector level to the A/D input, a logical zero selects the MO
1evel.
The free running A/D requires 25 milliseconds to convert the
input to a stable digital output. A timed loop using the KIM-1
programmable counter allows for the conversion time. The 12-bit A/D


25
at the drift frequency, ft. This produces an oscillation of the
population of guiding centers between a circular distribution and an
elliptical distribution at twice the drift frequency, which for the
numerical example above corresponds to 428 Hz. However, the duration
of the electron beam pulse, ~25 ms, is longer than the period of the
guiding center drift oscillation, -2.3 ms,and the ions will be
uniformly distributed along the elliptical orbits if ion formation is
constant during the electron beam pulse. Therefore, ions formed at
any instant exhibit a shifting population distribution but the total
collection of ions is uniformly distributed along elliptical drift
lines.
Ion Detection
Power absorption by an ion from an amplitude limited rf
electric field is the basis of ion cyclotron resonance detection.
Obviously the means for generating a suitably stable rf field and a
means of detecting absorption of the field are required. Both of these
functions can be accomplished with a marginal oscillator detector.
Marginal oscillator circuit applications in ion cyclotron
resonance detection (50) are completely analogous to their earlier
application in nuclear magnetic resonance (nmr) detection (51).
Consequently, ion cyclotron resonance marginal oscillators have evolved
with few modifications from nmr marginal oscillators. Two
alterations of the basic marginal oscillator circuit serve to adapt
it for use in a pulsed mode (52). First, the addition of a limiter
in the feedback loop of the oscillator insures reliable low level


Table 8.
Correlation of
with Calculated
the Observed Peaks (x, Tex
Transition Energies (Tca-|(
p) in the Cl2
y and Franck-
Photodetachment Spectrum
Condon Factors
X
T
exp
(V*, V**)
"^calc
Franck-Condon
Overlap Factor
(nm)
(cm"!)
(cml)
539.5
18535
(16,6)
18527
0.4067 E-l
533.5
18744
(15,6)
18739
0.4757 E-l
527
18975
(14,6)
18954
0.4426 E-l
521
19193
(13,6)
19172
0.3429 E-l
516
19379
(12,6)
(22,10)
19393
19369
0.2265 E-l
0.1401 E-l
496
20161
(11,7)
20138
0.2645 E-l
490
20408
(12,8)
20430
0.4769 E-l
486
20576
(16,10)
20578
0.2682 E-l
482
20746
(20,12)
20751
0.2742 E-2
476
21008
(14,10)
21005
0.3784 E-2
473.5
21119
(9,8)
21110
0.1761 E-l
471.5
21208
(20,13)
21237
0.6497 E-l
463
21598
(23,15)
21610
0.1291 E-l


131
lack of resolved structure which can be correlated with the internal
state of the ion precludes an estimation of the adiabatic electron
affinity for the bromine molecule.
Bromine Monochloride Molecular Anion
Formation of BrC1~
Bromine monochloride negative ions were produced from the same
mixtures of chlorine/bromine vapor-nitromethane used in the study of
bromine photo-excitation. A mass spectrum with BrCl at near peak
intensity is shown in Figure 25. Clearly, the signal level of BrCl"
was not satisfactory for photo-experiments considering the apparent
errors in the cross-sections observed for Cl^ and Br^" which were
produced and detected with much greater signal-to-noise characteristics.
Several attempts were made to increase the BrCl" intensity.
Variation of the ratio of partial pressures of bromine and chlorine
at the cell showed only deleterious effects when altered from a ratio
of one. Steps were taken to insure that the initial mixture of
bromine and chlorine was in equilibrium with bromine monochloride (117,118).
This did not improve the BrCl" signal intensity.
Analysis of BrC1~ Results
BrCl" has been observed as a product of the reaction of Cl^-
with bromine. This reaction was reported earlier and a rate constant
was determined (79). The value of this rate constant and that of
competing reactions is presented in Table 12. Evidently BrCl" will
be generated as a minor species regardless of the variation of
neutral gas pressures.


210
86. J.H. Richardson, L. M. Stephenson, and J. I. Brauman, Chem. Phys.
Lett. 25, 318 (1974)
87. R. M. Hochstrasser and A. P. Marchetti, J. Chem. Phys. 50, 1727
(1969).
88. G. Herzberg, Spectra of Diatomic Molecules (Van Nostrand,
Princeton, 1950):
a. 195
b. 519
c. 215
d. 512
89. B. A. Huber, P. C. Cosby, J. R. Peterson, and J. T. Moseley,
J. Chem. Phys. 66, 4520 (1977).
90. J. A. Stockdale, F. J. Davis, R. N. Compton, and C. E. Klots,
J. Chem. Phys. 60, 4279 (1974).
91. I, D. Roberts, R. Stewart, and M. C. McGovern, Organic Chemistry
(Benjamin, Menlo Park, 1971), p. 25.
92. S. A. Sullivan, B. S. Freiser, and J. L. Beauchamp, Chem. Phys.
Lett. 48,294 (1977).
93. W. C. Tam and S. F. Wong, J. Chem. Phys. 68, 5625 (1978).
94. R. E. Fox, Phys. Rev. 109, 2008 (1958).
95. T. L. Gilbert and A. C. Wahl, J. Chem. Phys. 55, 5247 (1971).
96. P. W. Tasker, G. G. Balint-Kurti, and R. N. Dixon, Molec. Phys.
32, 1651 (1976).
97. L. Andrews, J. Am. Chem. Soc. 98, 2147 (1976).
98. C. J. Delbecq, B. Smaller, and P. H. Yuster, Phys. Rev. Ill,
1235 (1958); C. J. Delbecq, W. Haynes, and P. H. Yuster,
Phys. Rev. 121,1043 (1958).
99. D. L, Griscorn, J. Chem. Phys. 5]_, 5186 (1969).
100. J. H. D. Eland, Photoelectron Spectroscopy (J. Wiley and Sons,
NY, 1974).
101. P. M. Morse, Phys. Rev. 34, 57 (1929).
102. H. M. Hulburt and J. 0. Hirschfelder, J. Chem. Phys. 9, 61 (1941).
103. A. L. G. Rees, Proc. Phys. Soc. 59, 998 (1947).


151
cross-section of the bromine anion precludes the estimation of a
reliable electron affinity. The experimental difficulties of operating
with halogen compounds were marked and are reflected in the data;
however, improvements in this area would necessitate an entirely
different design of the apparatus.
For acetophenone, confirmation of the nature of the resonances
near threshold was obtained. In addition, the electron affinity of
the enolate anion was determined to be 2.056 eV in excellent agreement
with earlier findings. This opens the possibility of differentiating
between different sources of structure in photodetachment cross-
section spectra.
The most significant result of this work has been the appearance
of structure in the photodetachment of the chlorine anion. In order
that this might be fully exploited the experimental design must be
improved. The availability of high energy, excimer-pumped dye lasers
is particularly significant. The optimization of the experiment is
most critically dependent upon the level and quality of the source and
the primitive dye laser system employed has been useful but is
severely limited.


20
Restricting consideration to the circularly polarized component of
the same sense as the ion motion, E ,(t) (48), the force equation in
component form becomes
dux qEj
"HF = ~2iT s1n (l11 + cuy
dt
qq
2m
cos (wjt) <^cux
(13)
Transforming and solving these equations yields the velocity components
driven by the rf electric field in a static magnetic field
qEl
ux(t) 2m(u--i., ) [cos ^c11 cos '1 c
(14)
"qEl
uy(t) = 2m(yT) [sin (V} sin (lt)]-
The time dependent expression for the energy of the motion, E (49),
attributable to the combined rf electric and static magnetic field is
d E q E1
dt 1-E- ) {Icos(coct> cos(Ujt) ] Sln(jt)
1 c (15)
-[sin(a)ct) sin(w^t)] cos(u^t) }.
Equating the instantaneous kinetic energy, dE/dt, to the spontaneous
power absorption, A(t), and simplifying the trigonometric terms
produces an expression for A(t)
q2E
4m (w.
sin (w -to )t.
v 1 c
A(t) = dE/dt =
(16)


Figure 25. Negative Ion Mass Spectrum with BrCl-.
A mixture of chlorine/bromine and nitro-
methane was inlet to the ICR and the
conditions optimized for BrCl" production.
The BrCl- signal intensity shown is the
maximum observed and was insufficient for
photo-studies.


76
If Nq represents the number of anions detected prior to irradiation
and N the number of anions detected following irradiation, then N and
N are related by
o
Nq-N = f Nq P(a) (36)
where f represents the probability that every detected anion is in the
radiation field. Substituting for P(a) and rearranging and taking the
logarithm of each side yields
kt / p(X) a(A) dA = In
1-
N -N
o
fNo
-1
(37)
If the bandwidth of the source is narrow and constant with respect
to the wavelength, then
kt / p(a) o (a) dA = Ckt p(a)a (a)
(38)
where C represents the effect of the constant bandwidth, and p(a)
anda (A) are assumed to be slowly varying with respect to wavelength.
Using the simplification and substituting for p(a), an expression for
the photodetachment cross-section containing only experimentally
observable quantities is obtained
k1 a(A) =
In
1-
N0-N
fNo
-1
A E,
(39)
where k' = Ck/hca. Rearranging the argument of the logarithm
term, the cross-section expression becomes
In
k a ( A) =
fNo
fNo-(Nn-N)|
A E,
(40)


470
480
490
Cl" Photodestruction
110 ms delay
500 510 520 530 540
o
CO


2
concentration extending from 60 to 450 kilometers above the earth's
surface. Fluctuations, either local or temporal, in the free electron
concentration in this region have profound effects on the
reflectivity to radiofrequencies exhibited by the region. Consequently,
the formation and destruction of negative ions with the concomitant
loss or gain of free electrons must be characterized to account for
the observed radiofrequency reflectivity.
Negative ion chemistry in the lower atmosphere, the stratosphere
(15-60 kilometers) and the troposphere (0-15 kilometers), is pertinent
to air pollution chemistry and had been suggested as a sink for
chlorofluorocarbons released into the atmosphere. Recent studies
have discredited this suggestion as the reactions of the hydrated
negative ions which predominate at the lower altitudes with
chlorofluorocarbons have been shown to proceed slowly (6).
The study of ions in flames is of current interest (7) and has
been of interest since Moreau's early studies of negative ion
transport in flames (8). The complexity of the negative ion
composition of flames is illustrated by the number of negative ions
in significant concentration in a simple, clean, methane-oxygen
flame in which no fewer than twelve negative ions have been
identified (9). Not only the characterization of flames by the study
of the ion distribution, which remains an active area of research (10),
but also the use of flames in spectroscopy rely upon the clarification
of negative ion-flame chemistry.
The accelerated search for laser media with output in the ultra
violet and vacuum ultraviolet wavelength regions (11) requires


Abstract of Dissertation Presented to the Graduate Council of
the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy
PHOTODETACHMENT OF GAS-PHASE HALOGEN MOLECULAR
ANIONS AND THE ENOLATE ANION OF
ACETOPHENONE
By
Ronald 0. Daubach
December 1983
Chairman: Dr. John R. Eyler
Major Department: Chemistry
The photodetachment of electrons from negative halogen
molecular ions has been investigated. An ion cyclotron resonance
mass spectrometer was employed for the generation, containment and
detection of the ions. Photoprocesses were induced by means of an
integrated, tunable dye laser system.
Structure was observed in the photodetachment spectra of chlorine
and bromine molecular anions. This structure was correlated to
vibronic fine structure of the photodetachment transition. An
adiabatic electron affinity value for chlorine of 2.36 +0-27
-0.32
eV was obtained. The absence of structure in the bromine photodetach
ment cross-section attributable to the anion precluded estimation
of the electron affinity of bromine. The interhalogen molecular


Figure 18. Time-dependent Mass Spectra of the Major Peaks of a Chlorine/
Nitromethane Mixture. Three major peaks are observed NOo",
Cl2 and Cl". Cl" is the most intense. N0?" is observed
only during the grid pulse when in the presence of chlorine.
Time zero corresponds to the beginning of the grid pulse.
The upper time limit is 350 ms.


79
-4
signal-to-noise ratio of 100, the squared relative error is 10 There-
-4
fore, the error contribution due to the NQ measurement is 10 times
the tabulated value of ABC. The error in the N measurement is tabulated
(column E, Table 3) for the same initial signal-to-noise ratio. ABCE
represents the squared relative error. ABCE will always be greater than
the NQ relative error term. Furthermore, ABCE exhibits a minimum near
A equal to 0.6. A reasonable value for W(f)/f is 0.05 (33). This large
relative error is combined with its coefficient and summed with the
other large error source, N measurement, to determine the optimum ion
attenuation. This occurs at an approximate A of 0.3. W(N)/N and
W(Ex)/Ex can be estimated to be 6x10"^ and 0.03 respectively. At the
optimum A for an ion signal-to-noise ratio of 100 and for the relative
errors as described and f equal to 1, the predicted relative error in
the cross-section is 0.08. The error at a given A is most sensitive
to changes in W(Ex)Ex and W(f)/f. If W(Ex)/Ex were doubled, the cross-
section relative error would increase to 0.095, similarly doubling
W(f)/f results in a relative error of 0.13. Departure from the optimum
A value results in less dramatic changes in the cross-section relative
error at least for deviations less than +0.3
To optimize the photo-induced experiments, the signal intensity
(N ) and the signal-to-noise ratio must be optimized. Increased apparent
intensity without increased signal-to-noise will not improve the
relative errors. Ex should be accurately variable with a constant
f value. For the best observed signal-to-noise ratio and W(f)/f of
0.10 to account for poor shot-to-shot beam quality, the anticipated
relative error in the cross-section is 16%.


95
result in the complete elimination of low-energy electrons from the
distribution of electrons generated by a current heated filament
(93). In addition, although certain aspects of the system may
recover quickly, such as the proper functioning of leak valves,
the effects due to surface reactions of a halogen at the electron
filament and the ionization gauge cathode may be irreversible. This
behavior certainly contributed to the experimental difficulties
encountered in the generation and maintenance of a measurable halogen
anion population.
Photodetachment of Cl2
In Figure 19 the raw data for the photodetachment of Clat two
wavelengths are presented. The bandwidth of the laser output as
measured at the monochromator was 0.4 nm. The x-axis is time and a
typical run at a single wavelength required 15 to 20 minutes to
complete. The experimental procedure and data reduction were as
described in Chapter III. The detect delay time for chlorine anion
photodetachment studies was selected with two factors in mind. First,
that the detect delay be long enough that all of the precursor
anions had reacted. Second, that the chlorine anion intensity be
as near to the peak chlorine anion intensity as the first criterion
would allow. Peak laser outputs varied strongly with dye, dye
concentration, dye age, wavelength, and the high voltage setting for
the laser discharge. The maximum laser output was about 100 mi 11i-
joules (mj) and the lowest outputs that produced measurable changes


603
Relative Cross-Section (Arb.Units)
O-
-O
on
CD
00
3
3
Hi
Acetophenone/H^O
150 ms delay


104
analyzed manually by the measurement of the ion signal intensities
from the hardcopy spectrum generated at an x-y recorder. The
individual laser shot intensities were measured visually with an
oscilloscope and manually recorded for later correlation with the
appropriate ion intensity value. A small amount of the data over the
wavelength range from 470 nm to 490 rim was collected with the
microcomputer-interface hardware. Microcomputer data collection
decreased the actual data collection time and more significantly
decreased the time required for data reduction. Typically, two hours
were required to manually reduce the data of a single pass (15 laser
shots) at a single wavelength. With the microcomputer interface
this time was reduced to approximately ten to fifteen minutes
depending upon the quality of the data. If the present microcomputer-
interface were tied into a more powerful microcomputer, the data
reduction time could be made significantly less and on-line analysis
could be approached.
Analysis of Results
Optically accessible electronic transitions of the halogen
molecular anions are restricted to symmetry-allowed, single-electron
transitions involving the valence molecular orbitals. The ground
electronic state molecular anion configuration of the halogens may
be written in the form
(agns)2 (auns)2 (agnp)2 (^np)4 Ugnp)4 (^np)1
where n equals 3 and 4 for chlorine and bromine, respectively. This


108
x2
/pdx = 2/ p dx = h (v+'s) = I (45)
X1
for p defined as the particle momentum. Where the effective potential
can be represented as a potential without rotation and a centri
fugal potential
2
MR) = U(R) + K = J(J+1), (46)
K R 2m
the phase integral condition has the form
Ro ,1/2
2/ [2y'(E U(R)P'dR = I (47)
R, K
where E is the energy of the (v, J) term value, i.e.,
E(I,K) = hcF(v, J). (48)
The Klein action integral is written
11
S(V,K) = (21r2|i)"3s fQ [\l-E(l,K)]h dl (49)
where I1 is determined by the stipulation
E(I',K) = V (50)
and V is the energy at the limit of the integration. The phase
integral condition and Klein action integral may be combined and
the intermediate expression evaluated to give a simple form of
the action integral


Figure 16. Negative Ion Mass Spectrum of Nitromethane.
The mass range is 5 to 105 amu. Sample
pressure was 1 x 10-5 Torr. Electron
energy was 2.4 eV. Detect delay time was
40 ms. The peak occurs at a mass-to-
charge ratio of 46 amu/e.


Figure 19. Photodetachment of C^".
The photodetachment of an optimized
Cl? ion signal at x= 478.5 nm(a)
ana X = 475 nm (b) is shown. The
signal-to-noise is exceptional in
this particular spectrum.


Appendix III. Microcomputer Programs (continued)
Main Program (continued)
Address Label Op Code Mnemonic
88
DEY
18
CLC
A9 10
LDA #10
65 0D
ADC 0D
85 0D
STA OD
20 58 08
JSR 0858
A5 1C
LDA 1C
91 0D
ST/\y OD
C8
INY
A5 IB
LDA IB
91 0D
STAy OD
C8
INY
38
SEC
A5 0D
LDA OD
E9 10
SBC #10
85 0D
STA OD
98
TYA
29 OF
AND #0F
85 0C
STA OC
C6 05
DEC 05
F0 02
BEQ 02
58
CLI
40
RTI
0961
MM iM
Comment
Stores MSB of 100 and Data
Jumps to Ob & Del
Stores LSB of 100 Photo Data
Stores MSB of 100 Photo Data
Changes Base Address to that
for 100 M0 Data
Insures that Y-register ranges
from 00 to OF for overwrite of
data
Checks to derermine if one half
of 100 data per laser pulse have
been taken


128
p
since the spectroscopic constants for the B^' £u+ anion state
are not known with any degree of accuracy (96). Since the errors
in the Franck-Condon overlap factors reach a level in the Cl^
calculation that becomes significant at the high (V =12) vibrational
level of the ion and since higher internal excitation is expected for
Br^', the value of such a refined calculation is mitigated.
For the data with the greater number of experimental points in
Figure 24, there are five identifiable peaks. The experimental
wavelengths for these peaks and the corresponding term values are
collected in Table 11. The first differences have been calculated
and are also tabulated. The predicted w the first-order anharmonic
vibration constant, for the ground state anion is 160 cirf^ (96).
The separation between the peaks exceeds this energy. Furthermore,
since wgxe is small and positive (0.7 cm'1) (96), the peak structure
o
cannot be attributed to a vibrational distribution in the u+
anion state. From the well-known spectroscopic constants for Br^
(79gr 81gr), an estimate of the vibrational levels in the neutral
ground state which would account for the empirically determined
spacings can be obtained. Retaining only terms up to second-order
in the anharmonic oscillator energy expression, an expression for
the separation of vibrational levels in the ground state neutral
(aG) as a function of vibrational quantum number is obtained,
A G = oj 2u x 2u x v
e e e e e
where v" is the vibrational quantum number in the £g+ state of
(60)


INTENSITY
138
O
TIME (sec)
170


Appendix III. Microcomputer Programs (continued)
Multiplexer Select Photo Detector Subroutine
Address
Label
Op Code
Mnemonic
Comment
0869
MUX Photo
EA
NOP
EA
NOP
A9 5F
LDA #5F
8D 03 17
STA 1703
0870
8D 01 17
STA 1701
Configure PADD's and PAD'S
8D 00 17
STA 1700
8D 02 17
STA 1702
CE 00 17
DEC 1700
Drop inhibit
A9 53
LDA #5E

0881
8D 02 17
A9 5F
STA 1702
LDA #5F
-
Toggle clock line PBO
8D 02 17
STA 1702
J
EE 00 17
INC 1700
Raise inhibit
A9 02
85 40
LDA #02
STA 40
IF
Set 'Type of Data' Flag
088D
60
RTS
LD
CO


Appendix Vb. Molecular Chlorine and Molecular Chlorine Anion Franck-Condon Overlap Factors (con't)
V*,
v**
T(cml)
O'
Lambda
QT**3
QT**4
RC
R**2C
Phase
l 3.
- 1 9 2 P 0 "
0 :* 9 2.)- 05
62 76,2 37
0.14920
CP
0.23770
12
2.1361
45655
_
1 4 .
c
-15 71 Oc ? 5
P
l 1 76 0-04
^ 3 6 5 152
0.4 5580
08
0. 7 1600
1 2
2. 1 208
4. 63 4 0
4
1
- 1 4 9 5 2 5
p
? c 3463D- 04
6 4 5 3 o C 7 4
0.12980
09
C l9960
l 3
2.1214
4.5025
-
! S
u
- 1 "203,05
P
0,94^10-04
f 54.3. 1 C7
j, 3 38 10
0 9
0. 5 l 67 3
1 3
2.1143
4,4710
4
1 7 .
- 15? 74o C5
D
; 24 1 2*^ O*1
*633 .PI 7
0.6 26 2 0
09
3l2450
1 4
2.1065
4.4394

1 1
- 1 5 3 a e : 5
P
*,f7?4O-02
6725,829
C.19950
1 C
C 2 8 0 2 0
14
2.0993
4.4077

1 9,
J
- 1 4 6 6 5 r 35
P
1 2 750- 02
6 9 1P 9 31
0.4 02 00
1 0
3. 58960
1 4
2.0914
4.3753
-
2 7
- 14 46 5.0 5
P
0. 2 655 0- C2
*913.213
0.90350
10
0.1 1620
l 5
2.0637
4.3437
4
? 1 .
- 14?6 0.0 5
P
", 5 1 87D-02
7008,664
0, 1 50 70
1 1
0.21500
15
2.0759
4.3112
-
22 ,
z
- 140 74, 05
P
C,95 3 00 02
7105.273
C .2 65 70
11
0. 37390
15
2.C60 0
4 27 8 3
4
-13593.05
P
,oie540-01
72 03.0 26
0.4 4 ? 5 0
l 1
0.61430
15
20599
4.2446
-
4
1
-1 3695c 0^
P
^ 27 3 70- 0 1
73 01 6 06
0.70040
L 1
0.95920
15
2.0515
4.21 J 4
4
25.
J
- 1 051 C,05
P
.42900-01-
7401.395
10590
1 2
Cl4290
l 6
?.0420
4. 1744
-
1 1.
l
- 1 -> 4 8 ? 4 3
0 336 9i.n- 04
6067,077
0 o 2 54 60
09
3 4 196 0
l j
2. 1549
4.6455
-
1 4 ,
1
- 1 6 2 6 4 ,AQ
. 1* 080-0.3
61 -8.3 99
0.6Q190
3 6
0.11250
14
2.1479
4.6153
4
15.
1
-10*5.40
1. 41 920-02
62 30.76?
017290
1 0
0.27750
l 4
2. 14 09
4. 58 5 l
-
1 5.
1
-lc8.37o4D
. o 10 030- 02
* 3 1 4. 16 1
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4.5551
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: C 2 1 9*)-OC
f- 398.60 9
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1 0
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4.5253
-
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1
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:,454lo-0?
5484,073
0.16660
l 1
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15
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4.4955
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1
1
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C.30290
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Jt 15010-01
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3.76 38 0
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r 7 465 4 3
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l 6
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0 14 7 7'"'
l 2
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l
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0.*0950-01
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1 !
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-


Appendix III. Microcomputer Programs (continued)
Four/Channel Intermediate Storage Subroutine (continued)
Address
Label
Op Code
Mnemonic
Comment
0A7A
A4 1A
LDY 1A i
A5 1C
LDA 1C
91 OA
STAy OA
0A80
C8
INY
A5 IB
LDA IB
91 OA
STAy OA
A5 40
LDA 40
C9 03
CMD #03
- Vector Storage of Data
FO 02
BEQ 02
88
DEY
88
DEY
C8
INY
98
TYA
85 1A
STA 1A
0A91
60
RTS J


LIST OF TABLES
Table Page
1 Laser Dyes and Observed Lasing Wavelength Regions. 41
2 Grating Characteristics as a Function of
Wavelength for a 1200 line/mm Grating in
Autocol1imation 45
3 Factors in the Relative Errors in the Cross-Section
for a Range of A Values and f Equal to 1.0 and 0.75. 78
4 Variation of ICR Operating Parameters During Studies
to Maximize Formation of the Nitrite Ion from
Nitromethane 82
5 Empirical Electron Affinities for NO2 in eV 92
6 Spectroscopic Constants Used in the Determination
of the Rydberg-Klein-Rees Potential Curve for Cl^. 113
7 Spectroscopic Constants Used in the Determination
of the Rydberg-Klein-Rees Potential Curve for Cl2~ 114
8 Correlation of the Observed Peaks (A, T ) in
the Clp" Photodetachment Spectrum with exp
Calculated Transitions Energies (T ) and
Franck-Condon Factors ? 117
9 Adiabatic Electron Affinity Values for Chlorine
Determined from the Assignment of the Photo
detachment Spectrum Structure 121
10 Comparison of Literature Values for the Electron
Affinity of Chlorine 122
11 Experimental Wavelengths.(A) and Term Values (T )
and First Differences (a1) for the Observed exp
Photoreduction of Bromine Molecular Negative Ions. 129
12 Rate Coefficients for the Reaction of Cl" with
Br2 134
13 Values for Instrumental Parameters Pertinent to
Acetophenone Anion Production and OH" and F"
Precursor Anions 141
VI


58
as the peak detector reset and, consequently, must occur after the
photodetector read is completed. For certainty, the pulse was
positioned to occur immediately prior to the quench pulse.
Microcomputer Software
Programs are coded in 6502 machine language. The architecture
of the 6502 processor minimizes the volume of code, since operations
are frequently performed on a single specialized memory location,
the accumulator. Addressing codes are varied and specialized to
transfer rapidly and efficiently selected data to and from the
accumulator.
The software is designed to reduce the need for operator attention
during a complete measurement sequence. The microcomputer is no
longer merely a data router/interface controller. Data analysis codes
are included to perform simple data reduction. The zero baseline
average code averages the results of thirty-two (hex 20) zero baseline
measurements. The ion baseline average code derives the average of
eight ion baseline values symmetric about a laser shot sequence.
Zero baseline correction of the ion baseline and laser level is
coded. Similar functions, zero baseline measurement and correction
of signal levels, are coded for the photodetector output. Full double
precision (16-bit 16-bit) division is implemented. Vectored
storage of intermediate results(raw data) to temporary storage areas
and the relocation of reduced data prior to overlay of the
temporary storage areas are provided to conserve memory. With the
addition of simple data reduction codes the storage capacity required
for a single complete sequence (thirty-two zero MO measurements, sixty-


29
The expression for the instantaneous power absorption of a resonant
ion (Equation 19) is equated to Equation 25 and solved for AVg
AVG
qVt ( Rf )
4mVG l + GRf '
(26)
The criterion for maximum power transfer is
(27)
as would be anticipated. This solution is extended to n ions and
the average value of AVG for such an ensemble is
AVG
= nq2Ei2t ( Rf )
4mVq 1 + GRf
(28)
Equation 28 contains the important aspects of the detection process.
First, signal intensity is a direct measure of the number of
resonant ions. Implicit is the assumption that the ion-field
interaction is not interrupted by particle collisions, reactive or
nonreactive, or by loss of ions due to containment leaks. In practice,
t is short with respect to ion loss mechanism characteristic times and
this expression is valid. Second, the signal intensity is inversely
related to the mass of the ion. This complicating behavior must be
considered in pulsed ICR mass spectrometry analyses. Third, the
average voltage level change as derived has an ambiguous dependence
on the rf field strength. An alternate expression clarifies this
dependence
2,
nq t
2
ma
Rf
VG ^1 + GR,
-).
(29)


134
Table 12. Rate Coefficients for the Reaction of C^- with B^.
Reaction Rate Coefficient
- If) 3
(x 10 cm /molecule-sec)
Cl2~ + Br2
B^" + CT 2
1.8
Br2CT + Cl
0.38
-
BrCl" + BrCl
0.16
*
BrC^ + Br
0.10


Generate
Laser Pulse
Read
MO Data
Store
MO Data
Read
Laser Data
Store
Laser Da
Decrement
Laser Shot
Counter
Chan<
>e IV
to
.
Decrement
ID Flap,


101
were determined by inefficient lasing of the dye laser system toward
blue wavelengths. The short-wavelength limit was 457 nm. Efficient
dyes are available for wavelengths shorter than 457 nm, however, the
particular Xe flashlamp employed does not effectively populate the
upper state of the shorter wavelength dyes and lasing could not be
achieved. The long-wavelength limit at 540 nm was the result of a
gap in the lasing ranges of the available dyes. Fluorol 555 was
obtained to extend the measurements into the red, however it did not
lase (63). Measurements made to the red of the Fluorol 555 range
(£>565 nm) resulted in no photo-reduction from 565 nm to 622 nm. The
gap in the photo-excitation spectra between 500 nm and 510 nm occurs
at a region where both LD 490 and Coumarin 540 dyes lased, but with
poor beam quality and poor shot-to-shot repeatability of the beam
profile.
The variation of the photodetachment cross-section with wave
length as restricted by the laser source considerations is presented
in Figure 21. All data points were taken under identical
spectrometer conditions: grid pulse delay, 1ms; grid pulse width,
30 ms; free pulse delay (laser trigger), 100 ms; detect pulse delay,
100 ms; marginal oscillator level, 50 to 60 mV; filament current,
2.5A; filament voltage, 4v; filament offset voltage, -2.4v; and grid
offset voltage, -12.5v. Source pressures were held as constant as
possible considering the stability difficulties described.
Each point on the spectrum represents an average of between four to
ten runs at the individual wavelength corresponding to sixty to one
hundred and fifty laser shots per point. The bulk of this data was


Appendix III. Microcomputer Programs (continued)
Main Program (continued)
Address
Label
Op Code
Mnemonic
Comment
0989
A9 00
85 40
LDA #00
STA 40
H
b
Sets Laser/ICR flag to ICR
0991
A5 04
85 08
85 18
LDA 04
STA 08
STA 18
]
h
Sets counter for 100 photo
MO sums as well as division
AO 00
LDY #00
18
CLC
A5 15
LDA 15
71 OD
ADCy OD
85 15
STA 15
C8
INY
A5 16
LDA 16
71 OD
ADCy OD
09A1
85 16
STA 16
Sums the eight 100 MO Data
A9 00
LDA #00
per laser pulse
65 17
ADC 17
85 17
STA 17
C8
INY
C6 08
DEC 08
DO E7
BNE E7
20 90 OB
JSR 0B90
Jumps to 3-byte Avg.
09B1
20 50 OA
JSR 0A50
Jumps to STORE
18
CLC


54
microcomputer from the external device or vice versa. This transfer
takes place across 15input/output lines, divided into two ports,
peripheral A data, PAD and peripheral B data, PBD. The 6502
architecture and operating system treat these ports as memory
locations which can be written to or read. The direction of the data
transfer is established by the status of the control ports, peripheral
A data direction register, PADD, and peripheral B data direction
register, PBDD. These registers are interpreted as collections of
status bits which correspond directly to the PAD or PBD bits. A
status bit value of 0 indicates that the corresponding peripheral
device bit is to be read as an input, while a status bit set to 1
indicates that the bit is written to by the microprocessor. All
combinations of inputs and outputs are permissible and buffering in
both directions has been implemented on board.
A general appreciation of the input/output structure of the
microcomputer is necessary for interfacing, in this case it is also
necessary to be aware of the memory (RAM) architecture, due to the
on-board modifications dictated by the limited memory available on
the standard system. The 1024, 8-bit RAM words of the 6502 processor
are constructed from eight 1-bit x 1024-location, memory chips. The
address lines of all eight chips are tied together so that the same
address is selected at each chip. The IK of memory supplied by the
KIM-1 is insufficient for complex control and data manipulation
routines in addition to data storage. Consequently unused address
lines were decoded and memory chips sufficient to increase the RAM
to 2K were added. The details of this modification are in Appendix I.


Appendix III. Microcomputer Programs (continued)
Laser Trigger Subrouti ne
Address
Label
Op Code Mnemonic
Comment
0BB1
0BE3
A9 9F
8D 01 17
8D 03 17
8D 02 17
8D 00 17
CE 00 17
A9 9E
8D 02 17
A9 OE
8D 00 17
A9 7F
8D 05 17
2C 07 17
10 FB
A9 8E
8D 11 17
A9 9F
8D 02 17
EE 00 17
60
LDA #9F
STA 1701
STA 1703
STA 1702
STA 1700
DEC 1700
LDA #9E
STA 1702
LDA #0E
STA 1700
LDA #7F
STA 1705
BIT 1707
BPL FB
LDA #8E
STA 1700
LDA #9F
STA 1702
INC 1700
60
Configure PADD and PBDD
Configure PAD and PBD
Lower the Inhibit
Hold clock line high
Hold pulse line low
_ Pulse Duration Loop
3
3
Raise pulse line
Raise clock line
Raise inhibit
"-4
CT>


59
eight ion MO and photodetector measurements and sixteen laser MO
and photodetector measurements) is reduced from four hundred bytes
to sixty-four bytes.
Flowcharts outline the data conversion/collection and analysis
software (Figures 10-14). A memory map showing the allocation of the
expanded RAM is provided (Figure 15).
Run Time Operation
Due to memory limitations some critical registers are not set by
the initialization routine, these registers require keypad
initialization. The status register (hex address 00F1) must be set to
00 to clear the interrupt request flag. No maskable interrupt (IRQ)
can be acknowledged until the flag is cleared. Certain system
interrupts are non-maskable and always acknowledged. The interrupt
vector low (IVL, hex address 17FE) and interrupt vector high (IVH,
hex address 17FF) are manually set to DO and 08 respectively. The
KIM-1 is thus configured to acknowledge an IRQ and to respond by
calling the main control program (Figure 11). The status and interrupt
vector registers must be reset for each complete measurement sequence.
Three memory locations (hex addresses OF, 10, and 11) contain the
running sum of zero baseline values. These registers must also be
zeroed at the start of a complete measurement sequence. The remaining
registers require initialization prior to the first complete measure
ment sequence, but their status is then correctly maintained by the
program for subsequent sequences. Zero page hex addresses 0C, 12,
14, 15, 16, 17, 40, 41 and 43 should be zeroed. Zero page hex


APPENDIX I
ON-BOARD MICROCOMPUTER HARDWARE MODIFICATIONS
The details of the modifications to the KIM-1 microcomputer are
presented as a useful diagnostic. Memory chips (2102) are soldered
on top of the on-board memory chips pin for pin with the exception
of CS, the chip select line, on each added memory chip (pin 13).
The CS line of the eight 2102's comprising the additional IK of RAM
are tied together. The unmodified, on-board memory is selected by the
KO output of the KIM-1 8K decode chip (74 LS 145, pin 1) through
the buffer/invertor (7404, pins 1 & 2). The direct KO select is
cut by clipping the input and output at the buffer/inverter, pins
1 & 2. A four-input NAND gate is mounted on top of the disabled
7404 with ground (pin 7) and power (pin 14) the only connections made
to the NAND gate from the 7404 pins. KO and K1 from the 8K decode
chip are connected to the inputs of the four-input NAND gate. The
K1 line must include a 560 pull-up resistor tied to +5 volts.
KO is already supplied with an on-board pull-up resistor. The
remaining NAND inputs are tied directly to the +5 volt line. The
output of the four-input NAND gate is input to the 7400 AND gate.
K1 is also connected to the chip select array of the add-on memory
chips. Additional +5 volt supply and ground lines to the memory chips
from the KIM-1 edge connector were added due to the increased current
demands.
152


Figure 2. Trapped Ion Cyclotron Resonance Cell Schematic.
Components of the trapped ion cell which influence
the geometry of the electrostatic cell potential
are Tc and Tf, the collector and filament
trapping plates, respectively; U, the upper plate;
L, the lower plate; E, and E2, equivalent, open
end plates.


107
accurate electronic potentials are known or can be generated for the
two electronic states involved in the transition. Three types of
potential energy curves are generally available: empirical,
computational, and quantum mechanical. Empirical procedures rely on
a parameterized model for the potential curve where spectroscopic
constants determine the parameters. This method includes the Morse
potential energy curve generation scheme (101) and several
variations including the Hulbert-Hirschfelder potential function
method (102). Quantum techniques involve numerical solution of the
wave equation to some selected approximation over a range of nuclear
configurations. A computational technique relies upon the spectro
scopic constants for the generation of discrete molecular energy
levels and upon the assumption of a functional form for the
distribution of the levels. The most well-known computational method
is the Rydberg-Klein-Rees (RKR) technique (103). The RKR potential
is the best approximation to the true potential up to the term
value for which the spectroscopic constants are unperturbed and
valid. For this reason, the RKR technique with a Hulbert-Hirsch
felder extension beyond the region of valid spectroscopic constants
was used in this study.
The RKR method for potential curve construction is founded upon
the Dunham phase integral (104, 105) and the Klein action integral
(106, 105). The Dunham phase integral expresses the energy levels
of a potential function with a single minimum. The expression for
the phase integral is


Figure 23. The Negative Ion Mass Spectrum of a Mixture of Chlorine/Bromine
and Nitromethane. The mass range is from 34 to 190 amu. Peaks
are observed at mass-to-charge ratios of 35, 46, 70, 80, 129 and
160 amu/e. These correspond to Cl", NO^, Br", CH^ClBr"
and Brg" respectively.




Appendix III. Microcomputer Programs (continued)
A/D Subroutine (continued)
Address
Label
Op Code
Mnemonic
A9 07
LDA #07
08D6
8D 00 17
STA 1700
0BE7
CE 00 17
DEC 1700
AD 00 17
LDA 1700
85 ID
STA ID
AD 02 17
LDA 1702
85 IE
STA IE
EE 00 17
INC 1700
A5 ID
LDA ID
4A
LSR
4A
LSR
4A
LSR
4A
LSR
4C 81 OB
JMP 0B81
0B81
4A
LSR
OA
ASL
85 ID
STA ID
A9 01
LDA #01
25 IE
AND IE
05 ID
ORA ID
05 1C
ORA 1C
85 1C
STA 1C
60
RTS
Comment
Read the Least Significant
Nibble
- Format the Least Significant
Nibble
Combine the Two Least Signifi
cant Nibbles into the Low Orde
Byte


43
<
\ -1
)
Q
CD
GO
CD
5
O
E2Z2 ^


Figure 21. Cl^" Photodetachment Cross-Section as a Function of Wavelength.
The Cl2 photodetachment spectrum is shown from 460 nm to 540
nm. Absolute cross-sections were not measured. The maximum
photoreduction of Cl2~ observed over this wavelength range
was approximately 80% in the blue region. Structure is evident
in the cross-section.


INTENSITY
t?8


81
energies were varied to cover all combinations of these parameters.
The observed dissociative attachment generated CT only; no Clwas
detected. A charge transfer to chlorine from a suitable precursor
anion was investigated. Nitrite ion, NC^", was readily produced from
nitromethane, CH^NC^. Electron transfer was expected to occur for
the interaction of NC^" with a species of greater electron affinity.
Optimization of the nitrite ion intensity, followed by the addition
of chlorine yielded C^- at levels acceptable for pursuing the
photo-excitation study. Finally, was produced in low-energy
(0 ev) electron impact with a sample of chlorotrifluoroethylene
^F^Cl). The Cl2~ signal intensity was not as strong as that
observed from the charge transfer process. The means selected for
Cl2 generation in the ensuing photo-excitation study was the electron
transfer from nitrite ion to molecular chlorine.
Prior to undertaking the discussion of the photo-excitation
study of the chlorine molecular anion, the precursor anion's negative
ion mass spectrum and generation will be analyzed. The nitrite
ion intensity was optimized with respect to all ICR and sample
parameters. The range of the parameters and the resolution of the
variation of each parameter are presented in Table 4. The negative
ion mass spectrum of nitromethane contained a single peak at a mass-
to-charge (m/e) ratio of 46 amu/e. The signal-to-noise ratio at the
optimized system settings was approximately 40 to 1 (Figure 16).
No other ions were detected over the mass-to-charge range, 5 to 105
amu/e. No secondary or precursor ions were identified. The


Appendix Vb. Molecular Chlorine and Molecular Chlorine Anion Franck-Condon Overlap Factors (con't)
V*,
v**
T(cm 1)
O'
Lamdba
QT**3
QT**4
RC
R**2C
Phase
- 1 ?5 74. 3 3
0. 2 0H8O- 03
5639*968
' c 1 l 3 4 .0
l l
0l9920
1 5
2 18 9 6
4.79 5 v
_
1
3
- 1 7 ? 16 8 0
c 4 5 65 D-3 2
5761.432
j 2 36 7r>
1 1
0. 4 1430
1 5
2.1330
4 76 73

15,
3
- 1 7 1 4 1 f\ C
0.9C156-0?
68 13.694
;.65410
l 1
3.77840
1 5
2.1765
4. 7364
-
-U-97S.HJ
0. 1 bD 70- 0 l
5906.745
0. 7 7o* Q
l 1
0 1 320 0
16
2.1700
4.7101

17.
j
-1*720*43
C 5 750-31
59 80c 7 ,
312 0 4 0
12
0.20130
1 6
c 9 16 36
4.682?
-
13,
3
- 1 '>51 4.8 3
' 7 6 91 5 0i
6055*174
0 1 5 6 * O
1 2
^2 74 60
1 6
2. 15 7 1
4 e 654 fa
4
l >
3
- U 3 1 l .80
4 0 33D- 0 1
6 1 30. 531
0c 2 3129
1?
C J 3 1 5 0
l 6
2.1511
4.6274
-
20.
3
-1M l l 0
',51 71 D 0 1
fa 2 C 5 fa 7 1
'.21670
1 2
O.3 4 350
16
? 1449
4.6008

?\ *
7
- 1 c 9 1 4 .4 0
; 4 3290-0 1
6283.459
0.1 94 o0
l 2
0.30980
16
2.1390
4.5748
-
22 .
}
*157D90
0 *6 0 30-01
6 3 60* 999
0.14023
1 2
C. 22 04 0
16
2.1333
4.55 O 1
4-
23.
3
-l 552 9*8 0
0. 1 394 0-0 1
6439 .23?
0.7 3 4 4 D
1 1
0.1l020
l 6
2. 1234
4. 52 31
-
2* .
3
-15341*30
0, 4 7 4 PD- 0 7
65lH.139
0. 1 *3 7 00
1 l
3.2 4 09 0
15
?.1270
4.5133
4
2*3.
3
-I5156o30
. 33 2 7|'. o 3
05 97.693
0.1 15 3D
1 0
C 1 7 56 O
14
2.0797
4.3466
4
1 1
4
- 131 12* 7 9
'71 300-02
5520.964
0.42710
1 1
0.77360
1 5
2.2060
4. 96 7b
-
14 .
4
-17B44*7Q
v.13550-01
55 p8 s 2 2?
0,77653
1 1
0. 1 3 39 0
16
2 1996
4.8392
4
15.
4
-1 76 79.73
:o 22 74 0-01
56 56 1 30
0.12570
1 2
0.22220
1 6
2. 19 3?
4.8110
-
1 *
4
- 1 7457* 78
0. 37 800- 01
57 24.3 26
Do 1831D
1 2
0 3 1 4 7 D
16
2. t 869
4.7832
4
17 ,
4
-17253*73
0 4 4 0 ? D- 0 1
5794,153
Co 22630
1 2
0.39060
l 6
2.1807
4.7559
-
1 >.
4
-17052.78
0.49380-01
5364.145
0.24490
1 2
0.4 17 60
16
21746
4.7293
4
1 4*
4
- 1 5349* 78
9. 46 240-0l
5934.7 95
0.22120
t 2
0.37270
16
2 1 637
4.7028
-
2 3.
4
-ie649o_,8
0.34010-01
6 0 06 C 5 4
0. 1 57 00
1 2
C 2 6 1 30
1 6
2.1630
4.6775
4
* l .
4
- 15452. 7 8
J 1 699r Cl
6 0 77 .99 ?
0.75670
1 l
0!2450
1 6
2. 1579
4 o 6 5 4 .1
-
??
4
-If ? 5 8 7 8
13 34 U-0 2
61 50 c 122
0, i43 30
1 1
0.2 3300
16
2.15 5fa
4.6407
4
2 1.
4
-10067.78
J 56 1 .7 0-07
6222.614
0 23?80
1 0
3.3741D
14
21276
4. 54 1 7
4
24 ,
4
-15379.78
' .10160-01
6297,315
0. 4 06 30
1 l
0 .54600
15
2.1339
4.5867
-
25 .
a
-15694,78
; 76 0 76-c1
6371.644
0. 9 69 30
1 1
0.15210
l 0
2 1297
4.51^7
4
1 3.
5
- 1 664b.2 3
. 1 32 3 0-01
c3 3 .3 01
0 1 1 u 3 0
l 2
3.^2030
1 6
2. 22 19
4. 9? 79
-
1 4 ,
fa
- 1 8 4 2 7 ? 5
>6930- 0 l
54 2o 751
0c 1 31 JO
l 2
3.3341O
16
2.2156
4.9 j 9/.
4
1 5 .
5
- 1 9 ? 1 2 ? 3
Co lOCfiD-O 1
54 90.3 1 5
0.24 ?:0
1 2
4 4 070
1 6
?.2094
4.8817
-
1 1*
5
- 1 5 000.2 7
: 4 7 4 1 f 0 1
556" .4 34
0,2 7*1^
l 2
3.49770
1 6
2.203?
4. 35 4 ?

1 7 ,
e.
- 1 *T 7 9 1 ? 3
46,6 70- 0 l
5o20o 7-o
0, 2 52 9
1 2
0.4 6 760
l 6
2 19 7?
4.8774
-
1 3 .
5
-1753524
? O 76 1 2 0-C 1
50 8f c 5 6 3
3.14640
1 2
3.34540
1 6
2. 19 14
4.80l2
4-
1 V- .
5
- 17382.2 4
0. 1 92 90- Cl
5 752,999
0, l 01 30
l 2
0.17610
l 6
2. 1859
4.7764
-
2:,
5
-17!32,4
C,4 4 4q0-0 2
5319.964
0, 22320
1 1
0. 3 9210
1 5
2. 18 20
4.75f 4
4
2 l .
t
- 1 69 8 5.2 4
0.2?160-03
r; 0 5 7.4 6
0.1 MOD
l 0
3.1 8 450
l 4
?. 1551
4.6653
4
- 1 5 7 > 1 0 ? 4
: 04 8*0- 0 2
5955.4 87
c.4 01O0
l 1
0.67430
15
2,1640
4.68 6 2
-
2 3 .
5
- 1 f 5 0 0 , > 4
' o *> ? 0 5 0 0 1
60 04 a 0 1 0
i : 0 / 0
1 2
C16750
1 6
?1596
4.66 5 0
4
P i f
c
-IM12.P4
; P 8970- 01
6 0 *3 ,0 1 5
3 1 23 1 O
1 2
: .2 1 32 0
16
2. 1546
4 o fa 4 2 2
-
1* >
- 1 Pr> 7, *> ^
fa 1 6 0 4 7.1
3,44320
1 1
-3, 1 5 31 0
1 6
? t 498
4.6 20?
4
o


21
This general expression for instantaneous power absorption may be
evaluated for the conditions of ion resonance and extended rf
irradiation to determine the average power absorption per resonant ion.
Substituting into the expression for the kinetic energy, E^v ,
yields the particle kinetic energy due to rf excitation
2f 2
C q 1 2,W1 wCn
E = ozrr w sin ( 5 ) t.
2m(w1 u¡c) 2
(17)
The instanteous power absorption is then readily converted to the
average power absorption, A(wj), over the period of irradiation, Tt
q2E2
A(l) = T 4ni'(u:-')2 Il-cosfuj-u
1 c
)T]
(18)
Finally, the behavior of these quantities at resonance (<^=a)c) can be
evaluated
A (t) = (dE/dt) =
q?El2t
4m
E =
A(c)
2f 2.2
q Ej t
8m
q2Ei2T
8m
(19)
The rf electric field directly influences the cyclotron motion of the
ion about the magnetic field lines. The nature of the interaction
becomes evident when the time dependent radius of the cyclotron motion
in the field is derived
cE, sin (w.-u) )t
1 1 c
r(t) =
B
-/ (20)


Appendix Vb. Molecular Chlorine and Molecular Chlorine Anion Franck-Condon Overlap Factors
V*
, V**
T(cm1)
Q
Lambda
QT**3
QT**4
RC
R**2C
Phase
0
3
-2)8a 1,30
r>
:. 1 2640- 12
4835.170
0. 1 1 1 80
C 1
0.23120
05
2.2809
5.20 5?
1.
3
-2042 4.ac
0.46300-11
4896.0 l 0
0.30450
02
0.80570
06
2.273*
5. 17 12
-
?
3
-20l 70.3 0
C84450-1C
4957.662
Oo 6930D
03
G.13980
OR
2.2660
5. 1376

3 ,
3
-l99l9.8 0
C. 10210-08
5020.132
0£ 8 0 730
04
C. 1 6 080
09
2.2587
5.1045
-
%
3
- 1 9671.8 0
0. 9203 0-08
5083 .4 2 D
G 7 0 0 6 D
05
0.1 3 780
1 0
2.2515
5.0719
5
3
- 19 426*8 0
065820-07
5147.529
0. 4 92 50
06
0.93 74 0
10
2.2*4*
5.0397
6.
3
-19184.80
39360-06
5212.461
G 2 7440
07
0.52640
1 1
2.2373
5.DG75
4
7,
7
- 18045.8 0
0.19460-05
5273.216
0 1 -*?3D
06
0.25070
1?
2.2303
4. 976
-
8#
3
-18709.30
0.84180-05
5344.794
0.55130
08
0.1 032 D
1 3
2.223*
4.9455
f
5 .
3
-18476.80
0 o 31920-04
5412.194
0.20130
0 9
0.37200
1 3
2.2 165
4. 91 49
-
10 t
3
-13246.80
0. 10 71 O- 03
5480.4l4
0.65090
09
0.1 188 0
14
2.2097
4.9847
f
1 1
3
-13019.80
0. 3209 D-03
5549.452
0. 19780
10
0. 33 840
1 4
2. 20 30
4.8548
-
12,
3
- 1 7 795. 80
0.86260-0?
5619.304
0.48610
10
0.86510
1 4
2.1963
4.825?
4
0
4
-21219.78
P
0. 166 10- 1 t
4712.585
Oc15870
02
0.33680
06
2.2965
5*2766
4
1 ,
4
-20962.7a
0.56000-10
4770.360
0. 51590
03
0. 1 0810
08
2.2890
5.2423
-
2#
4
-20708.73
C. 9381 D-09
4823 .9 70
0.8 3320
04
0.17250
09
2.2917
5.2085
f
3 ,
4
-20 457.78
0.10400-07
4880.11t
0. 6Q0 30
05
0. 1 821 0
1 0
2.274
5* 17 5 3

4 ,
4
-20209.78
0.85660-07
4948.1 00
0.70710
06
0.14290
1 1
2.2672
5* 1426
4
5t
4
- 1996 4.78
D. 55 8 50-06
5008.821
0.44450
07
0.98 74 D
1 1
2.260 1
5.1103


4
-19722.73
029970-05
5070.280
0.2 3003
08
0. 45350
12
2.2531
5.0785
4-
7
4
- 1948 3. 78
0. 13590-04
51 32 .475
0.10050
09
0.19590
1 3
2.2*62
5. 04 7 2
-
a
4
- 19 247.73
3. 53 C40- 04
5195.405
0. 37820
09
0. 72Q0D
13
2.2393
5. 0 163
4
9,
4
- 190 1 4. 78
0,13050-03
5259.067
C 1 24 10
1 0
0.23600
14
2.2325
4.9958
-
10#
4
-1B7e4.78
0.54l1D-03
5323.459
0 o 35870
1 0
0 .6 7 38 0
1 4
2.2258
4.9557
4
11,
4
-1 .35 5 7,7 8
0 14380-0?
5388.576
0. 9 1910
1 0
0. 1 7060
15
2.2191
4.92 5 0
-
12,
4
-18333.78
: 34 0 3 D 02
5454.413
0.2 0970
11
033450
1 5
2.2125
4.3967
4
)*
f
-21752.23
3
0. 17520- 10
4597.229
0. 1 3 0 3D
03
0.3922D
07
2.3119
5. 34 77
4
i ,
5
-21495.23
0 54 220-09
4652.194
0.538 50
04
0. 1 157 0
09
2.30*5
5.31 **1
-
2.
5
-21241.23
0.83200-08
4 7 07.825
0 .79740
05
0.16940
10
2.2971
5.2790
4
3 .
5
-20990.2 3
0. 84 270-07
4764. I 21
0, 7 79 30
Ot
J 1 6 36 D
1 1
2.2898
5.2456
-
4 ,
5
-20742.2 3
C u63 2 6D06
4 S 2 1.0 3 2
0. 5 64 50
07
0.11710
1 2
2.2826
5.2127

3,
5
-2 049 7. 2 3
0. 374 70-05
4379.707
0.32260
06
0.65130
l 2
2.2756
5.1803
-
6 #
5
-2 0 255.? 3
0. 19 2 0 0-C4
45 36. 9 96
Oc 1 5120
09
0. 30630
13
2.2686
5. 14*4
*-
7 *
5
-20016.23
0.74370-04
4995.945
C59640
0 9
0 L 1940
l 4
2.2617
5. 1 1 70
-
3.
5
- 19780.23
0.26030-03
5055.552
0.201 40
l 0
0.39840
14
2.25*8
5.0860
4
9 .
5
-1 9 54 7 t 2 3
w.78990-03
5 1 15.8 14
0.59000
1 C
0. 1 1530
1 5
2.2*81
5 05 5 3
-
1 3 ,
5
- 19317. 23
0.20970-0?
51 76 .725
0.151 ID
l 1
0.29 20 0
15
2.2*1
5. 0? 55
4
l 1

- 19090.2 3
0.43930-02
5238.281
0.34040
1 1
G64 98 O
1 5
2.23*9
4.95 39
-
l 2 ,
5
- 1*366.2 3
0. 1 0 060- 01
5100.473
0.67930
1 1
0. 1 2 750
16
2.228
4.96 6 7
4-
f'O


Appendix
Vb. Molecular Chlorine and
Molecula
V*,V**
T(cm"1)
O'
Lambda
1 \c
-20953. 68
o. i £ s > -: i
A 7 73
1 1 6
1 .12
-> 7 5 0.!. 9
:O 4 7 20-c?
48 l 9
l 20
21*12
: PI DO 0- Dr*
4 86 5
3 1 0
2 ? 1 2
-20359.fed
0. 1 3 53 ('-01
4911
6 69
13 1 2
-70168.68
3*t e 350-:i
4 9 58
1 84
24.12
-19930.68
0.552 CD-02
5004
8 3 6
? .* 1 2
-1^795.69
336970-03
5051
5 05
ni3
-22700,11
0.22770-01
44 05
265
14.13
-22482.11
3. 56' 9 0-0?
4 4 47
981
15*13
-2 2 6 7 1 i
0.56 *2 0-0 3
4 4 90
929
1 5. 1 3
-22053.11
0.1351^-01
4534
397
l7. 13
-21846.11
"21l10-21
4577
4 74
Im.13
-21640,11
2* 13 780-01
46 21
0 48
10. 1 3
-2 1437. 1 1
0. 1 74 50-03
4664
807
23.13
-21237.11
0. 64 970- 32
4708
738
21.13
-21040.11
C.16930-01
4752
826
2 2. 13
-2 0846. 1 1
Cm 12270-01
4797
057
23.13
-20655.11
3.11210-0?
4341
4 l 6
24. 13
-2 046 7.1 1
0. 37 03 0-02
48 85
887
2 5,1 3
-20232.11
2.14590-01
49 30
4 53
13.14
-23180,53
0.34670-02
43 13
966
14. 14
-22962.53
0.25Q10-02
4354
921
15,14
-2274 7.83
0.17090-01
43 90
0 82
14,14
-22535,53
0 e 20 20 0-0 1-
4437
4 38
17.14
-22326.5 3
0. 651 80- 02
44 78
977
14,14
-22120,53
0.40 30 0-0 3
4520
6 67
1 1 4
-2191 7.53
0. 1 1 290-01
45 6 2
5 53
. 14
-21717.53
3. 17420- 31
4604
575
21.14
-2 1520.53
3.71840-02
4 6 4 6
725
22. 1 4
-21326.53
0.60350-04
4 6 35
995
2 3,14
-21135.53
0.37200-02
47 31
3 69
24. 14
-2094 7. 53
C.15300-01
47 73
8 3?
75, 14
-207(2.S3
C.62800-02
48 1 6
3 68
13.15
-? 3654,85
0.4466 O-3?
4227
463
14, 15
-23436,85
C 1 9 7 0 C 0 1 -
4 3 66
73:
1 1 4
-2 3221 .8 5
~l3480-?1
4306
290
i e. 15
-73309.86
3 o 3 36 80-0 2
4346
965
17, 15
-22300.85
0.23490-0?
4 3 35
80?
l -1 1 5
-27594.85
W l8l90-0 l
44 25
787
10. 15
-27391.85
? ,15570-01
4 465
9 l 0
n 15
-22151.35
0. 295 -30- 02
4 5 Go
l 53
21.15
-21604,35
:. ?: 3^0-or*
* 5 46
5 1 8
22. 15
- 2130 0.35
C. 1 3 1 3'^*-01
4 5 86
977
75 If
-21609.85
J 12910-31
40 27
5 t 9
2 4,15
-21421.38
O 13c?0-02
4 6 6 3
1 30
3,15
-21236.85
0. 30210-0?
4703
7 96
OQOOOOooUOOOOuuO
Chlorine Anion Franck-Condon Overlap Factors (con't)
QT**3
QT**4
RC
R**2C
Phase
'l4350
1 2
0.2995D
l 6
2.2886
5.2364
-
0* ? ? 0 8*>
i 1
0.45530
15
2,2830
5 2 C 1 J
4
}.1*210
1 1
> 3 7 480
1 5
2.2770
5 1 C Z 3
4
0.1 14 ?'>
1 2
0.23250
16
2.2717
b 1C 19
-
Do l 34 lO
1 2
0.2 7 05 D
l 6
2.266 3
5, l 356
4
:4 40 30
1 1
7.87980
15
2.2614
5. 1055
-
0.28680
1 G
0 .5678 0
14
2.2521
5.GO l 7
-
Co 26630
t 2
0.60450
16
2.3387
5.46 84
4
0.64410
1 L
C.14480
1 6
2.3316
5. 4.3?4
-
0. 95640
10
0. 21300
15
2.3288
5.4353

0.14490
l 2
0.3 I960
16
2.3206
5.3873
4
Co 2201 0
l 2
0.48090
16
2.3143
5.3558
-
C. 1090
1 2
0.2364D
1 6
2.3 091
5.3249
4
0.17190
10
0.3685D
1 4
2.3001
5.2625
-
0 6 2 2 30
1 1
0. 1 3220
16
2 .2971
5.2802
-
015770
1 2
0.33190
16
2.2912
5. 25C 3
0,1 11 ID
l 2
0.23 170
16
2.2857
5.2224
-
0. 98790
1 0
0.20400
15
2.2804
5.1055
4
0.31750
1 1
0.64980
1 5
2.2744
5. 1 785
4
0. 1 21 30
1 2
0.2470 0
16
2.269 2
5. 15 00
-
0.41190
1 1
0.10010
16
2. 351 1
5.5217
4
0.31250
1 1
0.71770
15
2.3486
5.5223
4
0. 20120
1 2
0.45770
16
2.3407
5.4800
-
C.23120
l 2
0.52110
16
2.3340
5. 44 7C
4
0 7254 0
l 1
0.1 6 19 D
16
2.3273
5.4125
-
0. 43620
l 0
0.96490
1 4
2.3256
54266

0 1 1380
1 2
0.26050
16
2.3167
5.3692
4
0.17640
l 2
0.38740
16
2.3106
5.3384
-
0.71600
1 1
0.15410
16
2.3046
5 3 0 7 5
4
0.5354D
09
0.12480
1 4
2.3931
5.3524
4
0. 82330
1 1
0.17400
1 6
2.2940
5. 26 5 3
-
0 1 40 6D
1 2
7.29460
16
2.2885
b.2363
4
0.5 62 l 0
1 l
0.11670
16
2.2830
5. 2033
-
Oo 5C120
1 1
0.13 980
16
2.3698
5.6160

C 2 5 .1 7 0
l 2
0.59450
1 6
2. 36 Od
5.574?
4
Oo 2 3140
1 2
0.53730
16
2. 3538
be 53 92
-
0.41030
1 1
0.94400
15
2. 2461
5.4583
4
0.27840
1 l
0.63480
l 5
7.3439
5.50 1 0
4
0. 1 7520
l 2
0.39580
1 6
2.3362
3.4551
-
3.17490
1 2
0. 39150
16
2.3298
54267
4
0.32330
l l
0.71740
l j
7.3230
b.3095
-
3.216 30
1 1
0.47580
15
2.3199
5.3096

^13630
1 2
0.29660
1 6
2.3132
5 35 ? 1
4
Oo l 3 030
1 2
0.28160
16
2.30 73
5.3225
-
C 1 8 3 1 0
1 1
0.3922D
1 5
2.3013
5.2075
4
0 a 289 30
l 1
0.6145 0
IS
2.2969
5.2821
4-
202


INTENSITY
-P*
o


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FILES


Appendix IV. Sample Preparation
Samples were prepared in standard pyrex bulbs
fitted with ground glass or teflon vacuum stopcocks. All samples
condensed at liquid nitrogen temperature (77K) and consequently
could undergo freeze-pump-thaw cycles to remove volatile
impurities. The sample bulbs were initially pumped down to 20
microns and filled on a glass vacuum line. Pressures were measured
by a cold cathode gauge and an eight-inch Bourdon type
differential pressure gauge. Final freeze-pump-thaw purification
was performed on the ICR low vacuum manifold and was done prior
to each use of the sample.
Acetophenone, nitromethane (Baker Chemical Co.) and water are
liquids and were introduced as such into the sample bulbs. The
vapor pressure of each was sufficient to maintain the necessary
pressures at the jeweled leak valves and the ion cell. Bromine
(Baker Chemical Co.) is liquid at room temperature; however, the
sample was made up to the vapor pressure of bromine to facilitate
mixing with chlorine at a constant ratio with sample use. Chlorine
(Matheson) was obtained as 99% pure gas. No special preparation
was involved other than freeze-pump-thaw purification. Sulfuryl
fluoride (Matheson) was treated in the same manner.
In an attempt to increase the number of bromine monochloride
anions generated, a mixture of bromine and chlorine was irradiated
with a 450 watt quartz envelope Hg lamp to insure that an
181


Figure 22. Rydberg-Klein-Rees Potential Energy Curves for Cl2
and Cl?". The RKR curves for the anion-neutral
pair are drawn on a single energy scale. The zero
of energy corresponds to the minimum of the
potential energy curve of the anion.


Appendix III. Microcomputer Programs (continued)
Four/Channel Intermediate Storage Subroutine
Address Label Op Code Mnemonic
Comment
0A50
0A61
0A71
18
CLC
A5
40
LDA
40
64
00
ADC
00
85
00
STA
40
C9
03
CMP
#03
90
10
BCC
10
FO
07
BEQ
07
A9
90
LDA
#90
85
OA
STA
OA
4C '
7 A OA
JMP
0A7A
A9
BO
LDA
#B0
85
OA
STA
OA
4C '
7A OA
JMP
0A7A
C9
02
CMP
#02
90
07
BCC
07
A9
50
LDA
#50
85
OA
STA
OA
4C
7A OA
JMP
0A7A
A9
70
LDA
#70
85
OA
STA
OA
Data Routing
Set Laser Photodetector Vector
Set 100 Photodetector Vector
Data Routing Flag
Set Laser MO Vector
Set 100 MO Vector


119
bulb containing nitromethane and methanol was made up and used in
place of the nitromethane alone. The subsequent C^" signal was
reduced; however, this may be attributed to a¡ (decreased in c
collision frequency between nitrite ions and chlorine and less
efficient production of nitrite ion due to attenuation of the electron
beam by methanol molecules rather than reaction of Cl^" and CH^OH.
The technique could not be successfully applied in light of these
instrumental limitations.
The spectrum of the C^ photoreduction (Figure 19) does not
exhibit the expected limiting wavelength dependence for the photo
detachment cross-section near threshold at each transition (41, 42,
43). The onset behavior of the cross-section is predicted to be
o{E) k^'+* (aQ + a^k^ + 82^ + ...) (59)
where k. is the magnitude of the linear momentum of the photoelectron
and 1 is the angular momentum quantum number of the ejected electron.
For Cl^~ 1 equals zero and a sharp onset is predicted at threshold.
The absence of this behavior is due to masking by the enhancement
of the cross-section near the sharp onset associated with each new
vibrational resonance in the long wavelength tail regions.
The observation of Cl production had led to the conclusion that
photodissociation is the primary process observed in this wavelength
region for C^ (75, 92). This is definitely the case for the
peak UV absorption centered at 365 nm. However, for vibrationally


39
ionization gauge joints. In addition, valves B and G contain polyimide
0-rings and valve C a Viton A seal. Two-inch oil diffusion pumps
(A) (CVC Model PM-120) (55) with appropriate backing pumps maintain
the vacuum of the two independent vacuum manifolds. The ultimate
-8
pressure attained in the high vacuum manifold is (1-3) x 10 Torr as
measured at the Bayard-Alpert ionization gauge (I). Pressure of the
inlet manifold is determined with a cold cathode discharge gauge
(J). Typical inlet manifold pressures are (0.1-1.0) x 10 ^ Torr. The
sample is leaked from the inlet manifold to the main vacuum can through
sapphire seal leak valves (F) (56). The titanium sublimation pump (H)
(55) maintains the vacuum in the high vacuum manifold during periods
of inactivity.
The location of the trapped ion cell (N) and the V-3400 low
impedance electromagnet (57) pole faces (M) are shown for clarity. An
anti reflectivity-coated optical glass window (L) was mounted on the
end of the main vacuum can by modifying a standard flange.
Optical Apparatus
A standard Candela dye laser system comprised of an ED-100U head
assembly, CL-100 flashlamp, a dye cavity with antireflectivity-coated
optical windows, and a variable high voltage (25 kV maximum)
power supply was employed in the photo-experiments (58). The ED-100U
head produces a high energy discharge through the Xe flashlamp of
the CL-100 flashlamp assembly upon sparkgap triggering. The pressurized
(5-7 PSI dry N2) sparkgap can be triggered manually or electronically.


Figure 28. Photodetachment of Acetophenone at 150 ms Delay.
Detect Delay time of 150 ms. Sample and
spectrometer conditions as for Figure 26.


Appendix Va. Potential Energy Curves (con't)
R PE
O' 1 4.0 71 67570
0 1
0 3 1 3 0 9 -a 5 8 0 0
.14,; 7945370
? 1
0. 5 76 C7 92 66 0
0 S*
0 15 7 8123200
: i
: a 2, 9 6 3 31 1 5 .70
C 5
0. 1568601 040
0 1
0.2666598750
0 5
1649077.370
0 1
7. 1 7 0 90271 70
05
0a 17 0 9556 710
0 1
0 1 0 23356 3 70
09
4 1711966510
01
0.1 0 0 63 03 66 0
) 5
^ : 1 71 4 4.7 0 970
71
0. 984 0874 250
0 4
0) 1 71 s 550590
4 1
3o 56 1 7C8808D
04
- a 17 19528 0 60
0 1
0. 53 51 6 89 2 3 0
J4
a 17221655 3D
) 1
0.16 46 88 780
04
0-1724365470
0 1
0 0 = 360 3 7 2 1 0
04
". 1 72 7630360
01
0.87 O 59 2 4 97 0
ca
0 a 1 7 70 46.7 170
0 1
0.6 4 74182 2 lO
04
0* 1 73 3 366 9.8 )
01
0 a 8 2 4 08 78 86 .0
34
) 1 7 76344 960
0 1
0.8'0 6 024 6 00
04
) 17 39400 980
0 1
0 a 7 7*; 96 28 = 2 0
34
174253878''
01
0o7tr-3 1 701 07 '
0 a
' 17-~7ft?870
0 1
j. 72 92 26 o 120
04
0 1 74 9077970
0 1
0,1284040
0 4
' 178 2439 3 1 0
C 1
0.66 j83 14 177
Ca
'.1756007650
0 1
0.7 :;a 6 4 8 4 6 300
3 4
0 1759624370
C 1
3.6 3 I 933961 >
0 4
' 1 7 3 7 6 l 5 7 j
: i
0. 6724 52 2 OO
04
1 17 5 7 7 9?! if)
9 1
j.6824041950
j4
3. 177 1 2 143 40
0 1
0.55741 Of 7 3o
3 -
- 1 7 7 5 .349 650
0 1
0.6322833890
04
0 a 177 9637 77 0
0 1
0 .507005 0 6 30
3 a
1734091570
01
0.461 58 25 01 '>
04
1 a 1 78 3 726 650
.0 1
0 o 4 6 6 0 16 3 120
0 4
Oal753559730
0 1
0.433 3072090
0 4
. 179 8 6 0 7 6 3D
0 1
0. 4 G4 45 58 540
04
1 80 3 8 96 1 80
3 1
3.7 7 046)28 5 00
0 4
Oo 1905451 3 7 o
0 1
0.3 6 7 3280 42 .3
2 u.
0. 1 81 57 056 '0
0 1
0.32fcwb46120
04
0 182 1493 1 90
0 1
3.29964.4870
0 4
1828077740
01
C. 2 73 0871 18'7
0 4
3 a 13 3 5 1 o 5 4 4D
0 l
Jo 2467953 650
C4
0.1842660 1 3 0
0 1
0.2195648100
r a
: 18 50 2 465 00
:i
0.1925568780
04
0 a l359 808 380
0 1
3 1 7 34 9 1 7 26D
J +
o 1 36 = 753 2 50
0 1
Oa 1 3 3249797 ')
04
R
PE
- .)
133l3001SD
C l
0 ,
1 89 4 086 77 9
0 1
7.
191 0 3636 2,9
3 1
0 .>
193l 647 90D
3 1
0.
1947449249
0 1
7 .
19875396 5D
0 l
Oo
23335^8239
0 1
9.
2049295829
01
3.
2 376 776 349
0 1
0:
2C98682899
0 1
- V
2117731380
C 1
O
2 1 34 977 340
0 l
Oo
2150945950
3 1
J
"1 ,
2l8 025l2 3D
1
0 1
0.
219 293569H
0 1
0.
223 7127950
0 1
0 n
2219907320
C l

2232335 530
0 1
0 o
2244461749
3 1
0.
2256325939
0 1
3 .
2267961129
3 1
0 a
2 27 9 39504 0
0 l
' o
2290651279
01
3S
73 3 1 750 0 3D
0 1
Oo
231 2 7 C91 OD
0 1
3 .
2323543779
01
0 o
233 4267 789
3 1
0 o
234 4 8 93 34 9
3 1

2355431429
0 1
3 9
2365891960
3 1
0.
2376 2840 10
0 1
3.
2 38 6. 6 l 6 8 3D
3 1
0 a
23969 96 220
3 1
3.
2437129150
01
3a
24 1 7324300
0 t
Oa
242 7486 919
0 1
3 .
2437622860
0 1
0 o
244 7737779
0 l
Oo
245 7836 790
3 1
,*

2467925170
3 1
0 -
2473007761)
3 1
. I 10 8 7 1 5 3 99 7 8
3 3 3 5 7 2 4 8 3 9 : ~
. 65 707376 8 r -
.2 7922224 09 % 7
. 1 -7^0 lie ? O'1
. 0
. 1 39 79 0 1 1 39 : '
8 7 9 2 2. 2 2 4 0 9 0 7
. 5&70737f-80 0 3
I 1 108715090 O'-
o 138 940797 ') '.
. 1 L5 4117 2 o 0 0-
. 1 92 595 6 73'' C-
.2 19564 8100 C 4
.24f 7I55C55 1 08
. 27308 71 1 d.o c 9
.2=56434*39 - .
. 32 605461 2 ' 0 -
. 3 5 2 3 2 8 9 4 2' _ -4
.38462550) 0 -
. 4044558540 C 4
. 4 7 0 3 v 7 2 0 = 9 O -
.45 6 015312'' 0 4
o 4 6 t 58 25 0 10 0 a
. 5 0 7 c 0 5 0 = 7 1 C 8
.532 25 33699 C-
.55741 66700 04
.5;240419o
. 60 72h 52 2 30 ca
.63 193 896 10 0 4
656484630 3 0 a
,6808814170 Ca
.70518849-0
.7292250120 o%
.753 170 10' 0 4
.7 76 96 2 8 9 20
.6006024603 0-
824 08788 60 04
. R4 74 1 4? 2 1 0 oa
. 8705924570 0-
8 976087 21O r a
CO
cn
0
o
9/
0
0
0
0
0
0
0
0.
r<
J
0
0
J
0
0
J
0
o
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0


16
o


7
of a photodetachment spectrum. Means of estimating electron affinities
and evaluating cross-section behavior have been developed and may be
classified as semiempirical, ab initio,and collision theory techniques.
Semiempirical results deal solely with the prediction of electron
affinities. Pritchard (34) gave a very complete historical summary
of semiempirical estimation of electron affinities based on observed
lattice energies and thermodynamic arguments. Person (35) suggested a
semiempirical scheme based upon the charge-transfer frequency of
donor-acceptor complexes (36) and its relation to the vertical electron
affinity of the acceptor and derived good results for several
diatomic halogen molecules. Recently, a means of estimating molecular
electron affinities from the constituent atoms' electron affinities and
positions in the Periodic Table has been proposed (37).
Theoretical determinations of electron affinities have employed
either direct or indirect schemes (38). Indirect methods consist of
individual calculations for the potential energy of the neutral and
negative ion states. The potential energy curves generated are then
used to obtain values for the adiabatic and vertical electron
affinities. These methods are constrained by the necessity of very
high precision in the individual state energies since the electron
affinities are given as the difference of two large values, yet are
quite small with respect to the total energies of either state. In
addition, it is not trivial to insure that the calculations for both
states employing a common calculation technique, Hartree-Fock, Cl, or
perturbation theory, are carried out to the same order when the number
of electrons is changed by one. Finally, the electron affinity is


Figure 7. Vacuum System Schematic.
The vacuum can which provides the
proper environment for the ICR cell
(N) has separate inlet manifold
and high vacuum manifold to facilitate
mixing of gases and control of gas
flows.


Figure 27. Photoreduction of the Enolate Anion.
The most pronounced reduction of the
acetophenone enolate anion signal level
occurred at the peak of the first
resonance. The anion reduction is about
70% at the maximum.


Appendi x 111. Microcomputer Programs (continued)
Main Program (continued)
Address
Label
Op Code
Mnemonic
A5 07
LDA 07
C5 06
CMP 06
90 20
BCC 0989
0969
EA
NOP
EA
NOP
EA
NOP
EA
NOP
EA
NOP
EA
NOP
EA
NOP
0970
4C 11 09
JMP 0911
0973
EA
NOP
EA
NOP
C6 00
DEC 00
C6 19
INC 19
A9 FI
LDA #F1
8D FE 17
STA 17FE
A9 08
LDA #08
0980
8D FF 17
STA FF
A5 02
LDA 02
85 03
STA 03
58
CLI
40
RTI
Comment
Determines if any laser shots
have been taken, if so takes
branch
Jumps to AlV's to ID
Decrement ID Flag
Increment Interrupt Request Flag
Changes Interrupt Vector to ZH,ZL
Resets half zero counter
O'*
CO


Page
Analysis of Clp Results 104
ComDutation or Franck-Condon Factors ^ . . 106
Bromine Molecular Anion-Formation of Br? .... 120
Photodetachment of Br? 123
Analysis of BrZ Results 123
Bromine Monochforide Molecular Anion 131
Analysis of BrCl Results 131
CHAPTER IV PHOTODETACHMENT STUDY OF THE EMOLATE ANION
OF ACETOPHENONE 135
Formation of the Enolate Anion 135
Analysis of the Acetophenone Enolate Anion
Results 142
CHAPTER V SUMMARY 150
APPENDIX I ON-BOARD MICROCOMPUTER HARDWARE MODIFICATION . 152
APPENDIX II MICROCOMPUTER CONTROL REGISTERS 153
APPENDIX III MICROCOMPUTER PROGRAMS 155
APPENDIX IV SAMPLE PREPARATION 181
APPENDIX V NUMERICAL VALUES OF THE RKR POTENTIALS AND
THE FRANCK-CONDON OVERLAP PROGRAM OUTPUT .... 183
REFERENCES 205
BIOGRAPHICAL SKETCH ... 212
v


112
1.5
i
2.0
2.5
A
3. 0
I
3.5


69


npjJCIIU 1 A
vo. noiecuiar Chlorine
and Molecular
Chlorine
Anion
Franck-
Condon Overlap
Factors (con't)
v*,V**
T( cirri)
Q
Lamdba
QT**3
QT**4
RC
R**2C
Phase
' v
-?. '25.7
3
, 4 * 76 ^-0 7
4 15 7.1 13
:,'mo
) L
'*14110
1 1
2 37
5. -*7 7
f
l '
- ? 356 8.00
'0 3 0 70- >
4 2 42, 60*4
Oo l 2 l 10
3 6
3.23720
1 2
3 3 65 1
5 ~3'J 9
-
** 9
-2331 a#, ee
. 0 56 8 7 .1 O
23''. 1 07
0 1 7? 80
0 9
?Q6?D
1 3
2 35 75
5 5r 9

!.
-23 3 6 3.8 8
5 b8r* 0 4
4.3 35 0 7 85
0 0 8 0 4 0
15
j 1 8 5 6 D
l 4
2.7531
5.6247
-
4 9
-22515,33
: 32 AO" ?7
*387,913
0. 3 *4 1 0
l C
0.3764 0
1 4
2 34 ? 7
5.49G1

5. 9
-22 570o 8 3
:*12320-0"
44 30 .46b
0. 1 4 1 70
1 1
0.31980
1 8
2.3355
5. 4b f3
-
0. 9
-27328.88
0 3 7S50-02
4 4 78. 5 06
0.41800
l 1
0.93 34 0
15
7.3285
5.4230
7, 9
-22039-38
:,93 3 0 0-0 3
457^961
0. 1 0 0 6 D
1 2
3.22 22J
16
?. 32 1 5
5 39 05
-
4 9
-2185 3* 3h
1 5 09n 01
4575.848
0 1 r'9?9
1 2
0.4 3530
1 0
2.3146
5. 3605
f
9
- 2 l 6 2 0 o 5 8
, 32 150- 0 t
4 6 25, l b 0
j.32490
1 2
0*70250
16
2.3079
5.3271
-
10* c
-21390,38
: 4 4 1 2001
46 74.89 1
M411 80
1 2
0. 5 2 37D
1 6
2.3013
5.?9'2

11. V
- 2 l 15 3.3d
:. -8O00-01
4 7 2 5 0 013
0,48510
l 2
3.96310
l b
2 29 4 7
5. 2t5H
-
12. s
-2 0 939 3 R8
: ?8 95D-C 1
4 7 75.6 78
Oo 357 7L)
1 2
0. 74 390
1 6
2.2883
5.2359

0. 1
-24329.95
p
Co 2254 0 08
4110.153
0.32470
37
0.79000
l l
2.3880
5. 70*. 4

1.1'
- 24 0 7 2.59
C43140-35
4 1 54 0 3.3
0.6 01 9 0
08
0.14 490
l 3
2.3502
5. 66 7 3
-
2 1 C
-23813,59
Go 4 0 240-04
4193.330
Oo 5 4 3 70
09
0.12950
1 4
2.3725
5.63 C5
3. 1 C
-2 355 7.99
0. 242 70-03
4243 .043
0.31770
10
0.74870
1 4
2.3649
5. 594f
-
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v.10360-0?
42 88. 1 66'
0.13420
1 1
0.31300
15
2 3575
b.554 4

5.10
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Oo 15 350-00
4333.696
: .4 34 40
1 1
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5. 5?r0
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93330-02
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l 2
0.25 37 0
10
2.3431
5. 49 1
7 1 C
-22593,99
0 15 780- 0 1
4 4 25. 955
9* 228 1 D
1 2
3.5 t 54 0
1 b
233b 1
5.4^4!
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-2? 357,99
: u 33 760-01
4472.574
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1 2
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1 t
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5. 42 t36
*
9. i:
- 2212 4.9 9
C. 4 5000-0 1
4519.776
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2.3224
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10.10
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4567.264
0.50540
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11. 10
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? lb 080-01
4615102
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b.3312
-
12.10
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15540- 0 l
4 6 b 3 3 1 1
0,15330
1 2
3.3 2 87 0
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2.3026
5.2999
0.11
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p
:<.10410-08
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15960
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G.39620
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5.7775
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b. 73c 1
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5.7015

3. 1 1
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-


208
48. C. E. Berry, J. Appl. Phys. 25, 28 (1954).
49. J. D. Jackson, Classical Electrodynamics (J. Wiley and Sons,
New York, 19751.
50. A. Warnick, L. R. Anders, and T. E. Sharp, Rev. Sci. Instrum. 45,
929 (1974).
51. a. R. A. Brooks, Rev. Sci. Instrum. 43, 807 (1972).
b. Y. T. Yang and T. C. Chen, Rev. Sci. Instrum. 36, 706 (1965).
c. J. R. Singer and S. D. Johnson, Rev, Sci. Instrum. 30, 92
(1 959).
52. R. T. Mclver, Jr., Rev. Sci. Instrum. 44, 1071 (1973).
53. R. J. Dugan, L. N. Morgenthaler, R. 0. Daubach, and J. R. Eyler
Rev. Sci. Instrum. 50, 691 (1979).
54. Kepco, Inc. 131-38 Sanford Ave., Flushing, NY 11352.
55. CVC Products, Inc., P. 0. Box 1886, Rochester, NY 14603.
56. Varian Associates, Palo Alto Vacuum Div., 611 Hansen Way,
Palo Alto, CA 94303.
57. Varian V-5900 Ion Cyclotron Resonance Spectrometer Component,
Varian Associates, 611 Hansen Way, Palo Alto, CA 94303.
58. Candela Corporation, 96 South Ave., Natick, MA 01760.
59. Candela Corporation, 96 South Ave., Natick, MA 01760. Manual
on the operation of an ED-100U Head Assembly.
60. Micropump Corp., 1935 Shary Ct., Concord, CA 94518.
61. F. P. Schafer, Dye Lasers (Springer-Verlag, Berlin, 1977), p. 61.
62. Pall Corp./Mectron Industries, Inc., 330 Turnbull Canyon Rd.,
City of Industry, CA 91744.
63. Exciton Chemical Co., Inc., P. 0. Box 3204, Overlook Station,
Dayton, OH 45431.
64. PTR Optics Corp., 145 Newton St., Waltham, MA 02154.
65. Bausch and Lomb, Inc., Instrum, and Systems Div., 42 East Ave.,
Rochester, NY 14603.
66. Edmund Scientific, Inc., 101 E. Gloucester Pike, Barrington,
NJ 08007.


Figure 8. Dye Laser Apparatus and Orientation.
The primary components of the dye laser
system are: the optical cavity (OC);
Xe flashlamp (FL); antireflectivity
coated windows (ARW); high voltage
discharge power supply and capacitor (HV).
Wavelength selection is accomplished with
a diffraction grating (G), mounted on a
base (B) which is rotated by a motor-
driven (GDM) lever arm (LA). Wavelength
determination is accomplished with a beam
splitter (BS) and monochromator (GM). A window
(W) permits the laser cavity extension to the
end mirror (M) in the cell(C).


TIME (sec) 400
INTENSITY
Z6


93
N02~ peak at an appearance potential of 0.6 eV was found in the
negative ion mass spectrum of nitromethane (90). N02" produced in
this manner is anticipated to have a level of internal excitation
that is essentially thermal since the appearance potential only
slightly exceeds the minimum energy required for the process.
This energy difference, the energy of bond rupture (DH (C-N)= 73
kcal/mole) (91) minus the electron affinity of N0^ (EA(N02) = 2.38
0.06 eV) (87), amounts to 0.8 eV. Since the potential for peak
NO^ ion intensity occurred at 0.83 eV in this study, the N02~ ion
is presumed to be vibrationally cool.
The experimental conditions for which the nitromethane negative
ion mass spectrum was observed overlap those of previous investigations.
In addition to the nitrite ion, CN~ and 0" have been observed in
the nitromethane spectrum (90). The peak CN" and 0" intensities
are considerably less than the N0^" peak intensity, on the order
of one one-hundredth and one two-hundred-and fiftieth the NO^-
intensity, respectively. It is understandable that such low
intensity ions should not be observed for the signal-to-noise
evidenced in this study.
The electron transfer reaction
N02 + Cl2 - Cl2" + N02 (43)
has been investigated (79). For N02" ions with 0.3 eV translational
energy the rate constant for the reaction was determined to be 2.2 x
10 cm /molecule-second. At higher translational energies the


Figure 30. Photodetachment of Acetophenone at 250 ms Delay.
Detect delay time of 250 ms. Sample and spectro
meter conditions for Figure 26.


I certify that I have read this study and that in my opinion
it conforms to acceptable standards of scholarly presentation and is
full adequate, in scope and quality, as a dissertation for the
degree of Doctor of Philosophy.
Johrij R. Eyler, Cha/i/rman
Associate Professor of Chemistry
I certify that I have read this study and that in my opinion
it conforms to acceptable standards of scholarly presentation and is
full adequate, in scope and quality, as a dissertation for the
degree of Doctor of Philosophy.
Wallace S. Brey
Professor of Chemistry
I certify that I have read this study and that in my opinion
it conforms to acceptable standards of scholarly presentation and is
full adequate, in scope and quality, as a dissertation for the
degree of Doctor of Philosophy.
Martin T. Vala
Professor of Chemistry
I certify that I have read this study and that in my opinion
it conforms to acceptable standards of scholarly presentation and
full adequate, in scope and quality, as a dissertation for the
degree of Doctor of Philosophy. M
V
IS
Richard T. Schneider
Professor of Nuclear Engineering




CHAPTER V
PHOTODETACHMENT STUDY OF THE ENOLATE
ANION OF ACETOPHENONE
Formation of the Enolate Anion
The enolate anion of acetophenone was produced by proton
abstraction from the a-carbon of the neutral. This was accomplished
via the acid-base reaction of acetophenone with a selected anion
of greater gas phase basicity than the product enolate anion of
acetophenone. Two anionic bases were used to abstract the
proton, OH", produced from H^O by low energy electron impact and
F", generated from SO2F2 also by electron impact.
The OH" anion is not produced directly upon electron impact
with H2O. Initially, H" is generated (119)
e" + H20 -* H" + OH. (61)
H" was not observed in this study since the minimum time-
resolution of the pulsed ion cyclotron resonance mass spectrometer
was insufficient to detect the extremely rapidly decaying parent
ion. H" does react further with water (120)
H~ + H20 OH" + H2 (62)
producing OH The OH anion was selected as the precursor anionic
base for this study, because of the ease with which it could be
produced, the simplicity of the negative ion mass spectrum of water
135


603 598 (nm)
Relative Cross-Section (Arb. Units)
-O
9trt
Acetophenone/h^O
200 ms delay


71
0800 -
0851
Initialization Subroutine
0852 -
0868
Obtain Data and A/D Delay Subroutine
0869 -
088D
MUX Select Photodetector Subroutine
088E -
08B4
MUX Select M0 Subroutine
08B7 -
08CE
A/D Read Subroutine (Part II)
08D0 -
09F0
Main Control Program
0A00 -
0A45
A/D Read Subroutine (Part I)
0A50 -
0A91
Four Channel Storage Subroutine
0A9A -
OAFC
Data Analysis and Storage Subroutine
0B00 -
0B80
Double Precision Divide Subroutine
0B81 -
0B8F
A/D Read Subroutine (Part IV)
0B90 -
OBBO
Triple Precision Average Subroutine
0BB1 -
0BE3
Laser Trigger Subroutine
0BE7 -
OBFF
A/D Read Subroutine (Part III)


113
Table 6.
Spectroscopic Constants Used in the Determination of the
Rydberg-Klein-Rees Potential Curve for Clg.
t
e e
559.75 cm'1
2.694 cm"1
B
e
0.2442 cirr1
ag 1.516 x 10"3 cm-1
Dq 19997.14 cm'1


142
Observed photodetachment cross-section spectra are plotted in Figures
28-30 for the various detect delay times. The detect delays were
limited at short and long times by the concentration of the aceto
phenone enolate anions. The anion signal peaked at 200 ms and was
significantly lower below 150 ms and above 250 ms. The total pressure
was maintained as accurately as possible throughout a photodetachment
run to insure that the effects of collisions would not vary drastically.
The photodetachment spectra indicate that the electron detachment
process is not affected by collisions over the range that could be
induced here.
Analysis of the Acetophenone
Enolate Anion Results
The photodetachment spectra of the acetophenone enolate anion
indicate that a resonance occurs just above the threshold which is not
affected by collisional de-excitation. The acetophenone anion has been
studied and resonances have been observed throughout the near
threshold region (121, 122). The analysis of these resonances
indicated that they were attributable to electron-dipole resonances
and not to different vibrational transitions between the anion and
neutral states. These studies confirm this result as the first
resonance above threshold is not influenced by delaying irradiation
of the anion. The number of collisions is anticipated to vary by
35 to 40 over the range of detect delays at the pressures employed.
The vibrational de-excitation is expected to be efficient, since
the anion vibrational modes are not anticipated to be drastically


Experimental Techniques
Two types of charge transfer techniques have proven useful in the
study of electron affinities: exothermic charge transfer (CT) and
endothermic charge transfer (ECT). Exothermic charge transfer yields
limits on a molecular electron affinity by observation of the direction
of spontaneous charge transfer between negative ions and target
neutrals. More accurate values of the limits for the electron affinity
may be surmised if the exothermicity of the charge transfer reaction
can be estimated (24). Endothermic charge transfer employs the
energy of translation to induce a nominally endothermic charge transfer
(25). This technique enables the energy dependence of the cross-
section above threshold to be determined. Collisional ionization is
a related scheme in which both of the initial reactants are neutrals.
Collision-induced, ion-pair formation lends itself to the evaluation
of the product negative ion electron affinity provided the positive
ion's ionization potential is independently known (26). These
techniques are limited by the residual uncertainties in the distributi
of the excess energy between translation and internal modes and the
detailed distribution of the internal energy for systems with more
than one degree of internal freedom.
A variety of photodetachment techniques for obtaining electron
affinities have been developed. These include fixed (27) and
variable (28) frequency photoelectron spectrometry and variable
frequency crossed beam (29) and drift tube (30) photodetachment
techniques. The rapid development of variable wavelength, wide-wave-


PHOTODETACHMENT OF GAS-PHASE HALOGEN MOLECULAR
ANIONS AND THE ENOLATE ANION OF
ACETOPHENONE
by
Ronald 0. Daubach
A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL
OF THE UNIVERSITY OF FLORIDA IN
PARTIAL FULFILLMENT OF THE REQUIREMENTS
FOR THE DEGREE OF DOCTOR OF PHILOSOPHY
1983


Appendix III. Microcomputer Programs (continued)
Initialization Subroutine (continued)
Address
Label
Op Code
Mnemonic
Comment
A5 02
LDA 02
I
Determine if last zero h
DO 16
BNE 16
1
been taken
A5 OF
LDA OF
85 15
STA 15
0831
A5 10
LDA 10
85 16
STA 16
A5 11
LDA 11
Perform zero average and
85 17
STA 17
Data Analysis
A5 01
LDA 01
85 18
STA 18
20 90 OB
JSR 0B90
0840
20 9A OA
JSR 0A9A
DISPLAY
A5 00
LDA 00
85 FA
STA FA
A9 00
LDA #00
Prompt Operator
85 FB
STA FB
4C 4F 1C
JMP 1C4F
58
CLI
084 F
4C 22 08
JMP 0822
cn
cr,


115
from the lower integration limit. This solution satisfies the wave
equation at all points except for the single point where the inward
and outward integrations overlap. This point is used to test for
convergence with respect to variation of the trial eigenvalue. When
the energy difference between the inward and outward wavefunctions
is less than the selected convergence limit, the final wavefunction
is obtained by a point normalization routine. The integrations are
simplified if the potential is known at regularly spaced values of
r, therefore, an eighth-order Lagrangian interpolation of the input
RKR potentials is performed prior to wave function generation.
The evaluation of the wave function integrations and the FC overlap
integrals and other integrals take place over the range RMIN to
RMAX. For the ground anionic state of chlorine and the chlorine
neutral RMIN and RMAX were selected as 1.5A and 3.5A, respectively.
These values are selected due to the constraints of the Lagrangian
interpolation routine and the range of validity for the
spectroscopic constants, and provide precise wavefunctions up to
v"maX=12 fr anion and v'max=20 for the ground state neutral.
The quantum numbers of the transitions (V*, V**), the term value,
T(cm 1), the Franck-Condon factor, Q, the wavelength of the
transition, LAMBDA (A) and the FC factor times the cubic and fourth
powers of the wave number, QT**3 and QT**4, as well as the
r-centroid and r-squared-centroid and the sign of the overlap
integral prior to squaring to obtain the FC factor, RC, R**2C and
PHASE, respectively, are tabulated in Appendix V. The potential


Table 9. Adiabatic Electron Affinity Values for Chlorine Determined from the Assigment
of the Photodetachment Spectrum Structure
(nm)
^exp
(cm-!)
(V*,V**)
Tcalc Tcalc <->
(cm"1)
Adiabatic Electron
Affinity
(cm"l) eV
539.5
18535
(16,6)
-505
19040
2.3606
533.5
18744
(15,6)
-296
19404
2.3606
527.0
18975
(14,6)
-81
19056
2.3626
521.0
19193
(13,6)
137
19056
2.3626
516.0
19379
(12,6)
358
19021
2.3583
(22,10)
334
19045
2.3612
496.0
20161
(11,7)
1103
19058
2.3628
490.0
20408
(12,8)
1395
19013
2.3573
486.0
20576
(16,10)
1543
19033
2.3597
482.0
20746
(20,12)
1716
19030
2.3594
476.0
21008
(14,10)
1973
19038
2.3604
473.5
21119
(9,8)
2076
19044
2.3611
471.5
21208
(20,13)
2173
19006
2.3564
463.0
21598
(23,15)
2563
19023
2.3585


114
Table 7
Spectroscopic Constants Used in the Determination of the
Rydberg-Klein-Rees Potential Curve for Cl2~-
w,x
e e
260.0 cm"
1.50 cm-*-
0.136 cm-*
0.01 cm *
10324.1 cnf1


anion of bromine monochloride was generated but was of low signal
intensity. The photodetachment spectrum of the enolate anion of
acetophenone exhibited behavior which supported previous
explanations of the source of the structure in the cross-section near
threshold.
x


no
The Hulbert-Hirschfelder (H-H) five-parameter empirical
potential is a generalization of the Morse potential given by
U(R) U(R0) = ax (l-e'x)2 + a2 x3e DX + a3 x4e'DX
(57)
where
(58)
and a^, a^, a^ and D are fitting parameters which may be related to
spectroscopic constants by means of Dunham's analysis (102). This
potential function is used to extend the RKR potential curve so
that vibrational wave functions may be determined up to the RKR limit.
A Fortan RKR-HH potential energy function program (107)
was used and calculations were performed on the Amdahl computer.
The RKR-HH numerical potentials for Cl2 and Cl2 are given in Appendix
V. The potentials are drawn in Figure 22. The input spectroscopic
constants are listed in Tables 6 and 7.
The RKR potentials are the inputs to an FC factor program due to
Zare and Cashion (107) which utilizes a solution of the radial
Schrodinger wave equation by Cooley (108). Cooley's algorithm
solves the second-order differential radial Schrodinger equation
from a numerical input potential. The algorithm starts with limiting
values for the wave function at the integration limits. From the
upper limit, the wavefunction is integrated inward since the wave-
function's value at rn_j can be expressed as a function of r ,
rn i Vn Vn i the numerical potentials of r and r P ; and E,
a trial eigenvalue. An outward integration is performed similarly


Figure 6. Schematic Diagram of the Digital Pulse Electronics.
Cell interconnections are shown with respect to the
dc level pick-offs and the varying rf fields. Pulse
destinations are as indicated from the main control
unit to the ancillary detection, collection and control
equipment.


22
At resonance
( cE,
r =
2B
t.
(21)
The radius of gyration of an ion in resonance increases linearly with the
irradiation time and with the electric field amplitude. At higher
magnetic fields the resonant ion radius is smaller for the same rf
irradiation conditions. The radius of a nonresonant ion is seen to
be varying with time but is bounded as a result of the phase mismatch
between the resonant frequency of the ion and the driving rf
field (Figure 3).
The motion of a collection of ions with a distribution of
velocities has been determined from the equations for single particle
motion (47). In the trapped ion cell, ions are formed through the
interaction of a pulsed electron beam directed along the z-axis with
a sample gas in thermal equilibrium. Assuming that there is no
gradient of electron energy along the electron beam (generally invalid)
and that the electron pulse is long with respect to the period for
simple harmonic motion along the z-axis (generally true), then the
ions can be assumed to be uniformly distributed along the z-axis.
The uniform distribution of guiding centers along the z-axis drifts
along equipotential field lines. If an electron beam of circular
cross-section is assumed the initial distribution of guiding centers
is circular in the xy-plane. The geometry of the initial distribution
is altered due to the variation in ellipticity of the paths followed
by individual ions as a function of the distance from the z-axis


Appendix III. Microcomputer Programs (continued)
Obtain Data and A/D Delay Subroutine
Address
Label
Op Code
Mnemonic
Comment
0852
Ob & Del
20 90 08
JSR 0890
Sets MUX to ICR Channel
4C 5B 08
JMP 985B
Jumps to Delay
20 69 08
JSR 0869
Sets MUX to Photo Channel
DELAY
A9 40
LDA #40 1
Sets Time for Delay &
80 07 17
STA 1707
0860
2C 97 17
BIT 1707
Checks for End of Delay Period
10 FB
BPL 0860
20 00 OA
JSR 0A00
Jumps to Read A/D Subr.
0868
60
RTS
cn


74
read as before and stored. The laser counter is decremented and ID
register decremented (01). Interrupt vectors are set to E so that
the (100/2) level counter is reset and a new sequence of 100 levels
taken. If the laser has fired, average 100 M0 and 100 PHOTO levels are
calculated and stored. If the laser counter is nonzero, the interrupt
vectors and ID register are set to fire the laser on the ensuing
interrupt. For a zero laser counter, the interrupt vectors and (0/2)
level counter are reset to read the required zero baseline levels
commencing with the next interrupt. The ID register is set to zero
and PIRQ set (01) to initiate an operator prompt. The display
"0000 xx" requests the operator to tune the ions off resonance. When
the (0/2) counter tests zero, an RTI occurs and since PIRQ is set a
test of the total zero (0) counter is made. The total zero counter
will be zero and the zero baseline average is determined.
Data analysis consists of the evaluation of
1 = M0Lnl molbase
M0Ll M0Lbase (31)
and
LSRL = PDLl PDLnl (32)
where MOL represents a marginal oscillator level, PDL a photodetector
level, L refers to a laser shot sequence with ions, ML refers to an ion
resonance sequence with no laser shot and BASE refers to no resonant
ions or laser shot. Thus F ^ is the inverse of the fractional remainder
of the ion signal upon irradiation by a laser pulse with a power
level related to LSRL, the measured laser level. These four bytes


26
operation as required for ion detection. Second, a gated amplifier
serves to pulse the circuit output with the application of an
externally derived gate pulse.
The analysis of marginal oscillator detection can be carried out
in terms of the gated, limited feedback oscillator (Figure 4). The
parallel, GLC (conductance-inductance-capacitance) tank circuit
of the oscillator has a resonant frequency
w0 = (LC)^ (22)
where L is the circuit inductance and C is the circuit:and cell
capacitance. The conductance, G, represents resistive losses in the
circuit. The limiter supplies a constant amplitude signal,
Vq, to the resonant circuit through the feedback resistor, R^. At
resonance, jqC = (c^L) \ hence the admittance is a pure conductance
and the voltage across G, Vp, becomes
V
,-l
+ R
-).v = -=
' o 1 + GR,
where VQ is the rms voltage level from the limiter and is
voltage level across the resonant circuit. An infinitesimal
in conductance directly affects the rms voltage level of the
resonant circuit
(23)
the rms
change
AVG = VpRf = VGRf (24)
AG (1 + GRf)2 1 + GRf
The power absorption (AA) due to a change in the cell conductance
is represented by the total derivative of the instantaneous power
with respect to the conductance and the voltage across the conductance,
,1 + GRf,
AA = -V,
G
AV, l-
R,
-)
(25)


APPENDIX II
MICROCOMPUTER CONTROL REGISTERS
The control registers required for the data collection and
analysis microcomputer system are given. Initial values are indicated.
Hex Address
Description (Initial Value)
00
01
02
03
04
05
06
07
08
0A
oc
OD
OE
OF
10
11
12
14
15
16
17
18
19
Main control register (00)
Number of zero levels (20)
Number of zero levels counter
One-half number of zero levels counter
Number of 100 levels per laser shot (08)
One-half number of 100's per laser shot
Number of laser shots (10)
Number of laser shots counter (10)
Index for average routines
Four-channel store base address (00)
Index storage for memory overlap (00)
Base address low for temporary storage (20)
Base address high for temporary storage (00)
Storage for zero level (00) Running Sum
ID for the data to be averaged (00)
Index for final data store (00)
Dividend for three-byte average
Divisor for three-byte average
Programmable Interrupt Request (PIRQ) (00)
153


operator prompt to tune the ions into resonance and charge the laser
capacitor 084E' is entered in the address field of the display
and GO is depressed to clear the interrupt flag and to return the
KIM to the wait loop.
The next IRQ enters the main control program at A. The ID
register contains 01 and branch C is selected. The interrupt vectors
are changed to point to E to protect the ion baseline counters. The
100 level counters are set and MO level is read exactly as before.
The two byte result is stored via the y-indexed address mode. The
appropriate value for the y-register is loaded from 0C. The base
address is located in 0D. The PHOTO level is read and stored as for
the MO level, however, the base address is first incremented by hex
10 so that the two types of data are mapped into different memory
locations. The base address is restored to its original value after
the PHOTO read/store in preparation for the next cycle. The program
requests eight two-byte MO levels and eight two-byte PHOTO levels
per laser shot for the determination of the respective averages.
Once the averages have been evaluated and stored, the first four level
of each type may be over written. "AND"ing the y-register value
with hex OF prior to saving its value in 0C accomplishes the overlay.
If the (100/2) level counter is nonzero a simple return from
interrupt is taken. If the counter is zero, the software determines
if the laser has been fired. If not, the interrupt vectors are
altered to point to A and the ID register incremented (02) so that
the next interrupt fires the laser. Figure 11 illustrates the laser
firing sequence and is straightforward. M0 and PHOTO levels are


30
Thus, the voltage change due to absorption is linearly related to the
voltage across the circuit and inversely proportional to the square
of the plate separation, a, across which the rf field is applied.
In practical pulsed ICR, the transient voltage level change is
integrated over the period of the rf irradiation. The resulting
amplitude may be sampled and held for display or transfer.
Integration alters the dependence of the signal on the irradiation
period so that the integrator output level is now described by
nq2E!2t2 Rf
8mVQ ll + GRf;
AV
G
or
nq\t2 Rf ,
2ma ll + GRf'
(30)
when the instantaneous change in the voltage level is linear over
the period of integration. The negative sign in the numerator of
Equations 26-30 is removed by inversion of the signal voltage
level in the post-detection electronics.


190
125
i
m

CVJ
X
o
I
V-
CD
I
o
A1ISN31NI


Appendix Vb. Molecular Chlorine and Molecular Clorine Anion Franck-Condon Overlap Factors (con't)
V*
,v**
T(crrf 1)
O'
Lambda
QT**3
QT**4
RC
R**2C
Phase
>.
r
2227**12 .-
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8
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CHAPTER IV
EXPERIMENTAL RESULTS AND DISCUSSION
OF THE HALOGEN ANION STUDIES
The ions discussed in this chapter are those for which
observable ion intensities could be produced. C^" and B^" were
generated with sufficient intensities to assure reasonable signal-to-
noise ratios for the photo-excitation studies. BrCl" was observed
and the instrumental parameters pertinent to its formation were
optimized, but under no operating conditions was the signal quality
adequate to undertake photo-excitation measurements.
Chlorine Molecular Anion
Formation of Cl
The generation of Cl2 was not straightforward. Four means of
producing the chlorine molecular anion were attempted; two
procedures were successful. Direct attachment of low-energy electrons
to chlorine molecules was attempted over the nominal electron
energy range, 0 to 10eV,for chlorine sample pressures at the ion
cell vacuum can ranging from 1x10"^ to 1x10^ Torr. No molecular
chlorine anion was observed for any combination of these parameters.
At all experimental conditions, dissociative attachment yielding
Cl- was seen to occur exclusively. Dissociative attachment of
low-energy electrons to carbon tetrachloride was tested for Cl,,"
production. As for chlorine, sample pressures and electron
80


Appendix ILL Microcomputer Programs
A/D Subroutine
Address
Label
Op Code
Mnemonic
0A00
Read A/D
A9 OF
LDA #0F
80 01 17
STA 1701
A9 FE
LDA #FE
8D 03 17
STA 1703
A9 03
LDA #03
8D 00 17
STA 1700
CE 00 17
DEC 1700
AD 00 17
LDA 1700
85 ID
STA ID
AD 02 17
LDA 1702
85 IE
STA IE
EE 00 17
INC 1700
0A21
4A
LSR
4A
LSR
4A
LSR
4A
LSR
4A
LSR
OA
ASL
85 ID
STA ID
A9 01
LDA #01
25 IE
AND IE
05 ID
ORA ID
85 IB
STA IB
Comment
Configure PADD and PBDD
Read the Most Significant
Nibble
Format the Most Significant
Nibble


Appendix III. Microcomputer Programs (continued)
Double Precision Divide Subroutine (continued)
Address Label
0B62
Op Code Mnemonic Comment
46 D7
LSR D7
FO 05
BEQ 0B6B
66 D6
RCR D6
4C 79 2A
JMP 0B79
66 D6
ROR D6
DO OA
BNE 0B79
E6
INX
E6
INX
E4 DB
CPX DB
FO OB
BEQ 0B80
A9 80
LDA 80
65 D7
STA D7
06 DF
ASL DF
26 DE
ROL DE
B8
CLU
50 A5
BVC 0B25
10
RTS
0B80


149
different from those of the neutral acetophenone. Consequently,
it seems reasonable to agree with the previously reported results
that the structure is due to electron-dipole resonances of the
enolate anion. The electron affinity value taken from the wave
length at which a measurable reduction of the enolate anion occurs
is 2.056 eV in excellent agreement with the reported value of
2.057 eV (122).


Figure 10. Operator/Microcomputer Interaction Flowchart.
This flowchart describes the required operator
attention. Programs are loaded from
cassette tape and operation initializations
are performed. Initial interrupt vector values
are set and the microcomputer enters an NOP
loop until interrupted. An end-of-experiment
test determines the experiment status and
then analyzes and stores the data in final
form.


Appendix III. Microcomputer Programs (continued)
Double Precision Divide Subroutine (continued)
Address Label Op Code Mnemonic Comment
C5 DD
CMP DD
70 2B
FCC 0B62
A5 DF
LDA DF
E5 DD
SBC DD
BO OD
STA DF
BO OD
BCS 0B4C
A5 DE
LDA BE
E5 01
SBC 01
38
SEC
E5 DC
SBC DC
65 DE
STA DE
16
CLC
A5 DE
LDA DE
38
SEC
E5 DC
SBC DC
65 DE
STA DE
16
CLC
B5 D2
LDA D2
65 D6
ADC D6
95 D2
STA D2
E6
INX
B5 D2
LDA D2
65 D7
ADC D7
95 D2
STA D2
CA
DEX
L£)


Figure 4. GLC Circuit Emulation of ICR Detection.
V is the output of the limiter. is
the amplifier feedback resistance. G,
L, and C represent the conductance,
inductance and capacitance of the ion
cyclotron resonance cell.


Figure 14. Laser Status Flowchart.
Determination of a laser firing
is necessary for subsequent data
reduction and memory overlap
decision. In addition, the last
laser shot of a sequence must be
identified to reduce the data to
final form.


141
Table 13. Values for Instrumental Parameters Pertinent to Aceto
phenone Anion Production and OH- and F~ Precursor Anions.
OH"
F"
Filament Voltage
-7.22 V
-4.93 V
Filament Current
1.5 A
1.5 A
Trapping Plate Voltage
-1.75 V
-1.75 V
End, Upper, Lower Plate
Voltage
+1.00 V
+1.00 V
Sample Pressure
2x10~5 Jorr
3.5 x 10^ Torr
Partial Pressure Ratio
(Acetophenone/Base)
1/10
4/1
Grid Pulse Width
20 msec
20 msec
Detect Delay
150-200-250 msec
100-200-250 msec


17
where a is the cell width, Vj is the trapping plate potential, Vq is
the upper and lower plate potential and a, A and 3 are constants
related to the actual dimensions of the cell. The restriction of ion
motion is evident when the guiding center motion is evaluated for the
approximately quadrupolar cell potential.
The expression for the drift velocity of the guiding center, v^,
is
y^ = E x B / B2. (5)
With the magnetic field direction as defined (Figure 2), the drift
velocity in component form becomes
vdx = Ey/B =[2A(Vr VQ)/a2B]y
and
Vdy = -Ex/B = [-2ot(V-j V0)/a2B]x (6)
Clearly, the drift velocity vector in any plane of constant z lies
in the plane and is perpendicular to the electric field vector, E.
Since £ is everywhere perpendicular to the equipotential lines,
ion drift occurs along the closed equipotential lines of the electro
static field. The frequency of the drift along the elliptical
equipotential lines is derived from the solution of the equations of
motion in the quadrupolar field as (47)
n = 2(VT-V0) (aAft
a2B (7)
Therefore, in the trapped ion cell, the circulation of the guiding
centers about elliptical paths defined by the electrostatic equi-


K
A. Two-inch oil diffusion pumps with
liquid nitrogen traps
B. High vacuum manifold cut off valve
C. Low vacuum manifold cut off valve
D. Inlet valve
E. Inlet low vacuum manifold cutoff valve
F. Leak valve
G- Vac ion cut off valve
H. Vac ion pump
W///////W L

MMZK
M
I Ionization gauge
J. Discharge gauge
K. Gold wire gasket seal
L. Laser window assembly
M. Magnet pole faces
N. Ion cell
O. Tapered joints
GO
00


116
curves and Franck-Condon and associated integrals determined here
were evaluated to assist in the interpretation of the structure
present in the photodestruction spectrum of the molecular chlorine
anion.
Table 8 contains the locations of the major peaks of the photo
reduction spectrum of C^ expressed in wavelength and wavenumbers.
Based on the output of the FC factor program, vibronic transitions
have been assigned to the observed transition energies. The results
of the FC factor program are indicative of, but not conclusive
evidence for, the assignment of the photoreduction of C^" to a
photodetachment process. The FC factor term values are accurate
as far as the spectroscopic constants for each state retain validity.
The spectroscopic constants for the X1^ ground state of chlorine
are well known for v $ 49 (109, 88b). Therefore, exceptional
accuracy in the term value is expected with respect to the neutral
vibration-rotation manifold. The constants for the molecular anion
are not well established and this hampers the peak assignments at
higher vibrational quantum numbers of the anion (110, 111). Several
of the assignments in Table 8 may be questionable, especially those
at 471.5 nm (V*=20, V**=13) and 463 nm (V*=23, V**=15). However,
at longer wavelengths the assigned transitions are obviously the
best possible fit of the calculations to the experiment. The
assigned FC factors, especially at the long wavelengths, are the only
overlap factors of reasonable magnitude in the wavelength region.
At shorter wavelengths more transitions could be contributing
significant intensity to the observed spectrum.


Appendix III. Microcomputer Programs (continued)
Main Program
Address
Label
Op Code
Mnemonic
Comment
08D0
ID
A5 00
LDA 00
C9 01
CMP #01
90 08
BCC 08
Identifies the type of data
F0 08
BEQ 03
- (zero, 100 or Laser) to be
4C 08 09
JMP 09DB
taken and routes accordingly
4C IF 09
JMP 091F
ZERO
A9 FI
LDA #F1
Sets interrupt vectors to
08E0
8D FE 17
STA 17FE
avoid ID & Zero for Zero
A9 08
LDA #08
points after the 1st, i.e.,
8D FF 17
STA 17FF
changes IV s to ZH,' ZL
A5 01
LDA 01
Sets up running counters
85 02
STA 02
for total number of zeroes
A5 01
LOA 01
- taken and half of total to
4A
LSR
be taken
85 03
STA 03
08F1
ZH, ZL
20 52 08
JSR 0852
Jumps to Obtain & Delay Subr.
18
CLC
A5 OF
LDA OF
65 1C
ADC 1C
85 OF
STA OF
A5 10
LDA 10
Maintains a running sum of
65 IB
ADC IB
~ Zero values
85 10
STA 10
0901
A5 11
LDA 11
69 00
ADC #00
85 11
STA 11
CTi
O


Figure 29. Photodetachment of Acetophenone at 200 ms Delay.
Detect delay time of 200 ms. Sample and
spectrometer conditions as for Figure 26.


603 598 (nm)
Relative Cross-Section (Arb. Units)
O
ro
CJl
o
3
to
CL
fD
i
Q)
'c
8t7l
Acetophenone/H?0


Figure 13. Resonant Baseline Data Flowchart.
The procedure for taking baseline MO
values with resonant ions while
simultaneously taking zero photo
detector values is diagrammed. Data
overlap occurs for each four sets of
measurements after the first eight
baseline measurements are stored.


40
Circuitry was constructed to transform a 1 ms TTL level pulse into
the 150 volt, 1.5 us sparkgap firing pulse to permit synchronous
control by a TTL pulse sequence (59).
The dye reservoir volume and circulation speed are sufficient
to insure that the dye cavity is flushed with fresh dye for each
laser shot. A Micropump Model 10-85-316-865 pump circulates the
dye solutions (60). Dye lines of polypropylene tubing are employed to
minimize dye degradation due to leaching of impurities from the
lines (61). A Pall liquid filtration system was added to the dye
circulation system to remove particles which scatter light and
reduce the efficiency of the dye laser (62).
Dye solutions were made up to a total volume of two liters in
100% ethanol obtained from chemical stores. The procedure for mixing
the dye solutionswas to start with an initially highly concentrated
solution and dilute the solution with ethanol until the output was
maximized. This resulted in dye solution concentrations on the order
-4 -5
of 10 to 10 molar. Laser dyes which were used in the photo
experiments,as well as dyes which were tested but did not lase
with sufficient intensity or lased only over a very restricted
wavelength range, are listed in Table 1. Nomenclature for the dyes
is that of Exciton, the primary supplier of dyes used in this
study (63). The position of the dye laser cavity relative to the
main vacuum can and subsidiary optical components is illustrated in
Figure 8.
Wavelength selection was achieved by incorporating a blazed
relection grating in autocollimation as one end of the optical


Appendix Vb. Molecular Chlorine and Molecular
V*,
v**
T(cm M
T ,
t
- 1 >1 7 2.12
! 4 *
L
-nvo4c i ?
1 6.
f
- 1 7 1 9 1 2
1 5 .
f.
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1 7,
b
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1 .
e
- 1 .U 1 2. 1 2
1 ') .
r
-17909.12
2? .
o
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21 .
6
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2? .
6
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21.
<~
-17127.12
?A,
-1*919*12
2 5 .
t
-lo754l2
1 1.
7
- 1 6 9 3. 19
1 % .
7
-in 475*39
13.
7
-19 260 39
16.
7
- 1 '04 P. 3 9
1 7 ,
7
-1383939
1 1.
7
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1
7
- 1 14 39.
20.
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2! .
7
- 1 8 3 3 3 3 9
2 ? ,
7
- 1 7 5 3 9 e 1 9
3,
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2 i.
7
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25,
7
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1 3.
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t 4,
6
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1 5 .
6
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1 r .
£J
- 1 7 563.9 9
I 7 ,
n
-19 35 4.99
18,
8
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lr'.
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2 ,
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21 .
n
- 1 3 5 4 6 9 v
2 ,
h
- 1 1 5 4.9 O
2 3 .
-H161.19
,
a
- 1 *9 75. v 9
PS,
u
-1 7 7no,o.,,
cr
Lambda
14 3 >0- ) l
52l5c 906
?6n-ri
5?75.6C9
. 4 7 9 7 0-9 1
53 2* .4 3 1
;o a o-70-ci
5 3 57 o 4 9 4
: w ,r oo n-o i
54 55.0 7*'
:. 6 l 580-02
53 21 .16 4
0,63 003- 'A4
5503 747
; 54 2 9 D-02
5646.307
C 18960-01
5710.130
07**50-C1
5774.2 93
0.2 2 66 r -01
5513.693
: 0 8'^ 2 40-0 2
5903.4 94
:.82609-04
5963.590
0 4664 D-01
50 7 7 .8 4 7
C.4^510-01
51 34. 6 86
Oo13360-01
5192.004
)15300-01
5249 o 7 88
0 1C 1 25- 82
5108.021
.18240-02
53 66 7 1 9
: O 13 5 70-0l
5425 621
0 25223-01
54 35.1 4 6
0* 24 785-01
5545.269
,l2415-cl
56 05o 5 7 2
;,1C790-07
56 66.2 39
Co 30 950- C2
5 7 27.2 49
?. If 520-01
5788.591
0.42335-01
4948.291
? 26 2 40-?1
5C 02 254
) * 1 300 02
5 0 5'; .6 17
0. 44 l 7^-03
5 1 l 1 .4 32
69 i 70- 0?
51 66 o 62 7
0 2 J 74 0-01
3222.?C7
'026570-:l
52 78 16 1
: o 1 76 0 5-21
5.134.4 73
' 401 2 5-07
53 91 .12 1
, f.4 720- 02
5440l09
j, \ 2 76 j-: i
55;3* 397
:. 2; 811) o i
5367 5 975
' 1 -45b- -> 1
5c 0* 2
Chlorine Anion Franck-Condon Overlap Factors (con't)
QT**3
QT**4
RC
R**2C
Phase
-.24170
l 2
0.46330
l 6
2.2374
5. 0 0 6 6
_
C.30140
1 2
0.57131
1 6
2.2112
4.9785
Â¥
0.3 l 30i0
l ?
0.58660
1
2.2250
4. 95ce
-
0 o 2 5 66 0
1 2
0 A 7 9 2 0
16
2.2190
4.9236

015160
1 2
0.29150
16
2.2133
4.8973
-
0 4 o 4 7 D
1 1
0.97790
1 5
2.2092
4. e7 ?fa
0 36190
09
0*6481D
13
2.2223
4.89 67
-
Oo 3 Cl5D
1 1
0 *5 .1390
1 5
2. 1923
4. 81 01
-
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l 2
0 l 755 0
16
2. 1878
4. 7830

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4.7£ 4 4
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1 6.
7.1777
4. 7414
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0.4 33 70
l 1
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4.7215
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0.1340
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0. 65080
1 3
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47996
015620
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0. 1 2 790
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lo
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0.27860
16
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4.8842
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l 2
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1 t
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4.8597
f
0. 70440
1 1
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2. 1998
4.8368
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4. 8256

Oc l 54 70
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2. 183 1
4.7723

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lb
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1
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Appendix III. Microcomputer Programs (continued)
Double Precision Divide Subroutine
Address Label Op Code Mnemonic
Comment
A2 DA
LDX DA
A9 00
LDA 00
95 00
STA 00
CA
DEX
EO D1
CPX D1
DO F9
BNE 0B04
DB 02 04 06 08
AA
TAX
36
SEC
D3 D2 D5 D4 D7 D6 D9 D8
26
D6
ROL
D6
26
D7
ROL
D7
A5
DC
LDA
DC
30
10
BMI
0825
26
D6
ROL
D6
A5
DC
LDA
DC
DO
FO
BNE
OB 11
A5
DD
LDA
DD
DO
EC
BNE
0B11
A5
DE
LDA
DE
BO
OE
BCS
2A37
C5
DC
CMP
DC
90
35
BCC
0B62
FO
02
BEQ
0B31
BO
06
BCS
0B37
A5
DF
LDA
DF
00


PHOTODETACHMENT OF GAS-PHASE HALOGEN MOLECULAR
ANIONS AND THE ENOLATE ANION OF
ACETOPHENONE
by
Ronald 0. Daubach
A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL
OF THE UNIVERSITY OF FLORIDA IN
PARTIAL FULFILLMENT OF THE REQUIREMENTS
FOR THE DEGREE OF DOCTOR OF PHILOSOPHY
1983

Copyright 1983
by
Ronald 0. Daubach

ACKNOWLEDGEMENTS
The author thanks Dr. John R. Eyler for his instruction,
assistance, and direction in this research effort. In addition,
the patience and concern of Dr. Eyler in all stages of this research
and manuscript preparation are gratefully acknowledged.
The stimulation provided by fellow graduate students was
valuable. Particular thanks are extended to Dr. L. Morgenthaler,
R. J. Doyle,and D. A. Atherton. The design of the microcomputer
interface was initially generated by Dr. Ed Voigtman without
whose assistance no subsequent progress would have been possible.
The construction of the apparatus used in this work involved
the efforts of many. The professional workmanship of Mr. Art Grant,
Mr. Ed Whitehead, Mr. Rudy Strohschein, Mr. James Chamblee,and
Mr. Robert Dugan is thankfully commended.
The author thanks Ms. Constance Miller for the patient and
careful preparation of this dissertation.
The impetus to accomplish when the desire lagged was provided
by the love, concern,and devotion of Joni Meno Daubach which is
deeply appreciated.
Funding for this research has been provided by the Division
of Sponsored Research and the Department of Chemistry.

TABLE OF CONTENTS
Page
ACKNOWLEDGEMENTS iii
LIST OF TABLES vi
LIST OF FIGURES vi i
ABSTRACT ix
CHAPTER I INTRODUCTION 1
Historical and Scientific Interest in
Negative Ions 1
Electron Affinity 3
Experimental Techniques 5
Theoretical Techniques 6
Outline of Dissertation 9
CHAPTER II THEORY OF ION CYCLOTRON RESONANCE 10
Ion Motion in Static Fields 10
Ion Motion in an RF Electric Field 19
Ion Detection 25
CHAPTER III EXPERIMENTAL APPARATUS 31
Trapping Cell 31
Vacuum Apparatus 34
Optical Apparatus 39
Pulsed Electronics 46
Microcomputer 52
Microcomputer and Modifications 53
Microcomputer Interface Hardware 55
Microcomputer Software 58
Run Time Operation 59
Derivation of the Expression for the Photo
detachment Cross-Section 75
CHAPTER IV EXPERIMENTAL RESULTS AND DISCUSSION OF
THE HALOGEN ANION STUDIES 80
Chlorine Molecular Anion-Formation of Cl?. . 80
Photodetachment of Cl^ 95

Page
Analysis of Clp Results 104
ComDutation or Franck-Condon Factors ^ . . 106
Bromine Molecular Anion-Formation of Br? .... 120
Photodetachment of Br? 123
Analysis of BrZ Results 123
Bromine Monochforide Molecular Anion 131
Analysis of BrCl Results 131
CHAPTER IV PHOTODETACHMENT STUDY OF THE EMOLATE ANION
OF ACETOPHENONE 135
Formation of the Enolate Anion 135
Analysis of the Acetophenone Enolate Anion
Results 142
CHAPTER V SUMMARY 150
APPENDIX I ON-BOARD MICROCOMPUTER HARDWARE MODIFICATION . 152
APPENDIX II MICROCOMPUTER CONTROL REGISTERS 153
APPENDIX III MICROCOMPUTER PROGRAMS 155
APPENDIX IV SAMPLE PREPARATION 181
APPENDIX V NUMERICAL VALUES OF THE RKR POTENTIALS AND
THE FRANCK-CONDON OVERLAP PROGRAM OUTPUT .... 183
REFERENCES 205
BIOGRAPHICAL SKETCH ... 212
v

LIST OF TABLES
Table Page
1 Laser Dyes and Observed Lasing Wavelength Regions. 41
2 Grating Characteristics as a Function of
Wavelength for a 1200 line/mm Grating in
Autocol1imation 45
3 Factors in the Relative Errors in the Cross-Section
for a Range of A Values and f Equal to 1.0 and 0.75. 78
4 Variation of ICR Operating Parameters During Studies
to Maximize Formation of the Nitrite Ion from
Nitromethane 82
5 Empirical Electron Affinities for NO2 in eV 92
6 Spectroscopic Constants Used in the Determination
of the Rydberg-Klein-Rees Potential Curve for Cl^. 113
7 Spectroscopic Constants Used in the Determination
of the Rydberg-Klein-Rees Potential Curve for Cl2~ 114
8 Correlation of the Observed Peaks (A, T ) in
the Clp" Photodetachment Spectrum with exp
Calculated Transitions Energies (T ) and
Franck-Condon Factors ? 117
9 Adiabatic Electron Affinity Values for Chlorine
Determined from the Assignment of the Photo
detachment Spectrum Structure 121
10 Comparison of Literature Values for the Electron
Affinity of Chlorine 122
11 Experimental Wavelengths.(A) and Term Values (T )
and First Differences (a1) for the Observed exp
Photoreduction of Bromine Molecular Negative Ions. 129
12 Rate Coefficients for the Reaction of Cl" with
Br2 134
13 Values for Instrumental Parameters Pertinent to
Acetophenone Anion Production and OH" and F"
Precursor Anions 141
VI

LIST OF FIGURES
Figure Page
1 Trochoidal Trajectory of a Charged Particle
in Uniform and Static Crossed Electric and
Magnetic Fields 13
2 Trapped Ion Cyclotron Resonance Cell Schematic ... 16
3 Time-Dependent Radii for Non-Resonant Particles. . 24
4 GLC Circuit Emulation of ICR Detection 28
5 Trapped Ion Cyclotron Resonance Cell 33
6 Schematic Diagram of the Digital Pulse Electronics 36
7 Vacuum System Schematic 38
8 Dye Laser Apparatus and Orientation 43
9 A Typical Pulsed ICR Experiment Pulse Sequence ... 48
10 Operator/Microcomputer Interaction Flowchart .... 61
11 Main Program Branch Flowchart 63
12 Baseline MO Data Flowchart 65
13 Resonant Baseline Data Flowchart 67
14 Laser Status Flowchart 69
15 Microcomputer RAM Memory Map 71
16 Negative Ion Mass Spectrum of Nitromethane 84
17 Negative Ion Mass Spectrum for a Chlorine/
Nitromethane Mixture 87
18 Time-Dependent Mass Spectra of the Major Peaks
of a Chlorine/Nitromethane Mixture 89
vi i

Figure Page
19 Photodetachment of Cl-? 97
20 Photoproduction of Cl 100
21 Cl^~ Photodetachment Cross-Section as a Function
of Wavelength 103
22 Rydberg-Klein-Rees Potential Energy Curves for
C12 and C^" 112
23 The Negative Ion Mass Spectrum of a Mixture of
Chlorine/Bromine and Nitromethane 125
24 Photodetachment Spectrum of B^" 127
25 Negative Ion Mass Spectrum with BrCl" 133
26 Acetophenone Signal Intensity 138
27 Photoreduction of the Enolate Anion 140
28 Photodetachment of Acetophenone as a Function of
Wavelength at 150 ms Delay 144
29 Photodetachment of Acetophenone as a Function of
Wavelength at 200 ms Delay 146
30 Photodetachment of Acetophenone as a Function of
Wavelength at 250 ms Delay 148
vi i i

Abstract of Dissertation Presented to the Graduate Council of
the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy
PHOTODETACHMENT OF GAS-PHASE HALOGEN MOLECULAR
ANIONS AND THE ENOLATE ANION OF
ACETOPHENONE
By
Ronald 0. Daubach
December 1983
Chairman: Dr. John R. Eyler
Major Department: Chemistry
The photodetachment of electrons from negative halogen
molecular ions has been investigated. An ion cyclotron resonance
mass spectrometer was employed for the generation, containment and
detection of the ions. Photoprocesses were induced by means of an
integrated, tunable dye laser system.
Structure was observed in the photodetachment spectra of chlorine
and bromine molecular anions. This structure was correlated to
vibronic fine structure of the photodetachment transition. An
adiabatic electron affinity value for chlorine of 2.36 +0-27
-0.32
eV was obtained. The absence of structure in the bromine photodetach
ment cross-section attributable to the anion precluded estimation
of the electron affinity of bromine. The interhalogen molecular

anion of bromine monochloride was generated but was of low signal
intensity. The photodetachment spectrum of the enolate anion of
acetophenone exhibited behavior which supported previous
explanations of the source of the structure in the cross-section near
threshold.
x

CHAPTER I
INTRODUCTION
Historical and Scientific Interest in Negative Ions
The study of negative ions in the gas phase has elicited
increasing interest since Wildt ascertained the importance of H" to
the explanation of the anomalous infrared opacity of the solar
spectrum (1). This insight was founded upon the investigation of the
"affinity continuum" associated with the radiative attachment of an
electron to an atom by Gerlach and Gromann (2). Wildt further proposed
that the radiative behavior of diatomic negative ions of neutral
diatomics of established astrophysical importance such as H,,, 0^,
NH, OH,and CH might be of significance in stellar radiation spectral
analysis. Subsequent study of negative ions for astrophysical
applications has been largely concerned with defining the wavelengtn
dependence of the interaction of light with the selected ions (3).
Following the recognition of the import of negative ions in stellar
plasmas, an awareness of negative ions evolved in atmospheric
chemistry, flame chemistry, gas laser plasma chemistry, and radiation
chemistry and biology.
Consideration of the behavior of negative ions in the atmosphere
is essential in accounting for effects such as the reflection of radio
waves at the lower ionosphere (4) and the fate of atmospheric
pollutants (5). The ionosphere is a region of high free electron

2
concentration extending from 60 to 450 kilometers above the earth's
surface. Fluctuations, either local or temporal, in the free electron
concentration in this region have profound effects on the
reflectivity to radiofrequencies exhibited by the region. Consequently,
the formation and destruction of negative ions with the concomitant
loss or gain of free electrons must be characterized to account for
the observed radiofrequency reflectivity.
Negative ion chemistry in the lower atmosphere, the stratosphere
(15-60 kilometers) and the troposphere (0-15 kilometers), is pertinent
to air pollution chemistry and had been suggested as a sink for
chlorofluorocarbons released into the atmosphere. Recent studies
have discredited this suggestion as the reactions of the hydrated
negative ions which predominate at the lower altitudes with
chlorofluorocarbons have been shown to proceed slowly (6).
The study of ions in flames is of current interest (7) and has
been of interest since Moreau's early studies of negative ion
transport in flames (8). The complexity of the negative ion
composition of flames is illustrated by the number of negative ions
in significant concentration in a simple, clean, methane-oxygen
flame in which no fewer than twelve negative ions have been
identified (9). Not only the characterization of flames by the study
of the ion distribution, which remains an active area of research (10),
but also the use of flames in spectroscopy rely upon the clarification
of negative ion-flame chemistry.
The accelerated search for laser media with output in the ultra
violet and vacuum ultraviolet wavelength regions (11) requires

3
knowledge of electron-neutral interactions and negative ion formation.
Typically, short wavelength lasers have employed some variation
of a fast-risetime, high-energy electron discharge pumping scheme (12).
The excited neutrals and positive ions formed during discharge have
been included in models of laser performance (13). A recent
investigation has extended consideration to negative ions produced by
the attachment of secondary electrons to and NF^, the alternate
sources of fluorine in XeF laser gas mixtures (14). In addition, the
mobility of Cl- in Xe, a factor in evaluating the XeCl excimer
mixtures, has been investigated (15) and it has been suggested that the
molecular bromine anion contributes to XeBr* excimer formation in
electron discharge pumped mixtures through reaction with Xe+ (16).
Negative ions are of interest in radiation and nuclear chemistry.
Biologically active free radicals, excited states,and negative ions
are generated by radiation incident on biological matter (17). The
development of nuclear pumped lasers and gas-core reactors employing
UFg as the fuel /medium requires that the negative ion formation of
this compound of relatively large electron affinity be evaluated (18).
Electron Affinity
The electron affinity of the corresponding neutral is the most
fundamental property associated with a negative ion. The electron
affinity is defined as the change in the total energy of the system
upon the addition of an electron. The change in the system energy
may be positive or negative. Conventionally, stabilization of the
system corresponds to a positive sense for the electron affinity.

4
Negative electron affinities are associated with unstable systems which
may, however, exhibit resonances related to the formation of a
transient negative ion state (19).
For an atomic negative ion, the given definition of electron
affinity is complete. A complication arises for molecular negative ions
due to the change in the nuclear configuration associated with the
addition of the electron. Two distinct types of electron affinities
are conceivable. The energy difference associated with the ground state
neutral and ground state ion both with zero internal energy and both
at their respective equilibrium geometries is referred to as the
adiabatic electron affinity. A more readily observable energy
difference, the vertical electron affinitycorresponds to the change
in energy between the neutral and negative ion ground electronic states
at the equilibrium nuclear configuration of the neutral. In general,
the term vertical electron affinity is used for all values of observed
electron affinities for which either the negative ion or the neutral
possess internal excitation. Herein lies the basic problem in the
interpretation of experimental measurements of molecular electron
affinities, the difficulty encountered in the evaluation of the internal
energy of the initial and final states. In general, experimental
techniques measure vertical electron affinities which provide upper or
lower limits to the adiabatic or thermodynamic electron affinity
based upon some estimate of the internal excitation. Several reviews
(20-23) of the techniques applied in the evaluation of electron
affinities of molecular species have appeared including the recent
article by Janousek and Brauman which provides an excellent overview
of the topics discussed here.

Experimental Techniques
Two types of charge transfer techniques have proven useful in the
study of electron affinities: exothermic charge transfer (CT) and
endothermic charge transfer (ECT). Exothermic charge transfer yields
limits on a molecular electron affinity by observation of the direction
of spontaneous charge transfer between negative ions and target
neutrals. More accurate values of the limits for the electron affinity
may be surmised if the exothermicity of the charge transfer reaction
can be estimated (24). Endothermic charge transfer employs the
energy of translation to induce a nominally endothermic charge transfer
(25). This technique enables the energy dependence of the cross-
section above threshold to be determined. Collisional ionization is
a related scheme in which both of the initial reactants are neutrals.
Collision-induced, ion-pair formation lends itself to the evaluation
of the product negative ion electron affinity provided the positive
ion's ionization potential is independently known (26). These
techniques are limited by the residual uncertainties in the distributi
of the excess energy between translation and internal modes and the
detailed distribution of the internal energy for systems with more
than one degree of internal freedom.
A variety of photodetachment techniques for obtaining electron
affinities have been developed. These include fixed (27) and
variable (28) frequency photoelectron spectrometry and variable
frequency crossed beam (29) and drift tube (30) photodetachment
techniques. The rapid development of variable wavelength, wide-wave-

6
length-tuning-range lasers of excellent monochromaticity has greatly
assisted the application of photodetachment schemes. The major
characteristic distinguishing the different photodetachment techniques
is the detailed means by which the process is instigated and detected.
The fixed frequency photoelectric experiment employs an argon ion
(Ar+) laser (488.0 nm) to eject electrons from a beam of negative ions.
The photoelectrons are energy analyzed over a defined angular collection
aperture to obtain the photoelectron spectrum. Variable frequency
photoelectron spectrometry measures the production of photoelectrons
as a function of the irradiation wavelength. Beam and drift tube photo
detachment employ either neutral beam or residual ion beam detection
rather than direct analysis of the ejected electrons. The important
advantage of a drift tube experiment is the reasonable assurance that
an ion has a thermal internal energy distribution prior to photo-
excitation.
Ion cyclotron resonance (ICR) techniques for the study of photo-
induced processes of ions merge the advantage of drift tube thermaliza-
tion with controlled, low energy, electron-impact production of
negative ions to minimize ion internal excitation (31-32). The pulsed
ICR technique is capable of characterizing effects of ion internal
excitation by varying the time available for the collisional de-excitation
prior to photoexcitation (33).
Theoretical Techniques
Evaluation of the experimental measurement of electron affinities
has been hampered by the absence of reliable, theoretical predictions
of the electron affinity and by the inability to predict the features

7
of a photodetachment spectrum. Means of estimating electron affinities
and evaluating cross-section behavior have been developed and may be
classified as semiempirical, ab initio,and collision theory techniques.
Semiempirical results deal solely with the prediction of electron
affinities. Pritchard (34) gave a very complete historical summary
of semiempirical estimation of electron affinities based on observed
lattice energies and thermodynamic arguments. Person (35) suggested a
semiempirical scheme based upon the charge-transfer frequency of
donor-acceptor complexes (36) and its relation to the vertical electron
affinity of the acceptor and derived good results for several
diatomic halogen molecules. Recently, a means of estimating molecular
electron affinities from the constituent atoms' electron affinities and
positions in the Periodic Table has been proposed (37).
Theoretical determinations of electron affinities have employed
either direct or indirect schemes (38). Indirect methods consist of
individual calculations for the potential energy of the neutral and
negative ion states. The potential energy curves generated are then
used to obtain values for the adiabatic and vertical electron
affinities. These methods are constrained by the necessity of very
high precision in the individual state energies since the electron
affinities are given as the difference of two large values, yet are
quite small with respect to the total energies of either state. In
addition, it is not trivial to insure that the calculations for both
states employing a common calculation technique, Hartree-Fock, Cl, or
perturbation theory, are carried out to the same order when the number
of electrons is changed by one. Finally, the electron affinity is

8
normally of the order of the correlation energy (39),the energy
associated with the assumption of an average potential due to all of
the electrons with the exception of the electron whose energy state is
calculated. This average potential is an assumption basic to all
Hartree-Fock schemes and limits the value of this particular scheme
for electron affinity determination. Cl accounts for correlation effects
by including a number of electronic configurations into the energy
calculations (40). Generally, the validity of any indirect method
depends upon the system as well as the technique.
Several variations of a direct method for calculating potential
energy differences between electronic states at a selected nuclear
configuration have recently been developed (38). These techniques
eliminate the inaccuracies of the indirect procedures. The method
begins with a calculation of the neutral potential energy curve. An
operator simulating the addition or removal of an electron is then
applied to a specific point on the potential energy surface. This
determines the ion energy. For vertical and adiabatic electron
affinity estimation, this method appears promising. It is feasible,
although computationally extensive, to generate the detailed anion
potential surfaces necessary to predict spectral behavior for the
transitions.
Photodetachment spectral analysis consists of modeling the energy
dependence of the cross-section at threshold. The rigorous mathematical
basis for the threshold behavior has been delineated by Wigner (41).
An excellent, detailed derivation of the theory has been published by
Lane and Thomas (42) and the extension of the formalism to a coordinate

9
system applicable to diatomics is well documented (43). The details
of the theory and derivation will not be of significance here; however,
the results will be applied in analysis of the observed spectral
behavior.
Outline of the Dissertation
This dissertation presents a description of photodetachment
studies executed on molecular negative ions. These investigations were
carried out using a pulsed ion cyclotron resonance mass spectrometer
combined with a pulsed, flashlamp-pumped dye laser. A data collection
and analysis system was interfaced to the experiment to simplify and
accelerate data reduction. Chapter II describes the theory of ion
cyclotron resonance as it pertains to ion containment and detection.
Chapter III addresses the details of the experimental procedure and
set-up. Chapter IV presents the results for the diatomic halogen
anions investigated, Cl^-, Br^-, and BrCl". Chapter V presents the
results for the enolate anion of acetophenone. A summary of the results
and assessment of the technique for the study of molecular anions is
put forward in Chapter VI.
Appendix I documents alterations made to the microcomputer to
enhance its data handling performance. Appendix II itemizes the
control registers for the software data collection and analysis.
Appendix III contains the microcomputer programs written to implement
the data collection. Appendix IV describes the sample preparations
and handling techniques for the parent compounds. Appendix V
contains the calculated potential energy curves and Franck-Condon
analysis for Cl^ ~ Cl.

CHAPTER II
THEORY OF ION CYCLOTRON RESONANCE
The study of photo-induced processes of gas phase ions
necessitates a well-defined region of observation and the minimization
of non photo-induced ion losses. In addition, a sensitive method of
sufficient resolution is required for the detection of ions of
varying mass-to-charge ratios. The classical motion of a charged
particle in electric and magnetic fields is applied to the spatial
restriction and the detection of ions.
Ion Motion in Static Fields
An isolated, charged particle in motion located in a magnetic
field interacts with the field classically. This interaction of
charged particle and magnetic field constrains the particle motion in
the plane perpendicular to the field. For a uniform and static
magnetic field, the interaction of the particle and the field results
in the gyration of the particle about the magnetic field lines.
The field-induced motion is characterized by the frequency of the
rotation, u>, given as (44)
w = qB/m (1)
where q is the charge on the particle, m is the particle mass, B is
the magnitude of the magnetic field strength and u> is the natural
cyclotron frequency. Although the component of the initial particle
10

11
velocity perpendicular to the field, Vg ,must be nonzero for this
interaction, significantly, the frequency of gyration is independent
of the actual magnitude of the velocity component. Therefore, ions
of identical charge-to-mass ratios circulate about the magnetic field
lines at a single natural cyclotron frequency regardless of the
distribution of velocity components, Vg^. The component, Vg remains
significant since the radius of gyration, r, retains a functional
dependence on vg
r
_ V0J_
qB (2)
The motion of a charged particle in the presence of uniform and
static electric and magnetic fields, E and B, respectively, is
governed by the Lorentz force law,
F = q(E + v x B) (3)
where v^ is the particle velocity. This equation is readily soluble
for the assumed field conditions for the equations of motion of the
particle (44). For the simplified field conditions in which E. and B
are mutually perpendicular, the equations of motion dictate a
trochoidal path, the superposition of the cyclotron motion and the
drift of the center of the cyclotron orbit perpendicular to both
fields (Figure 1). The separation of the complex trajectory of the
particle into the cyclotron and drift components is a useful
modification for the analysis and visualization of ion motion in
complicated electrostatic fields. The center of the cyclotron motion
is referred to as the "guiding center" and the separation of motions
is called the 'guiding center or "drift approximation (45).

Figure 1. Trochoidal Trajectory of a Charged Particle in Uniform
and Static Crossed Electric and Magnetic Fields. A
nonzero component of particle velocity in the y-direction
is presumed in the generation of the trochoidal path.

13

Three-dimensional ion containment is not accomplished with the
simple field conditions thus far treated. In neither of the cases
considered has the motion of the particle parallel to the magnetic
field lines been restricted. Also, the transverse electric field
induces a particle drift producing a channel for ion loss perpendicular
to both the electric and magnetic fields. Consequently, a configuration
of fields eliminating these ion loss channels must be selected.
The trapped ion cell developed by Mclver produces an electro
static potential for which the equipotential lines close on themselves
in the plane perpendicular to the magnetic field in addition to
forming an electrostatic potential well parallel to the magnetic
field axis (46). The cell geometry and definition of coordinate axes
are indicated in Figure 2, which also indicates the direction of the
magnetic field for subsequent discussion. The cell consists of six
electrically independent plates. For effective negative ion trapping,
the upper (U), lower (L), and end (E) plates are held at +1.0 volt,
while the trapping (T) plate potentials are -1.5 volts. In the case
of positive ion trapping, the polarity of each plate potential
is reversed. The solution of Laplace's Equation for a cell identical
to that shown in Figure 2 has provided an expression for the three-
dimensional potential produced in the cell interior (47). An
analytic approximation to this expression valid near the center of
the cell yields a quadrupolar electric field

Figure 2. Trapped Ion Cyclotron Resonance Cell Schematic.
Components of the trapped ion cell which influence
the geometry of the electrostatic cell potential
are Tc and Tf, the collector and filament
trapping plates, respectively; U, the upper plate;
L, the lower plate; E, and E2, equivalent, open
end plates.

16
o

17
where a is the cell width, Vj is the trapping plate potential, Vq is
the upper and lower plate potential and a, A and 3 are constants
related to the actual dimensions of the cell. The restriction of ion
motion is evident when the guiding center motion is evaluated for the
approximately quadrupolar cell potential.
The expression for the drift velocity of the guiding center, v^,
is
y^ = E x B / B2. (5)
With the magnetic field direction as defined (Figure 2), the drift
velocity in component form becomes
vdx = Ey/B =[2A(Vr VQ)/a2B]y
and
Vdy = -Ex/B = [-2ot(V-j V0)/a2B]x (6)
Clearly, the drift velocity vector in any plane of constant z lies
in the plane and is perpendicular to the electric field vector, E.
Since £ is everywhere perpendicular to the equipotential lines,
ion drift occurs along the closed equipotential lines of the electro
static field. The frequency of the drift along the elliptical
equipotential lines is derived from the solution of the equations of
motion in the quadrupolar field as (47)
n = 2(VT-V0) (aAft
a2B (7)
Therefore, in the trapped ion cell, the circulation of the guiding
centers about elliptical paths defined by the electrostatic equi-

18
potential lines at frequency n eliminates the mechanism of drift
loss of ions.
The remaining component of the electric field, E is of the
form (47)
= -Kz k (8)
where
K = 2(Vr VQ)e/a2.
Substitution of this expression into the z-component of the Lorentz
force law (2) yields the equation for simple harmonic motion of a
charged particle along the magnetic field lines
vz = -y
(9)
where w-p = (qK/m)2. Oscillatory motion along the z axis is imposed
upon ions whose initial total energy, kinetic and potential, is less
than the trapping potential well. A side-effect of the electrostatic
restriction of the ions in the z-directi on is a shift in the observed
cyclotron frequency from the natural cyclotron frequency, to. The
effective cyclotron frequency, uj is (47)
aB
no)
Clearly, alteration of the trapping potentials results in a shift
of the cyclotron frequency unless compensated with an appropriate
alteration of the magnetic field strength.
Typical values of the ion motion parameters for an ion of mass
number 70 and unit negative charge in a magnetic field of 0.70 Telsa
with the standard plate potentials are

19
Natural cyclotron frequency, 00/2-n
Radius of cyclotron orbit, r
Drift frequency, fi /2tt
Drift velocity, v Trapping frequency, o^/2ir
Observed cyclotron frequency, \/2t\
24.4 kHz
214 Hz
0.2 mm
0.27 m/sec
153.6 kHz
152 kHz
where v =v =v is 2 x 10^ m/sec. The motion of the ion proceeds as
x y
follows: during the period of one complete oscillation of the guiding
center along the magnetic field line (Twj ~ 40 us) the ion will have
completed six rotations about the guiding center (T^ ~ 6us) and the
guiding center will have drifted along an electrostatic equipotential
line and perpendicular to the magnetic field axis a distance of
approximately 0.01 mm.
Ion Motion in an RF Electric Field
An rf electric field takes the form
E_j(t) = Ej sin (a) t) i
(11)
for a field linearly polarized in the x-direction. A linearly
polarized rf field may be decomposed into counterrotating circularly
polarized fields
and
E1 E1
E j(t) = ~y sin (u^) i -j- cos (w-jt) j
(12)

20
Restricting consideration to the circularly polarized component of
the same sense as the ion motion, E ,(t) (48), the force equation in
component form becomes
dux qEj
"HF = ~2iT s1n (l11 + cuy
dt
qq
2m
cos (wjt) <^cux
(13)
Transforming and solving these equations yields the velocity components
driven by the rf electric field in a static magnetic field
qEl
ux(t) 2m(u--i., ) [cos ^c11 cos '1 c
(14)
"qEl
uy(t) = 2m(yT) [sin (V} sin (lt)]-
The time dependent expression for the energy of the motion, E (49),
attributable to the combined rf electric and static magnetic field is
d E q E1
dt 1-E- ) {Icos(coct> cos(Ujt) ] Sln(jt)
1 c (15)
-[sin(a)ct) sin(w^t)] cos(u^t) }.
Equating the instantaneous kinetic energy, dE/dt, to the spontaneous
power absorption, A(t), and simplifying the trigonometric terms
produces an expression for A(t)
q2E
4m (w.
sin (w -to )t.
v 1 c
A(t) = dE/dt =
(16)

21
This general expression for instantaneous power absorption may be
evaluated for the conditions of ion resonance and extended rf
irradiation to determine the average power absorption per resonant ion.
Substituting into the expression for the kinetic energy, E^v ,
yields the particle kinetic energy due to rf excitation
2f 2
C q 1 2,W1 wCn
E = ozrr w sin ( 5 ) t.
2m(w1 u¡c) 2
(17)
The instanteous power absorption is then readily converted to the
average power absorption, A(wj), over the period of irradiation, Tt
q2E2
A(l) = T 4ni'(u:-')2 Il-cosfuj-u
1 c
)T]
(18)
Finally, the behavior of these quantities at resonance (<^=a)c) can be
evaluated
A (t) = (dE/dt) =
q?El2t
4m
E =
A(c)
2f 2.2
q Ej t
8m
q2Ei2T
8m
(19)
The rf electric field directly influences the cyclotron motion of the
ion about the magnetic field lines. The nature of the interaction
becomes evident when the time dependent radius of the cyclotron motion
in the field is derived
cE, sin (w.-u) )t
1 1 c
r(t) =
B
-/ (20)

22
At resonance
( cE,
r =
2B
t.
(21)
The radius of gyration of an ion in resonance increases linearly with the
irradiation time and with the electric field amplitude. At higher
magnetic fields the resonant ion radius is smaller for the same rf
irradiation conditions. The radius of a nonresonant ion is seen to
be varying with time but is bounded as a result of the phase mismatch
between the resonant frequency of the ion and the driving rf
field (Figure 3).
The motion of a collection of ions with a distribution of
velocities has been determined from the equations for single particle
motion (47). In the trapped ion cell, ions are formed through the
interaction of a pulsed electron beam directed along the z-axis with
a sample gas in thermal equilibrium. Assuming that there is no
gradient of electron energy along the electron beam (generally invalid)
and that the electron pulse is long with respect to the period for
simple harmonic motion along the z-axis (generally true), then the
ions can be assumed to be uniformly distributed along the z-axis.
The uniform distribution of guiding centers along the z-axis drifts
along equipotential field lines. If an electron beam of circular
cross-section is assumed the initial distribution of guiding centers
is circular in the xy-plane. The geometry of the initial distribution
is altered due to the variation in ellipticity of the paths followed
by individual ions as a function of the distance from the z-axis

Figure 3. Time-Dependent Radii for Non-Resonant Particles
For <7S£) = 1 HZ rmax Is el r + T and rrain is etlual t0 r'f- For (T7)
2 HZ cE3* 15 e<|Ua t0 r + a"d r" iS
equal to r-£p.


25
at the drift frequency, ft. This produces an oscillation of the
population of guiding centers between a circular distribution and an
elliptical distribution at twice the drift frequency, which for the
numerical example above corresponds to 428 Hz. However, the duration
of the electron beam pulse, ~25 ms, is longer than the period of the
guiding center drift oscillation, -2.3 ms,and the ions will be
uniformly distributed along the elliptical orbits if ion formation is
constant during the electron beam pulse. Therefore, ions formed at
any instant exhibit a shifting population distribution but the total
collection of ions is uniformly distributed along elliptical drift
lines.
Ion Detection
Power absorption by an ion from an amplitude limited rf
electric field is the basis of ion cyclotron resonance detection.
Obviously the means for generating a suitably stable rf field and a
means of detecting absorption of the field are required. Both of these
functions can be accomplished with a marginal oscillator detector.
Marginal oscillator circuit applications in ion cyclotron
resonance detection (50) are completely analogous to their earlier
application in nuclear magnetic resonance (nmr) detection (51).
Consequently, ion cyclotron resonance marginal oscillators have evolved
with few modifications from nmr marginal oscillators. Two
alterations of the basic marginal oscillator circuit serve to adapt
it for use in a pulsed mode (52). First, the addition of a limiter
in the feedback loop of the oscillator insures reliable low level

26
operation as required for ion detection. Second, a gated amplifier
serves to pulse the circuit output with the application of an
externally derived gate pulse.
The analysis of marginal oscillator detection can be carried out
in terms of the gated, limited feedback oscillator (Figure 4). The
parallel, GLC (conductance-inductance-capacitance) tank circuit
of the oscillator has a resonant frequency
w0 = (LC)^ (22)
where L is the circuit inductance and C is the circuit:and cell
capacitance. The conductance, G, represents resistive losses in the
circuit. The limiter supplies a constant amplitude signal,
Vq, to the resonant circuit through the feedback resistor, R^. At
resonance, jqC = (c^L) \ hence the admittance is a pure conductance
and the voltage across G, Vp, becomes
V
,-l
+ R
-).v = -=
' o 1 + GR,
where VQ is the rms voltage level from the limiter and is
voltage level across the resonant circuit. An infinitesimal
in conductance directly affects the rms voltage level of the
resonant circuit
(23)
the rms
change
AVG = VpRf = VGRf (24)
AG (1 + GRf)2 1 + GRf
The power absorption (AA) due to a change in the cell conductance
is represented by the total derivative of the instantaneous power
with respect to the conductance and the voltage across the conductance,
,1 + GRf,
AA = -V,
G
AV, l-
R,
-)
(25)

Figure 4. GLC Circuit Emulation of ICR Detection.
V is the output of the limiter. is
the amplifier feedback resistance. G,
L, and C represent the conductance,
inductance and capacitance of the ion
cyclotron resonance cell.


29
The expression for the instantaneous power absorption of a resonant
ion (Equation 19) is equated to Equation 25 and solved for AVg
AVG
qVt ( Rf )
4mVG l + GRf '
(26)
The criterion for maximum power transfer is
(27)
as would be anticipated. This solution is extended to n ions and
the average value of AVG for such an ensemble is
AVG
= nq2Ei2t ( Rf )
4mVq 1 + GRf
(28)
Equation 28 contains the important aspects of the detection process.
First, signal intensity is a direct measure of the number of
resonant ions. Implicit is the assumption that the ion-field
interaction is not interrupted by particle collisions, reactive or
nonreactive, or by loss of ions due to containment leaks. In practice,
t is short with respect to ion loss mechanism characteristic times and
this expression is valid. Second, the signal intensity is inversely
related to the mass of the ion. This complicating behavior must be
considered in pulsed ICR mass spectrometry analyses. Third, the
average voltage level change as derived has an ambiguous dependence
on the rf field strength. An alternate expression clarifies this
dependence
2,
nq t
2
ma
Rf
VG ^1 + GR,
-).
(29)

30
Thus, the voltage change due to absorption is linearly related to the
voltage across the circuit and inversely proportional to the square
of the plate separation, a, across which the rf field is applied.
In practical pulsed ICR, the transient voltage level change is
integrated over the period of the rf irradiation. The resulting
amplitude may be sampled and held for display or transfer.
Integration alters the dependence of the signal on the irradiation
period so that the integrator output level is now described by
nq2E!2t2 Rf
8mVQ ll + GRf;
AV
G
or
nq\t2 Rf ,
2ma ll + GRf'
(30)
when the instantaneous change in the voltage level is linear over
the period of integration. The negative sign in the numerator of
Equations 26-30 is removed by inversion of the signal voltage
level in the post-detection electronics.

CHAPTER III
EXPERIMENTAL APPARATUS
The pulsed ion cyclotron resonance experiments presented in this
dissertation required the interfacing of electronic, optical, and
vaccum components. The central component of any ion cyclotron
resonance experiment is the ion cell. The electronics apply
required, properly timed pulses and excitations to the ion cell and
detect the influence of the contained ions on an applied rf field.
The vacuum system provides a suitable environment at the cell for
the production, maintenance, and detection of ions. Since the
experiments described involve radiative transitions of ions, a suit
able radiation source must be coupled to the ion containment region
through the vacuum hardware and ion cell. In addition, the
radiation source must be controlled by an appropriate trigger so as
to operate synchronously with the potentials and excitations employed
in the ion detection process.
Trapping Cell
The trapped ion analyzer cell (Figure 5) requires six dc
potentials in conjunction with the uniform, static magnetic field to
produce an effective ion trap. The dc potential polarities are
dictated by the polarity of the ion. The trapping plate potentials
are the same polarity as the ion, while end, lower, and upper plates
are of opposite polarity. Typically the dc potentials are
31

Figure 5. Trapped Ion Cyclotron Resonance Cell.
Six dc plate potentials produce the
necessary electrostatic potential at
the cell interior. Upper and lower
plates both have multiple roles. The
upper plate is used for o>2 excitation
and quenching of ions. The lower plate
is the marginal oscillator input/detect
plate. The grid, filament and collector
comprise the electron beam generation
system.

X
Upper Plate, +lv
1)^2 Irradiation
2) Quench Pulse
Lower Plate, +lv
Marginal Oscillator
CO
CO

34
symmetric. Absolute voltage levels of one volt for the end, upper, and
lower plates with trapping plate potentials of one and one-half volts
are sufficient for effective trapping.
The cell dc potentials are taken from the regulated five-volt
power supply of the digital pulse electronics (53) (Figure 6). A
500 n, ten-turn variable resistance connected across the +5 volt and
-5 volt busses defines the dc level. The dc lines are buffered to
the appropriate cell plates to insure that the dc power supply loading
is minimal.
Filament and grid dc potentials are also produced in the digital
pulse electronics package (53). The voltage range is 0 to -100 volts
for each. The filament current is provided by a Kepco 1000-0.2 (M)
Filament Power Supply (54).
The electron current through the cell is monitored at a
positively biased collector plate. Current-to-voltage conversion
and amplification produce a measurement suitable for display on an
oscilloscope. A collector output voltage of 1 volt corresponds to
an electron current of 1 microamp. Typical electron currents are on
the order of 0.01 microamps.
Vacuum Apparatus
The vacuum apparatus is illustrated schematically in Figure 7.
The main vacuum can and low vacuum and high vacuum manifolds are
constructed of stainless steel. A variety of gasket materials are
used in the manifold connections. A gold wire gasket is used at the
main vacuum can to high vacuum manifold connection. Copper gaskets
are used at manifold-pump connections and nickel gaskets are used for

Figure 6. Schematic Diagram of the Digital Pulse Electronics.
Cell interconnections are shown with respect to the
dc level pick-offs and the varying rf fields. Pulse
destinations are as indicated from the main control
unit to the ancillary detection, collection and control
equipment.

CO
CT)

Figure 7. Vacuum System Schematic.
The vacuum can which provides the
proper environment for the ICR cell
(N) has separate inlet manifold
and high vacuum manifold to facilitate
mixing of gases and control of gas
flows.

K
A. Two-inch oil diffusion pumps with
liquid nitrogen traps
B. High vacuum manifold cut off valve
C. Low vacuum manifold cut off valve
D. Inlet valve
E. Inlet low vacuum manifold cutoff valve
F. Leak valve
G- Vac ion cut off valve
H. Vac ion pump
W///////W L

MMZK
M
I Ionization gauge
J. Discharge gauge
K. Gold wire gasket seal
L. Laser window assembly
M. Magnet pole faces
N. Ion cell
O. Tapered joints
GO
00

39
ionization gauge joints. In addition, valves B and G contain polyimide
0-rings and valve C a Viton A seal. Two-inch oil diffusion pumps
(A) (CVC Model PM-120) (55) with appropriate backing pumps maintain
the vacuum of the two independent vacuum manifolds. The ultimate
-8
pressure attained in the high vacuum manifold is (1-3) x 10 Torr as
measured at the Bayard-Alpert ionization gauge (I). Pressure of the
inlet manifold is determined with a cold cathode discharge gauge
(J). Typical inlet manifold pressures are (0.1-1.0) x 10 ^ Torr. The
sample is leaked from the inlet manifold to the main vacuum can through
sapphire seal leak valves (F) (56). The titanium sublimation pump (H)
(55) maintains the vacuum in the high vacuum manifold during periods
of inactivity.
The location of the trapped ion cell (N) and the V-3400 low
impedance electromagnet (57) pole faces (M) are shown for clarity. An
anti reflectivity-coated optical glass window (L) was mounted on the
end of the main vacuum can by modifying a standard flange.
Optical Apparatus
A standard Candela dye laser system comprised of an ED-100U head
assembly, CL-100 flashlamp, a dye cavity with antireflectivity-coated
optical windows, and a variable high voltage (25 kV maximum)
power supply was employed in the photo-experiments (58). The ED-100U
head produces a high energy discharge through the Xe flashlamp of
the CL-100 flashlamp assembly upon sparkgap triggering. The pressurized
(5-7 PSI dry N2) sparkgap can be triggered manually or electronically.

40
Circuitry was constructed to transform a 1 ms TTL level pulse into
the 150 volt, 1.5 us sparkgap firing pulse to permit synchronous
control by a TTL pulse sequence (59).
The dye reservoir volume and circulation speed are sufficient
to insure that the dye cavity is flushed with fresh dye for each
laser shot. A Micropump Model 10-85-316-865 pump circulates the
dye solutions (60). Dye lines of polypropylene tubing are employed to
minimize dye degradation due to leaching of impurities from the
lines (61). A Pall liquid filtration system was added to the dye
circulation system to remove particles which scatter light and
reduce the efficiency of the dye laser (62).
Dye solutions were made up to a total volume of two liters in
100% ethanol obtained from chemical stores. The procedure for mixing
the dye solutionswas to start with an initially highly concentrated
solution and dilute the solution with ethanol until the output was
maximized. This resulted in dye solution concentrations on the order
-4 -5
of 10 to 10 molar. Laser dyes which were used in the photo
experiments,as well as dyes which were tested but did not lase
with sufficient intensity or lased only over a very restricted
wavelength range, are listed in Table 1. Nomenclature for the dyes
is that of Exciton, the primary supplier of dyes used in this
study (63). The position of the dye laser cavity relative to the
main vacuum can and subsidiary optical components is illustrated in
Figure 8.
Wavelength selection was achieved by incorporating a blazed
relection grating in autocollimation as one end of the optical

41
Table 1. Laser Dyes and Observed Lasing Wavelength Regions
Dye
Observed Useful Wavelength Range (nm)
LD 423
No activity
LD 440
No activity
LD 450
No activity
LD 460
445-465
LD 473
Extremely weak
LD 480
470-485
LD 490
470-510
Coumarin 540
510-550
Fluorol 555
No activity
Rhodamine 6G
575-605

Figure 8. Dye Laser Apparatus and Orientation.
The primary components of the dye laser
system are: the optical cavity (OC);
Xe flashlamp (FL); antireflectivity
coated windows (ARW); high voltage
discharge power supply and capacitor (HV).
Wavelength selection is accomplished with
a diffraction grating (G), mounted on a
base (B) which is rotated by a motor-
driven (GDM) lever arm (LA). Wavelength
determination is accomplished with a beam
splitter (BS) and monochromator (GM). A window
(W) permits the laser cavity extension to the
end mirror (M) in the cell(C).

43
<
\ -1
)
Q
CD
GO
CD
5
O
E2Z2 ^

44
resonator. All gratings used were blazed at 500 nm. Either a 1200
line/mm PTR (64) or Bausch and Lomb grating (65) was employed for
these studies. The general characteristics of these gratings are
presented in Table 2. In a few studies a 600 line/mm grating obtained
from Edmund Scientific (66) was also used. The grating selected
was mounted on a Burleigh SG-101 Star Gimbal Mount and SG-305 Mount
Base (67). This assembly was fixed to a rotating base driven by a
motor-turned lead screw/lever arm assembly.
At the ion cell, the laser cavity optical element was a copper
mirror attached physically to and contacting electrically the end
plate of the trapped ion cell. Visual inspection of this mirror
indicated that it was of low quality and the surface was in poor
condition. Replacement of the copper mirrorwith a reconditioned 90%
reflecting A1 mirror did not markedly improve the laser output.
Wavelength selection is determined solely by the dispersive
cavity element, the diffraction grating. Since the grating drive
was uncalibrated, a beamsplitter on the optical axis split a fraction
of the incident light to a monochromator for spectral analysis.
An American Instrument Company Model 1-8401 monochromator (68) and
and Instruments SA J-Y H20 0.5 meter monochromator (69) were used.
Both were periodically calibrated versus Hg lines and the 632.8 nm
line of a HeNe laser.
Following wavelength determination at a particular grating angle,
a GenTec ED 200 Joulemeter (70) was positioned to intercept the
fraction of the beam split to the monochromator. The joulemeter

Table 2. Grating Characteristics as a Function of Wavelength for a 1200 line/mm Grating
in Autocol1imation
x(nm)
Littrow Angle, 3(deg)
Angular Dispersion (yrad/nm)
Inverse
Linear Dispersion*
nm/mm
300
10.4
1224
0.41
400
13.9
1237
0.40
500
17.5
1264
0.40
600
21.1
1286
0.39
700
24.8
1320
0.39
*Linear dispersion is calculated based upon an intracavity single-pass pathlength of
two meters.

46
output and was read from an oscilloscope or transferred through
properly buffered inputs (1 Mft) to a data collection system.
The simplicity of the optical arrangement did not lead to fast and
simple alignment, since one element of the laser cavity was
contained inside the vacuum can and was not stationary with respect
to the remaining laser cavity components. Alignment was aided by
use of a Spectra Physics 155 HeNe Laser (71) which could be directed
first to align the vacuum can laser cavity element relative to the
oscillator cavity and then redirected to align the grating with respect
to the oscillator cavity.
The dye laser head and high voltage power supply were contained
in separate rf shield cages. This shielding eliminated rf inter
ference with the marginal oscillator detector circuitry.
Pulsed Electronics
A pulsed ion cyclotron resonance experiment requires a sequence
of control pulses of variable delay and, in some instances, variable
width to govern the timing of ion formation, ion detection, ion
removal from the cell and when desired, ion irradiation. A digital
synchronously-timed control system has been constructed for the
generation of the requisite pulses (53) (Figure 9).
A typical pulse sequence is initiated by two internal pulses
that are required to reset and clamp the counters and flip-flops
(precondition pulse) and serve as the zero time reference (start
pulse) for the working pulses: "grid', "detect", "sample",
'integrator reset", "quench", "w2 and "free" pulses. The grid,

Figure 9. A Typical Pulsed ICR Experiment Pulse Sequence.
Breaks in the line indicate variability. The
pulses are: precondition, PC; start, S; grid, G;
C2i free, F; detect, D; quench, Q. Not shown
are the integrate, sample and integrate reset
pulses. The integrate pulse coincides with D
and the sample pulse is a 2ms pulse triggered
at the falling edge of D. The integrate reset
pulse is generated prior to detection.

PC SJ
//
// L
0
TIME (ms)
F
D
-U-
Q
PC
FPD DD
CO

49
detect, quench, and pulses are of variable delay and variable width
and consequently each pulse has two assigned timing circuits. The
emaining pulses, sample, integrator reset, and free are of variable
delay but constant width and each requires only a single timing
circuit. Delay timers for all pulses are referenced to the 25 ys start
pulse. Pulse width timers begin counting at the end of their
corresponding pulse delay. The delay timers may be collectively
operated at one of three available clock frequencies. Clock frequencies
of 10 kHz, 1 kHz, and 100 Hz may be selected to yield minimum pulse
delays of 0.1 ms, 1 ms, and 10 ms, respectively. The pulse width timers
are operated from a set clock frequency of 10 kHz and produce a minimum
width pulse of 0.1 ms. Each pulse delay and width is selected by
three-decade thumbwheel switches.
The grid pulse is the first working pulse generated following the
start pulse. The grid pulse is amplified so that low is 0 volts and
high is +10 volts. This pulse is mixed with a variable dc level and
applied to the grid separating the rhenium filament from the electron,
beam entrance slit in the side plate of the trapped ion cell. The
variable dc grid potential is set to be 5 volts more negative than
the variable dc filament potential and the electrons, emitted at the
filament, do not pass through the grid into the cell. During the grid
pulse the potential of the grid is 5 volts more positive than the
filament potential and electrons are accelerated into the cell.

50
The detect pulse serves several functions. First, it controls
the marginal oscillator rf output to the lower plate of the cell
through the gated amplifier in the limiter feedback circuit of the
marginal oscillator as described by Mclver (46). Second, in
combination with a variable length, inverted pulse from a one-shot
which itself is triggered by the rising edge of the detect pulse,
the detect pulse produces an integrate pulse during which the integrator
is active. The logical 'ANDing of the detect pulse and inverted
one-shot pulse eliminates the initial spike observed in the marginal
oscillator output due to mismatching in the marginal oscillator
compensation circuitry (53), The falling edge of the detect pulse
triggers a one-shot which produces a 2 ms sample pulse to activate the
sample/hold circuit. Ion detection is a concerted action of the
marginal oscillator, integrator, and sample/hold circuits. The detect
pulse gates on the marginal oscillator and integrator and the ions
are irradiated, the power absorption is determined and is converted to
a voltage level at the integrator output. At the end of the detect
(and integrate) pulse the 2 ms sample pulse is generated and the
sample/hold circuit samples its input which is the output of the
integrator. Finally, an independently generated integrator reset
pulse resets the integrator prior to the next pulse sequence.
To insure that only ions produced during a single grid pulse are
present during a detect, a quench pulse is applied to the upper
plate to eject all ions from the cell prior to repetition of the
pulse sequence. A pulse of either polarity will perturb the trapping
field and remove the ions from the cell.

51
The >2 pulse is used as a gate for an external gateable rf
oscillator whose output is then applied to the upper cell plate for
excitation of ions which are nonresonant at the selected magnetic
field and marginal oscillator frequency. This excitation serves two
purposes. At low voltage levels excitation increases the ion
translational energy while trapping remains efficient. At high voltage
levels (2 excitation ejects the nip resonant ion from the cell (72).
The free pulse is a one millisecond width, variable delay pulse
designed as a general, external trigger pulse. The free pulse operates
on TTL logic levels. It has been used as the synchronous trigger
for the flashlamp-pumped dye laser sparkgap discharge circuitry.
Initiation of a complete pulse sequence can be accomplished in
three different modes: single cycle, fixed rate,or automatic
operation. The single cycle mode results in one complete pulse
sequence occurring whenever a front panel pushbutton is depressed.
Fixed rate mode causes the complete pulse sequence to be repeated at
a selected time interval which ranges from 20 milliseconds to 5
seconds in a 1-2-5 sequence. The automatic mode starts a pulse
sequence 175 milliseconds after the quench pulse terminating the
preceeding sequence.
A typical pulsed ion cyclotron resonance (PICR) experiment
proceeds in the following manner. With no resonant ions, the previously
set digital pulse sequence is performed to obtain a zero level
for the marginal oscillator signal. Ions are then tuned into
resonance by an appropriate adjustment of the magnetic field.
Marginal oscillator and photodetector levels are recorded. The laser

52
capacitor is charged and the trigger pulse, normally the free pulse
or a microcomputer-generated pulse, is activated to fire the laser
immediately prior to ion detection. The digital pulse sequence is
repeated for the required number of laser shots. Marginal
oscillator and photodetector data are recorded for each laser shot.
The laser trigger is deactivated and with the ions still resonant the
pulse sequence repeats until sufficient marginal oscillator level and
photodetector level measurements have been obtained. Finally, the
ions are tuned off resonance and the marginal osci llator zero level
data is recorded for several pulse sequences. This scheme allows for
the correction of zero baseline and resonant ion baseline drifts.
Microcomputer
The resonant absorption of the output of the marginal oscillator
is detected as a change in the analog voltage level of the marginal
oscillator frequency envelope. To convert this analog signal to a
digital signal suitable for analysis by a digital microcomputer a
data conversion/collection system has been developed. The system is
comprised of a microcomputer and an analog to digital (A/D) converter
as well as input signal conditioning elements and programmable
data routing components. The microcomputer architecture is addressed
to the degree to which it has influenced the interface design and
operation. The description of the interface is functional and non
specific with regard to chip designation. The operating system
software is summarized by functional unit as it would be encountered
in the course of normal operation. Analysis of the current status

53
of the data conversion/collection system delineates its limitations
and suggests refinements to attain 'key-on' operation. Experimental
data was analyzed manually to verify the system performance.
Microcomputer and Modifications
A KIM-1 microcomputer served as the control element for the data
conversion/collection system (73). The KIM-1, a single-board, 6502-
processor-based microcomputer, has integrated input/output hardware,
hex keypad, system ROM (read-only memory) and IK (1024 words) of RAM
(random-access memory). The structure of the input/output hardware as
to the available control and data lines requires further mention.
The KIM-1 can respond to an external event in a programmed fashion.
This implies that the microcomputer acknowledge and correctly identify
an external event. Recognition of ari external event requires a
combination of hardware and software. The level of the interrupt
request line (IRQ) is altered synchronously with the external event
and interrupts the processor upon completion of a logical machine
step. Critical status registers are preserved by the IRQ software
residing in ROM. Control is transferred to a program located through
the interrupt request vectors (IV) which have been preprogrammed
by user code to select the correct response to the external event.
Once the external event has been correctly handled the critical
registers are restored and operation is resumed from the point of
interrupt.
An interrupt request is an externally generated request for
service. The servicing of the interrupt involves data transfer to the

54
microcomputer from the external device or vice versa. This transfer
takes place across 15input/output lines, divided into two ports,
peripheral A data, PAD and peripheral B data, PBD. The 6502
architecture and operating system treat these ports as memory
locations which can be written to or read. The direction of the data
transfer is established by the status of the control ports, peripheral
A data direction register, PADD, and peripheral B data direction
register, PBDD. These registers are interpreted as collections of
status bits which correspond directly to the PAD or PBD bits. A
status bit value of 0 indicates that the corresponding peripheral
device bit is to be read as an input, while a status bit set to 1
indicates that the bit is written to by the microprocessor. All
combinations of inputs and outputs are permissible and buffering in
both directions has been implemented on board.
A general appreciation of the input/output structure of the
microcomputer is necessary for interfacing, in this case it is also
necessary to be aware of the memory (RAM) architecture, due to the
on-board modifications dictated by the limited memory available on
the standard system. The 1024, 8-bit RAM words of the 6502 processor
are constructed from eight 1-bit x 1024-location, memory chips. The
address lines of all eight chips are tied together so that the same
address is selected at each chip. The IK of memory supplied by the
KIM-1 is insufficient for complex control and data manipulation
routines in addition to data storage. Consequently unused address
lines were decoded and memory chips sufficient to increase the RAM
to 2K were added. The details of this modification are in Appendix I.

55
Microcomputer Interface Hardware
The limitations of the KIM-1 microcomputer's input/output
architecture place constraints on interface design. The KIM-1 is
restricted to digital input/output with a maximum of 8 bits transferred
per input/output operation. Consequently, external analog signals
to be transferred to the microcomputer memory must be converted to
digital format. The KIM-1 is a TTL level microcomputer which requires
that valid TTL levels be provided as inputs. These constraints are
easily attended to; thus the interface design, although dependent on
the KIM-1 input/output architecture and implementation, is more
stringently defined by the nature of the external signals.
For a typical pulsed ion cyclotron resonance (PICR) experiment
the values to be measured are zero baseline, the marginal oscillator
output in the absence of resonant ions; ion baseline, the marginal
oscillator output in the presence of resonant ions; laser level,
the marginal oscillator output after laser irradiation of the
resonant ions; laser energy values, the output of the photodetector
with and without laser irradiation. Each of these signals is an
analog voltage level and two separate channels to the A/D converter
are required for the marginal oscillator and photodetector outputs.
Since the A/D has a single analog input these signals are multiplexed
to that input under software control. The sequence of control
functions resulting in the input of converted marginal oscillator
and photodetector levels may be summarized for a general, two-channel
read.

56
The KIM-1 will be in a no operation (NOP) loop which can only
be exited via an interrupt request or a keypad interrupt. An IRQ
transfers control to programs addressed by the interrupt vectors,
which contain either system start-up or program-defined values. What
ever the actual program location accessed, the scheme of the interrupt
service requires a resetting of the interrupt vectors in preparation
for an ensuing interrupt and the updating of running counters which
identify the type and count of marginal oscillator and photodetector
data on line. The transfer of the marginal oscillator or photodetector
voltage via the A/D to the KIM is controlled through the microcomputer
PAD (PA0-PA7) via four 3-bit, 8-bidirectional-channel multiplexers
(MUX). PA0-PA3 are always configured as KIM-1 outputs. PAO controls
MUX inhibit lines and PA1-PA3 constitute a 3-bit, binary word which
selects the MUX channels. The input to a MUX is transferred to the out
put on an inhibit low with the transfer direction determined by the
PADD status bits. PA6 serves as the channel select line for the 1-bit,
2-channel (A/D input) MUX. A clocked latch intervenes to preserve
the status of the select lines of the 2-channel MUX until it is
reselected. PBO is used as the software generated clock line for the
clocked logic. (PBO replaced PA4 which was defective on the KIM-1
used). A logical one on the 2-channel MUX select line transfers the
photodetector level to the A/D input, a logical zero selects the MO
1evel.
The free running A/D requires 25 milliseconds to convert the
input to a stable digital output. A timed loop using the KIM-1
programmable counter allows for the conversion time. The 12-bit A/D

57
output is read into the KIM-1 in three 4-bit parts through the four
8-bidirectional-channel MUX's. The data direction registers configure
PBO and PA5-PA7 as KIM-1 inputs. PA1-PA3 select the A/D channels.
Channel one selects the least significant four bits of the conversion,
channel two the next four significant bits, and channel three the four
most significant bits. The conversion result is recombined and
stored by the A/D read software.
The interface provides a pulse to the laser trigger electronics
for program-defined counter states. In a preliminary version of the
software a latch was set (1) during the read sequence prior to that
for which the laser was to be fired. The latch output was AND'ed
with the free pulse of the ensuing pulse sequence to provide the
laser trigger pulse. The latch input was then reset (0) to prevent
laser triggering by successive pulse sequences. This technique is
cumbersome and a simplified scheme has been implemented in which the
trigger pulse is generated by software immediately after the interrupt
pulse is received. This scheme results in nontrivial simplification
of the software.
The IRQ is provided by the free pulse for automatic triggering
and by an debounced pushbutton for manual triggering. Both inputs
are conditioned by a pair of Schmitt triggers, which feed into a
one-shot pulse generator to produce a sharp, clean IRQ pulse at the
microprocessor.
The output of the laser photodetector is buffered and amplified
(x50) and the level held by a peak detector. The pulse is used

58
as the peak detector reset and, consequently, must occur after the
photodetector read is completed. For certainty, the pulse was
positioned to occur immediately prior to the quench pulse.
Microcomputer Software
Programs are coded in 6502 machine language. The architecture
of the 6502 processor minimizes the volume of code, since operations
are frequently performed on a single specialized memory location,
the accumulator. Addressing codes are varied and specialized to
transfer rapidly and efficiently selected data to and from the
accumulator.
The software is designed to reduce the need for operator attention
during a complete measurement sequence. The microcomputer is no
longer merely a data router/interface controller. Data analysis codes
are included to perform simple data reduction. The zero baseline
average code averages the results of thirty-two (hex 20) zero baseline
measurements. The ion baseline average code derives the average of
eight ion baseline values symmetric about a laser shot sequence.
Zero baseline correction of the ion baseline and laser level is
coded. Similar functions, zero baseline measurement and correction
of signal levels, are coded for the photodetector output. Full double
precision (16-bit 16-bit) division is implemented. Vectored
storage of intermediate results(raw data) to temporary storage areas
and the relocation of reduced data prior to overlay of the
temporary storage areas are provided to conserve memory. With the
addition of simple data reduction codes the storage capacity required
for a single complete sequence (thirty-two zero MO measurements, sixty-

59
eight ion MO and photodetector measurements and sixteen laser MO
and photodetector measurements) is reduced from four hundred bytes
to sixty-four bytes.
Flowcharts outline the data conversion/collection and analysis
software (Figures 10-14). A memory map showing the allocation of the
expanded RAM is provided (Figure 15).
Run Time Operation
Due to memory limitations some critical registers are not set by
the initialization routine, these registers require keypad
initialization. The status register (hex address 00F1) must be set to
00 to clear the interrupt request flag. No maskable interrupt (IRQ)
can be acknowledged until the flag is cleared. Certain system
interrupts are non-maskable and always acknowledged. The interrupt
vector low (IVL, hex address 17FE) and interrupt vector high (IVH,
hex address 17FF) are manually set to DO and 08 respectively. The
KIM-1 is thus configured to acknowledge an IRQ and to respond by
calling the main control program (Figure 11). The status and interrupt
vector registers must be reset for each complete measurement sequence.
Three memory locations (hex addresses OF, 10, and 11) contain the
running sum of zero baseline values. These registers must also be
zeroed at the start of a complete measurement sequence. The remaining
registers require initialization prior to the first complete measure
ment sequence, but their status is then correctly maintained by the
program for subsequent sequences. Zero page hex addresses 0C, 12,
14, 15, 16, 17, 40, 41 and 43 should be zeroed. Zero page hex

Figure 10. Operator/Microcomputer Interaction Flowchart.
This flowchart describes the required operator
attention. Programs are loaded from
cassette tape and operation initializations
are performed. Initial interrupt vector values
are set and the microcomputer enters an NOP
loop until interrupted. An end-of-experiment
test determines the experiment status and
then analyzes and stores the data in final
form.

Initialize
Registers
Calculate
Average Zero
Base]ine

Figure 11. Main Program Branch Flowchart.
The program flow about the primary
decision is shown. Primary decision
is the nature of the data to be
obtained at the next interrupt. A
test value of 0 corresponds to
baseline data for the marginal
oscillator (B). Test value 1
corresponds to ion baseline data
for the marginal oscillator and
the photodetector (C). Test value
2 corresponds to laser MO and photo
detector data.

Generate
Laser Pulse
Read
MO Data
Store
MO Data
Read
Laser Data
Store
Laser Da
Decrement
Laser Shot
Counter
Chan<
>e IV
to
.
Decrement
ID Flap,

Figure 12. Baseline MO Data Flowchart.
The functions required for baseline
data collection are indicated.
A single decision is made to
determine when ions should be tuned
into resonance which when true
prompts the operator.

65

Figure 13. Resonant Baseline Data Flowchart.
The procedure for taking baseline MO
values with resonant ions while
simultaneously taking zero photo
detector values is diagrammed. Data
overlap occurs for each four sets of
measurements after the first eight
baseline measurements are stored.

Read
100 Data
Overlay
100 Data
Storage
Y

Figure 14. Laser Status Flowchart.
Determination of a laser firing
is necessary for subsequent data
reduction and memory overlap
decision. In addition, the last
laser shot of a sequence must be
identified to reduce the data to
final form.

69

Figure 15. Microcomputer RAM Memory Map.
The major divisions indicate blocks
of four pages, natural machine divisions
of memory. The beginning and ending hex
address for each logical software unit
is provided. Note that the A/D subroutine
is dispersed throughout the available
memory.

71
0800 -
0851
Initialization Subroutine
0852 -
0868
Obtain Data and A/D Delay Subroutine
0869 -
088D
MUX Select Photodetector Subroutine
088E -
08B4
MUX Select M0 Subroutine
08B7 -
08CE
A/D Read Subroutine (Part II)
08D0 -
09F0
Main Control Program
0A00 -
0A45
A/D Read Subroutine (Part I)
0A50 -
0A91
Four Channel Storage Subroutine
0A9A -
OAFC
Data Analysis and Storage Subroutine
0B00 -
0B80
Double Precision Divide Subroutine
0B81 -
0B8F
A/D Read Subroutine (Part IV)
0B90 -
OBBO
Triple Precision Average Subroutine
0BB1 -
0BE3
Laser Trigger Subroutine
0BE7 -
OBFF
A/D Read Subroutine (Part III)

72
address 42 should be set to 02 and following the fourth complete
sequence set to 03. The initialization routine resides at hex
address 0800. To run the initialization routine, 0800 is keyed to
the address display and GO is keyed. The remaining critical registers
are set and the microcomputer enters the nc operation (NOP) loop
until interrupted by an IRQ or keypad interrupt (Figure 10). The
function of each register is given in Appendix II.
The first IRQ enters the main control program at A (Figure 11).
The initial value of the ID register (hex address 0000) is 0,
consequently the B branch (Figures 11 and 12) is taken. The interrupt
vectors are altered to point to D to protect the zero baseline
counters which are subsequently set. The zero M0 level is read and
the result summed into the initially zeroed registers OF, 10 and 11.
The zero baseline counters are decremented. If less than one half
of the zero baseline readings have been taken there is a simple return
from interrupt (RTI), returning the KIM-1 to the NOP loop. Subsequent
interrupts enter the main control program at D until one half of the
zero baseline measurements have been accumulated. Then, interrupt
vectors are changed to point to A, the ID register is incremented
and a programmable interrupt request (PIRQ) flag set, prior to an RTI.
As before the RTI returns the system to the wait loop, however, since
PIRQ is the test value of the loop, the system will "fall through"
the loop. The test of the total zero baseline counter will be
negative at this point. A branch to the read-only memory (ROM)
operating system is taken which displays "0001 xx". This is the

operator prompt to tune the ions into resonance and charge the laser
capacitor 084E' is entered in the address field of the display
and GO is depressed to clear the interrupt flag and to return the
KIM to the wait loop.
The next IRQ enters the main control program at A. The ID
register contains 01 and branch C is selected. The interrupt vectors
are changed to point to E to protect the ion baseline counters. The
100 level counters are set and MO level is read exactly as before.
The two byte result is stored via the y-indexed address mode. The
appropriate value for the y-register is loaded from 0C. The base
address is located in 0D. The PHOTO level is read and stored as for
the MO level, however, the base address is first incremented by hex
10 so that the two types of data are mapped into different memory
locations. The base address is restored to its original value after
the PHOTO read/store in preparation for the next cycle. The program
requests eight two-byte MO levels and eight two-byte PHOTO levels
per laser shot for the determination of the respective averages.
Once the averages have been evaluated and stored, the first four level
of each type may be over written. "AND"ing the y-register value
with hex OF prior to saving its value in 0C accomplishes the overlay.
If the (100/2) level counter is nonzero a simple return from
interrupt is taken. If the counter is zero, the software determines
if the laser has been fired. If not, the interrupt vectors are
altered to point to A and the ID register incremented (02) so that
the next interrupt fires the laser. Figure 11 illustrates the laser
firing sequence and is straightforward. M0 and PHOTO levels are

74
read as before and stored. The laser counter is decremented and ID
register decremented (01). Interrupt vectors are set to E so that
the (100/2) level counter is reset and a new sequence of 100 levels
taken. If the laser has fired, average 100 M0 and 100 PHOTO levels are
calculated and stored. If the laser counter is nonzero, the interrupt
vectors and ID register are set to fire the laser on the ensuing
interrupt. For a zero laser counter, the interrupt vectors and (0/2)
level counter are reset to read the required zero baseline levels
commencing with the next interrupt. The ID register is set to zero
and PIRQ set (01) to initiate an operator prompt. The display
"0000 xx" requests the operator to tune the ions off resonance. When
the (0/2) counter tests zero, an RTI occurs and since PIRQ is set a
test of the total zero (0) counter is made. The total zero counter
will be zero and the zero baseline average is determined.
Data analysis consists of the evaluation of
1 = M0Lnl molbase
M0Ll M0Lbase (31)
and
LSRL = PDLl PDLnl (32)
where MOL represents a marginal oscillator level, PDL a photodetector
level, L refers to a laser shot sequence with ions, ML refers to an ion
resonance sequence with no laser shot and BASE refers to no resonant
ions or laser shot. Thus F ^ is the inverse of the fractional remainder
of the ion signal upon irradiation by a laser pulse with a power
level related to LSRL, the measured laser level. These four bytes

of data are stored for each laser shot and a prompt is generated to
signal that the data collection system is prepared for a new sequence.
Implementation of the division in Equation 31 requires a 16
bit by 16-bit divide routine and a 12-bit shift routine to format pro
perly the data for storage. These routines have been coded and
incorporated into the analysis loop.
Programs are listed in Appendix III. Memory addresses, machine
codes and mnemonic codes are included to facilitate use, alteration,
adaptation and relocation of the various subroutines. Comments have
been included to simplify the reading of the code.
Derivation of the Expression for the
Photodetachment Cross-Section
The probability of photodetaching a negative ion of photo
detachment cross-sectiono (a) at wavelength A of the incident
radiation field of photon flux p(a) in time t is given by the expressi
P(a) = 1 exp [-kt / p(a) o (a) da 1 (33)
where k is a constant related to the interaction region (74). For
a pulsed radiation source with pulse duration t and energy per pulse,
E the number of photons per pulse is
A
nA = xEA/hc. (34)
This quantity is directly related to the photon flux provided a, the
radiation beam cross-sectional area, is known
p(a ) = A EA/hcat.
(35)

76
If Nq represents the number of anions detected prior to irradiation
and N the number of anions detected following irradiation, then N and
N are related by
o
Nq-N = f Nq P(a) (36)
where f represents the probability that every detected anion is in the
radiation field. Substituting for P(a) and rearranging and taking the
logarithm of each side yields
kt / p(X) a(A) dA = In
1-
N -N
o
fNo
-1
(37)
If the bandwidth of the source is narrow and constant with respect
to the wavelength, then
kt / p(a) o (a) dA = Ckt p(a)a (a)
(38)
where C represents the effect of the constant bandwidth, and p(a)
anda (A) are assumed to be slowly varying with respect to wavelength.
Using the simplification and substituting for p(a), an expression for
the photodetachment cross-section containing only experimentally
observable quantities is obtained
k1 a(A) =
In
1-
N0-N
fNo
-1
A E,
(39)
where k' = Ck/hca. Rearranging the argument of the logarithm
term, the cross-section expression becomes
In
k a ( A) =
fNo
fNo-(Nn-N)|
A E,
(40)

Clearly this expression exhibits the correct limiting dependence on f,
for as f approaches one, indicating that all ions are within the
radiation field, the argument of the logarithm becomes Nq/N. Finally,
k'a(A) can be written as
k' a(a) =
In
f-A
A E,
(41)
where a is the fractional decrease in the ion signal upon irradiation,
A standard error analysis yields the expression for the relative
error for k'0(A),
w2rk'c(x)i |
"n/N0\ 2 W2(Nn)/N02 /
UY
w2(n)/n2
[k'o(x)]2 '
\f-Aj
In (f/f-A)
2 \
kf-V
"ln(f/f-A)J
. w;(f)./f; + m +
f-A J jfn (f/f-Aj 2 + x2 E-2
(42)
where W(x) represents the random error of variable x. The influence
of each of the factors involved in the error terms is indicated in Tabl
3 for a range of a values. The magnitudes of the coefficients of the
relative errors in Table 3 do not completely characterize the errors.
The relative errors themselves must also be considered. N W(n)/N ,
o oo
W(f)/f and W(Ex)/Ea are constant for a constant amplitude ion signal
with a constant S/N ratio. The relative error associated with N,
W(N)/N increases with decreasing N, that is, for a constant S/N ratio
increased ion attenuation leads to increased relative error in the
determination of the residual ion concentration. ABC represents the
coefficient sguared for the relative error of N For an ion

Table 3. Factors in the Relative Errors in the Cross-Section for a Range of A Values and f Equal to
1.0 and 0.75
A
B
C
D
E
ABC
BD
A
(N/N0)2
{1n[f/(f-A)]}-2
1.0 0.75
1.0 0.75
t A/ (f-A )] 2
1.0 0.75
w2(n)/n2
1.0
0.75
1.0
0.75
.99
lxlO-4
0.05
104
9801
1
0.05

490
.9
lxlO"2
0.19
--
100
--
81.0
--
lxlO-2
0.19
15.4
--
.8
4xl0'2
0.39
--
25
--
16.0
--
2.5xl0-3
0.39
--
6.24
--
.7
9xl0-2
0.69
0.14
11.1
400
5.44
196
l.llxlO-3
0.69
3.24
3.75
27.4
.6
0.16
1.19
0.39
6.25
44.4
2.25
16.0
6.25xl04
1.19
2.77
2.68
6.24
.5
0.25
2.08
0.83
4.00
16.0
1.00
4.00
-4
4x10
2.08
3.33
2.08
3.32
.4
0.36
3.83
1.72
2.78
8.16
0.44
1.31
2.78xl0-4
3.83
5.04
1.69
2.25
.3
0.49
7.86
3.83
2.04
4.94
0.18
0.44
2.04xl0~4
7.86
9.26
1.41
1.69
.2
0.64
20.08
10.4
1.56
3.31
0.06
0.13
1.56xl0-4
20.08
22.02
1.20
1.35
. 1
0.81
90.01
48.8
1.23
2.37
0.01
0.02
1.23xl0-4
90.01
93.15
0.90
0.98

79
-4
signal-to-noise ratio of 100, the squared relative error is 10 There-
-4
fore, the error contribution due to the NQ measurement is 10 times
the tabulated value of ABC. The error in the N measurement is tabulated
(column E, Table 3) for the same initial signal-to-noise ratio. ABCE
represents the squared relative error. ABCE will always be greater than
the NQ relative error term. Furthermore, ABCE exhibits a minimum near
A equal to 0.6. A reasonable value for W(f)/f is 0.05 (33). This large
relative error is combined with its coefficient and summed with the
other large error source, N measurement, to determine the optimum ion
attenuation. This occurs at an approximate A of 0.3. W(N)/N and
W(Ex)/Ex can be estimated to be 6x10"^ and 0.03 respectively. At the
optimum A for an ion signal-to-noise ratio of 100 and for the relative
errors as described and f equal to 1, the predicted relative error in
the cross-section is 0.08. The error at a given A is most sensitive
to changes in W(Ex)Ex and W(f)/f. If W(Ex)/Ex were doubled, the cross-
section relative error would increase to 0.095, similarly doubling
W(f)/f results in a relative error of 0.13. Departure from the optimum
A value results in less dramatic changes in the cross-section relative
error at least for deviations less than +0.3
To optimize the photo-induced experiments, the signal intensity
(N ) and the signal-to-noise ratio must be optimized. Increased apparent
intensity without increased signal-to-noise will not improve the
relative errors. Ex should be accurately variable with a constant
f value. For the best observed signal-to-noise ratio and W(f)/f of
0.10 to account for poor shot-to-shot beam quality, the anticipated
relative error in the cross-section is 16%.

CHAPTER IV
EXPERIMENTAL RESULTS AND DISCUSSION
OF THE HALOGEN ANION STUDIES
The ions discussed in this chapter are those for which
observable ion intensities could be produced. C^" and B^" were
generated with sufficient intensities to assure reasonable signal-to-
noise ratios for the photo-excitation studies. BrCl" was observed
and the instrumental parameters pertinent to its formation were
optimized, but under no operating conditions was the signal quality
adequate to undertake photo-excitation measurements.
Chlorine Molecular Anion
Formation of Cl
The generation of Cl2 was not straightforward. Four means of
producing the chlorine molecular anion were attempted; two
procedures were successful. Direct attachment of low-energy electrons
to chlorine molecules was attempted over the nominal electron
energy range, 0 to 10eV,for chlorine sample pressures at the ion
cell vacuum can ranging from 1x10"^ to 1x10^ Torr. No molecular
chlorine anion was observed for any combination of these parameters.
At all experimental conditions, dissociative attachment yielding
Cl- was seen to occur exclusively. Dissociative attachment of
low-energy electrons to carbon tetrachloride was tested for Cl,,"
production. As for chlorine, sample pressures and electron
80

81
energies were varied to cover all combinations of these parameters.
The observed dissociative attachment generated CT only; no Clwas
detected. A charge transfer to chlorine from a suitable precursor
anion was investigated. Nitrite ion, NC^", was readily produced from
nitromethane, CH^NC^. Electron transfer was expected to occur for
the interaction of NC^" with a species of greater electron affinity.
Optimization of the nitrite ion intensity, followed by the addition
of chlorine yielded C^- at levels acceptable for pursuing the
photo-excitation study. Finally, was produced in low-energy
(0 ev) electron impact with a sample of chlorotrifluoroethylene
^F^Cl). The Cl2~ signal intensity was not as strong as that
observed from the charge transfer process. The means selected for
Cl2 generation in the ensuing photo-excitation study was the electron
transfer from nitrite ion to molecular chlorine.
Prior to undertaking the discussion of the photo-excitation
study of the chlorine molecular anion, the precursor anion's negative
ion mass spectrum and generation will be analyzed. The nitrite
ion intensity was optimized with respect to all ICR and sample
parameters. The range of the parameters and the resolution of the
variation of each parameter are presented in Table 4. The negative
ion mass spectrum of nitromethane contained a single peak at a mass-
to-charge (m/e) ratio of 46 amu/e. The signal-to-noise ratio at the
optimized system settings was approximately 40 to 1 (Figure 16).
No other ions were detected over the mass-to-charge range, 5 to 105
amu/e. No secondary or precursor ions were identified. The

82
Table 4. Variation of ICR Operating Parameters During Studies to
Maximize Formation of the Nitrite Ion from Nitromethane.
Parameter
Range
Resolution
Electron Energy3
1.8 18 eV
2 eV
Sample Pressure^
4xl0-7 1x10^ mm Hg
lxlO"7 lxl0-5 mm
Grid Pulse
8 ms 25 ms
5 ms
Detect Delay
0 300 ms
1 ms
Detect Widthc
5 ms
Not varied
Marginal Oscillator
Level
50 100 mV
10 mV
QA true estimate of the electron energy is obtained by subtracting
the trapping plate potential of 1.50 v.
^The background sample pressure was 2-4 x 107 mm Hg.
c
Detect width and marginal oscillator level are related, however, over
the range of marginal oscillator levels attempted detect width did
not require change.

Figure 16. Negative Ion Mass Spectrum of Nitromethane.
The mass range is 5 to 105 amu. Sample
pressure was 1 x 10-5 Torr. Electron
energy was 2.4 eV. Detect delay time was
40 ms. The peak occurs at a mass-to-
charge ratio of 46 amu/e.

INTENSITY
t?8

85
electron energy for peak nitrite ion intensity was 0.83 eV. Nitrite
ion generation from nitromethane was deemed to be a suitable, clean
choice as the precursor for the molecular anion of chlorine.
The chlorine molecular anion was generated and its signal
intensity optimized in a manner that simplified the tuning procedure.
Nitrite ions were detected and the intensity of the signal was
maximized for a nitromethane pressure between 5x10 and 1x10 Torr.
Chlorine was leaked to the cell through the second inlet manifold
and jeweled leak valve. The NC^" signal intensity was monitored as
the chlorine was added.. The nitrite ion intensity fell off rapidly
with the introduction of chlorine. When the NC^' intensity had
decreased to less than 10% of its peak value, the chlorine pressure
at the cell was stabilized. The magnetic field was set to bring the
Cl ion into resonance and once this signal was located the detect
pulse delay was increased unti 1 the Cl" peak intensity had dropped to
approximately 20% of the initially observed level. At this detect
delay, the magnetic field was altered to bring the C^" anion into
resonance. In some instances, scans of the magnetic field about
the nominal resonant magnetic field for Cl2_ proved necessary to locate
the ion. The Cl2 signal was maximized with respect to the ratio
of components inlet to the ion cell region, the total sample
pressure at the ion cell, and all of the tuning parameters of the
spectrometer. A negative ion mass spectrum for a chlorine/nitro-
methane mixture (pressure ratio determined at the ionization gauge
on the main vacuum manifold) is reproduced in Figure 17. The time
dependences of the predominant negative ions, NO2, Cl2, and Cl",
are indicated in the time-scanned spectra (Figure 18).

Figure 17. Negative Ion Mass Spectrum for a Chiorine/Nitromethane Mixture.
The mass range is 10 to 100 amu. Total sample pressure of the
1 to 2 chlorine/nitromethane mixture was 2x10^ Torr. Electron
energy was 2.5 eV. Detect delay time was 70 ms. The Cl2 peak
is weak at this detect delay, but increases with increasing
detect delay.

200
8

Figure 18. Time-dependent Mass Spectra of the Major Peaks of a Chlorine/
Nitromethane Mixture. Three major peaks are observed NOo",
Cl2 and Cl". Cl" is the most intense. N0?" is observed
only during the grid pulse when in the presence of chlorine.
Time zero corresponds to the beginning of the grid pulse.
The upper time limit is 350 ms.

TIME (ms)
INTENSITY

90
It was difficult to maintain stable Cl^- signal levels. The
total pressure at the ionization gauge drifted markedly. This
variation was the result of the fluctuation of the chlorine delivery
or the nitromethane delivery with equal frequency. After the sample
pressures were continuously monitored and adjusted for periods of up
to three hours, the drift was reduced and slowly varying Cl^" signals
were obtained.
There are discrepancies between the results of the molecular
chlorine anion formation behavior observed in this study and previous
studies. Cl2 has been generated by electron attachment at total
pressures as low as 4x10 ^ Torr at electron energies of 1 to 2 eV
(75). The resultant Clions exhibited lifetimes up to one second in
the cell of an ion cyclotron resonance mass spectrometer. This lifetime
is significantly longer than those observed in this study; however,
this may be attributed to the relatively high pressures used in this
-5
investigation (total pressure on the order of 10 Torr). Generation
of Cl2 from carbon tetrachloride has been reported with an appearance
potential of 2.3 eV in a time-of-flight mass spectrometer (76). The
inability to generate Cl2 from CC1^ in this study could not be
attributed to a single instrumental parameter, but is likely the result
of some combination of electron energy distribution aberrations,
trapping imperfections, and relative detection sensitivity.
A number of investigations have been performed on NC^- due to its
possible atmospheric importance and the chance of overlap of its photo
detachment spectrum with the solar radiation spectrum (77-84, 85, 86).

91
Experimental evaluations of the electron affinity of nitrogen dioxide
are relevant to this study and are summarized in Table 5. Exact
determination of the adiabatic electron affinity of nitromethane has
been hampered by the significant structural differences between the
ground states of the neutral and anion which lead to excited vibronic
transitions (84, 87, 88a).
A long wavelength tail in the photodetachment spectrum of NC^-
led to a proposed peroxy isomer of lower electron affinity than the
ground state anion (85). The existence of a low-energy isomer could
have a significant impact on the subsequent spectral study of an ion
formed by electron transfer from a mixture of the two isomers. Although
the appearance of a long wavelength tail in the NC^- nhotodetachment
spectrum was corroborated (8G), a recent study has been able to
interpret the results of the previous works in terms of variations
in the measured collisional de-excitation rates for vibrationally
excited NO2" by different bath gases (89). The appearance of the long
wavelength tail in the photodetachment spectrum is best interpreted as
the result of detachment from inefficiently quenched vibrationally-hot
ions.
Although suggestion of an isomeric form of NC^' has been discredited,
the experimental results still indicate signficiant internal
excitation for NC^" produced by electron attachment to nitrogen
dioxide. An alternate source of NO^- for which the internal
excitation could be minimized or at the very least permit the
determination of an upper limit on the internal energy is essential
in electron transfer generation of the chlorine anion. A strong

Table 5. Empirical Electron Affinities for NOg in eV.
Electron Affinity
Method
Reference
2.36 0.10
Tunable laser photodetachment
Hot cathode source beam
85
2.8 (threshold)
Conventional source photodetachment
Ion cyclotron resonance
86
2.29 0.1
Endothermic charge transfer
79
2.30 0.15
Endothermic charge transfer
80
2.38 0.06
Charge transfer
78
2.7 0.2 (threshold)
Conventional source photodetachment
Ion cyclotron resonance
84
2.04
Endothermic charge transfer
81
3.1
Photodetachment
82
3.9
Chemical ionization
83

93
N02~ peak at an appearance potential of 0.6 eV was found in the
negative ion mass spectrum of nitromethane (90). N02" produced in
this manner is anticipated to have a level of internal excitation
that is essentially thermal since the appearance potential only
slightly exceeds the minimum energy required for the process.
This energy difference, the energy of bond rupture (DH (C-N)= 73
kcal/mole) (91) minus the electron affinity of N0^ (EA(N02) = 2.38
0.06 eV) (87), amounts to 0.8 eV. Since the potential for peak
NO^ ion intensity occurred at 0.83 eV in this study, the N02~ ion
is presumed to be vibrationally cool.
The experimental conditions for which the nitromethane negative
ion mass spectrum was observed overlap those of previous investigations.
In addition to the nitrite ion, CN~ and 0" have been observed in
the nitromethane spectrum (90). The peak CN" and 0" intensities
are considerably less than the N0^" peak intensity, on the order
of one one-hundredth and one two-hundred-and fiftieth the NO^-
intensity, respectively. It is understandable that such low
intensity ions should not be observed for the signal-to-noise
evidenced in this study.
The electron transfer reaction
N02 + Cl2 - Cl2" + N02 (43)
has been investigated (79). For N02" ions with 0.3 eV translational
energy the rate constant for the reaction was determined to be 2.2 x
10 cm /molecule-second. At higher translational energies the

94
cross section for this reaction dropped sharply indicating that
it was exothermic. The reverse reaction was not observed ; however,
a competing reaction
ci2_ + no2 N02C1 + Cl' (44)
has been reported (78).
The generation of Cl2 from chlorotrifluoroethylene was also
observed. This behavior has been reported, but the mechanism for the
formation was not determined (92). Investigation of this source of
Cl2 included a search for precursor and intermediate ions, however
none were identified. The original investigators' conclusion that
a pyrolytic reaction was occurring on a hot filament surface is
a reasonable explanation of this behavior and is not contradicted
by this study.
Halogens are known to be highly reactive, corrosive compounds.
Reactions with pump oils, ion gauge cathodes, gaskets, etc. have
hindered measurements of halogen properties. There is also
empirical evidence confirmed by the experience of this study that
passivation of the system is required prior to obtaining stable
halogen ion signals (93, 94). This passivation time may be hours
or days depending upon the vacuum containment system geometry,
surface area and surface condition. Of particular significance is
the effect of chlorine reactions at the surface of an electron
filament which may alter the work function of the filament material
and change the characteristics of the electron beam. This effect
is pronounced for low-energy electrons and has been observed to

95
result in the complete elimination of low-energy electrons from the
distribution of electrons generated by a current heated filament
(93). In addition, although certain aspects of the system may
recover quickly, such as the proper functioning of leak valves,
the effects due to surface reactions of a halogen at the electron
filament and the ionization gauge cathode may be irreversible. This
behavior certainly contributed to the experimental difficulties
encountered in the generation and maintenance of a measurable halogen
anion population.
Photodetachment of Cl2
In Figure 19 the raw data for the photodetachment of Clat two
wavelengths are presented. The bandwidth of the laser output as
measured at the monochromator was 0.4 nm. The x-axis is time and a
typical run at a single wavelength required 15 to 20 minutes to
complete. The experimental procedure and data reduction were as
described in Chapter III. The detect delay time for chlorine anion
photodetachment studies was selected with two factors in mind. First,
that the detect delay be long enough that all of the precursor
anions had reacted. Second, that the chlorine anion intensity be
as near to the peak chlorine anion intensity as the first criterion
would allow. Peak laser outputs varied strongly with dye, dye
concentration, dye age, wavelength, and the high voltage setting for
the laser discharge. The maximum laser output was about 100 mi 11i-
joules (mj) and the lowest outputs that produced measurable changes

Figure 19. Photodetachment of C^".
The photodetachment of an optimized
Cl? ion signal at x= 478.5 nm(a)
ana X = 475 nm (b) is shown. The
signal-to-noise is exceptional in
this particular spectrum.

TIME (sec) 400
INTENSITY
Z6

in ion intensity were 10-15 mj for wavelengths correspondng to a
maximum in the absorption spectrum of the ion.
In addition to observing the decrease in Cl2_ signal intensity
upon irradiation, fragment/product ions were sought. In the case of
Cl, the ion cyclotron resonance mass spectrometer could be tuned
to the ion at a detect delay time at which the Cl signal was measurabl
The detect aperture was then returned to the time at which the Cl2
reduction was observed; however, the Cl resonance conditions were
not altered. Subsequently, photo-produced Cl or Cl generated
from some photo-produced intermediate could be measured. A photo-
induced spectrum of Cl is presented in Figure 20. Other product
ions were sought as well. CH3N02C1~, N02cr, NOCI ~, CH3CT, and
CH^Cl were possible product ions that were sought at each peak of
Cl2" photodestruction. Since these ions were not present in the
original negative ion mass spectrum of the nitromethane/chlorine
mixture, the procedure for determining their presence was more
involved than those for Cl. While photoreduction of the Cl2"
signal intensity was taking place, a slow, magnetic field scan over
0.050 Tesla and centered at a possible product anion's nominal,
resonant magnetic field strength was conducted. These measurements
were performed for each postulated anion at each wavelength where
a significant reduction in the Cl2' intensity was observed. None
of the proposed product anions with the exception of Cl was
observed.
The energy range covered in the photo-excitation experiments
was limited to 0.39 eV (3170 cm ^). The short wavelength limits

Figure 20. Photoproduction of CT.
This spectrum was generated as
described in the text. The Cl"
signal levels exceed that of the
photodetachment Cl2" due to the
mass dependence of the detectivity
and the photo production of Cl"
from Cl2" of varying isotopic
character.

INTENSITY
001

101
were determined by inefficient lasing of the dye laser system toward
blue wavelengths. The short-wavelength limit was 457 nm. Efficient
dyes are available for wavelengths shorter than 457 nm, however, the
particular Xe flashlamp employed does not effectively populate the
upper state of the shorter wavelength dyes and lasing could not be
achieved. The long-wavelength limit at 540 nm was the result of a
gap in the lasing ranges of the available dyes. Fluorol 555 was
obtained to extend the measurements into the red, however it did not
lase (63). Measurements made to the red of the Fluorol 555 range
(£>565 nm) resulted in no photo-reduction from 565 nm to 622 nm. The
gap in the photo-excitation spectra between 500 nm and 510 nm occurs
at a region where both LD 490 and Coumarin 540 dyes lased, but with
poor beam quality and poor shot-to-shot repeatability of the beam
profile.
The variation of the photodetachment cross-section with wave
length as restricted by the laser source considerations is presented
in Figure 21. All data points were taken under identical
spectrometer conditions: grid pulse delay, 1ms; grid pulse width,
30 ms; free pulse delay (laser trigger), 100 ms; detect pulse delay,
100 ms; marginal oscillator level, 50 to 60 mV; filament current,
2.5A; filament voltage, 4v; filament offset voltage, -2.4v; and grid
offset voltage, -12.5v. Source pressures were held as constant as
possible considering the stability difficulties described.
Each point on the spectrum represents an average of between four to
ten runs at the individual wavelength corresponding to sixty to one
hundred and fifty laser shots per point. The bulk of this data was

Figure 21. Cl^" Photodetachment Cross-Section as a Function of Wavelength.
The Cl2 photodetachment spectrum is shown from 460 nm to 540
nm. Absolute cross-sections were not measured. The maximum
photoreduction of Cl2~ observed over this wavelength range
was approximately 80% in the blue region. Structure is evident
in the cross-section.

470
480
490
Cl" Photodestruction
110 ms delay
500 510 520 530 540
o
CO

104
analyzed manually by the measurement of the ion signal intensities
from the hardcopy spectrum generated at an x-y recorder. The
individual laser shot intensities were measured visually with an
oscilloscope and manually recorded for later correlation with the
appropriate ion intensity value. A small amount of the data over the
wavelength range from 470 nm to 490 rim was collected with the
microcomputer-interface hardware. Microcomputer data collection
decreased the actual data collection time and more significantly
decreased the time required for data reduction. Typically, two hours
were required to manually reduce the data of a single pass (15 laser
shots) at a single wavelength. With the microcomputer interface
this time was reduced to approximately ten to fifteen minutes
depending upon the quality of the data. If the present microcomputer-
interface were tied into a more powerful microcomputer, the data
reduction time could be made significantly less and on-line analysis
could be approached.
Analysis of Results
Optically accessible electronic transitions of the halogen
molecular anions are restricted to symmetry-allowed, single-electron
transitions involving the valence molecular orbitals. The ground
electronic state molecular anion configuration of the halogens may
be written in the form
(agns)2 (auns)2 (agnp)2 (^np)4 Ugnp)4 (^np)1
where n equals 3 and 4 for chlorine and bromine, respectively. This

105
notation is abbreviated to (2441) in which only pa and pa occupancies
are explicitly given. This configuration (2441) yields a Eu mole
cular electronic term (Hund's case b ). Consistent with the anti
bonding nature of the ounp electron, the chlorine anion exhibits
an increased bond length (2.66A) and decreased vibrational frequency
(260 cnf^) (95) relative to the ground state of the neutral (1.988A,
565 cm 1) (88b). No first-order spin-orbit coupling is expected for
a 2e+ state (88c).
The lowest, excited-state electeonic configurations correspond to
single-electron excitations from the a np, a np, or a np orbital
9 U 9
to the aunp orbital. These states, (2432) 2ng, (2342) 2nu, and
(1442) Eg are repulsive. Potential energy curves have been
calculated both for the ground anionic state and the repulsive excited
states for chlorine (95,96) and bromine (96). In addition, for
2 2 + 2 + 2 +
chlorine the it +- E and E + E electronic transitions have
9 u g u
been observed in the gas phase (75,92), as well as in rare gas
matrices (97), crystals (98), and glasses (99). The transition
from the e, to the E state is strongly forbidden and has not been
u u 3 J
2 2
observed. The n and n states exhibit first-order, spin-orbit
g u
splitting; for chlorine the magnitude of the splitting is anticipated
to be small (100).
The only state of neutral chlorine accessible with the wave
lengths used in this study is the X^E^ground state. The next
-1 3
neutral state, 18310.5 cm above the ground state, is the A nQ+u state (88d).
This state lies at an energy significantly higher than can be

106
reached with the current laser source and does not contribute further
to the discussion of these results.
The spectrum for the photoreduction of Cl^ exhibits
significant, complex structure not observed in previous studies (75,
92, 97, 98, 99). Studies employing polarized incident radiation have
identified the two transitions observed for chlorine anions as the
2 + 2 + 2 2 +
zn - X e transition at approximately 365 nm and the n *- Xi
9 u J g u
transition peaked at 750 nm (75,92,97). For chlorine the spin-
orbit splitting of the state was not observed (97). The photo-
induced decrease of the Cl^ intensity observed in this study cannot
be explained in terms of transitions to the dissociative excited
states of the anion. The wavelength range covered by this work
corresponds to the region of the long wavelength tail of the ultra
violet transition (365 nm). In this range, the photodissociation
of the molecular chlorine anion occurs with a lower probability and
photodetachment processes from excited vibrational levels of the
chlorine molecular anion may be observed.
Computation of Franck-Condon Factors
The anticipated transitions are those occurring from a
vibration-rotation manifold of the £u state of the anion to the
vibration-rotation manifold of the neutral ground state ^e* The
relative intensities of the individual lines in such a spectrum
depend upon the relative values of the Franck-Condon (FC) overlap
factors, in conjunction with rotational parameters, for a constant
electric dipole transition moment. FC factors may be obtained if

107
accurate electronic potentials are known or can be generated for the
two electronic states involved in the transition. Three types of
potential energy curves are generally available: empirical,
computational, and quantum mechanical. Empirical procedures rely on
a parameterized model for the potential curve where spectroscopic
constants determine the parameters. This method includes the Morse
potential energy curve generation scheme (101) and several
variations including the Hulbert-Hirschfelder potential function
method (102). Quantum techniques involve numerical solution of the
wave equation to some selected approximation over a range of nuclear
configurations. A computational technique relies upon the spectro
scopic constants for the generation of discrete molecular energy
levels and upon the assumption of a functional form for the
distribution of the levels. The most well-known computational method
is the Rydberg-Klein-Rees (RKR) technique (103). The RKR potential
is the best approximation to the true potential up to the term
value for which the spectroscopic constants are unperturbed and
valid. For this reason, the RKR technique with a Hulbert-Hirsch
felder extension beyond the region of valid spectroscopic constants
was used in this study.
The RKR method for potential curve construction is founded upon
the Dunham phase integral (104, 105) and the Klein action integral
(106, 105). The Dunham phase integral expresses the energy levels
of a potential function with a single minimum. The expression for
the phase integral is

108
x2
/pdx = 2/ p dx = h (v+'s) = I (45)
X1
for p defined as the particle momentum. Where the effective potential
can be represented as a potential without rotation and a centri
fugal potential
2
MR) = U(R) + K = J(J+1), (46)
K R 2m
the phase integral condition has the form
Ro ,1/2
2/ [2y'(E U(R)P'dR = I (47)
R, K
where E is the energy of the (v, J) term value, i.e.,
E(I,K) = hcF(v, J). (48)
The Klein action integral is written
11
S(V,K) = (21r2|i)"3s fQ [\l-E(l,K)]h dl (49)
where I1 is determined by the stipulation
E(I',K) = V (50)
and V is the energy at the limit of the integration. The phase
integral condition and Klein action integral may be combined and
the intermediate expression evaluated to give a simple form of
the action integral

109
R2(V)
S(V,K) = V/ (V- U (R ) dR (51)
RX(V) R
The potential derivatives with respect to V and K of the simplified
form of the action integral are
f = § = h (R2-Rx) (52)
9 = § = h These equations may be evaluated for R1 and the classical
turning points.
Rl,2 (V) = + (54)
Both f and g are determined as functions of V from the complex
form of the Klein action integral
f (V) = (8n2v)~h
r
/
o
dl
J V-E(I,o)
(55)
g (v) =
( 8 ji p
2)%
r
o
B y (I) d I
7v-e(i,0)
(56)
where BV(I) = BeCe('h") + and other constants are defined as
usual. The method evaluates numerically the f(V) and g(V) and
determines the classical turning points.

no
The Hulbert-Hirschfelder (H-H) five-parameter empirical
potential is a generalization of the Morse potential given by
U(R) U(R0) = ax (l-e'x)2 + a2 x3e DX + a3 x4e'DX
(57)
where
(58)
and a^, a^, a^ and D are fitting parameters which may be related to
spectroscopic constants by means of Dunham's analysis (102). This
potential function is used to extend the RKR potential curve so
that vibrational wave functions may be determined up to the RKR limit.
A Fortan RKR-HH potential energy function program (107)
was used and calculations were performed on the Amdahl computer.
The RKR-HH numerical potentials for Cl2 and Cl2 are given in Appendix
V. The potentials are drawn in Figure 22. The input spectroscopic
constants are listed in Tables 6 and 7.
The RKR potentials are the inputs to an FC factor program due to
Zare and Cashion (107) which utilizes a solution of the radial
Schrodinger wave equation by Cooley (108). Cooley's algorithm
solves the second-order differential radial Schrodinger equation
from a numerical input potential. The algorithm starts with limiting
values for the wave function at the integration limits. From the
upper limit, the wavefunction is integrated inward since the wave-
function's value at rn_j can be expressed as a function of r ,
rn i Vn Vn i the numerical potentials of r and r P ; and E,
a trial eigenvalue. An outward integration is performed similarly

Figure 22. Rydberg-Klein-Rees Potential Energy Curves for Cl2
and Cl?". The RKR curves for the anion-neutral
pair are drawn on a single energy scale. The zero
of energy corresponds to the minimum of the
potential energy curve of the anion.

112
1.5
i
2.0
2.5
A
3. 0
I
3.5

113
Table 6.
Spectroscopic Constants Used in the Determination of the
Rydberg-Klein-Rees Potential Curve for Clg.
t
e e
559.75 cm'1
2.694 cm"1
B
e
0.2442 cirr1
ag 1.516 x 10"3 cm-1
Dq 19997.14 cm'1

114
Table 7
Spectroscopic Constants Used in the Determination of the
Rydberg-Klein-Rees Potential Curve for Cl2~-
w,x
e e
260.0 cm"
1.50 cm-*-
0.136 cm-*
0.01 cm *
10324.1 cnf1

115
from the lower integration limit. This solution satisfies the wave
equation at all points except for the single point where the inward
and outward integrations overlap. This point is used to test for
convergence with respect to variation of the trial eigenvalue. When
the energy difference between the inward and outward wavefunctions
is less than the selected convergence limit, the final wavefunction
is obtained by a point normalization routine. The integrations are
simplified if the potential is known at regularly spaced values of
r, therefore, an eighth-order Lagrangian interpolation of the input
RKR potentials is performed prior to wave function generation.
The evaluation of the wave function integrations and the FC overlap
integrals and other integrals take place over the range RMIN to
RMAX. For the ground anionic state of chlorine and the chlorine
neutral RMIN and RMAX were selected as 1.5A and 3.5A, respectively.
These values are selected due to the constraints of the Lagrangian
interpolation routine and the range of validity for the
spectroscopic constants, and provide precise wavefunctions up to
v"maX=12 fr anion and v'max=20 for the ground state neutral.
The quantum numbers of the transitions (V*, V**), the term value,
T(cm 1), the Franck-Condon factor, Q, the wavelength of the
transition, LAMBDA (A) and the FC factor times the cubic and fourth
powers of the wave number, QT**3 and QT**4, as well as the
r-centroid and r-squared-centroid and the sign of the overlap
integral prior to squaring to obtain the FC factor, RC, R**2C and
PHASE, respectively, are tabulated in Appendix V. The potential

116
curves and Franck-Condon and associated integrals determined here
were evaluated to assist in the interpretation of the structure
present in the photodestruction spectrum of the molecular chlorine
anion.
Table 8 contains the locations of the major peaks of the photo
reduction spectrum of C^ expressed in wavelength and wavenumbers.
Based on the output of the FC factor program, vibronic transitions
have been assigned to the observed transition energies. The results
of the FC factor program are indicative of, but not conclusive
evidence for, the assignment of the photoreduction of C^" to a
photodetachment process. The FC factor term values are accurate
as far as the spectroscopic constants for each state retain validity.
The spectroscopic constants for the X1^ ground state of chlorine
are well known for v $ 49 (109, 88b). Therefore, exceptional
accuracy in the term value is expected with respect to the neutral
vibration-rotation manifold. The constants for the molecular anion
are not well established and this hampers the peak assignments at
higher vibrational quantum numbers of the anion (110, 111). Several
of the assignments in Table 8 may be questionable, especially those
at 471.5 nm (V*=20, V**=13) and 463 nm (V*=23, V**=15). However,
at longer wavelengths the assigned transitions are obviously the
best possible fit of the calculations to the experiment. The
assigned FC factors, especially at the long wavelengths, are the only
overlap factors of reasonable magnitude in the wavelength region.
At shorter wavelengths more transitions could be contributing
significant intensity to the observed spectrum.

Table 8.
Correlation of
with Calculated
the Observed Peaks (x, Tex
Transition Energies (Tca-|(
p) in the Cl2
y and Franck-
Photodetachment Spectrum
Condon Factors
X
T
exp
(V*, V**)
"^calc
Franck-Condon
Overlap Factor
(nm)
(cm"!)
(cml)
539.5
18535
(16,6)
18527
0.4067 E-l
533.5
18744
(15,6)
18739
0.4757 E-l
527
18975
(14,6)
18954
0.4426 E-l
521
19193
(13,6)
19172
0.3429 E-l
516
19379
(12,6)
(22,10)
19393
19369
0.2265 E-l
0.1401 E-l
496
20161
(11,7)
20138
0.2645 E-l
490
20408
(12,8)
20430
0.4769 E-l
486
20576
(16,10)
20578
0.2682 E-l
482
20746
(20,12)
20751
0.2742 E-2
476
21008
(14,10)
21005
0.3784 E-2
473.5
21119
(9,8)
21110
0.1761 E-l
471.5
21208
(20,13)
21237
0.6497 E-l
463
21598
(23,15)
21610
0.1291 E-l

118
The interpretation of these results is complicated by the fact
that no long progressions are present. From the (V*,V**) transitions
(16,6), (15,6), (14,6), and (13,6) an average first difference
of 219 cm ^ is obtained as compared to an average first difference
of 215 cm ^ from the calculated term values. The average second
difference from the experimentally determined term values is 4.5 cm"\
but a positive and negative value are generated indicating that the
wavelengths are not accurately enough determined to justify
assigning any significance to this value.
Calculated Franck-Condon factors are not expected to predict
the intensity pattern of the spectrum. This is due to the fact that
the initial level populations cannot be controlled and only broad
estimates of the energy available for internal excitation of the
anion are known. For the accepted values of the electron affinities
of nitrogen dioxide and of chlorine 2.38 + 0.06 eV and 2.52 + 0.17 eV,
respectively, the maximum available energy for internal excitation
from the electron transfer process alone is 0.37 eV (2985 cm^)
which could account for anion excitation up to V** = 12.
One means for determining the internal energy of the molecular
anion is through the observation of endothermic reactions of the
anion (75). If the amount of endothermicity can be gauged, a limit on
the anion's internal excitation may be set. This was attempted
using the Cl^ -CH^OH reaction. The experiment was complicated by the
fact that there were only two gas inlets to the cell region. For Cl^
formation, both inlets were already used. Consequently, a sample

119
bulb containing nitromethane and methanol was made up and used in
place of the nitromethane alone. The subsequent C^" signal was
reduced; however, this may be attributed to a¡ (decreased in c
collision frequency between nitrite ions and chlorine and less
efficient production of nitrite ion due to attenuation of the electron
beam by methanol molecules rather than reaction of Cl^" and CH^OH.
The technique could not be successfully applied in light of these
instrumental limitations.
The spectrum of the C^ photoreduction (Figure 19) does not
exhibit the expected limiting wavelength dependence for the photo
detachment cross-section near threshold at each transition (41, 42,
43). The onset behavior of the cross-section is predicted to be
o{E) k^'+* (aQ + a^k^ + 82^ + ...) (59)
where k. is the magnitude of the linear momentum of the photoelectron
and 1 is the angular momentum quantum number of the ejected electron.
For Cl^~ 1 equals zero and a sharp onset is predicted at threshold.
The absence of this behavior is due to masking by the enhancement
of the cross-section near the sharp onset associated with each new
vibrational resonance in the long wavelength tail regions.
The observation of Cl production had led to the conclusion that
photodissociation is the primary process observed in this wavelength
region for C^ (75, 92). This is definitely the case for the
peak UV absorption centered at 365 nm. However, for vibrationally

120
excited Cl,, favorable Franck-Condon factors lead to photodetachment
at longer wavelengths than predicted from the zero state energetics.
Chlbrine has been shown to react rapidly and efficiently with low energy
electrons, the type produced by photodetachment (112, 113, 114).
Consequently, even if photodetachment alone occurred, an increase in Cl~
signal intensity is anticipated.
Table 9 lists the assigned transitions, wavelengths, term values,
energy differences between the assigned transition and the (0,0)
transition, and the adiabatic electron affinity of each peak. An
average electron affinity of 2.3601 0.0040 eV is determined based
upon the peak assignments. This error reflects errors in the correct
determination of the individual peak term values, but not the possibility
of an incorrect numbering of the peaks. Due to the restricted range
of the experiment, V** values could be off by +2 to -3 and V* values
by +5 to -5 corresponding to a total error of +2164 cm-^, -2576 cm-^
(Table 10). Clearly, this error is a direct result of an incomplete
spectrum of mediocre quality. Coverage of a wider spectral range would
eliminate the questionable peak assignment and the higher precision
error estimate would definitely apply.
Bromine Molecular Anion
Formation of Br^
The molecular bromine anion, Br, was produced from Cl2 by elec
tron transfer. Direct formation of Br^ by electron transfer fron nitrite
ion was not observed. Direct electron attachment to bromine generated
Br by dissociative attachment. For a maximized Br^ signal strength
the ion cyclotron resonance mass spectrometer was first optimized for

Table 9. Adiabatic Electron Affinity Values for Chlorine Determined from the Assigment
of the Photodetachment Spectrum Structure
(nm)
^exp
(cm-!)
(V*,V**)
Tcalc Tcalc <->
(cm"1)
Adiabatic Electron
Affinity
(cm"l) eV
539.5
18535
(16,6)
-505
19040
2.3606
533.5
18744
(15,6)
-296
19404
2.3606
527.0
18975
(14,6)
-81
19056
2.3626
521.0
19193
(13,6)
137
19056
2.3626
516.0
19379
(12,6)
358
19021
2.3583
(22,10)
334
19045
2.3612
496.0
20161
(11,7)
1103
19058
2.3628
490.0
20408
(12,8)
1395
19013
2.3573
486.0
20576
(16,10)
1543
19033
2.3597
482.0
20746
(20,12)
1716
19030
2.3594
476.0
21008
(14,10)
1973
19038
2.3604
473.5
21119
(9,8)
2076
19044
2.3611
471.5
21208
(20,13)
2173
19006
2.3564
463.0
21598
(23,15)
2563
19023
2.3585

122
Table 10. Comparison of Literature Values for the Electron
Affinity of Chlorine.
Electron Affinity
(eV) Technique
Reference
9 OC _L 0.27
2.36 032
Photodetachment
Present Work
2.32 0.1
Endothermic Charge Transfer
79
2.5 0.5
Chemionization
115
2.52 0.17
Dissociative Electron Capture
76
2.35 0.15
Exothermic Charge Transfer
78
2.38 0.1
Endothermic Charge Transfer
116

123
nitrite ion production from nitromethane, then a mixture of chlorine
and bromine vapor was inlet and the signal intensity was maximized.
Finally, the Br2~ signal was located and the system was tuned for the
maximum Br^' signal intensity. B^ signal satisfactory for subsequent
photo-experiments was produced at a detect delay of 110 ms. The NC^-
and Cl2"" signal intensities had decreased to low levels at this detect
delay time for the selected operating conditions. The negative ion mass
spectrum of the chiorine/bromine-nitromethane mixture is presented in
Figure 23. The intensity of the well-tuned B^- signal is approximately
one-half the intensity of the optimum C^ signal levels used in the
Cl2 photo-excitation study.
Photodetachment of B^"
The photo-excitation spectrum of Br^ was investigated from 470
nm to 498 nm. At longer wavelengths (520-540 nm), the low ion signal
intensity contributed to a reduced signal-to-noise ratio and this com
bined with the small cross-section for photo-excitation at longer wave
lengths precluded cross-section measurements distinguishable from the
background noise level. The photoreduction spectrum is presented in
Figure 24. The dashed line spectrum shows more pronounced structure;
this is due to more stable output and better wavelength coverage by the
dye laser system for these points. The spectra show similar gross
behavior. The determination of the cross-sections plotted was discussed
in Chapter III.
Analysis of Br^" Results
RKR potentials and Franck-Condon overlap factors were not
evaluated for the Zg state of Br^ and the state of Br^,

Figure 23. The Negative Ion Mass Spectrum of a Mixture of Chlorine/Bromine
and Nitromethane. The mass range is from 34 to 190 amu. Peaks
are observed at mass-to-charge ratios of 35, 46, 70, 80, 129 and
160 amu/e. These correspond to Cl", NO^, Br", CH^ClBr"
and Brg" respectively.

190
125
i
m

CVJ
X
o
I
V-
CD
I
o
A1ISN31NI

Figure 24. Photodetachment Spectrum of BrI.
The optimized BrZ signal photo
detachment was observed from 470
nm to 500 nm. The structure apparent
in the cross-section is not explained
by the expected cross-section behavior
near threshold.

Relative Cross-Section (Arb. Units)

128
p
since the spectroscopic constants for the B^' £u+ anion state
are not known with any degree of accuracy (96). Since the errors
in the Franck-Condon overlap factors reach a level in the Cl^
calculation that becomes significant at the high (V =12) vibrational
level of the ion and since higher internal excitation is expected for
Br^', the value of such a refined calculation is mitigated.
For the data with the greater number of experimental points in
Figure 24, there are five identifiable peaks. The experimental
wavelengths for these peaks and the corresponding term values are
collected in Table 11. The first differences have been calculated
and are also tabulated. The predicted w the first-order anharmonic
vibration constant, for the ground state anion is 160 cirf^ (96).
The separation between the peaks exceeds this energy. Furthermore,
since wgxe is small and positive (0.7 cm'1) (96), the peak structure
o
cannot be attributed to a vibrational distribution in the u+
anion state. From the well-known spectroscopic constants for Br^
(79gr 81gr), an estimate of the vibrational levels in the neutral
ground state which would account for the empirically determined
spacings can be obtained. Retaining only terms up to second-order
in the anharmonic oscillator energy expression, an expression for
the separation of vibrational levels in the ground state neutral
(aG) as a function of vibrational quantum number is obtained,
A G = oj 2u x 2u x v
e e e e e
where v" is the vibrational quantum number in the £g+ state of
(60)

129
Table 11. Experimental Wavelengths (A) and Term Values (Texp) and
First Differences (a!) for the Observed Photoreduction
of Bromine Molecular Negative Ions.
\(nm)
^exp
(cm-1)
495.4 0.3
20186
+ 12
-13
488.6
20467
+12
-13
481.8
20756
+13
-13
475.7
21022
+ 13
-14
470.5
21254
+ 14
-14
A^cm"1)
281
289
266
232

130
bromine Using andwgxe, 323.2 cm 1 and 1.07 cm respectively
(88d), this expression indicates that levels up to v' equal twenty
must be involved in the transition.
No identifiable structure which can be associated with ground
state anion excitation appears in the spectrum. This is due to the
fact that high vibrational levels of the anion will produce closely
spaced lines which remain unresolved here. From the correlation of
the Cl2" photoreduction spectrum with the term values generated by
the FC overlap factor calculation it is apparent that the process for
formation of C^" from NO2 (Equation 43) populates. Cl2 vibrational
levels at least up to v ' = 16. This corresponds to 3752 cm* of
vibrational excitation of Cl 2". The nominal difference between the
accepted electron affinities for nitrogen dioxide and chlorine can
account for only one-third of this excitation. The excess
excitation may result from two effects. First, for a vertical
attachment process between the neutral and anion potential curves,
highly excited vibrational levels of the anion are expected to be
populated due to the large difference between the equilibrium bond
lengths of the two states (88b). Second, electron-impact., vibrational
excitation of chlorine neutral molecules may be competing with
dissociative attachment. Then, attachment may occur to vibrationally
hot neutrals with more favorable Franck-Condon overlap factors, but
with a range of final state internal excitation (114). Assuming
3752 cm"1 of excitation of Br2', an estimated v' of 23 is obtained.
This corresponds to a vibrational energy spacing for the anion of
approximately 108 cm ^. This spacing would be observable under the
resolution used here only under fortuitous circumstances. The

131
lack of resolved structure which can be correlated with the internal
state of the ion precludes an estimation of the adiabatic electron
affinity for the bromine molecule.
Bromine Monochloride Molecular Anion
Formation of BrC1~
Bromine monochloride negative ions were produced from the same
mixtures of chlorine/bromine vapor-nitromethane used in the study of
bromine photo-excitation. A mass spectrum with BrCl at near peak
intensity is shown in Figure 25. Clearly, the signal level of BrCl"
was not satisfactory for photo-experiments considering the apparent
errors in the cross-sections observed for Cl^ and Br^" which were
produced and detected with much greater signal-to-noise characteristics.
Several attempts were made to increase the BrCl" intensity.
Variation of the ratio of partial pressures of bromine and chlorine
at the cell showed only deleterious effects when altered from a ratio
of one. Steps were taken to insure that the initial mixture of
bromine and chlorine was in equilibrium with bromine monochloride (117,118).
This did not improve the BrCl" signal intensity.
Analysis of BrC1~ Results
BrCl" has been observed as a product of the reaction of Cl^-
with bromine. This reaction was reported earlier and a rate constant
was determined (79). The value of this rate constant and that of
competing reactions is presented in Table 12. Evidently BrCl" will
be generated as a minor species regardless of the variation of
neutral gas pressures.

Figure 25. Negative Ion Mass Spectrum with BrCl-.
A mixture of chlorine/bromine and nitro-
methane was inlet to the ICR and the
conditions optimized for BrCl" production.
The BrCl- signal intensity shown is the
maximum observed and was insufficient for
photo-studies.

INTENSITY
eei

134
Table 12. Rate Coefficients for the Reaction of C^- with B^.
Reaction Rate Coefficient
- If) 3
(x 10 cm /molecule-sec)
Cl2~ + Br2
B^" + CT 2
1.8
Br2CT + Cl
0.38
-
BrCl" + BrCl
0.16
*
BrC^ + Br
0.10

CHAPTER V
PHOTODETACHMENT STUDY OF THE ENOLATE
ANION OF ACETOPHENONE
Formation of the Enolate Anion
The enolate anion of acetophenone was produced by proton
abstraction from the a-carbon of the neutral. This was accomplished
via the acid-base reaction of acetophenone with a selected anion
of greater gas phase basicity than the product enolate anion of
acetophenone. Two anionic bases were used to abstract the
proton, OH", produced from H^O by low energy electron impact and
F", generated from SO2F2 also by electron impact.
The OH" anion is not produced directly upon electron impact
with H2O. Initially, H" is generated (119)
e" + H20 -* H" + OH. (61)
H" was not observed in this study since the minimum time-
resolution of the pulsed ion cyclotron resonance mass spectrometer
was insufficient to detect the extremely rapidly decaying parent
ion. H" does react further with water (120)
H~ + H20 OH" + H2 (62)
producing OH The OH anion was selected as the precursor anionic
base for this study, because of the ease with which it could be
produced, the simplicity of the negative ion mass spectrum of water
135

136
and the large concentration of OH' which could be generated and
trapped at the ion cell.
Electron attachment to sulfuryl fluoride produces F" in a single-
step, dissociative attachment process. Nitrogen trifluoride also
produces considerable F~ upon electron impact, however, sulfuryl
fluoride generates F~ with markedly lower translational energy (121).
For this reason, F produced from surfuryl fluoride should produce
fewer excited state secondary anions upon proton abstraction and
SO2F2 was the source selected.
The enolate anion of acetophenone was efficiently produced
using both anionic bases by the reaction
The enolate anion signal level for optimum conditions with OH" is
reproduced in Figure 26. The negative ion mass spectrum of the
acetophenone/base mixtures contained only the precursor anion and
the acetophenone enolate anion (Figure 27).
Photodetachment of the Enolate Anion
The photodetachment of the enolate anion of acetophenone was
examined near threshold at differing delays between ion formation
and ion irradiation and detection. The experimental conditions
employed for the ion formation for each base are tabulated in Table
13. Laser irradiation preceded the detect pulse by 10 ms. The

Figure 26. Acetophenone Signal Intensity.
The optimum acetophenone signal was
obtained with OH as the precursor
for the spectrometer conditions:
sample pressure, 2.0x10"* Torr,
(1/10 mixture of acetophenone to
H?0), electron energy, 7.42 eV,
detect delay, 170 msec, and detect
width of 3.0 msec.

INTENSITY
138
O
TIME (sec)
170

Figure 27. Photoreduction of the Enolate Anion.
The most pronounced reduction of the
acetophenone enolate anion signal level
occurred at the peak of the first
resonance. The anion reduction is about
70% at the maximum.

INTENSITY
-P*
o

141
Table 13. Values for Instrumental Parameters Pertinent to Aceto
phenone Anion Production and OH- and F~ Precursor Anions.
OH"
F"
Filament Voltage
-7.22 V
-4.93 V
Filament Current
1.5 A
1.5 A
Trapping Plate Voltage
-1.75 V
-1.75 V
End, Upper, Lower Plate
Voltage
+1.00 V
+1.00 V
Sample Pressure
2x10~5 Jorr
3.5 x 10^ Torr
Partial Pressure Ratio
(Acetophenone/Base)
1/10
4/1
Grid Pulse Width
20 msec
20 msec
Detect Delay
150-200-250 msec
100-200-250 msec

142
Observed photodetachment cross-section spectra are plotted in Figures
28-30 for the various detect delay times. The detect delays were
limited at short and long times by the concentration of the aceto
phenone enolate anions. The anion signal peaked at 200 ms and was
significantly lower below 150 ms and above 250 ms. The total pressure
was maintained as accurately as possible throughout a photodetachment
run to insure that the effects of collisions would not vary drastically.
The photodetachment spectra indicate that the electron detachment
process is not affected by collisions over the range that could be
induced here.
Analysis of the Acetophenone
Enolate Anion Results
The photodetachment spectra of the acetophenone enolate anion
indicate that a resonance occurs just above the threshold which is not
affected by collisional de-excitation. The acetophenone anion has been
studied and resonances have been observed throughout the near
threshold region (121, 122). The analysis of these resonances
indicated that they were attributable to electron-dipole resonances
and not to different vibrational transitions between the anion and
neutral states. These studies confirm this result as the first
resonance above threshold is not influenced by delaying irradiation
of the anion. The number of collisions is anticipated to vary by
35 to 40 over the range of detect delays at the pressures employed.
The vibrational de-excitation is expected to be efficient, since
the anion vibrational modes are not anticipated to be drastically

Figure 28. Photodetachment of Acetophenone at 150 ms Delay.
Detect Delay time of 150 ms. Sample and
spectrometer conditions as for Figure 26.

603
Relative Cross-Section (Arb.Units)
O-
-O
on
CD
00
3
3
Hi
Acetophenone/H^O
150 ms delay

Figure 29. Photodetachment of Acetophenone at 200 ms Delay.
Detect delay time of 200 ms. Sample and
spectrometer conditions as for Figure 26.

603 598 (nm)
Relative Cross-Section (Arb. Units)
-O
9trt
Acetophenone/h^O
200 ms delay

Figure 30. Photodetachment of Acetophenone at 250 ms Delay.
Detect delay time of 250 ms. Sample and spectro
meter conditions for Figure 26.

603 598 (nm)
Relative Cross-Section (Arb. Units)
O
ro
CJl
o
3
to
CL
fD
i
Q)
'c
8t7l
Acetophenone/H?0

149
different from those of the neutral acetophenone. Consequently,
it seems reasonable to agree with the previously reported results
that the structure is due to electron-dipole resonances of the
enolate anion. The electron affinity value taken from the wave
length at which a measurable reduction of the enolate anion occurs
is 2.056 eV in excellent agreement with the reported value of
2.057 eV (122).

CHAPTER VI
SUMMARY
The investigation of negative ions has proved a complex,
difficult and perplexing problem. The rewards associated with
performing such investigations have increased with the recognition
of the significance of negative ions to a variety of scientific
concerns. In this work, an ion cyclotron resonance mass spectrometer
was employed as a negative ion source, containment device, and detector.
Since the ions chosen for this study were known to exhibit small
cross-sections for the transitions of interest, a tunable, flash-
lamp-pumped dye laser system with a high output per pulse was employed.
The possibility of time-resolved effects on negative ion spectra
was investigated. In this study, no effects were observed but this
in itself confirms the results of studies attributing structure to
effects other than simple internal excitation.
This experimental technique allowed the observation of structure
in the photodetachment cross-sections of the halogen molecular anions,
Cl2 and This structure was attributed to vibronic transitions
between the ground state of the ankln and the neutral. The adiabatic
electron affinity of chlorine is derived fron the assigned transitions,
as 2.36 eV. This electron affinity has an error associated with the
peak assignment of +0.27 and -0.32 eV. In the case of the bromine anion,
the absence of structure due to the anion in the photodetachment
150

151
cross-section of the bromine anion precludes the estimation of a
reliable electron affinity. The experimental difficulties of operating
with halogen compounds were marked and are reflected in the data;
however, improvements in this area would necessitate an entirely
different design of the apparatus.
For acetophenone, confirmation of the nature of the resonances
near threshold was obtained. In addition, the electron affinity of
the enolate anion was determined to be 2.056 eV in excellent agreement
with earlier findings. This opens the possibility of differentiating
between different sources of structure in photodetachment cross-
section spectra.
The most significant result of this work has been the appearance
of structure in the photodetachment of the chlorine anion. In order
that this might be fully exploited the experimental design must be
improved. The availability of high energy, excimer-pumped dye lasers
is particularly significant. The optimization of the experiment is
most critically dependent upon the level and quality of the source and
the primitive dye laser system employed has been useful but is
severely limited.

APPENDIX I
ON-BOARD MICROCOMPUTER HARDWARE MODIFICATIONS
The details of the modifications to the KIM-1 microcomputer are
presented as a useful diagnostic. Memory chips (2102) are soldered
on top of the on-board memory chips pin for pin with the exception
of CS, the chip select line, on each added memory chip (pin 13).
The CS line of the eight 2102's comprising the additional IK of RAM
are tied together. The unmodified, on-board memory is selected by the
KO output of the KIM-1 8K decode chip (74 LS 145, pin 1) through
the buffer/invertor (7404, pins 1 & 2). The direct KO select is
cut by clipping the input and output at the buffer/inverter, pins
1 & 2. A four-input NAND gate is mounted on top of the disabled
7404 with ground (pin 7) and power (pin 14) the only connections made
to the NAND gate from the 7404 pins. KO and K1 from the 8K decode
chip are connected to the inputs of the four-input NAND gate. The
K1 line must include a 560 pull-up resistor tied to +5 volts.
KO is already supplied with an on-board pull-up resistor. The
remaining NAND inputs are tied directly to the +5 volt line. The
output of the four-input NAND gate is input to the 7400 AND gate.
K1 is also connected to the chip select array of the add-on memory
chips. Additional +5 volt supply and ground lines to the memory chips
from the KIM-1 edge connector were added due to the increased current
demands.
152

APPENDIX II
MICROCOMPUTER CONTROL REGISTERS
The control registers required for the data collection and
analysis microcomputer system are given. Initial values are indicated.
Hex Address
Description (Initial Value)
00
01
02
03
04
05
06
07
08
0A
oc
OD
OE
OF
10
11
12
14
15
16
17
18
19
Main control register (00)
Number of zero levels (20)
Number of zero levels counter
One-half number of zero levels counter
Number of 100 levels per laser shot (08)
One-half number of 100's per laser shot
Number of laser shots (10)
Number of laser shots counter (10)
Index for average routines
Four-channel store base address (00)
Index storage for memory overlap (00)
Base address low for temporary storage (20)
Base address high for temporary storage (00)
Storage for zero level (00) Running Sum
ID for the data to be averaged (00)
Index for final data store (00)
Dividend for three-byte average
Divisor for three-byte average
Programmable Interrupt Request (PIRQ) (00)
153

154
Hex Address
Description (Initial Value)
1A
Index for four channel store
IB
A/D high order byte
1C
A/D low order byte
40
ID for data storage
41
Final data store low order address (00)
42
Final data store high order address (02)
43
Final data store index (00)
DB-DF
Registers for full 16-bit divide

APPENDIX III
MICROCOMPUTER PROGRAMS
Initialization Subroutine
Address Label Op Code Mnemonic
Comment
0800
0810
0820
IN IT
LOOP
A9
00
LDA
#00
85
00
STA
00
85
1A
STA
1A
85
OA
STA
OA
85
OE
STA
OE
85
19
STA
19
A9
20
LDA
#20
85
01
STA
01
A9
08
LDA
00
o
85
04
STA
04
A9
10
LDA
# 10
85
06
STA
06
85
07
STA
07
A9
40
LDA
#40
85
OD
STA
OD
A9
02
LDA
#02
85
OB
STA
OB
A5
19
LDA
19
FO
FC
BEQ
FC
78 SEI
C6 19 DEC 19
A5 02 LDA 02
DO 16 BNE 16
Register Initialization
NOP Loop
155

Appendix III. Microcomputer Programs (continued)
Initialization Subroutine (continued)
Address
Label
Op Code
Mnemonic
Comment
A5 02
LDA 02
I
Determine if last zero h
DO 16
BNE 16
1
been taken
A5 OF
LDA OF
85 15
STA 15
0831
A5 10
LDA 10
85 16
STA 16
A5 11
LDA 11
Perform zero average and
85 17
STA 17
Data Analysis
A5 01
LDA 01
85 18
STA 18
20 90 OB
JSR 0B90
0840
20 9A OA
JSR 0A9A
DISPLAY
A5 00
LDA 00
85 FA
STA FA
A9 00
LDA #00
Prompt Operator
85 FB
STA FB
4C 4F 1C
JMP 1C4F
58
CLI
084 F
4C 22 08
JMP 0822
cn
cr,

Appendix III. Microcomputer Programs (continued)
Obtain Data and A/D Delay Subroutine
Address
Label
Op Code
Mnemonic
Comment
0852
Ob & Del
20 90 08
JSR 0890
Sets MUX to ICR Channel
4C 5B 08
JMP 985B
Jumps to Delay
20 69 08
JSR 0869
Sets MUX to Photo Channel
DELAY
A9 40
LDA #40 1
Sets Time for Delay &
80 07 17
STA 1707
0860
2C 97 17
BIT 1707
Checks for End of Delay Period
10 FB
BPL 0860
20 00 OA
JSR 0A00
Jumps to Read A/D Subr.
0868
60
RTS
cn

Appendix III. Microcomputer Programs (continued)
Multiplexer Select Photo Detector Subroutine
Address
Label
Op Code
Mnemonic
Comment
0869
MUX Photo
EA
NOP
EA
NOP
A9 5F
LDA #5F
8D 03 17
STA 1703
0870
8D 01 17
STA 1701
Configure PADD's and PAD'S
8D 00 17
STA 1700
8D 02 17
STA 1702
CE 00 17
DEC 1700
Drop inhibit
A9 53
LDA #5E

0881
8D 02 17
A9 5F
STA 1702
LDA #5F
-
Toggle clock line PBO
8D 02 17
STA 1702
J
EE 00 17
INC 1700
Raise inhibit
A9 02
85 40
LDA #02
STA 40
IF
Set 'Type of Data' Flag
088D
60
RTS
LD
CO

Appendix I LI. Microcomputer Programs (continued)
Multiplexer Select Marginal Oscillator Subroutine
Address Label Op Code Mnemonic Comment
088E
08B4
MUX MO
EA
EA
A9 5F
8D 03 17
8D 01 17
8D 02 17
A9 IF
8D 00 17
CE 00 17
A9 5E
8D 02 17
A9 5F
8D 02 17
EE 00 17
A9 00
85 40
60
NOP
NOP
LDA #5F
STA 1703
STA 1701
STA 1702
LDA #1F
STA 1700
DEC 1700
LDA #5E
STA 1702
LDA #5F
STA 1702
INC 1700
LDA #00
STA 40
RTS
_ Configure PADD's & PAD'S
Drop inhibit
- Toggle clock line PBO
Raise inhibit
|_ Set 'Type of Data' Flag
<_n
LO

Appendix III. Microcomputer Programs (continued)
Main Program
Address
Label
Op Code
Mnemonic
Comment
08D0
ID
A5 00
LDA 00
C9 01
CMP #01
90 08
BCC 08
Identifies the type of data
F0 08
BEQ 03
- (zero, 100 or Laser) to be
4C 08 09
JMP 09DB
taken and routes accordingly
4C IF 09
JMP 091F
ZERO
A9 FI
LDA #F1
Sets interrupt vectors to
08E0
8D FE 17
STA 17FE
avoid ID & Zero for Zero
A9 08
LDA #08
points after the 1st, i.e.,
8D FF 17
STA 17FF
changes IV s to ZH,' ZL
A5 01
LDA 01
Sets up running counters
85 02
STA 02
for total number of zeroes
A5 01
LOA 01
- taken and half of total to
4A
LSR
be taken
85 03
STA 03
08F1
ZH, ZL
20 52 08
JSR 0852
Jumps to Obtain & Delay Subr.
18
CLC
A5 OF
LDA OF
65 1C
ADC 1C
85 OF
STA OF
A5 10
LDA 10
Maintains a running sum of
65 IB
ADC IB
~ Zero values
85 10
STA 10
0901
A5 11
LDA 11
69 00
ADC #00
85 11
STA 11
CTi
O

Appendix 111. Microcomputer Programs (continued)
Main Program (continued)
Address
0911
091F
0921
092E
0931
Label
Op Code
Mnemonic
Comment
C6 02
DEC 02
H
Decrements total and half
C6 03
DEC 03
-
total counters
F0 02
BEQ 02

If half total taken, skip
58
CLI
-
return from interrupt and
40
RTL
_
alter Interrupt Vectors (IV
s)
E6 19
INC 19
Increment Int. Req. Flag
A9 DO
LDA #D0
8D FE 17
STA 17FE
Change Interrupt Vectors to
A9 08
LDA #08
ID
8D FF 17
STA 17 FF
E6 00
INC 00
Increment ID Flag
58
CLI
40
RTI
A9 2E
LDA #2E
8D FE 17
STA 17FE
Change Interrupt Vectors to
A9 09
LDA #09
100 Data
8D FF 17
STA 17FF
A5 04
LDA 04

4A
LSR
Sets Counter to one half of
100
85 05
STA 05
_
r
per Laser Shot
20 52 08
JSR 0852
Jumps to Obt & Del
A4 OC
LDY OC

Loads Y-register
A5 1C
91 OD
LDA 1C
STAy OD
I
F
Stores LSB of 100 MO Data
AIV 1 S

Appendix III. Microcomputer Programs (continued)
Main Program (continued)
Address Label Op Code Mnemonic
88
DEY
18
CLC
A9 10
LDA #10
65 0D
ADC 0D
85 0D
STA OD
20 58 08
JSR 0858
A5 1C
LDA 1C
91 0D
ST/\y OD
C8
INY
A5 IB
LDA IB
91 0D
STAy OD
C8
INY
38
SEC
A5 0D
LDA OD
E9 10
SBC #10
85 0D
STA OD
98
TYA
29 OF
AND #0F
85 0C
STA OC
C6 05
DEC 05
F0 02
BEQ 02
58
CLI
40
RTI
0961
MM iM
Comment
Stores MSB of 100 and Data
Jumps to Ob & Del
Stores LSB of 100 Photo Data
Stores MSB of 100 Photo Data
Changes Base Address to that
for 100 M0 Data
Insures that Y-register ranges
from 00 to OF for overwrite of
data
Checks to derermine if one half
of 100 data per laser pulse have
been taken

Appendi x 111. Microcomputer Programs (continued)
Main Program (continued)
Address
Label
Op Code
Mnemonic
A5 07
LDA 07
C5 06
CMP 06
90 20
BCC 0989
0969
EA
NOP
EA
NOP
EA
NOP
EA
NOP
EA
NOP
EA
NOP
EA
NOP
0970
4C 11 09
JMP 0911
0973
EA
NOP
EA
NOP
C6 00
DEC 00
C6 19
INC 19
A9 FI
LDA #F1
8D FE 17
STA 17FE
A9 08
LDA #08
0980
8D FF 17
STA FF
A5 02
LDA 02
85 03
STA 03
58
CLI
40
RTI
Comment
Determines if any laser shots
have been taken, if so takes
branch
Jumps to AlV's to ID
Decrement ID Flag
Increment Interrupt Request Flag
Changes Interrupt Vector to ZH,ZL
Resets half zero counter
O'*
CO

Appendix III. Microcomputer Programs (continued)
Main Program (continued)
Address
Label
Op Code
Mnemonic
Comment
0989
A9 00
85 40
LDA #00
STA 40
H
b
Sets Laser/ICR flag to ICR
0991
A5 04
85 08
85 18
LDA 04
STA 08
STA 18
]
h
Sets counter for 100 photo
MO sums as well as division
AO 00
LDY #00
18
CLC
A5 15
LDA 15
71 OD
ADCy OD
85 15
STA 15
C8
INY
A5 16
LDA 16
71 OD
ADCy OD
09A1
85 16
STA 16
Sums the eight 100 MO Data
A9 00
LDA #00
per laser pulse
65 17
ADC 17
85 17
STA 17
C8
INY
C6 08
DEC 08
DO E7
BNE E7
20 90 OB
JSR 0B90
Jumps to 3-byte Avg.
09B1
20 50 OA
JSR 0A50
Jumps to STORE
18
CLC

Appendix III. Microcomputer Programs (continued)
Main Program (continued)
Address Label Op Code Mnemonic
Comment
A9 10
LDA #10
64 OD
ADC OD
09B9
85 OD
STA OD
A9 02
LDA #02
85 40
STA 40
E6 12
INC 12
09C1
A5 12
LDA 12
C9 01
CMP #01
FO C6
BEQ C6
C6 12
DEC 12
C6 12
DEC 12
A5 OD
LDA OD
E9 20
SBC #20
85 OD
STA OD
09D1
A5 07
LDA 07
DO 03
BNE 03
4C 73 09
JMP 0973
4C 69 09
JMP 0969
09DB
20 B1 OB
JSR 0BB1
20 52 08
JSR 0852
09E1
20 50 OA
JSR 0A50
20 58 08
JSR 0858
20 50 OA
JSR 0A50
Alters Base Address to that
for Photo Data 100
{- Sets Laser/ICR Flag to Laser
Sets Laser/M0 Avg. Flag to
Laser
Returns to Avg. Laser
IF Resets Laser/MO Avg. Flag to 0
Checks for final laser shot
Sets up for final four 100's
Jump to change IVs to ID
Jump to Laser Trigger Subr.
Obtain and store laser MO and
Photo data

Appendix III. Microcomputer Programs (continued)
Main Program (continued)
Address
Label
Op Code
Mnemonic
Comment
EA
NOP
EA
NOP
EA
NOP
EA
NOP
C6 07
DEC 07
Decrement Laser Counter
09F0
A9 IF
LDA #1F .
r
8D FE 17
STA 17F6
L Change IV s to 100 Data
A9 09
LDA #09
8D FF 17
STA 17FF _J
1
C6 00
DEC 00
Decrement ID Flag
58
CLI
09FD
40
RTI
CT>
CT>

Appendix ILL Microcomputer Programs
A/D Subroutine
Address
Label
Op Code
Mnemonic
0A00
Read A/D
A9 OF
LDA #0F
80 01 17
STA 1701
A9 FE
LDA #FE
8D 03 17
STA 1703
A9 03
LDA #03
8D 00 17
STA 1700
CE 00 17
DEC 1700
AD 00 17
LDA 1700
85 ID
STA ID
AD 02 17
LDA 1702
85 IE
STA IE
EE 00 17
INC 1700
0A21
4A
LSR
4A
LSR
4A
LSR
4A
LSR
4A
LSR
OA
ASL
85 ID
STA ID
A9 01
LDA #01
25 IE
AND IE
05 ID
ORA ID
85 IB
STA IB
Comment
Configure PADD and PBDD
Read the Most Significant
Nibble
Format the Most Significant
Nibble

Appendix III. Microcomputer Programs (continued)
Address
0A3E
08B7
A/D Subroutine (continued)
Label
Op Code
Mnemonic
A9 05
LDA #05
8D 00 17
STA 1700
CE 00 17
DEC 1700
AD 00 17
LDA 1700
85 ID
STA ID
AD 02 17
LDA 1702
46 87 08
JMP 0887
85 IE
STA IE
EE 00 17
INO 1700
A9 EO
LDA #E0
25 ID
AND ID
85 ID
LDA IE
OA
ASL
OA
ASL
OA
ASL
OA
ASL
85 IE
STA IE
A9 10
LDA #10
25 IE
AND IE
05 ID
AND IE
85 1C
STA 1C
Comment
Read the Next Most Significant
Nibble
Format the Next Most Significant
Nibble
CTT
00

Appendix III. Microcomputer Programs (continued)
A/D Subroutine (continued)
Address
Label
Op Code
Mnemonic
A9 07
LDA #07
08D6
8D 00 17
STA 1700
0BE7
CE 00 17
DEC 1700
AD 00 17
LDA 1700
85 ID
STA ID
AD 02 17
LDA 1702
85 IE
STA IE
EE 00 17
INC 1700
A5 ID
LDA ID
4A
LSR
4A
LSR
4A
LSR
4A
LSR
4C 81 OB
JMP 0B81
0B81
4A
LSR
OA
ASL
85 ID
STA ID
A9 01
LDA #01
25 IE
AND IE
05 ID
ORA ID
05 1C
ORA 1C
85 1C
STA 1C
60
RTS
Comment
Read the Least Significant
Nibble
- Format the Least Significant
Nibble
Combine the Two Least Signifi
cant Nibbles into the Low Orde
Byte

Appendix III. Microcomputer Programs (continued)
Data Analysis Storage Subroutine
Address
Label
Op Code
Mnemonic
Comment
0A9A
A6 14
LDX 14
38
SEC
B5 50
LDAx 50
E5 1C
SBC 1C
0AA1
85 DD
STA DD
Subtract Zero Baseline from
E8
INX
Laser MO Levels
B5 50
LDAx 50
E5 IB
SBC IB
85 DC
STA DC
CA
DEX
38
SEC
B5 70
LDAx 70 i
E5 1C
SBC 1C
OABO
85 DF
E8
B5 70
STA DF
INX
LDAx 70
_ Subtract Zero Baseline from
100 MO Levels
E5 IB
SBC IB
85 DE
STA DE
A9 04
LDA #04 ,
85 DB
STA DB
86 14
STX 14
20 00 0B
JSR 0B00
Perform 16 bit Division and
0AC2
20 C2 03
JSR 0302
Reformat the Result
EA
NOP
EA
NOP
O

Appendix III. Microcomputer Programs (continued)
Address
OADO
OAEO
Data Analysis Storage Subroutine (continued)
Label
Op Code
Mnemonic
EA
NOP
EA
NOP
7 EA's
NOP
A6 14
LDX 14
95 50
STAx 50
CA
DEX
A5 D2
LDA D2
95 50
STA 50
38
SEC
B5 90
LDAx 90
F5 BO
SBCx BO
95 70
STAx 70
E8
INX
B5 90
LDAx 90
mm
F5 BO
SBCx BO
95 70
STAx 70
E8
INX
EO 20
CPX #20
90 50
BCC 0A9B
3-
A2 00
LDX #00
B5 50
LDAx 50
91 41
STA 41,Y
Comment
Store the Result
Subtract 100 Photodetector
Level from Laser Photode
tector Level
Test for Finish
OAFO

Appendix III. Microcomputer Programs (continued)
Data Analysis Storage Subroutine (continued)
Address Label Op Code Mnemonic
C8
INY
E8
INX
EO 40
CPX #40

90 F6
BCC F6
84 43
STY 43

60
RTS
Comment
Shift the results to the
permanent storage area
PO

Appendix III. Microcomputer Programs (continued)
Four/Channel Intermediate Storage Subroutine
Address Label Op Code Mnemonic
Comment
0A50
0A61
0A71
18
CLC
A5
40
LDA
40
64
00
ADC
00
85
00
STA
40
C9
03
CMP
#03
90
10
BCC
10
FO
07
BEQ
07
A9
90
LDA
#90
85
OA
STA
OA
4C '
7 A OA
JMP
0A7A
A9
BO
LDA
#B0
85
OA
STA
OA
4C '
7A OA
JMP
0A7A
C9
02
CMP
#02
90
07
BCC
07
A9
50
LDA
#50
85
OA
STA
OA
4C
7A OA
JMP
0A7A
A9
70
LDA
#70
85
OA
STA
OA
Data Routing
Set Laser Photodetector Vector
Set 100 Photodetector Vector
Data Routing Flag
Set Laser MO Vector
Set 100 MO Vector

Appendix III. Microcomputer Programs (continued)
Four/Channel Intermediate Storage Subroutine (continued)
Address
Label
Op Code
Mnemonic
Comment
0A7A
A4 1A
LDY 1A i
A5 1C
LDA 1C
91 OA
STAy OA
0A80
C8
INY
A5 IB
LDA IB
91 OA
STAy OA
A5 40
LDA 40
C9 03
CMD #03
- Vector Storage of Data
FO 02
BEQ 02
88
DEY
88
DEY
C8
INY
98
TYA
85 1A
STA 1A
0A91
60
RTS J

Appendix III. Microcomputer Programs (continued)
Triple Precision Average Subroutine
Address
Label
Op Code
Mnemonic
Comment
0B90
46 28
BO OA
LSR 18
BCS OA
D-
Test for Finish
46 17
LSR 17
]
66 16
ROR 16
Divide by two
66 15
ROR 15
r
18
4C 90 OB
CLC
JMP 0B90
3-
Repeat Division
A5 15
LDA 15
OBAO
85 1C
STA 1C
A5 16
LDA 16
85 IB
STA IB
A9 00
LDA #00
Store result and initialize
85 15
STA 15
the Average Registers
85 16
STA 16
85 17
STA 17
85 18
STA 18
OBBO
60
RTS

Appendix III. Microcomputer Programs (continued)
Laser Trigger Subrouti ne
Address
Label
Op Code Mnemonic
Comment
0BB1
0BE3
A9 9F
8D 01 17
8D 03 17
8D 02 17
8D 00 17
CE 00 17
A9 9E
8D 02 17
A9 OE
8D 00 17
A9 7F
8D 05 17
2C 07 17
10 FB
A9 8E
8D 11 17
A9 9F
8D 02 17
EE 00 17
60
LDA #9F
STA 1701
STA 1703
STA 1702
STA 1700
DEC 1700
LDA #9E
STA 1702
LDA #0E
STA 1700
LDA #7F
STA 1705
BIT 1707
BPL FB
LDA #8E
STA 1700
LDA #9F
STA 1702
INC 1700
60
Configure PADD and PBDD
Configure PAD and PBD
Lower the Inhibit
Hold clock line high
Hold pulse line low
_ Pulse Duration Loop
3
3
Raise pulse line
Raise clock line
Raise inhibit
"-4
CT>


Appendix III. Microcomputer Programs (continued)
Twelve Significant
Bit Shift
Subroutines
Address Label
Op Code
Mnemonic
Comment
03C2 Begin
A5 03
LDA D3
Shifts the output of the
DO 13
BNE 13
Double Precision Divide
03C6 D2
A5 D2
LDA D2
Routine into the standard
30 IE
BMI IE
two byte format
A9 00
LDA #00
85 D9
STA D9
06 D4
RSL D4
26 D5
ROL D5
26 D2
ROL D2
E6 D8
INC D8
4C 06 03
JMP 03C6
D3
A9 07
LDA #07
85 D9
STA D9
46 D3
LSR D3
66 D2
ROR D2
66 D5
ROR D5
E6 D8
INC D8
4C C2 03
JMP 03C2
STO
18
CLC
A5 D8
LDA D8
65 D9
ADC D9
85 D8
STA D8
A5 D5
LDA D5
29 FO
AND #F0
05 08
ORA D8
85 D5
STA D5
60
RTS

Appendix III. Microcomputer Programs (continued)
Double Precision Divide Subroutine
Address Label Op Code Mnemonic
Comment
A2 DA
LDX DA
A9 00
LDA 00
95 00
STA 00
CA
DEX
EO D1
CPX D1
DO F9
BNE 0B04
DB 02 04 06 08
AA
TAX
36
SEC
D3 D2 D5 D4 D7 D6 D9 D8
26
D6
ROL
D6
26
D7
ROL
D7
A5
DC
LDA
DC
30
10
BMI
0825
26
D6
ROL
D6
A5
DC
LDA
DC
DO
FO
BNE
OB 11
A5
DD
LDA
DD
DO
EC
BNE
0B11
A5
DE
LDA
DE
BO
OE
BCS
2A37
C5
DC
CMP
DC
90
35
BCC
0B62
FO
02
BEQ
0B31
BO
06
BCS
0B37
A5
DF
LDA
DF
00

Appendix III. Microcomputer Programs (continued)
Double Precision Divide Subroutine (continued)
Address Label Op Code Mnemonic Comment
C5 DD
CMP DD
70 2B
FCC 0B62
A5 DF
LDA DF
E5 DD
SBC DD
BO OD
STA DF
BO OD
BCS 0B4C
A5 DE
LDA BE
E5 01
SBC 01
38
SEC
E5 DC
SBC DC
65 DE
STA DE
16
CLC
A5 DE
LDA DE
38
SEC
E5 DC
SBC DC
65 DE
STA DE
16
CLC
B5 D2
LDA D2
65 D6
ADC D6
95 D2
STA D2
E6
INX
B5 D2
LDA D2
65 D7
ADC D7
95 D2
STA D2
CA
DEX
L£)

Appendix III. Microcomputer Programs (continued)
Double Precision Divide Subroutine (continued)
Address Label
0B62
Op Code Mnemonic Comment
46 D7
LSR D7
FO 05
BEQ 0B6B
66 D6
RCR D6
4C 79 2A
JMP 0B79
66 D6
ROR D6
DO OA
BNE 0B79
E6
INX
E6
INX
E4 DB
CPX DB
FO OB
BEQ 0B80
A9 80
LDA 80
65 D7
STA D7
06 DF
ASL DF
26 DE
ROL DE
B8
CLU
50 A5
BVC 0B25
10
RTS
0B80

Appendix IV. Sample Preparation
Samples were prepared in standard pyrex bulbs
fitted with ground glass or teflon vacuum stopcocks. All samples
condensed at liquid nitrogen temperature (77K) and consequently
could undergo freeze-pump-thaw cycles to remove volatile
impurities. The sample bulbs were initially pumped down to 20
microns and filled on a glass vacuum line. Pressures were measured
by a cold cathode gauge and an eight-inch Bourdon type
differential pressure gauge. Final freeze-pump-thaw purification
was performed on the ICR low vacuum manifold and was done prior
to each use of the sample.
Acetophenone, nitromethane (Baker Chemical Co.) and water are
liquids and were introduced as such into the sample bulbs. The
vapor pressure of each was sufficient to maintain the necessary
pressures at the jeweled leak valves and the ion cell. Bromine
(Baker Chemical Co.) is liquid at room temperature; however, the
sample was made up to the vapor pressure of bromine to facilitate
mixing with chlorine at a constant ratio with sample use. Chlorine
(Matheson) was obtained as 99% pure gas. No special preparation
was involved other than freeze-pump-thaw purification. Sulfuryl
fluoride (Matheson) was treated in the same manner.
In an attempt to increase the number of bromine monochloride
anions generated, a mixture of bromine and chlorine was irradiated
with a 450 watt quartz envelope Hg lamp to insure that an
181

182
equilibrium mixture was being inlet to the ion generation
region (117). A 50-50 mixture of bromine and chlorine was made up
in the standard manner. The sample was then irradiated for 2 hours.
As noted in the main text, no improvement in the BrCl" signal
intensity was observed.

APPENDIX V
RKR POTENTIAL ENERGY CURVES
AND FRANCK-CONDON FACTORS
FOR C12-C12

Appendix Va. Potential Energy Curves
********** jL'iCU 4 9 CHL',' Nc 4 NO MOL£CUL4P CHLC-il N'" ANltN ***********
********** ************* P-C V £RL AP F ACT ********************* *****
T H£ c JLLJ.V NS IATa 3-.5TMU 70 THE LO WCf- S T A 71: o STATE NU^fJEF IS 1 0
fj =
'U \ 1747(P5 13rJ 02
Tc J o TC -2 ^ j J a ? C 3 5
r = -'>*2792 222 49 13
L I V1 J > 5 o 0 0 0 2
L M v 7 ; j D ^ I
'Hr 1 N 3U V
TE'lTl \L
I'll S ANT ~N~
1
^ T I C
: r t ; -2 i G V)
-

d)429211uT
07
J-56 1 A 7 7 6GET
3s
.7 V 7 6 8 8 8 31D
: 7
Co 62095567 IT
00
0.
3C7?40324T
07
'*6314335060
0 0
).
2 3732 364 60
07
j741911342T
0 3
0 ,
1530716200
C 7
'o 502 3691 7 7")
0 0
J 0
14 1 0?19 63 0
07
0 862 J673 1 70
C 0
r>
0
t r 34 3 38 3 40
C 7
0- 92 3344843T
00
0 *
3313178730
0 6
">.93 33 226840
c3
3
6362 04600 0
06
0 o 1 0 4 4 3005 ?0
0 l
0
4^47537590
0*
0* 1 10 47 76 3 50
01
0 .
3t 76 1 29700
06
1 1 65?56 l 90
0 1
0
2 7 71 2 1 0 6 00
06
0- 122573407:1
0 1
0,
2073545640
C 6
1 12562 1 1 860
0 1
0
1 57 71 32 00 J
<"} F
o 1 3 4 6 6 v 7 IT
0 1
3 a
l 1 36 2 42 1 26
*
Af- r. G I V i£ N ^rLC'A

Appendix Va. Potential Energy Curves (con't)
R PE
O' 1 4.0 71 67570
0 1
0 3 1 3 0 9 -a 5 8 0 0
.14,; 7945370
? 1
0. 5 76 C7 92 66 0
0 S*
0 15 7 8123200
: i
: a 2, 9 6 3 31 1 5 .70
C 5
0. 1568601 040
0 1
0.2666598750
0 5
1649077.370
0 1
7. 1 7 0 90271 70
05
0a 17 0 9556 710
0 1
0 1 0 23356 3 70
09
4 1711966510
01
0.1 0 0 63 03 66 0
) 5
^ : 1 71 4 4.7 0 970
71
0. 984 0874 250
0 4
0) 1 71 s 550590
4 1
3o 56 1 7C8808D
04
- a 17 19528 0 60
0 1
0. 53 51 6 89 2 3 0
J4
a 17221655 3D
) 1
0.16 46 88 780
04
0-1724365470
0 1
0 0 = 360 3 7 2 1 0
04
". 1 72 7630360
01
0.87 O 59 2 4 97 0
ca
0 a 1 7 70 46.7 170
0 1
0.6 4 74182 2 lO
04
0* 1 73 3 366 9.8 )
01
0 a 8 2 4 08 78 86 .0
34
) 1 7 76344 960
0 1
0.8'0 6 024 6 00
04
) 17 39400 980
0 1
0 a 7 7*; 96 28 = 2 0
34
174253878''
01
0o7tr-3 1 701 07 '
0 a
' 17-~7ft?870
0 1
j. 72 92 26 o 120
04
0 1 74 9077970
0 1
0,1284040
0 4
' 178 2439 3 1 0
C 1
0.66 j83 14 177
Ca
'.1756007650
0 1
0.7 :;a 6 4 8 4 6 300
3 4
0 1759624370
C 1
3.6 3 I 933961 >
0 4
' 1 7 3 7 6 l 5 7 j
: i
0. 6724 52 2 OO
04
1 17 5 7 7 9?! if)
9 1
j.6824041950
j4
3. 177 1 2 143 40
0 1
0.55741 Of 7 3o
3 -
- 1 7 7 5 .349 650
0 1
0.6322833890
04
0 a 177 9637 77 0
0 1
0 .507005 0 6 30
3 a
1734091570
01
0.461 58 25 01 '>
04
1 a 1 78 3 726 650
.0 1
0 o 4 6 6 0 16 3 120
0 4
Oal753559730
0 1
0.433 3072090
0 4
. 179 8 6 0 7 6 3D
0 1
0. 4 G4 45 58 540
04
1 80 3 8 96 1 80
3 1
3.7 7 046)28 5 00
0 4
Oo 1905451 3 7 o
0 1
0.3 6 7 3280 42 .3
2 u.
0. 1 81 57 056 '0
0 1
0.32fcwb46120
04
0 182 1493 1 90
0 1
3.29964.4870
0 4
1828077740
01
C. 2 73 0871 18'7
0 4
3 a 13 3 5 1 o 5 4 4D
0 l
Jo 2467953 650
C4
0.1842660 1 3 0
0 1
0.2195648100
r a
: 18 50 2 465 00
:i
0.1925568780
04
0 a l359 808 380
0 1
3 1 7 34 9 1 7 26D
J +
o 1 36 = 753 2 50
0 1
Oa 1 3 3249797 ')
04
R
PE
- .)
133l3001SD
C l
0 ,
1 89 4 086 77 9
0 1
7.
191 0 3636 2,9
3 1
0 .>
193l 647 90D
3 1
0.
1947449249
0 1
7 .
19875396 5D
0 l
Oo
23335^8239
0 1
9.
2049295829
01
3.
2 376 776 349
0 1
0:
2C98682899
0 1
- V
2117731380
C 1
O
2 1 34 977 340
0 l
Oo
2150945950
3 1
J
"1 ,
2l8 025l2 3D
1
0 1
0.
219 293569H
0 1
0.
223 7127950
0 1
0 n
2219907320
C l

2232335 530
0 1
0 o
2244461749
3 1
0.
2256325939
0 1
3 .
2267961129
3 1
0 a
2 27 9 39504 0
0 l
' o
2290651279
01
3S
73 3 1 750 0 3D
0 1
Oo
231 2 7 C91 OD
0 1
3 .
2323543779
01
0 o
233 4267 789
3 1
0 o
234 4 8 93 34 9
3 1

2355431429
0 1
3 9
2365891960
3 1
0.
2376 2840 10
0 1
3.
2 38 6. 6 l 6 8 3D
3 1
0 a
23969 96 220
3 1
3.
2437129150
01
3a
24 1 7324300
0 t
Oa
242 7486 919
0 1
3 .
2437622860
0 1
0 o
244 7737779
0 l
Oo
245 7836 790
3 1
,*

2467925170
3 1
0 -
2473007761)
3 1
. I 10 8 7 1 5 3 99 7 8
3 3 3 5 7 2 4 8 3 9 : ~
. 65 707376 8 r -
.2 7922224 09 % 7
. 1 -7^0 lie ? O'1
. 0
. 1 39 79 0 1 1 39 : '
8 7 9 2 2. 2 2 4 0 9 0 7
. 5&70737f-80 0 3
I 1 108715090 O'-
o 138 940797 ') '.
. 1 L5 4117 2 o 0 0-
. 1 92 595 6 73'' C-
.2 19564 8100 C 4
.24f 7I55C55 1 08
. 27308 71 1 d.o c 9
.2=56434*39 - .
. 32 605461 2 ' 0 -
. 3 5 2 3 2 8 9 4 2' _ -4
.38462550) 0 -
. 4044558540 C 4
. 4 7 0 3 v 7 2 0 = 9 O -
.45 6 015312'' 0 4
o 4 6 t 58 25 0 10 0 a
. 5 0 7 c 0 5 0 = 7 1 C 8
.532 25 33699 C-
.55741 66700 04
.5;240419o
. 60 72h 52 2 30 ca
.63 193 896 10 0 4
656484630 3 0 a
,6808814170 Ca
.70518849-0
.7292250120 o%
.753 170 10' 0 4
.7 76 96 2 8 9 20
.6006024603 0-
824 08788 60 04
. R4 74 1 4? 2 1 0 oa
. 8705924570 0-
8 976087 21O r a
CO
cn
0
o
9/
0
0
0
0
0
0
0
0.
r<
J
0
0
J
0
0
J
0
o
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

Appendix Va. Potential Energy Curves (con't)
R
PE
, 241 8 3 89 26")
: i
C-, 51 5 46 -38760
04
1 74 3 30
0 1
7 5 7 9 1 6 71 2 50
3 4
3 2538267 3 3
3 1
0 09r. 1 70 2 8 039
0*
' 251 6. 373 7 4 0
Cl
0 0 4i; 74250
04
3 3252 3 4 94 3 30
3 l
O. l CO 6 3 33 8 60
05
0 25 3 3o37 90 )
0 1
3.1.' 2 8 356 370
C 5
. 2553 251 £30
3 1
0. 1C 63165 689
05
2 c 25 5 7 365i6 o
3 l
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Appendix Va. Potential Energy Curves (con't)
R
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Appendix Va. Potential Energy Curves (con't)
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Appendix Va. Potential Energy Curves (con't)
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R PE
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Appendix Vb. Molecular Chlorine and Molecular Chlorine Anion Franck-Condon Overlap Factors
V*
, V**
T(cm1)
Q
Lambda
QT**3
QT**4
RC
R**2C
Phase
0
3
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r>
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4835.170
0. 1 1 1 80
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05
2.2809
5.20 5?
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0.46300-11
4896.0 l 0
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02
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5. 17 12
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3
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3
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Appendix Vb. Molecular Chlorine and Molecular Clorine Anion Franck-Condon Overlap Factors (con't)
V*
,v**
T(crrf 1)
O'
Lambda
QT**3
QT**4
RC
R**2C
Phase
>.
r
2227**12 .-
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npjJCIIU 1 A
vo. noiecuiar Chlorine
and Molecular
Chlorine
Anion
Franck-
Condon Overlap
Factors (con't)
v*,V**
T( cirri)
Q
Lamdba
QT**3
QT**4
RC
R**2C
Phase
' v
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3
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4.3 35 0 7 85
0 0 8 0 4 0
15
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l 4
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5.6247
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- 2 0 8 5 6.. 2 8
:*4724f;-0 1
4 3 75. 1 66
* .564 10
1 2
3.12890
l 7
7.3435
5.4975
Â¥
>. 1 1
- 2 7 p 3.0 J
r 4 86.70 0 l
44 20 2 ?6
0,5 b 2 4 0
l ?
0 1 2720
l 7
2.3367
5.4599
-
10.11
-2JQ 3,23
. 74 1 0-0 1
4 <4 C ~ 6 26
0 0 3 & 3 P1
1 2
) 55950
1 6
2.3299
5.4274

11.11
-22166.28
. 1 2 37 1
45 1 1 .357
0.10470
1 ?
0.29 860
1 6
2.7230
5.3942
-
l ?. 1 l
21342.23
* 0 l7650-03
4557. 4 1 2
0,18640
1 0
0.4090 D
1 4
2.3132
5.3272

0. 1 2
-2f 37 0o57
. 0 4 7 6 8 0 '''5 *
754i.34?
3.70740
0 8
C 1 7 9 0
1 3
2. 4 1 84
5. 85 39

1.12
2" 0 6. 1.8 7
. 66 310- 0**
19 89.0 38
0:10440
1 0
G 2 6 17 0
14
2.41CJ
5. 81 I 5

2 1 2
7
, 4r* ^0- o:;
90 ? 0.6 36
j* 74 1 70
1 0
0.18400
1 5
.4024
5.7730
-
7. 1 2
-2 i55e.C 7
' !2c:7 0-02
4 0 7 1 8 8 1
1 *, 0 * 5 1 0
1 1
3.82310
1 5
2.3946
5. 73c5
-
*12
-24310.67
..74'40-CO
4 l 1 1, 4 2 0
o,i 0 7 2n
l 2
JO?6070
l 5
2. 20 7G
5. < 98n

>. 1 ?
4o,5-t. 7
, 1 17.1- M
- 1 V- , .2 9 '
,25640
1 ?
3c 6 1 47 )
It'
2.3795
5.66'3
-

npfjcnu i A
vu. nuiecuiar
uniorme and
mo 1 ecu 1 a
v*,V**
T(cm-1)
Q
Lambda
ip
f ?
c w i 7 : i
<* 1 v 7 5 J .
7 1 ?
- 4 7
'*'J 0 )- 0 l
4 M ; c 4 2
i 1 ^
-? 7 7 4 Pvt 7
>; o 11-0?
4 ? f'45
ip
- ? M 1 5.' 7
JO ^rO' 01
4 3 26 O 0 6 *
i:, i 2
- v> H H S i- 7
M : >. 2- 0 1
43M 54"
11.12
-'7. fc^e.t 7
- 2 7 91 '-?5
4417.321
i i r
- 2 * 4 J. 4 o 5 7
- oo l 7f.- ; >
44 57* 3 66
v,l3
-2r>60 7o 1 1 >
: O 105 30-?4
3 74.9 G 1
l 1 l
-? 5"0. 1 1
2 2 1 8 0- 0*1
3913.573
Ml
- 1 4 l 90- 0 2
395 30 l 77
7,13
- 2 5 3 4 £ l 1
C V **> 7 ; 3 0 '
39 92.795
4,17
- ? 4 7 9 7 1 l
,o l 5 y90 G1
4 0 32 o 7 2 3
5,13
-3455 2.1 1
. O 3 ? 5 0- 0 1
4 3 7? 97 0
6, 1 3
-2471C.l1
? 4f?c;cn_'>i
4 1 13.513
7, l 3
- *071,1 l
:3 5i 4 oo i
4 1 54. 355
3. 1 3
-2 3 J5, 1 1
3 3 74 ?n-0 1
4 1 954 92
9.13
- 2 ** 6 7 2 1 1
: t c 04f- oi
4 2 36 .9 09
10, 1 3
-?337?. 1 l
o, l Of. 40- 0 3
4? 7b.6 0 4
1 1 1 .3
- ?. 3 1 4 5 o 1 1
31 ? ? i D -: i
4320.567
13, 13
- 7 ? 1 1 l
- 27 OoO- 0 l
4 3 62. 791
3,14
-2 6 7,5 ? J
jo f 7 39 0-0
30 04 063
1.14
- 2 i 0 >0.53
66 9 0*" -0 ?
7341.643
_ l 4
- ? 3 7 7 6 5 3
rO 36 96D-0 2
36 79.4 99
3.14
-?55255 3
j o 1 .? 5 3 CO 0 1
39 17.64 7
4,14
-25277,53
3, 29400- 01
3956.083
">14
-2 5 0 3 2.5.3
' .,4 759 D- ? 1
7094.002
',14
-2 4 79 C.5 3
.-b795O-0!
4032759
f % 14
-2455 l o53
"c 7 4 9 D C 1
4073.066
3.14
-2- 3 1 5,5 3
, i o c o o ; i
4112.595
.14
- 24 On 2. 5 3
0, 1 5 360 0?
4l 5? .386
i:, 14
- 2 3.9 5 2 5 7
Oa 1 3 660- 0 l
4192.428
11,14
- 2 35 2 5 7
j 2 6 *60-01
423?.710
12,14
- 2 '401,53
", 21 130-01
4273.225
3. 10
-f: 7 5 1- 75 t
<. 1 9 no-.^
7 7.36.66 7
1 13
? d 5 0 4 6 ->
r 1 a ?? :o- 0 7
37 72.655
? 1 4
-2-2 50, -.5
-o 4-' ?o C ?
3b J9, 401
3. 1 r
-?:><; 9 5,7 0
? 24 75 0- -1
3646.17*
4.15
-25751.95
, 45600 Cl
3883.217
5,15
- 7 5 5 0 b 5 5
rM.; 50- o 1
3920.516
Ml'
2*526 4*6 5
;,42440-01
39 5b '"'6 5
' 1 c
-250?5. .j5
v 1 3 5 00- 01
3*95,369
3.15
-2 4 769 n -<5
c 6 0-04
4 0 3 7. c QQ
. 15
-24556 a 55
-a 1 4 .40- 01
4<; 72.164
M, 1 c
-74 n < 5
c ? 4 jo : i
4 1 1 Oo 6 85
1 1 1 c
-2 4 09 9,35
. ?* 36.0-C 1
4145.40-
12,15
-?3375.6?
",221 6 O- y>
4 1 r< 6 ,33?
jOr.or O < ' O O o O o O O O O O O o fO O O j O O O
Chlorine Anion Franck-Condon Overlap Factors (con't)
QT**3
QT**4
RC
R**2C
Phase
, h 1 1 9
1
. 1 1 J l O
1 7
2 3 7 C 1
5. 6 2 71

0 5 82 39
1 "
J 1 4 91 J
1 7
3 36 4 .
5 59 7 1
-
: a 7 51 i;>
1 2
M4 740
1 7
2 35 6 b
5 5 6 . j

v.,4 1f or
1 2
0 > 5 9 3 0
16
2.3507
5 5 2 l
-
0. l ?e>9
1 2
0.2 8970
16
2.3435
6 c 4 9 r-
3.2 7-7 J
0 c
0.63040
l 2
2.3912
5. 92 1 5
f
2 3 l l 2 3 r
l 2
0.25120
l c
2.3318
5.4401
-
'.2 84 10
0<
0. 7 3 310
1 3
2.4338
6.9252
4
0.3659O
1
0.94 52 D
l 4
?.4 265
5. 8fl- 7
-
1 25 70
l 1
0.5811 D
15
2.4174
58452

: 6 > 6 80
1 1
0.2246D
1 6
2.4C >4
5. 30f C
-
0.24390
l 2
0 6 0 4 b D
l 0
2.4 0 l 7
6. 76 9C
4
j.46230
1 2
J. t l 840
l 7
?3940
5.7321

0 6 55?0
1 2
0l6970
1 7
2.3865
5. 69 59
4
0.71680
l 2
0.17250
17
P.3792
5.66 0 3
-
0.4 6 0 70
1 2
0. 1 1 170
17
2.3713
5.6247
4
0.13200
l 2
0.31160
1 6
2 364 ?
5.0807
-
Oc 17460
1 0
0.31450
1 4
2.3697
5.6 * 6 8
-
0.15160
1 2
0.35080
1 6
2. 35 26
5.5371
4
0 5 3 0 5 0 0
l 2
07 4 70 0
16
2.3455
5.50 1 3
-
0.10770
1 0
0. 2 7 260
1 4
2.4492
6 OC ? 4
4
0.11 800
1 1
0.30720
1 5
2.44C7
5.V567
-
0.0 3 7C0
1 1
0.1 6320
16
?4324
5 9lQ0
4
0. 2 1 C10
1 2
0. 5 36 30
1 6
2.424 7
5.3784
-
0 0 4 746 0
1 ?
0.12000
17
2.4164
5. 83 96
4
:75270
1 2
0. 1 8940
1 7
2.4036
5.801*
-
3.62560
1 2
0.20 340
1 7
2.4 009
5.7642
4
0.55490
1 2
3.13620
l 7
2.39 32
5.7263
-
C 1 f 690
1 2
0. 39 120
1 6
2.395?
5.6 9 c. _
4
0.2146Q
1 0
0.51660
l 4
2.39 1 4
5. 74 54
4
Co 185 40
1 2
0. 4 4 21 O
l b
2.373b
5 # b 31 1
-
v374:0
1 2
0. 9 8 37 0
16
2.3661
5.5986
4
C 0 2 7 1 8 0
1 2
0 .53520
l 5
?3590
5.563o
-
Oo 3 45 00
1 0
0.92 330
1 4
24647
tm07f 7
4
0. 3.7 >2 0
1 l
0.99900
1 5
2.456:
6. 035^
-
j. 1 54^0
1 2
0 4 0 b 5 0
16
2.4475
6 9 9 1 7
4
0 .4 ?*oa
1 2
:.i 1 130
1 7
2.4392
5.96 C d
-
0.77370
1 2
0.20050
1 7
2.4311
5.9107
4
Oo 036 90
1 P
C. 2 3 90 0
1 7
2.4231
5,8713
-
: c 6 84 ao
1 2
1 7 290
1 7
2.4151
5 d3 2 :
4
0.21179
1 2
j .5 2 97 0
16
2.4067
r'. 7 8 99
-
: 0 7 7150
0 9
0.19130
1 4
2 -,264
5.9347
-
: ? : 7; j
1 2
0.5 1 060
16
2.3940
5 7 7 7 7
4
0 0 4 ? 3'0
l 2
: .1 0 30 0
l 7
7.39 70
5596 I
-
0 ? 35 9.0
1 2
0 0 9 6 9 0
1 C
2. 3795
r 6 r.
4
0.7:ic 0
l 1
3.72010
1 5
2 J 7 0 3
5o 6 1 £:
-

Appendix Vb. Molecular Chlorine and Molecular
v*,v**
T(cm"1)
Q
Lambda
, i'
- 2 T 0.' l
, 1 '-AH- ; .<
56 72. 4 1 9
l If.
- ?* r. 7 J. o i
4 ;7;fi-A'
*707.410
* '
- ? 7 1 5 0 1

l 7r56f>- 0 1
3742.654
* 1 f
->*4 .8 5 1
- .
4 a 7j' J 1
37 70 1 46
4. 1 r
-2-22 C. 31

5 ; 3 5 13 ,961
i f-
- * > - 7 5 a 1
c
43')- ** 1
3*49. 854
6* 1 o
-2 ) 7.3 1.. o 1
>
1 5- 0 1
3 886 0 6 0
7*1'
-2CA04, ) i
. ,
4 6 77 6-0**
302?,490
1 '
-7 i59o 0 1

i /1 7D- : i
*959 140
-.It
- 2 6 02 5 0 1
o
30309-01
39 .003
1 If
-?47 >5.0 l
'J
2 0609-0 1
40 33. 0 70
1 1 t
-24568o91
o
if' 50-c :
4070.334
2* 1 t
-24344,01
o,
60 3 8!'-02
4107.787
>, 17
- ?7 Afv l o 7 ? >
. }
l 768 )-02
3611.161
1*17
-2 74 J4,; ?
- 1
9C 899-OP
3644 *989
1 7
- 2 7 1 in, 9 2
,
31 63 9-01
3 6 79 .C5 1
% 17
-?.r 2 9*9 p
- *
56 65 9- 01
3713.342
4. 17
-26601,92
*> a
j7 7 0 )-01
"*7*7.35f.
17
-26436.92
. o
27139-01
3782.569
6*17
-26
o
97700-03
3817.534
7. 1 7
-25s55. 9?
' ,
1 0809-^|
385? .6 85
'3*17
-?"719.9?
o
7 '*520- : l
38 38o 0 37
0* 1 7
-2 54 66c, 5?
a
22 1 5.0C 1
3 5?.59 1
',17
-26256.02
C1.
1 6 779-02
3959.311
1.17
-25029.92
' a
6 769- OP
3995.218
2, 1 7
-24 6 J 5 9?
?'
2281D- 0 1
4031.295
", It
-2 *3 147.52 ^
o
32 979- 0?
35 52. 71 l
i i e
0
. o
15 59 9- 0 1
3 5 .85. 4 4 8
?* 18
- 276 36,52
c
4 V 4 6'' 0 1
*''"19.401
1* 1 J
2 T 3 J 5 5 7
J 0
L '4 8 50 C l
3 6 61o 5 65
4 l H
-2 7 1 3 7-, 5 ?
' 0
40 14 9-21
*6 84 Q 3 6
1 b
-? r .2. 52
.
4 6 5 3 9-02
?. 7 1 3 6 C 7
~ 1 H
O60< ?
./ o
6 8 -p
*7 52.2 7.3
7. 14
-26 4 1 1,5?
J o
3 297.)-0 1
3786.227
5, 16
- 2 1 75.52
. 0
25239-01
3 2C o 36 4
c f 1 fy
-?594 5 ?
c
? 3 5 7 9 0 ?
3 9 64 ,6 7t
* 1 4
- 3 ; 7 12,52
ft
7 : 4 0 r 0 3
3 i' ,16 7
l 1
vt?#rV
c
7 >839- : 1
1923. 797
Chlorine
An i on
Franck-
Condon
Overlap
Factors (con't)
QT**3
QT**4
RC
R**2C
Phase
Oc 1 04 7 J
t 1
0.2 8*32 9
1 5
? 4 8 J >
t. 16 4 3

0.8756.)
1 1
3.2 380
If
.4713
D.1098
-
0 a 3 34 > 9
1 2
0 .39479
16
2.4623
c. 06d4

C. 74950
l 2
0.1 9 34)
1 7
? .4542
6 02 39
-
0 l 4 7 o
1 3
0.2744)
l 7
24453
5. 9Or 3
0. 666 20
l 2
0.22500
l 7
2.4375
5. 94 02
-
0.71 6
1 2
0.81410
16
2.420
5. 69 7 2

0.7 7=10 0
09
0.19 76D
14
23905
5.6623
-
0.21229
1 2
0.53599
16
2.4167
5.8428
-
0.47480
I 2
0.11860
1 7
2.4083
5. 6000

0o 3 l 4 1 o
1 2
0 .7 787 D
16
2.40 0 3
5. 7559
-
0.246^9
1 1
0.6 065D
15
2.3896
5.7013
? .871 10
1 1
0.21210
1 6
2.3394
5 7 1 33
f
C 2 9 0 5 9
1 l
0 *60 449
1 6
2.4983
6. 23 3 3
0*20420
1 2
0.56029
1 6
2.4871
6.1871
-
0 .6 -*52 0
1 2
0.1727D
l 7
?.4781
6. 1420
f
0.11060
1 3
0.2 9809
1 7
2.469 3
6. 05 75

0.10960
1 3
C.2924D
1 7
24605
6. 054 1
*
0.50140
l 2
J l 3 25 D
17
2 4 5 1 6
6. 00 88
-
0. 1 7560
1 1
0. 4 6 009
15
24366
5.5255
.
0.13390
1 ?
0.49030
l 6
2.4392
5. 95?7
*
Do 5 26 1 0
1 2
0l3530
17
2.430 0
5.5054
-
' .36:660
1 2
0.93489
16
2.4215
53626

C *270 2D
1 1
0.6 8 26 0
1 5
2.4097
o. 7976

0. 1 09 49
1 2
0.2 7 380
16
2.4105
5.8142
-
0. 3 48 ?D
1 2
C.3 6 260
1 6
2.4016
5. 7684
Co 73539
1 1
C.20 70 D
16
2.5 t 24
6. 3135
0. 4 2500
l 2
0.11850
1 7
2.5029
f2655
-
0.10440
1 3
0.28369
1 7
2.4936
6.218b
4-
0 1 3.3 2 0
1 3
0.36489
l 7
2.484a
6.1726
-
0.8 3? 30
1 2
p. 2 1 770
1 7
2.4752
c1264

0 9 C *5 0 D
l 1
0 2 4 34 0
l 6
2.46 35
6.0637
-
C 1 30 o0
1 2
0. 3 4 809
1 6
2.4629
6.070 l
-
0 o 5 650 0
1 2
0.14920
1 7
24524
6.0150
f
Oc 4 f>2 5 0
l 2
0.11349
1 7
2.4434
5.9691
-
0 w 4 1 1f9
1 1
:. i o e s o
1 6
2.4313
* 5:31
*
..1198 9
1 2
0.30810
1 6
2.432?
Da 5 1 9C
f-
J-. 3 >4 49
l 2
0. 1 0 05 9
1 7
I.4 226
5.66 5 d
-

Appendix
Vb. Molecular Chlorine
and Molecular
Chlorine
Ani on
Franck-Condon Overlap
Factors (con
11)
v*,v**
T(cnf2)
Q
Lambda
QT**3
QT**4
RC
R**2C Phase
1 ? 1^
-J'dcU 52
- C 1 *4 1 r' o 1
.- .' i
0.2 73 -ID
l 7
j 5 9 0 7 0
1 6
2 l 4 1
5.3? 58
4-
, 1 /
- 2 6 ; 6 c 7 r
, 7"550-r'P
3 4 Sbo 9 0 7
Ocl6970
l 2
J .4652 0
16
2.5?58
6.3960

1 i 5
-2~ 3 r*97 j
, Hc'.ii;-vl
3538*6 1 9
0.78610
1
C.??2S0
1 7
2.5139
0.3455
-
2, 15
-oOQ.S,7 0
, 656.2 n- oi
3560.571
0*14560
1 3
0.40560
1 7
2.509 3
6. 2 96 7
M'-
-27834*70
o 56 050-6i
3592.638
0. 122 30
1 3
D. 34 1 90
1 7
2.4956
6. 24 75
-
.IS
-27536.70
C 1 4 ? 1 ') 0
7524.930
0.29320
1 2
C.82270
16
2.4350
6.152P

5 15
-? 73*17 0
C. 2^580-02
3667.417
0.46160
1 1
J l 2 6 2 0
16
2.4893
6.2068

6 1 o
-P7QC9,70
O 36 3 0 0-01
369Q,o 78
0.56330
l 2
0.15260
1 7
2.4757
6.1300
-
7,10
-2636 0.7 0
C c 3061 o-oi
1722.911
C 5 7 8 0 D
12
015540
1 7
2.466l
6. 08 0c
4-
^ i :
-26624*70
Jo 4? 05")- 3 2
37 55. 91 1
0 e 7 9 3 7 D
l 1
0*2! 130
16
2.4542
6. 0172
-
0,10
-2 6 301 *70
~ 6 0 76 0-0?
i7o9o D70
9.11170
1 2
0.25400
16
2. 454 3
6 D 3 0 5
-
1 5 lr-
-26161*70
0* 2* 6 7' 0 1
3 >32 2 3 62
0.44170
1 2
0.11 560
l 7
24442
5.5746
4-
11*10
-?:i ->3 4*7 3
" o 14 300-0 1
3855.838
Oe 25320
l 2
066960
1 6
2.4350
5.5271
-
12, 10
-.26 7 1 0,7 0
>,*2080-0r
3389.4 31
C.13950
09
0.35870
1 3
2.3309
5.2768
f
D ?
-2 D 3 9. 30
> C*14 53^-01
3443.599
0.35560
l 2
C 1 0330
l 7
2.5453
6.4800
l ?c
-28 7 ft J?, 3 9
6. 5 3 66 0-0 1
34 74o 347
0.12790
1 3
0. 36630
17
2*5351
6.4275
-
?, 2 *
-2652 Gw 3 9
Ck72150-01
3505.?ei
0.16750
1 3
D. 4 7 79 0
1 7
2.5250
6.3757
4-
3, PC
- 2 P 2 7 7 o 3 9
0.33290-01
3536.395
0.75270
l 2
0 *2 l 29 0
17
2.5146
6.3217
-
- 2 0
-2*029*39
C 0 70 610-0 4
75O7.6 84
0*15550
1 C
0. 4 3590
1 4
24644
6*0233
4-
s, 2:
-2 7764. * 0
0* 22 2 3 0- 01
3 599.1 44
3 4 7250
1 2
0 l 3 1 30
1 7
2.4999
6*25 1
4-
t PC
- 27 6 4 2*IP
Do 35 2 70-0 l
3630.767
C,73700
12
0.203CJ
1 7
2 .4896
6. 1978
-
7.2 0
-3 73 0 3o 3 0
0 . 2 9 7 D ?
3662.549
016350
1 2
D.46110
16
2.4783
6. 13 7 6
4-
1 2 ?
-P7067.30
; 39900-0?
36v4t483
0,79130
l 1
L/ 2 14 2 0
lb
2.4789
6. 15 15
4-
0 2c
-263
'O 251 DO- 21
3726.562
J a 4 65 OD
1 2
0.1 3 01 0
i 7
2.4665
0.0844
-
1 '',20
-2o60*.!9
: o 1 t 4 0 D D 1
776ft.779
? 3 ^ 8 7 0
l 2
: .3 2 1 40
1 6
2.4567
6.0333
4-
11*2'
- PC 37 7.3C
>;c 02 00 CO
8791o126
Ool6550
09
''43 66 0
l 3
2. 340 2
5. 3 1 86
-
12,20
- ? f- 1 c 3 3 5
: 13530-D1
3623.5
o; .24200
1 2
0.6 3 280
16
p. 4 4 53
5 o v6 1 3
-

Appendix Vb. Molecular Chlorine and Molecular Chlorine Anion Franck-Condon Overlap Factors (con't)
V*,
v**
T(cml)
O'
Lambda
QT**3
QT**4
RC
R**2C
Phase
l 3.
- 1 9 2 P 0 "
0 :* 9 2.)- 05
62 76,2 37
0.14920
CP
0.23770
12
2.1361
45655
_
1 4 .
c
-15 71 Oc ? 5
P
l 1 76 0-04
^ 3 6 5 152
0.4 5580
08
0. 7 1600
1 2
2. 1 208
4. 63 4 0
4
1
- 1 4 9 5 2 5
p
? c 3463D- 04
6 4 5 3 o C 7 4
0.12980
09
C l9960
l 3
2.1214
4.5025
-
! S
u
- 1 "203,05
P
0,94^10-04
f 54.3. 1 C7
j, 3 38 10
0 9
0. 5 l 67 3
1 3
2.1143
4,4710
4
1 7 .
- 15? 74o C5
D
; 24 1 2*^ O*1
*633 .PI 7
0.6 26 2 0
09
3l2450
1 4
2.1065
4.4394

1 1
- 1 5 3 a e : 5
P
*,f7?4O-02
6725,829
C.19950
1 C
C 2 8 0 2 0
14
2.0993
4.4077

1 9,
J
- 1 4 6 6 5 r 35
P
1 2 750- 02
6 9 1P 9 31
0.4 02 00
1 0
3. 58960
1 4
2.0914
4.3753
-
2 7
- 14 46 5.0 5
P
0. 2 655 0- C2
*913.213
0.90350
10
0.1 1620
l 5
2.0637
4.3437
4
? 1 .
- 14?6 0.0 5
P
", 5 1 87D-02
7008,664
0, 1 50 70
1 1
0.21500
15
2.0759
4.3112
-
22 ,
z
- 140 74, 05
P
C,95 3 00 02
7105.273
C .2 65 70
11
0. 37390
15
2.C60 0
4 27 8 3
4
-13593.05
P
,oie540-01
72 03.0 26
0.4 4 ? 5 0
l 1
0.61430
15
20599
4.2446
-
4
1
-1 3695c 0^
P
^ 27 3 70- 0 1
73 01 6 06
0.70040
L 1
0.95920
15
2.0515
4.21 J 4
4
25.
J
- 1 051 C,05
P
.42900-01-
7401.395
10590
1 2
Cl4290
l 6
?.0420
4. 1744
-
1 1.
l
- 1 -> 4 8 ? 4 3
0 336 9i.n- 04
6067,077
0 o 2 54 60
09
3 4 196 0
l j
2. 1549
4.6455
-
1 4 ,
1
- 1 6 2 6 4 ,AQ
. 1* 080-0.3
61 -8.3 99
0.6Q190
3 6
0.11250
14
2.1479
4.6153
4
15.
1
-10*5.40
1. 41 920-02
62 30.76?
017290
1 0
0.27750
l 4
2. 14 09
4. 58 5 l
-
1 5.
1
-lc8.37o4D
. o 10 030- 02
* 3 1 4. 16 1
0. 30830
1 0
0.63 070
1 4
2 1339
4.5551
4
1 7 .
1
-1 5 628.40
: C 2 1 9*)-OC
f- 398.60 9
0.84720
1 0
:l3240
1 5
? 126*
4.5253
-
1 3.
1
- lr4??.4 l
:,454lo-0?
5484,073
0.16660
l 1
0.2569 D
15
2.1199
4.4955
4
1
1
-1 5? 1 9 -.4 1
S. O 95 90 .)-0 2
6570.559
C.30290
1 1
0.4 6 .39 0
15
2.1129
4.4659
-
2 ^ ,
1
-15019.41
Jt 15010-01
6659.053
0.50860
11
3.76 38 0
l 5
2. 1 060
4.4 363
4
2 t .
1
- 14 8 2 2,4 l
24l90- 01
r 7 465 4 3
0,79790
1 1
J.11680
1 6
20990
4.4073
-
22 .
1
- 1 4 6 > 8.4 1
"c^ooo-n
* 9 **6 0 1 5
0.1 12 40
1 2
3. 1 6443
l 6
2. 392 1
4.3777
4
7 3.
1
-14 4 3 7. 4 1
j. 4 8 920- 01
6926.452
0 14 7 7'"'
l 2
3.2 1 260
16
2.0852
4.3466
-
PA ,
l
- 1 4249,4 1
0.*0950-01
70 1 7, "37
C. l 7630
1 2.
3.25l30
l 6
2.0783
4.3198
4
25,
1
-14064,41
C68400-31 -
7110.14Q
0,190 *D
1 2
*'2 6 760
lc
2.0715
4.2912
-
1 1.
- i 7 Z 3 13 3
.4^990-32
5971,533
j.21240
l 0
C 3 6 1 7 0
14
2.1726
4. 7221
-
1 4 .
-
-1-913,33
~ P 740-C'3
5947.663
j 5 1 C 4 0
1 3
0.85620
1 c
2.1659
4.6926
4
15.
2
- 1 C 5 9 e *
. >4 4 .9 0-
6 -w 2 4 7 w 4
3.11200
l 1
* .18580
1 5
2.1591
4 66 14
-
1.
- 1 ?'< 6 7 3
C 990- 3 2
l}20o49
3,77440
1 1
3.3 6 7 6 0
15
p 1524
*.6344
4
1 7.
c.
-1 1 77,v
, ;7; 3'>-o:
6 13 1 8 4 p 1
., 41: 8o
1 1
3.66460
15
2.1453
4.60 8 e
-
1 -.
-l *>^71.33
. 1 6850- 01
62ol,21*
0 5 6 8610
1 1
0 I 0 96 0
16
2. 1 392
4.5771
4
1 y .
2
-1 3 7 9*. 1 3
* 266 1 L>- o 1
*041,8 26
Jr, 1 0 4 30
1 2
0.15450
1 6
21326
4.54 5 9
-
*
2
-155t 0. 3 3
.~39 3 3 o- :1
r 4 p 3.2 9 6
3,1 4350
1 2
C .2234 0
l 6
2. 126 1
4. 52 1 0
4
2 1 ,
-15271.33
;2 4 8 790 0 1
6 5 J 5 o 6 1 9
3,l77?o
l 2
3.2 7 24 D
1
2.1197
4.4935
-
22
2
-1:177,13
50i.-oi
f 5 98, 7 74
3.1C430
1 2
0.29450
16
2. 1 l 34
4.46 Aa
4
2 1
c
- 1 49tf. 33
3. 64 82 L J 1
06 7? r 74 8
) c 1 i 4 0
l 2
; .2 7650
1 5
2.1372
4.44 0 0
-
*' -* ,
p
-l^PPo <
.,46110-31
- 7 57* 5 1 9
14 6 2 0
l ?
0.21630
1 6
2.1313
4.4146
4
2 .
- 1 4 6 1 3o 3 1
27 9 2 O->i
* 9 4 "4 o 0 6 7
8 9 71 40
1 !
*.12730
1 6
396!
4 39 1*,
-

Appendix Vb. Molecular Chlorine and Molecular Chlorine Anion Franck-Condon Overlap Factors (con't)
V*,
v**
T(cm 1)
O'
Lamdba
QT**3
QT**4
RC
R**2C
Phase
- 1 ?5 74. 3 3
0. 2 0H8O- 03
5639*968
' c 1 l 3 4 .0
l l
0l9920
1 5
2 18 9 6
4.79 5 v
_
1
3
- 1 7 ? 16 8 0
c 4 5 65 D-3 2
5761.432
j 2 36 7r>
1 1
0. 4 1430
1 5
2.1330
4 76 73

15,
3
- 1 7 1 4 1 f\ C
0.9C156-0?
68 13.694
;.65410
l 1
3.77840
1 5
2.1765
4. 7364
-
-U-97S.HJ
0. 1 bD 70- 0 l
5906.745
0. 7 7o* Q
l 1
0 1 320 0
16
2.1700
4.7101

17.
j
-1*720*43
C 5 750-31
59 80c 7 ,
312 0 4 0
12
0.20130
1 6
c 9 16 36
4.682?
-
13,
3
- 1 '>51 4.8 3
' 7 6 91 5 0i
6055*174
0 1 5 6 * O
1 2
^2 74 60
1 6
2. 15 7 1
4 e 654 fa
4
l >
3
- U 3 1 l .80
4 0 33D- 0 1
6 1 30. 531
0c 2 3129
1?
C J 3 1 5 0
l 6
2.1511
4.6274
-
20.
3
-1M l l 0
',51 71 D 0 1
fa 2 C 5 fa 7 1
'.21670
1 2
O.3 4 350
16
? 1449
4.6008

?\ *
7
- 1 c 9 1 4 .4 0
; 4 3290-0 1
6283.459
0.1 94 o0
l 2
0.30980
16
2.1390
4.5748
-
22 .
}
*157D90
0 *6 0 30-01
6 3 60* 999
0.14023
1 2
C. 22 04 0
16
2.1333
4.55 O 1
4-
23.
3
-l 552 9*8 0
0. 1 394 0-0 1
6439 .23?
0.7 3 4 4 D
1 1
0.1l020
l 6
2. 1234
4. 52 31
-
2* .
3
-15341*30
0, 4 7 4 PD- 0 7
65lH.139
0. 1 *3 7 00
1 l
3.2 4 09 0
15
?.1270
4.5133
4
2*3.
3
-I5156o30
. 33 2 7|'. o 3
05 97.693
0.1 15 3D
1 0
C 1 7 56 O
14
2.0797
4.3466
4
1 1
4
- 131 12* 7 9
'71 300-02
5520.964
0.42710
1 1
0.77360
1 5
2.2060
4. 96 7b
-
14 .
4
-17B44*7Q
v.13550-01
55 p8 s 2 2?
0,77653
1 1
0. 1 3 39 0
16
2 1996
4.8392
4
15.
4
-1 76 79.73
:o 22 74 0-01
56 56 1 30
0.12570
1 2
0.22220
1 6
2. 19 3?
4.8110
-
1 *
4
- 1 7457* 78
0. 37 800- 01
57 24.3 26
Do 1831D
1 2
0 3 1 4 7 D
16
2. t 869
4.7832
4
17 ,
4
-17253*73
0 4 4 0 ? D- 0 1
5794,153
Co 22630
1 2
0.39060
l 6
2.1807
4.7559
-
1 >.
4
-17052.78
0.49380-01
5364.145
0.24490
1 2
0.4 17 60
16
21746
4.7293
4
1 4*
4
- 1 5349* 78
9. 46 240-0l
5934.7 95
0.22120
t 2
0.37270
16
2 1 637
4.7028
-
2 3.
4
-ie649o_,8
0.34010-01
6 0 06 C 5 4
0. 1 57 00
1 2
C 2 6 1 30
1 6
2.1630
4.6775
4
* l .
4
- 15452. 7 8
J 1 699r Cl
6 0 77 .99 ?
0.75670
1 l
0!2450
1 6
2. 1579
4 o 6 5 4 .1
-
??
4
-If ? 5 8 7 8
13 34 U-0 2
61 50 c 122
0, i43 30
1 1
0.2 3300
16
2.15 5fa
4.6407
4
2 1.
4
-10067.78
J 56 1 .7 0-07
6222.614
0 23?80
1 0
3.3741D
14
21276
4. 54 1 7
4
24 ,
4
-15379.78
' .10160-01
6297,315
0. 4 06 30
1 l
0 .54600
15
2.1339
4.5867
-
25 .
a
-15694,78
; 76 0 76-c1
6371.644
0. 9 69 30
1 1
0.15210
l 0
2 1297
4.51^7
4
1 3.
5
- 1 664b.2 3
. 1 32 3 0-01
c3 3 .3 01
0 1 1 u 3 0
l 2
3.^2030
1 6
2. 22 19
4. 9? 79
-
1 4 ,
fa
- 1 8 4 2 7 ? 5
>6930- 0 l
54 2o 751
0c 1 31 JO
l 2
3.3341O
16
2.2156
4.9 j 9/.
4
1 5 .
5
- 1 9 ? 1 2 ? 3
Co lOCfiD-O 1
54 90.3 1 5
0.24 ?:0
1 2
4 4 070
1 6
?.2094
4.8817
-
1 1*
5
- 1 5 000.2 7
: 4 7 4 1 f 0 1
556" .4 34
0,2 7*1^
l 2
3.49770
1 6
2.203?
4. 35 4 ?

1 7 ,
e.
- 1 *T 7 9 1 ? 3
46,6 70- 0 l
5o20o 7-o
0, 2 52 9
1 2
0.4 6 760
l 6
2 19 7?
4.8774
-
1 3 .
5
-1753524
? O 76 1 2 0-C 1
50 8f c 5 6 3
3.14640
1 2
3.34540
1 6
2. 19 14
4.80l2
4-
1 V- .
5
- 17382.2 4
0. 1 92 90- Cl
5 752,999
0, l 01 30
l 2
0.17610
l 6
2. 1859
4.7764
-
2:,
5
-17!32,4
C,4 4 4q0-0 2
5319.964
0, 22320
1 1
0. 3 9210
1 5
2. 18 20
4.75f 4
4
2 l .
t
- 1 69 8 5.2 4
0.2?160-03
r; 0 5 7.4 6
0.1 MOD
l 0
3.1 8 450
l 4
?. 1551
4.6653
4
- 1 5 7 > 1 0 ? 4
: 04 8*0- 0 2
5955.4 87
c.4 01O0
l 1
0.67430
15
2,1640
4.68 6 2
-
2 3 .
5
- 1 f 5 0 0 , > 4
' o *> ? 0 5 0 0 1
60 04 a 0 1 0
i : 0 / 0
1 2
C16750
1 6
?1596
4.66 5 0
4
P i f
c
-IM12.P4
; P 8970- 01
6 0 *3 ,0 1 5
3 1 23 1 O
1 2
: .2 1 32 0
16
2. 1546
4 o fa 4 2 2
-
1* >
- 1 Pr> 7, *> ^
fa 1 6 0 4 7.1
3,44320
1 1
-3, 1 5 31 0
1 6
? t 498
4.6 20?
4
o

Appendix Vb. Molecular Chlorine and Molecular
V*,
v**
T(cm M
T ,
t
- 1 >1 7 2.12
! 4 *
L
-nvo4c i ?
1 6.
f
- 1 7 1 9 1 2
1 5 .
f.
- 1 5 2 7.1 2
1 7,
b
- 1 -1318*1 2
1 .
e
- 1 .U 1 2. 1 2
1 ') .
r
-17909.12
2? .
o
-1770912
21 .
6
- 17512. i 2
2? .
6
-1 7 3 1 R 1 P
21.
<~
-17127.12
?A,
-1*919*12
2 5 .
t
-lo754l2
1 1.
7
- 1 6 9 3. 19
1 % .
7
-in 475*39
13.
7
-19 260 39
16.
7
- 1 '04 P. 3 9
1 7 ,
7
-1383939
1 1.
7
-1 8633.39
1
7
- 1 14 39.
20.
7
-132 3 0o39
2! .
7
- 1 8 3 3 3 3 9
2 ? ,
7
- 1 7 5 3 9 e 1 9
3,
7
-17648.19
2 i.
7
-17460.39
25,
7
-17275o19
1 3.
-2 0 2C 6 99
t 4,
6
- 1 y99 0*i9
1 5 .
6
-1'775*99
1 r .
£J
- 1 7 563.9 9
I 7 ,
n
-19 35 4.99
18,
8
- 19148.9 9
lr'.
-
-1^945.00
2 ,
- i 7 4 5 i r 9
21 .
n
- 1 3 5 4 6 9 v
2 ,
h
- 1 1 5 4.9 O
2 3 .
-H161.19
,
a
- 1 *9 75. v 9
PS,
u
-1 7 7no,o.,,
cr
Lambda
14 3 >0- ) l
52l5c 906
?6n-ri
5?75.6C9
. 4 7 9 7 0-9 1
53 2* .4 3 1
;o a o-70-ci
5 3 57 o 4 9 4
: w ,r oo n-o i
54 55.0 7*'
:. 6 l 580-02
53 21 .16 4
0,63 003- 'A4
5503 747
; 54 2 9 D-02
5646.307
C 18960-01
5710.130
07**50-C1
5774.2 93
0.2 2 66 r -01
5513.693
: 0 8'^ 2 40-0 2
5903.4 94
:.82609-04
5963.590
0 4664 D-01
50 7 7 .8 4 7
C.4^510-01
51 34. 6 86
Oo13360-01
5192.004
)15300-01
5249 o 7 88
0 1C 1 25- 82
5108.021
.18240-02
53 66 7 1 9
: O 13 5 70-0l
5425 621
0 25223-01
54 35.1 4 6
0* 24 785-01
5545.269
,l2415-cl
56 05o 5 7 2
;,1C790-07
56 66.2 39
Co 30 950- C2
5 7 27.2 49
?. If 520-01
5788.591
0.42335-01
4948.291
? 26 2 40-?1
5C 02 254
) * 1 300 02
5 0 5'; .6 17
0. 44 l 7^-03
5 1 l 1 .4 32
69 i 70- 0?
51 66 o 62 7
0 2 J 74 0-01
3222.?C7
'026570-:l
52 78 16 1
: o 1 76 0 5-21
5.134.4 73
' 401 2 5-07
53 91 .12 1
, f.4 720- 02
5440l09
j, \ 2 76 j-: i
55;3* 397
:. 2; 811) o i
5367 5 975
' 1 -45b- -> 1
5c 0* 2
Chlorine Anion Franck-Condon Overlap Factors (con't)
QT**3
QT**4
RC
R**2C
Phase
-.24170
l 2
0.46330
l 6
2.2374
5. 0 0 6 6
_
C.30140
1 2
0.57131
1 6
2.2112
4.9785
Â¥
0.3 l 30i0
l ?
0.58660
1
2.2250
4. 95ce
-
0 o 2 5 66 0
1 2
0 A 7 9 2 0
16
2.2190
4.9236

015160
1 2
0.29150
16
2.2133
4.8973
-
0 4 o 4 7 D
1 1
0.97790
1 5
2.2092
4. e7 ?fa
0 36190
09
0*6481D
13
2.2223
4.89 67
-
Oo 3 Cl5D
1 1
0 *5 .1390
1 5
2. 1923
4. 81 01
-
Go 1 002 0
l 2
0 l 755 0
16
2. 1878
4. 7830

Oo 14160
1 2
0* 2451 0
1 6
2. 1827
4.7£ 4 4
-
0.11190
1 2
0 l 9 50 D
1 6.
7.1777
4. 7414
4-
0.4 33 70
l 1
0.7 3 4 7 U
1 5
2.1737
4.7215
-
0.1340
09
0. 65080
1 3
2.2010
47996
015620
1 2
0*70150
16
2.2526
5.0745

?.336?^
1 2
0* 65480
1 6
2.2464
5.0462
Â¥
C.21340
1 2
0.45910
1 6
2.2404
5.0iet
-
Oo10530
l 2
0.2 0 l 4 D
16
?.2346
4.99 l 5

0. 1 2 790
1 1
0*2 4 090
1 5
2.230 3
4.9672
-
0.1 1300
1 1
0.21990
1 5
2. 2 19 3
4.9324
-
0 34930
l 1
0*l5650
lo
2.2152
4.9C9 1

? 1 5.2 90
1 2
0.27860
16
2.2099
4.8842
-
0 1 4C 10
l 2
0*26210
1 t
2.2 C 4 5
4.8597
f
0. 70440
1 1
0*1 2 570
16
2. 1998
4.8368
-
0.5914 D
1 0
C10470
1 5
2. 1992
4. 8256

Oc l 54 70
1 l
0*28770
15
2. 183 1
4.7723

9 2 0 60
1 1
0* 1 4l80
lb
2. 180 1
4 7546
-
0 4 9 4 0
1 2
1.70600
Ic
2.26 75
5. 14 10
-
Oc 2 -*060
l 2
1.41010
1 6
2*2613
5.112b
f
7 o oc30
1 1
1*12430
1 6
2.2555
5 0843
-
0*33030
08
0*64710
12
2.2791
5. C4 28
Oo 5 0 1 50
1 1
0* 97 07 D
15
2.2421
5.0 3 0 5

2.14570
1 2
?.27990
1
2.2367
5. 00 36
-
019070
1 2
0 *34 230
16
2*2311
4.97 7o

r. i 1 o
1 2
'.21980
1 6
2 *2255
4.9526
-
0.25* ID
1 1
w4 7500
1 5
2*2215
4.9299
o 4):20
i:
0. 7146 0
1 4
2.2079
4 88.So
Â¥
C r 4 4 9 0
1 1
0.11710
1 6
2.2070
4.373 3
-
0 -j l 2 )'0
l 2
0.21710
16
22023
4o 050 3
Â¥
7o 94 on
1 1
0.16 ISO
1 6
2*1976
4 c 3i 79
-

Appendix Vb. Molecular Chlorine and Molecular
V*,
v**
T(cml)
Q
Lambda
1 1.
f
- 7 l e h l
>? 16 '
*3 5 6.5 1 7
1 .
c
- 5 : 3 1
a 7|-- 3 7
4 6 77c 8 4 1
15.
9
- 2 : ? 3 5 3 *
. 1 o r-6 0 7
4C 2<- 52 8
1 .
o
07 -in
, 12 8 5^-01
4 9 ai ,599
i r .
9
- 1
2 5 20O-C l
5 3 34 Cl l
1 3.
"
- 1 v 6 55 c 5 *3
0.23 79 (' -01
5C .66.7c0
1 x .
-10455.*5
G 1 0 C : 1
5139.034
:) .
- 1 5 2 5 5 8 5
.21 1 4 0-0 3
5193.219
21 .
c
- 1 iC5eo bfa
: c 54 <70-0
5246.893
?>.
*
- 1 43 3
V l 7 5 8 ^ 0 t
5J 00 o 855
2 i.
9
-13673, Hb
: 1C 550-nI
8355074
24 .
9
- 13435.03
G. 83 64 0- 02
o 4 0 9 .5 3 4
25 .
c
- 13 30 0.35
wo 1 3 730- 04
5404,21 a
1 3,
l 0
-21 222.5 9
Go 1 1 470-0?
4711.371
14,
! 3
-210:4,99
:37840-02
4 760. 773
lt>,
IO
-20789,99
0.13240-01
48IGo007
1
10
-2 05 7 7*55
: 26 32 O-C1
48 59 561
1
l 0
- 2 ? ? 6 d 9 9
0. 1 83 70-0 1
4909.423
1 8.
l 0
-20163,00
.41220-0?
4959.580
19,
i :
- 1556 C.C 0
j 98 1 30-03
501G.0?1
23 ,
l o
-15760.00
?. 1 l 9 l D- 0 1
5060.730
21 .
l 0
-1C 56 3.00
0,2C510-01
5111.691
op
i:
- 1 9 36 9. 0 0
0. 1 4 010- 01
5162.390
23,
l c
-19178.00
:. 19950-0?
5214.309
24 .
i:
- 1999 0.0 0
C. 22 70 0-0?
5205.930
25,
l c
- 1 380 5.C C
C 14 080-0 l
5317.736
1 3 ,
11
-21771.28
0 9 59660-0?
4607.781
1 4 ,
11
-21503.28
C. 22 34 0- 01
4t 30 .4 54
l
11
-21288,29
3 3 0-21
$697. 421
16 ,
11
- 2 1 C 7 C 2 d
JO 1 3590-01
4 7 44.671
1 7,
11
-2'367.28
084000-07
4792.192
1 3 .
11
-2 0 66 1.28
0 o 44 7D 0- :?
4 33V.9 71
19,
11
-2 0458.28
:.1730^-01
4 3 87 .9 96
23 ,
11
2"' 253.8
2. 19330-0 t
49 36. 2 53
21 ,
11
-? C 6 1 3 *> 8
4 <~-84.726
2 ,
11
- 1 966 7.2d
G 3 8 y ?1' 0 5
5033 4 01
? i,
11
- 1 9 c 7 6 2 8
.7377 0-0 >
50 82.261
24,
11
- 1 94 8 8.28
, 1 7 32 0-0 1
5131.>89
2 5,
i i
-19302.28
J.ll900-0l
5 1 80 o 4 66
1 3 .
l 2
- ? > 2 1 3 6 7
S 33 1 9 D- 3 1
4 5 01 7 32
1 4,
l 2
- .? 1 99 5.6 7
C.2 4 690 01
4546.749
l ,
l 2
-21780.67
, rK 390- : e
4591e 22 ?
1 *5,
l 2
-2 1 5t 3.6 7
- 7 1 6 50-0r
4 6 36.3*4
1 7.
l ?
-21355.l7
0, 9 0 7 0"'- 02
4 6 31 72 0
1 <.
I 2
- > l l 6 3
' >0370- 0 l
4727,71i
Chlorine Anion Franck-Condon Overlap Factors (con't)
QT**3
QT**4
RC
R**2C !
Phase
: 1 7 VO
1 2
037 19 0
1 .
>. 232 1
6. ?rt.2
_
J,3 3770
1 1
0.63080
15
2.2760
5. 1 7' <

3c 60
1 0
G. 1 8 550
15
.2639
5.157?
3.10430
l ?
C.20940
l 6
r> 2 6 3 3
5. t 2 4c
-
j e 1 9 7 fcO
1 2
0.39250
1 6
2.2575
5.0919

i 8 0 70
1 2
35530
1 6
2.2518
5. 36 9 c
-
0,74330
1 l
0.14440
1 6
22464
5. 04 3 7
f
1 5090
1C
C. 2 9060
1 4
22462
5 C 2 1 2
-
).3 7640
1 1
07 1740
1 5
2.2332
4. 99 l ?
-
0.ll300
l 2
0.22260
16
2.2284
4,9667

0.12 730
1 2
C ? 3 7 7 0
1 6
2.2234
4.9427
-
0 .5 ? 8 4 D
1 1
0.9 7680
l 5
2.2 188
4.9200
4
O. 96 390
08
0. 1 764 0
1 3
2 .2547
4.9848
-
:. i: -9 6 o
1 1
C.23270
15
2.2959
5. 2t 20
-
0.38070
1 1
0.73660
l 5
2.2903
5.2505
-
0. 1 6390
1 2
3.34 080
l 6
22841
5.21*3

0.2 3 3 7 D
1 2
0.48090
l 6
2.2780
5. 1 894
-
0. 1 5950
l 2
C .3248 0
16
2.2721
5.1612

C73790
1 1
C.6 8 130
15
2.2666
5. 1327
-
G .7 0080
1 0
G13990
1 5
?2583
5. 1136
-
0. 9 I860
1 1
0.18150
1 6
2.2542
5.0827

0. 1 5150
1 2
0. 30030
1 6
2.2489
5.0577
-
o o i o i e o
l 2
0l9720
16
2.2437
5.0326

0. 14070
1 1
0.26980
15
2.2399
5.009?
-
0 a 1554D
l 1
2.29520
1 5
2.2303
4.9804
-
Ce 9363D
1 1
J 1 761 0
1 6
2.2262
4.9574
4
.71393
1 1
8. 15510
1 6
2.3111
5.34 17
4
0 a 222 20
1 2
v, *4 7 770
16
2.JO 46
5.312C
-
0.25400
l 2
C. t>4 07 0
1 5
2.2983
5 28 1 8

31272D
1 2
: 2 6 8 1 0
1 6
2.2922
5.2520
-
Oo 763 30
l 0
0.15930
15
22862
5.2148
4
0. 390 70
1 1
2. 80720
15
2.2803
5.204a
4
0.14310
1 2
C.30 300
l o
2.2745
5.1746

Co 1 6 070
l 2
C.32560
1 6
2 .2689
5. 14 74
4
0.60170
1 1
2. 1 2 070
16
2. 2636
5.1206
-
C .6977i0
06
C13350
l 3
?2394
5. 1375
-
2. 60 0 3D
1 1
0.11810
16
2.25 1 6
5.0727
4
3. 1?52D
1 2
3.24980
1 6
2.2466
5. 04 7f>
-
Oo 8*630
l I
0l653 D
16
2. 24 l 6
5. C2 ? 9
4
0. 276 ID
l 2
0.61320
16
2. 32 50
5.4 06 3
4
2- ? 6 ? 7 D
1 2
?.57790
l c
2.3185
5. 37 c. 7

J,93 4 OD
1 l
G20 34 0
16
2.3123
5.3424
4
> 7 1 8 9J
08
6.15510
1 3
232 C 7
5.5164
4-
3 3 3 7 9 U
1 1
;l8330
1 6
?.>006
5.2Q55
-
Go 19260
1 2
0.4 0 78 0
1 6
2.29 45
5, 26 5 1
4

Appendix
Vb. Molecular Chlorine and
Molecula
V*,V**
T(cm"1)
O'
Lambda
1 \c
-20953. 68
o. i £ s > -: i
A 7 73
1 1 6
1 .12
-> 7 5 0.!. 9
:O 4 7 20-c?
48 l 9
l 20
21*12
: PI DO 0- Dr*
4 86 5
3 1 0
2 ? 1 2
-20359.fed
0. 1 3 53 ('-01
4911
6 69
13 1 2
-70168.68
3*t e 350-:i
4 9 58
1 84
24.12
-19930.68
0.552 CD-02
5004
8 3 6
? .* 1 2
-1^795.69
336970-03
5051
5 05
ni3
-22700,11
0.22770-01
44 05
265
14.13
-22482.11
3. 56' 9 0-0?
4 4 47
981
15*13
-2 2 6 7 1 i
0.56 *2 0-0 3
4 4 90
929
1 5. 1 3
-22053.11
0.1351^-01
4534
397
l7. 13
-21846.11
"21l10-21
4577
4 74
Im.13
-21640,11
2* 13 780-01
46 21
0 48
10. 1 3
-2 1437. 1 1
0. 1 74 50-03
4664
807
23.13
-21237.11
0. 64 970- 32
4708
738
21.13
-21040.11
C.16930-01
4752
826
2 2. 13
-2 0846. 1 1
Cm 12270-01
4797
057
23.13
-20655.11
3.11210-0?
4341
4 l 6
24. 13
-2 046 7.1 1
0. 37 03 0-02
48 85
887
2 5,1 3
-20232.11
2.14590-01
49 30
4 53
13.14
-23180,53
0.34670-02
43 13
966
14. 14
-22962.53
0.25Q10-02
4354
921
15,14
-2274 7.83
0.17090-01
43 90
0 82
14,14
-22535,53
0 e 20 20 0-0 1-
4437
4 38
17.14
-22326.5 3
0. 651 80- 02
44 78
977
14,14
-22120,53
0.40 30 0-0 3
4520
6 67
1 1 4
-2191 7.53
0. 1 1 290-01
45 6 2
5 53
. 14
-21717.53
3. 17420- 31
4604
575
21.14
-2 1520.53
3.71840-02
4 6 4 6
725
22. 1 4
-21326.53
0.60350-04
4 6 35
995
2 3,14
-21135.53
0.37200-02
47 31
3 69
24. 14
-2094 7. 53
C.15300-01
47 73
8 3?
75, 14
-207(2.S3
C.62800-02
48 1 6
3 68
13.15
-? 3654,85
0.4466 O-3?
4227
463
14, 15
-23436,85
C 1 9 7 0 C 0 1 -
4 3 66
73:
1 1 4
-2 3221 .8 5
~l3480-?1
4306
290
i e. 15
-73309.86
3 o 3 36 80-0 2
4346
965
17, 15
-22300.85
0.23490-0?
4 3 35
80?
l -1 1 5
-27594.85
W l8l90-0 l
44 25
787
10. 15
-27391.85
? ,15570-01
4 465
9 l 0
n 15
-22151.35
0. 295 -30- 02
4 5 Go
l 53
21.15
-21604,35
:. ?: 3^0-or*
* 5 46
5 1 8
22. 15
- 2130 0.35
C. 1 3 1 3'^*-01
4 5 86
977
75 If
-21609.85
J 12910-31
40 27
5 t 9
2 4,15
-21421.38
O 13c?0-02
4 6 6 3
1 30
3,15
-21236.85
0. 30210-0?
4703
7 96
OQOOOOooUOOOOuuO
Chlorine Anion Franck-Condon Overlap Factors (con't)
QT**3
QT**4
RC
R**2C
Phase
'l4350
1 2
0.2995D
l 6
2.2886
5.2364
-
0* ? ? 0 8*>
i 1
0.45530
15
2,2830
5 2 C 1 J
4
}.1*210
1 1
> 3 7 480
1 5
2.2770
5 1 C Z 3
4
0.1 14 ?'>
1 2
0.23250
16
2.2717
b 1C 19
-
Do l 34 lO
1 2
0.2 7 05 D
l 6
2.266 3
5, l 356
4
:4 40 30
1 1
7.87980
15
2.2614
5. 1055
-
0.28680
1 G
0 .5678 0
14
2.2521
5.GO l 7
-
Co 26630
t 2
0.60450
16
2.3387
5.46 84
4
0.64410
1 L
C.14480
1 6
2.3316
5. 4.3?4
-
0. 95640
10
0. 21300
15
2.3288
5.4353

0.14490
l 2
0.3 I960
16
2.3206
5.3873
4
Co 2201 0
l 2
0.48090
16
2.3143
5.3558
-
C. 1090
1 2
0.2364D
1 6
2.3 091
5.3249
4
0.17190
10
0.3685D
1 4
2.3001
5.2625
-
0 6 2 2 30
1 1
0. 1 3220
16
2 .2971
5.2802
-
015770
1 2
0.33190
16
2.2912
5. 25C 3
0,1 11 ID
l 2
0.23 170
16
2.2857
5.2224
-
0. 98790
1 0
0.20400
15
2.2804
5.1055
4
0.31750
1 1
0.64980
1 5
2.2744
5. 1 785
4
0. 1 21 30
1 2
0.2470 0
16
2.269 2
5. 15 00
-
0.41190
1 1
0.10010
16
2. 351 1
5.5217
4
0.31250
1 1
0.71770
15
2.3486
5.5223
4
0. 20120
1 2
0.45770
16
2.3407
5.4800
-
C.23120
l 2
0.52110
16
2.3340
5. 44 7C
4
0 7254 0
l 1
0.1 6 19 D
16
2.3273
5.4125
-
0. 43620
l 0
0.96490
1 4
2.3256
54266

0 1 1380
1 2
0.26050
16
2.3167
5.3692
4
0.17640
l 2
0.38740
16
2.3106
5.3384
-
0.71600
1 1
0.15410
16
2.3046
5 3 0 7 5
4
0.5354D
09
0.12480
1 4
2.3931
5.3524
4
0. 82330
1 1
0.17400
1 6
2.2940
5. 26 5 3
-
0 1 40 6D
1 2
7.29460
16
2.2885
b.2363
4
0.5 62 l 0
1 l
0.11670
16
2.2830
5. 2033
-
Oo 5C120
1 1
0.13 980
16
2.3698
5.6160

C 2 5 .1 7 0
l 2
0.59450
1 6
2. 36 Od
5.574?
4
Oo 2 3140
1 2
0.53730
16
2. 3538
be 53 92
-
0.41030
1 1
0.94400
15
2. 2461
5.4583
4
0.27840
1 l
0.63480
l 5
7.3439
5.50 1 0
4
0. 1 7520
l 2
0.39580
1 6
2.3362
3.4551
-
3.17490
1 2
0. 39150
16
2.3298
54267
4
0.32330
l l
0.71740
l j
7.3230
b.3095
-
3.216 30
1 1
0.47580
15
2.3199
5.3096

^13630
1 2
0.29660
1 6
2.3132
5 35 ? 1
4
Oo l 3 030
1 2
0.28160
16
2.30 73
5.3225
-
C 1 8 3 1 0
1 1
0.3922D
1 5
2.3013
5.2075
4
0 a 289 30
l 1
0.6145 0
IS
2.2969
5.2821
4-
202

Appendix
Vb. Molecular Chlorine
and Molecular
Chlorine
Ani on
Franck-
Condon
Overlap
Factors (con't)
V* ^ y*
T(cm *)
Q
Lambda
QT**3
QT**4
RC
R**2C
Phase
11 it
- '4 l 22.0 1
. 21o20-0 1
4145.420
Oo 30200
1 2
0. 72 860
l 6
2.3811
5.670 1
-
14, u
-23905. 01
0# 16640-01
4183,224
0.22740
1 2
0.543SD
l 6
2.3736
5 6 3 ? 7

i =5 i e
2 3 690.0 l
0 14230-02
4221.189
Oo l 892 0
l 1
0 4 4 8 2 D
15
2.3640
5.5706
-
16,16
-23476.01
050 9 7D-??
4259.305
0.65960
l 1
0.1549D
16
2.3633
5.5899
-
17.lt
-27269.01
C 1 770 O- 01 -
42 97 #562
0.22300
1 2
0.51900
1 6
2.3557
5.5501
IS, 16
-23362.0 1
0 12 510-01-
4335.947
0.15350
12
0.35390
16
2.3489
5.5154
-
15, 16
-22860.01
0o 54 0 3 D 03
4374.451
0.65500
i D
0.14970
15
2.3389
5.454 ?

it
-22660.01
0. 57550-02
4413.060
0.66960
1 l
0.15 170
16
2.3388
5.474?
Â¥
2 1 it
-22463.01
0 15470-0 1-
4451763
0. 1 7530
1 2
0.39380
16
2.3321
5.439?

22, It
-22269.01
0.8744 D-02
4490.545
0.96560
l l
0.21500
l 6
2. 3259
5. 4071
Â¥
?1, 1 6
-22076.01
0.20000-04
4529.393
0.21520
09
0.47520
13
2.3052
5.227?
-
24,16
-21890.01
0.73750-02
4568. 293
0.77350
1 1
0. 16930
16
2.3159
5.3666

25, 16
-2170 5.0 t
C* 1 4030-01-
4607.231
0.14340
l 2
0.31130
16
2.3099
5.3353
13, 17
-24584.92
0.15210-01
40 67 5 34
0. 22600
12
0.55560
16
2.3937
5.72 fiC
-
14,17
-24366.52
0.44 790-03
4 103.924
0.6.4 8 00
1 0
0. 15790
1 5
2.3793
5.64 ?4
1 '), l 7
- 24 15 1.92
0. 792 70-02
4140.457
0.11170
l 2
0.2 6 97 0
16
2.3832
5.6820

16,17
-23939.92
0. 13 9 4 0-01
4177.123
C. 25990
1 2
0.62210
1 6
2.3754
5.6425
-
17,17
-2373 C.92
0. 92 340-02
4213.911
0.12340
1 2
0.29 28D
16
2.3680
5.6043
f
13, 17
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0.29890-04
4250.810
C.3 8920
09
0.9l550
13
2.3897
5. 78 1 7
Â¥
19,17
-23321.93
0.98 35D-02
4287.8 1 0
0.12480
1 2
0. 29090
16
2.3579
5.5623

2^,17
-23121.93
0. 15470-01
4324.899
0.19120
1 2
0.44210
l 6
2.3511
5.5269
21,17
-22924.93
0. 44 970-02
4362.064
0. 54 1 30
1 1
0.1 2 42 0
16
2.3440
5.4894
-
22, 1 7
-22730,93
dm 10 50 D 02
4399.293
0.12330
1 1
0.28040
15
2.3430
5.5010
-
2 3, 17
-22535.93
0. 11510-01
4436.572
0.1318D
l 2
0.29710
16
2.3346
5.4521
Â¥
?4, l 7
-2235 1.93
0.1l650-01
44 73.887
0. 1 30 10
1 2
0.29070
1 6
2.3284
5.4200
-
25, 1 7
-221 6.5 3
0.10470-02
4511 .225
0.1 1 4 1 D
l 1
0.25290
15
2.3209
5.3747
Â¥
l 3, 16
-25040.52
0. 96080-04
3993.528
0.13520
l 0
0.3384 0
1 4
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2.4033
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Appendix
Vb. Molecular Chlorine
and Molecular
Chlori ne
Anion
Franck-
Condon
Overlap
Factors (con
't)
v*,v**
T(cm1)
Q
Lambda
QT**3
QT**4
RC
R**2C
Phase
2 1 H
22622. 52
0. 06 37 0 02
4420.374
3.13069
1 2
0.22750
16
2.33 70
5.46 42
_
l 1 19
r 123 10-0l
3923. 153
3.20330
1 2
0.51960
16
2.4240
5.e7 02

14,19
-25271.70
j 19330 Cl
3556.995
0.31213
1 2
0.78960
16
2.4153
5,8331
-
1 3. 19
-25056. 70
C.4317D-02
3953 .949
0.67910
1 1
3.17020
1 6
2.4058
5* 782 l
4-
l l 9
-2*04 *.70
C.26390-02
4025.003
0.40470
l 1
0.10053
l 6
2.4066
5.7990
Â¥
17,19
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0.23603
1 2
0.58140
16
2.3966
5,7447
-
1 3. 19
-24425.70
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0,1619D
1 2
0.39540
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2.3888
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Â¥
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0.11040
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0.26530
1 6
2.3792
5.6636

2 I l 9
-23029.70
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4 196. 443
0. 1 91 73
12
0.45680
16
2.3718
5.6250
4-
22, 1 9
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337210-02
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5.5634

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4265.356
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24, 19
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23, 19
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5. 5130
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3.3430D
1 2
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16
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1 1
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16, 20
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3954.541
0.20030
l 2
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16
2.4164
5.0394
4-
17, 20
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0.34300-02
3967.497
0.1 3300
1 2
0.33340
16
2.4077
5.7930
-
l 0 ,20
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0. 27060-03
4020.522
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5.8702

19,20
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0. 1 1 500-01
4053.606
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1 2
0.42580
16
2.3982
5. 75-> 2
4
2 ) 20
-24465.39
C. 12580-0l
4 086. 7.38
0.18430
1 2
0.45090
16
2.3904
5.7124
-
21,20
-24272,39
0.98230-03
4119.907
0. 1 4053
l 1
0.34100
15
2.3792
5.64 77
4-
22, 2C
-24078.35
0.49350-0?
4153.101
0.63090
1 1
0.16550
16
2.3814
5. 6756
4-
2 3, 20
-23887.39
Oc 13 160-01
4186.309
0. 1 7940
l 2
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16
2.3737
5.6342
-
24,2 0
-23695,39
0. 47 770-0 .2
42ic.5 1 0
3.63590
1 1
9.15070
16
2.366?
5 59 4 p
4-
25, 20
-23514.35
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4252.713
0.13160
1 1
0.30940
1 5
2.3663
5.6 1 39
4-
204

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BIOGRAPHICAL SKETCH
Ronald 0. Daubach was born in Belleville. Illinois, on August
12, 1952. He graduated from Althoff Catholic High School in 1970
and Knox College in 1974. He attended the University of Florida
from 1974 to 1983. During the final three years of this period,
he worked as a research associate with the Magnetohydronamic Energy
Center, Mississippi State University, Starkville, Mississippi. On
August 22, 1981, he married Joni Meno. He is currently employed
with the Magnetohydronamic Energy Center.
212

I certify that I have read this study and that in my opinion
it conforms to acceptable standards of scholarly presentation and is
full adequate, in scope and quality, as a dissertation for the
degree of Doctor of Philosophy.
Johrij R. Eyler, Cha/i/rman
Associate Professor of Chemistry
I certify that I have read this study and that in my opinion
it conforms to acceptable standards of scholarly presentation and is
full adequate, in scope and quality, as a dissertation for the
degree of Doctor of Philosophy.
Wallace S. Brey
Professor of Chemistry
I certify that I have read this study and that in my opinion
it conforms to acceptable standards of scholarly presentation and is
full adequate, in scope and quality, as a dissertation for the
degree of Doctor of Philosophy.
Martin T. Vala
Professor of Chemistry
I certify that I have read this study and that in my opinion
it conforms to acceptable standards of scholarly presentation and
full adequate, in scope and quality, as a dissertation for the
degree of Doctor of Philosophy. M
V
IS
Richard T. Schneider
Professor of Nuclear Engineering

I certify that I have read this study and that in my opinion
it conforms to acceptable standards of scholarly presentation and is
full adequate, in scope and quality, as a dissertation for the
degree of Doctor of Philosophy.
Thomas L. Bailey
Professor of Physics
This dissertation was submitted to the Graduate Faculty of the
Department of Chemistry in the College of Liberal Arts and Sciences and
to the Graduate Council, and was accepted as partial fulfillment of the
requirements for the degree of Doctor of Philosophy.
December 1983
Dean for Graduate Studies and Research



Appendix III. Microcomputer Programs (continued)
Address
OADO
OAEO
Data Analysis Storage Subroutine (continued)
Label
Op Code
Mnemonic
EA
NOP
EA
NOP
7 EA's
NOP
A6 14
LDX 14
95 50
STAx 50
CA
DEX
A5 D2
LDA D2
95 50
STA 50
38
SEC
B5 90
LDAx 90
F5 BO
SBCx BO
95 70
STAx 70
E8
INX
B5 90
LDAx 90
mm
F5 BO
SBCx BO
95 70
STAx 70
E8
INX
EO 20
CPX #20
90 50
BCC 0A9B
3-
A2 00
LDX #00
B5 50
LDAx 50
91 41
STA 41,Y
Comment
Store the Result
Subtract 100 Photodetector
Level from Laser Photode
tector Level
Test for Finish
OAFO


34
symmetric. Absolute voltage levels of one volt for the end, upper, and
lower plates with trapping plate potentials of one and one-half volts
are sufficient for effective trapping.
The cell dc potentials are taken from the regulated five-volt
power supply of the digital pulse electronics (53) (Figure 6). A
500 n, ten-turn variable resistance connected across the +5 volt and
-5 volt busses defines the dc level. The dc lines are buffered to
the appropriate cell plates to insure that the dc power supply loading
is minimal.
Filament and grid dc potentials are also produced in the digital
pulse electronics package (53). The voltage range is 0 to -100 volts
for each. The filament current is provided by a Kepco 1000-0.2 (M)
Filament Power Supply (54).
The electron current through the cell is monitored at a
positively biased collector plate. Current-to-voltage conversion
and amplification produce a measurement suitable for display on an
oscilloscope. A collector output voltage of 1 volt corresponds to
an electron current of 1 microamp. Typical electron currents are on
the order of 0.01 microamps.
Vacuum Apparatus
The vacuum apparatus is illustrated schematically in Figure 7.
The main vacuum can and low vacuum and high vacuum manifolds are
constructed of stainless steel. A variety of gasket materials are
used in the manifold connections. A gold wire gasket is used at the
main vacuum can to high vacuum manifold connection. Copper gaskets
are used at manifold-pump connections and nickel gaskets are used for


129
Table 11. Experimental Wavelengths (A) and Term Values (Texp) and
First Differences (a!) for the Observed Photoreduction
of Bromine Molecular Negative Ions.
\(nm)
^exp
(cm-1)
495.4 0.3
20186
+ 12
-13
488.6
20467
+12
-13
481.8
20756
+13
-13
475.7
21022
+ 13
-14
470.5
21254
+ 14
-14
A^cm"1)
281
289
266
232


Appendix III. Microcomputer Programs (continued)
Address
0A3E
08B7
A/D Subroutine (continued)
Label
Op Code
Mnemonic
A9 05
LDA #05
8D 00 17
STA 1700
CE 00 17
DEC 1700
AD 00 17
LDA 1700
85 ID
STA ID
AD 02 17
LDA 1702
46 87 08
JMP 0887
85 IE
STA IE
EE 00 17
INO 1700
A9 EO
LDA #E0
25 ID
AND ID
85 ID
LDA IE
OA
ASL
OA
ASL
OA
ASL
OA
ASL
85 IE
STA IE
A9 10
LDA #10
25 IE
AND IE
05 ID
AND IE
85 1C
STA 1C
Comment
Read the Next Most Significant
Nibble
Format the Next Most Significant
Nibble
CTT
00


X
Upper Plate, +lv
1)^2 Irradiation
2) Quench Pulse
Lower Plate, +lv
Marginal Oscillator
CO
CO


CHAPTER III
EXPERIMENTAL APPARATUS
The pulsed ion cyclotron resonance experiments presented in this
dissertation required the interfacing of electronic, optical, and
vaccum components. The central component of any ion cyclotron
resonance experiment is the ion cell. The electronics apply
required, properly timed pulses and excitations to the ion cell and
detect the influence of the contained ions on an applied rf field.
The vacuum system provides a suitable environment at the cell for
the production, maintenance, and detection of ions. Since the
experiments described involve radiative transitions of ions, a suit
able radiation source must be coupled to the ion containment region
through the vacuum hardware and ion cell. In addition, the
radiation source must be controlled by an appropriate trigger so as
to operate synchronously with the potentials and excitations employed
in the ion detection process.
Trapping Cell
The trapped ion analyzer cell (Figure 5) requires six dc
potentials in conjunction with the uniform, static magnetic field to
produce an effective ion trap. The dc potential polarities are
dictated by the polarity of the ion. The trapping plate potentials
are the same polarity as the ion, while end, lower, and upper plates
are of opposite polarity. Typically the dc potentials are
31


CHAPTER II
THEORY OF ION CYCLOTRON RESONANCE
The study of photo-induced processes of gas phase ions
necessitates a well-defined region of observation and the minimization
of non photo-induced ion losses. In addition, a sensitive method of
sufficient resolution is required for the detection of ions of
varying mass-to-charge ratios. The classical motion of a charged
particle in electric and magnetic fields is applied to the spatial
restriction and the detection of ions.
Ion Motion in Static Fields
An isolated, charged particle in motion located in a magnetic
field interacts with the field classically. This interaction of
charged particle and magnetic field constrains the particle motion in
the plane perpendicular to the field. For a uniform and static
magnetic field, the interaction of the particle and the field results
in the gyration of the particle about the magnetic field lines.
The field-induced motion is characterized by the frequency of the
rotation, u>, given as (44)
w = qB/m (1)
where q is the charge on the particle, m is the particle mass, B is
the magnitude of the magnetic field strength and u> is the natural
cyclotron frequency. Although the component of the initial particle
10


4
Negative electron affinities are associated with unstable systems which
may, however, exhibit resonances related to the formation of a
transient negative ion state (19).
For an atomic negative ion, the given definition of electron
affinity is complete. A complication arises for molecular negative ions
due to the change in the nuclear configuration associated with the
addition of the electron. Two distinct types of electron affinities
are conceivable. The energy difference associated with the ground state
neutral and ground state ion both with zero internal energy and both
at their respective equilibrium geometries is referred to as the
adiabatic electron affinity. A more readily observable energy
difference, the vertical electron affinitycorresponds to the change
in energy between the neutral and negative ion ground electronic states
at the equilibrium nuclear configuration of the neutral. In general,
the term vertical electron affinity is used for all values of observed
electron affinities for which either the negative ion or the neutral
possess internal excitation. Herein lies the basic problem in the
interpretation of experimental measurements of molecular electron
affinities, the difficulty encountered in the evaluation of the internal
energy of the initial and final states. In general, experimental
techniques measure vertical electron affinities which provide upper or
lower limits to the adiabatic or thermodynamic electron affinity
based upon some estimate of the internal excitation. Several reviews
(20-23) of the techniques applied in the evaluation of electron
affinities of molecular species have appeared including the recent
article by Janousek and Brauman which provides an excellent overview
of the topics discussed here.


Figure 20. Photoproduction of CT.
This spectrum was generated as
described in the text. The Cl"
signal levels exceed that of the
photodetachment Cl2" due to the
mass dependence of the detectivity
and the photo production of Cl"
from Cl2" of varying isotopic
character.


206
13.
P.
J.
Jay, W.
R. Wad
t, and T
. H. Dunning, Jr.,
Ann.
Rev. Phys.
Chem. 30,
311 (1
979).
14.
D.
W.
Trainer
and J.
H. Jacob, Appl
. Phys. Lett. 35,
920 (1979).
15.
a.
M.
G. Thackston,
F. L. E
isele,
W. M. Pope,
H. W.
Ellis,
E. W
. McDan
iel, and
I. R.
Gatland, J.
Chem.
Phys.
73, :
3183 (1
980).
b.
R.
C. Sze
, A. E.
Greene,
and C.
A. Brau, J
. Appl
. Phys. 53,
1312
(1982)

16.
D.
J.
Ehrlich
and R.
M. Osgood, Jr.
, J. Chem.
Phys.
73, 3038 (1980)
17.
L.
G.
Christophorou,
Adv. in
Electron, and Electron
Phys.,
edited by L. Marton (Academic, New York, 1978), Vol. 46,
p. 55.
18. G. E. Streit and T. W. Newton, J. Chem. Phys. 73, 3178 (1980).
19. J. N. Bardsley and F. Mandl, Rep. Prog. Phys. 3^, 471 (1968).
20. B. K. Janousek and J. I. Brauman, Gas Phase Ion Chemistry, edited
by M. T. Bowers (Academic, New York, 1979), p. 53.
21. C. A. Dowell, Physical Chemistry: An Advanced Treatise, edited
by D. Henderson (Academic, New York, 1969), Vol. 3, p. 495.
22. L. N. Branscomb, Adv. in Electron, and Electron Phys. edited
by L. Marton (Academic, New York, 1957), Vol. 9, p. 43.
23. H.S.W. Massey, Negative Ions (Cambridge Univ. Press, Cambridge
1950).
24. D. B. Dunkin, F. C. Fehsenfeld, and E. E. Ferguson, Chem.
Phys. Lett. 15, 257 (1972).
25. C. Lifshitz, B. M. Hughes, and T. 0. Tiernan, Chem. Phys. Lett.
7, 469 (1970).
26. A. P. Hickman and K. T. Gillen, J. Chem. Phys. 73, 3672 (1980).
27. M. W. Siegel, R. J. Celotta, J. L. Hall, J. Levine, and R. A.
Bennett, Phys. Rev. 6, 631 (1972).
28. F. Breyer, P. Frey, and H. Hotop, Z. Phys. A 286, 133 (1978).
29. J. M. Slater, F. H. Reed, S. E. Novick, and W. C. Lineberger, Phys.
Rev. A 17, 201 (1978).


Appendix Va. Potential Energy Curves
********** jL'iCU 4 9 CHL',' Nc 4 NO MOL£CUL4P CHLC-il N'" ANltN ***********
********** ************* P-C V £RL AP F ACT ********************* *****
T H£ c JLLJ.V NS IATa 3-.5TMU 70 THE LO WCf- S T A 71: o STATE NU^fJEF IS 1 0
fj =
'U \ 1747(P5 13rJ 02
Tc J o TC -2 ^ j J a ? C 3 5
r = -'>*2792 222 49 13
L I V1 J > 5 o 0 0 0 2
L M v 7 ; j D ^ I
'Hr 1 N 3U V
TE'lTl \L
I'll S ANT ~N~
1
^ T I C
: r t ; -2 i G V)
-

d)429211uT
07
J-56 1 A 7 7 6GET
3s
.7 V 7 6 8 8 8 31D
: 7
Co 62095567 IT
00
0.
3C7?40324T
07
'*6314335060
0 0
).
2 3732 364 60
07
j741911342T
0 3
0 ,
1530716200
C 7
'o 502 3691 7 7")
0 0
J 0
14 1 0?19 63 0
07
0 862 J673 1 70
C 0
r>
0
t r 34 3 38 3 40
C 7
0- 92 3344843T
00
0 *
3313178730
0 6
">.93 33 226840
c3
3
6362 04600 0
06
0 o 1 0 4 4 3005 ?0
0 l
0
4^47537590
0*
0* 1 10 47 76 3 50
01
0 .
3t 76 1 29700
06
1 1 65?56 l 90
0 1
0
2 7 71 2 1 0 6 00
06
0- 122573407:1
0 1
0,
2073545640
C 6
1 12562 1 1 860
0 1
0
1 57 71 32 00 J
<"} F
o 1 3 4 6 6 v 7 IT
0 1
3 a
l 1 36 2 42 1 26
*
Af- r. G I V i£ N ^rLC'A


123
nitrite ion production from nitromethane, then a mixture of chlorine
and bromine vapor was inlet and the signal intensity was maximized.
Finally, the Br2~ signal was located and the system was tuned for the
maximum Br^' signal intensity. B^ signal satisfactory for subsequent
photo-experiments was produced at a detect delay of 110 ms. The NC^-
and Cl2"" signal intensities had decreased to low levels at this detect
delay time for the selected operating conditions. The negative ion mass
spectrum of the chiorine/bromine-nitromethane mixture is presented in
Figure 23. The intensity of the well-tuned B^- signal is approximately
one-half the intensity of the optimum C^ signal levels used in the
Cl2 photo-excitation study.
Photodetachment of B^"
The photo-excitation spectrum of Br^ was investigated from 470
nm to 498 nm. At longer wavelengths (520-540 nm), the low ion signal
intensity contributed to a reduced signal-to-noise ratio and this com
bined with the small cross-section for photo-excitation at longer wave
lengths precluded cross-section measurements distinguishable from the
background noise level. The photoreduction spectrum is presented in
Figure 24. The dashed line spectrum shows more pronounced structure;
this is due to more stable output and better wavelength coverage by the
dye laser system for these points. The spectra show similar gross
behavior. The determination of the cross-sections plotted was discussed
in Chapter III.
Analysis of Br^" Results
RKR potentials and Franck-Condon overlap factors were not
evaluated for the Zg state of Br^ and the state of Br^,


91
Experimental evaluations of the electron affinity of nitrogen dioxide
are relevant to this study and are summarized in Table 5. Exact
determination of the adiabatic electron affinity of nitromethane has
been hampered by the significant structural differences between the
ground states of the neutral and anion which lead to excited vibronic
transitions (84, 87, 88a).
A long wavelength tail in the photodetachment spectrum of NC^-
led to a proposed peroxy isomer of lower electron affinity than the
ground state anion (85). The existence of a low-energy isomer could
have a significant impact on the subsequent spectral study of an ion
formed by electron transfer from a mixture of the two isomers. Although
the appearance of a long wavelength tail in the NC^- nhotodetachment
spectrum was corroborated (8G), a recent study has been able to
interpret the results of the previous works in terms of variations
in the measured collisional de-excitation rates for vibrationally
excited NO2" by different bath gases (89). The appearance of the long
wavelength tail in the photodetachment spectrum is best interpreted as
the result of detachment from inefficiently quenched vibrationally-hot
ions.
Although suggestion of an isomeric form of NC^' has been discredited,
the experimental results still indicate signficiant internal
excitation for NC^" produced by electron attachment to nitrogen
dioxide. An alternate source of NO^- for which the internal
excitation could be minimized or at the very least permit the
determination of an upper limit on the internal energy is essential
in electron transfer generation of the chlorine anion. A strong


Appendix Va. Potential Energy Curves (con't)
****** **** vi^L PCOLAN CILl- IN" ANO M HL t'CO AN CHLORINE ANION ***********
*********************** ~ C" r,vE1 LAP AC TONS **************************
the
p ILL r
* I MG O AT A
FJ ~
0 0
;'mj
II
lo
7 4 7.19i Of. 0
Ob =
;. i *
45773 co
TOE
- -0.1
91646800 0
L I vi 1
-
>15 ) 0 j 1
L [M 2
-
.50000 Cl
Tnr
r NPUT
DnTf \1T I AL
G I N~
A NO ENf no IE
Ant:
11 V EN iJELO*.
). i o o o o oo a o o
0 1
0 O 1 JI ?71 1 C 0
Of
1 9 7 GO OF, 1,7 j
0 1
j6534629940
C4
*5 19.0 5 974 t TV
C 1
0.6450 0 04 940
0 4
0. 19 ? 2665320
0 1
0*6364629940
04
} j 19r 9371 900
: i
a o 6 2 7 0 6 0 4 9 40
04
0- 2006 095 35 0
0 1
0 6 1 = 16 29 9 4 0
JA
2012637210
Cl
0.6 1 9 400494O
04
Jo 20 l 4599 0 20
0 1
0.6 ai5629940
0 4
0. 2 026382 390
0 1
Oo592650454 0
04
0.20 7 3 1 SO J TO
C 1
A. 5836625940
04
0,2040020560
0 1
0.5746004940
04
0. 2046878 85D
01
0.565462994 0
0<+
0 > 2053765 740
0 l
0.8662504940
04
Oo 2 Oo 0683 1 4 a
0 1
Jo P96 29 9 40
0 4
a ? 0 1
0.5376004540
04


105
notation is abbreviated to (2441) in which only pa and pa occupancies
are explicitly given. This configuration (2441) yields a Eu mole
cular electronic term (Hund's case b ). Consistent with the anti
bonding nature of the ounp electron, the chlorine anion exhibits
an increased bond length (2.66A) and decreased vibrational frequency
(260 cnf^) (95) relative to the ground state of the neutral (1.988A,
565 cm 1) (88b). No first-order spin-orbit coupling is expected for
a 2e+ state (88c).
The lowest, excited-state electeonic configurations correspond to
single-electron excitations from the a np, a np, or a np orbital
9 U 9
to the aunp orbital. These states, (2432) 2ng, (2342) 2nu, and
(1442) Eg are repulsive. Potential energy curves have been
calculated both for the ground anionic state and the repulsive excited
states for chlorine (95,96) and bromine (96). In addition, for
2 2 + 2 + 2 +
chlorine the it +- E and E + E electronic transitions have
9 u g u
been observed in the gas phase (75,92), as well as in rare gas
matrices (97), crystals (98), and glasses (99). The transition
from the e, to the E state is strongly forbidden and has not been
u u 3 J
2 2
observed. The n and n states exhibit first-order, spin-orbit
g u
splitting; for chlorine the magnitude of the splitting is anticipated
to be small (100).
The only state of neutral chlorine accessible with the wave
lengths used in this study is the X^E^ground state. The next
-1 3
neutral state, 18310.5 cm above the ground state, is the A nQ+u state (88d).
This state lies at an energy significantly higher than can be


3
knowledge of electron-neutral interactions and negative ion formation.
Typically, short wavelength lasers have employed some variation
of a fast-risetime, high-energy electron discharge pumping scheme (12).
The excited neutrals and positive ions formed during discharge have
been included in models of laser performance (13). A recent
investigation has extended consideration to negative ions produced by
the attachment of secondary electrons to and NF^, the alternate
sources of fluorine in XeF laser gas mixtures (14). In addition, the
mobility of Cl- in Xe, a factor in evaluating the XeCl excimer
mixtures, has been investigated (15) and it has been suggested that the
molecular bromine anion contributes to XeBr* excimer formation in
electron discharge pumped mixtures through reaction with Xe+ (16).
Negative ions are of interest in radiation and nuclear chemistry.
Biologically active free radicals, excited states,and negative ions
are generated by radiation incident on biological matter (17). The
development of nuclear pumped lasers and gas-core reactors employing
UFg as the fuel /medium requires that the negative ion formation of
this compound of relatively large electron affinity be evaluated (18).
Electron Affinity
The electron affinity of the corresponding neutral is the most
fundamental property associated with a negative ion. The electron
affinity is defined as the change in the total energy of the system
upon the addition of an electron. The change in the system energy
may be positive or negative. Conventionally, stabilization of the
system corresponds to a positive sense for the electron affinity.


8
normally of the order of the correlation energy (39),the energy
associated with the assumption of an average potential due to all of
the electrons with the exception of the electron whose energy state is
calculated. This average potential is an assumption basic to all
Hartree-Fock schemes and limits the value of this particular scheme
for electron affinity determination. Cl accounts for correlation effects
by including a number of electronic configurations into the energy
calculations (40). Generally, the validity of any indirect method
depends upon the system as well as the technique.
Several variations of a direct method for calculating potential
energy differences between electronic states at a selected nuclear
configuration have recently been developed (38). These techniques
eliminate the inaccuracies of the indirect procedures. The method
begins with a calculation of the neutral potential energy curve. An
operator simulating the addition or removal of an electron is then
applied to a specific point on the potential energy surface. This
determines the ion energy. For vertical and adiabatic electron
affinity estimation, this method appears promising. It is feasible,
although computationally extensive, to generate the detailed anion
potential surfaces necessary to predict spectral behavior for the
transitions.
Photodetachment spectral analysis consists of modeling the energy
dependence of the cross-section at threshold. The rigorous mathematical
basis for the threshold behavior has been delineated by Wigner (41).
An excellent, detailed derivation of the theory has been published by
Lane and Thomas (42) and the extension of the formalism to a coordinate


PC SJ
//
// L
0
TIME (ms)
F
D
-U-
Q
PC
FPD DD
CO


Appendix
Vb. Molecular Chlorine
and Molecular
Chlorine
Ani on
Franck-
Condon
Overlap
Factors (con't)
V* ^ y*
T(cm *)
Q
Lambda
QT**3
QT**4
RC
R**2C
Phase
11 it
- '4 l 22.0 1
. 21o20-0 1
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Oo 30200
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5.670 1
-
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5 6 3 ? 7

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4259.305
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42 97 #562
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5.5501
IS, 16
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4335.947
0.15350
12
0.35390
16
2.3489
5.5154
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15, 16
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4374.451
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5.454 ?

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3. 234 i D- 04
4 3 34.5 1 9
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09
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2.3685
5.6880
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APPENDIX V
RKR POTENTIAL ENERGY CURVES
AND FRANCK-CONDON FACTORS
FOR C12-C12


46
output and was read from an oscilloscope or transferred through
properly buffered inputs (1 Mft) to a data collection system.
The simplicity of the optical arrangement did not lead to fast and
simple alignment, since one element of the laser cavity was
contained inside the vacuum can and was not stationary with respect
to the remaining laser cavity components. Alignment was aided by
use of a Spectra Physics 155 HeNe Laser (71) which could be directed
first to align the vacuum can laser cavity element relative to the
oscillator cavity and then redirected to align the grating with respect
to the oscillator cavity.
The dye laser head and high voltage power supply were contained
in separate rf shield cages. This shielding eliminated rf inter
ference with the marginal oscillator detector circuitry.
Pulsed Electronics
A pulsed ion cyclotron resonance experiment requires a sequence
of control pulses of variable delay and, in some instances, variable
width to govern the timing of ion formation, ion detection, ion
removal from the cell and when desired, ion irradiation. A digital
synchronously-timed control system has been constructed for the
generation of the requisite pulses (53) (Figure 9).
A typical pulse sequence is initiated by two internal pulses
that are required to reset and clamp the counters and flip-flops
(precondition pulse) and serve as the zero time reference (start
pulse) for the working pulses: "grid', "detect", "sample",
'integrator reset", "quench", "w2 and "free" pulses. The grid,


120
excited Cl,, favorable Franck-Condon factors lead to photodetachment
at longer wavelengths than predicted from the zero state energetics.
Chlbrine has been shown to react rapidly and efficiently with low energy
electrons, the type produced by photodetachment (112, 113, 114).
Consequently, even if photodetachment alone occurred, an increase in Cl~
signal intensity is anticipated.
Table 9 lists the assigned transitions, wavelengths, term values,
energy differences between the assigned transition and the (0,0)
transition, and the adiabatic electron affinity of each peak. An
average electron affinity of 2.3601 0.0040 eV is determined based
upon the peak assignments. This error reflects errors in the correct
determination of the individual peak term values, but not the possibility
of an incorrect numbering of the peaks. Due to the restricted range
of the experiment, V** values could be off by +2 to -3 and V* values
by +5 to -5 corresponding to a total error of +2164 cm-^, -2576 cm-^
(Table 10). Clearly, this error is a direct result of an incomplete
spectrum of mediocre quality. Coverage of a wider spectral range would
eliminate the questionable peak assignment and the higher precision
error estimate would definitely apply.
Bromine Molecular Anion
Formation of Br^
The molecular bromine anion, Br, was produced from Cl2 by elec
tron transfer. Direct formation of Br^ by electron transfer fron nitrite
ion was not observed. Direct electron attachment to bromine generated
Br by dissociative attachment. For a maximized Br^ signal strength
the ion cyclotron resonance mass spectrometer was first optimized for


Appendix III. Microcomputer Programs (continued)
Data Analysis Storage Subroutine
Address
Label
Op Code
Mnemonic
Comment
0A9A
A6 14
LDX 14
38
SEC
B5 50
LDAx 50
E5 1C
SBC 1C
0AA1
85 DD
STA DD
Subtract Zero Baseline from
E8
INX
Laser MO Levels
B5 50
LDAx 50
E5 IB
SBC IB
85 DC
STA DC
CA
DEX
38
SEC
B5 70
LDAx 70 i
E5 1C
SBC 1C
OABO
85 DF
E8
B5 70
STA DF
INX
LDAx 70
_ Subtract Zero Baseline from
100 MO Levels
E5 IB
SBC IB
85 DE
STA DE
A9 04
LDA #04 ,
85 DB
STA DB
86 14
STX 14
20 00 0B
JSR 0B00
Perform 16 bit Division and
0AC2
20 C2 03
JSR 0302
Reformat the Result
EA
NOP
EA
NOP
O


207
30. P. C. Cosby, R. A. Bennett, J. R. Peterson, and J. T. Moseley,
J. Chem. Phys. 63, 1612 (1975).
31. T. A. Lehman and M. M. Bursey, Ion Cyclotron Resonance Spectro
metry (Wiley-Interscience, New York, 19767^
32. J. D. Baldeschwieler and S. S. Woodgate, Acc- Chem. Res. 4,
114 (1971).
33. L. N. Morgenthaler, Ph. D. dissertation, Univ. of Florida,
Gainesville, FL 32611 (1979).
34. H. 0. Pritchard, Chem. Rev. 52^, 529 (1953).
35. W. B. Person, J. Chem. Phys. 38, 109 (1963).
36. R. S. Mulliken and W. B. Person, Physical Chemistry: An Advanced
Treatise, edited by D. Henderson~(Acadenric, New York, 19691T
Vol. 3, p. 537.
37. a. W. F. Scheehan, J. Am. Chem. Soc. 100, 1348 (1978).
b. G. V. Karachevtsev, Zh. Fiz. Khim. 52^, 2740 (1978).
38. H. A. Kurtz, Ph. D. dissertation, Univ. of Florida, Gainesville,
FL 32611 (1978).
39. J. Simons and W. D. Smith, J. Chem. Phys. 58, 4899 (1973).
40. E. Steiner, The Determination and Interpretations of Molecular
Wave Functions (Cambridge Univ. Press, Cambridge, 1976).
41. a. E. P. Wigner, Phys. Rev. 73, 1002 (1948).
b. E. P. Wigner and L. Eisenbud, Phys. Rev. 7_2_, 29 (1947).
42. A. M. Lane and R. G. Thomas, Rev. Mod. Phys. 30, 257 (1958).
43. S. Geltman, Phys. Rev. U^, 176 (1958).
44. S. Seely and A. D. Poularikas, Electromagnetics: Classical and
Modern Theory and Applications (Marcel Dekker, New "York,-
1979).
45. T. G. Northrop, The Adiabatic Motion of Charged Particles,
Interscience Tracts on Physics and" Astronomy (Interscience,
New York, 1963) No. 21.
46. R. T. Mclver, Jr., Rev. Sci. Instrum. 4Y, 555 (1970).
47. T. E. Sharp, J. R. Eyler, and E. Li, Int. J. Mass Spectrom. and
Ion Phys. 9, 421 (1972).


Appendix Va. Potential Energy Curves (con't)
R PE
a
32J05 97 4 00
0 1
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-i 4.
>
i?-? i eeg^eo
0 1
0.419 4004940
04
)>
33J3223460
0 1
0,4 ?9 66 ,?QCi o
0 4

331 476J 730
01
0 4398 50 4 94 O
0 i
V 0
7326 27^,6 10
0 1
0.44 Q9629940
04
0
333 7 7664 10
0 1
0.4; 0000494
0 4
).
3 34 0 2 5 7 30
0 1
0.4 6 9 96295 40
04
1 -
3 360 7 30 1 9 0
0 1
0.4 79 3504940
0 4
' a
3372274950
0!
0 4 *- 9 fc 6 2 9 9 4 <
0 4
. a
3 3 d 7 773 2 "0
0 1
''4v940 94 9 40
0 4
J '
3395275 720
0 l
0,3090529940
0 4
o.
34"6 794 7 50
0 1
0.5 1 36504 94ri
04
0 c
34 1 5374 7-0
J 1
0,578 1679940
04
Jo
342967200o
0 l
0.537600494O
J4

344 14 39 7 00
0 1
0. 54696? 9940
04
344 9 0 31 O?0
0 1
J a ,56 25 04 9 40
V. ft
9
3464649 0 1 1
: i
0.566462994
0 4
34 ^ f 296 7 3D
: i
9 0 57 4 60 04 9 49
04
J .
3 4 9 7 V 7 7 1 6 0
j i
0,6 " h *, :?c 9 4
-a 4

240 9693250
01
J.55265C4945
r .
-
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o i
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0 4
3
3523244080
01
Oafcl 0 4 0 C 4 0 4 _)
04

35 3-7 084 590
0 1
0.6191 629940
C4
J -
354697?3 30
0 1
0.6378504540
C 4
Jo
355891J130
01
0.6 76463994 9
0 4
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357 0 9 0 0 5 3D
0 I
do 4^ 00 04 9 40
0 4
Go
35 8 7 947330
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04

359 7 1 1 7 9 60
0 1
0.6661114610
04
Jo
36l 1288 34 0
0 l
0 6 7f 30 29 2 70
04
- a
36 2 5 4 5 8 9 1 O
Cl
C .6 P 6 32 54 1 6 0
04
-
3639629440
0 1
O.ft^Ol 769020
04
j a
36 53 796 9 7n
01
0 o 70c 6555 880
0 4
0
3667970490
0 1
0. 71 -03599005
0 4
>
3f3? 1 4 1 J 0
J 1
0.7746834790
04
0 0
3696311 550
0 1
0.7738401740
04
\
37 1 0 4 82 0 70
0 1
0. 742 31 40339
04
Jc
37 ^4 65 7 6 OD
0 1
0,7516092990
04
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3738323130
0 1
0. 76 0.7254 01 0
04

97529 07 6 50
0 1
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04
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3 7 f 7 164130
0 1
0*7769197130
0 4
3
378 1 334 71 0
01
0. 7349936490
04
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3 7 95 5 ^ 2 30
0 1
0. 7 02 0 97.3595
04
R
PE
0.
3809675 760
0 1
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3923846790
0 1
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ft
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01
0.8226917300
2 ft
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3866357870
0 1
0.8? 9 696993'"'
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0.
389 0 528 390
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4.
389 4698 920
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J ^
0.
390 8369 450
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r ft
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o 4
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A
Oo
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399389261D
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r .
0.
40C9063130
01
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4022233650
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0a
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0.90039 31650
r 1
-
405 0 574 7 10
01
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rm +
3 o
40 6 4 745 24 0
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j ft
0.
4078915770
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40 93 0 66 2 90
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ft
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01
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'ft
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).
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154
Hex Address
Description (Initial Value)
1A
Index for four channel store
IB
A/D high order byte
1C
A/D low order byte
40
ID for data storage
41
Final data store low order address (00)
42
Final data store high order address (02)
43
Final data store index (00)
DB-DF
Registers for full 16-bit divide


Table 5. Empirical Electron Affinities for NOg in eV.
Electron Affinity
Method
Reference
2.36 0.10
Tunable laser photodetachment
Hot cathode source beam
85
2.8 (threshold)
Conventional source photodetachment
Ion cyclotron resonance
86
2.29 0.1
Endothermic charge transfer
79
2.30 0.15
Endothermic charge transfer
80
2.38 0.06
Charge transfer
78
2.7 0.2 (threshold)
Conventional source photodetachment
Ion cyclotron resonance
84
2.04
Endothermic charge transfer
81
3.1
Photodetachment
82
3.9
Chemical ionization
83


APPENDIX III
MICROCOMPUTER PROGRAMS
Initialization Subroutine
Address Label Op Code Mnemonic
Comment
0800
0810
0820
IN IT
LOOP
A9
00
LDA
#00
85
00
STA
00
85
1A
STA
1A
85
OA
STA
OA
85
OE
STA
OE
85
19
STA
19
A9
20
LDA
#20
85
01
STA
01
A9
08
LDA
00
o
85
04
STA
04
A9
10
LDA
# 10
85
06
STA
06
85
07
STA
07
A9
40
LDA
#40
85
OD
STA
OD
A9
02
LDA
#02
85
OB
STA
OB
A5
19
LDA
19
FO
FC
BEQ
FC
78 SEI
C6 19 DEC 19
A5 02 LDA 02
DO 16 BNE 16
Register Initialization
NOP Loop
155


Appendix Vb. Molecular Chlorine and Molecular
V*,
v**
T(cml)
Q
Lambda
1 1.
f
- 7 l e h l
>? 16 '
*3 5 6.5 1 7
1 .
c
- 5 : 3 1
a 7|-- 3 7
4 6 77c 8 4 1
15.
9
- 2 : ? 3 5 3 *
. 1 o r-6 0 7
4C 2<- 52 8
1 .
o
07 -in
, 12 8 5^-01
4 9 ai ,599
i r .
9
- 1
2 5 20O-C l
5 3 34 Cl l
1 3.
"
- 1 v 6 55 c 5 *3
0.23 79 (' -01
5C .66.7c0
1 x .
-10455.*5
G 1 0 C : 1
5139.034
:) .
- 1 5 2 5 5 8 5
.21 1 4 0-0 3
5193.219
21 .
c
- 1 iC5eo bfa
: c 54 <70-0
5246.893
?>.
*
- 1 43 3
V l 7 5 8 ^ 0 t
5J 00 o 855
2 i.
9
-13673, Hb
: 1C 550-nI
8355074
24 .
9
- 13435.03
G. 83 64 0- 02
o 4 0 9 .5 3 4
25 .
c
- 13 30 0.35
wo 1 3 730- 04
5404,21 a
1 3,
l 0
-21 222.5 9
Go 1 1 470-0?
4711.371
14,
! 3
-210:4,99
:37840-02
4 760. 773
lt>,
IO
-20789,99
0.13240-01
48IGo007
1
10
-2 05 7 7*55
: 26 32 O-C1
48 59 561
1
l 0
- 2 ? ? 6 d 9 9
0. 1 83 70-0 1
4909.423
1 8.
l 0
-20163,00
.41220-0?
4959.580
19,
i :
- 1556 C.C 0
j 98 1 30-03
501G.0?1
23 ,
l o
-15760.00
?. 1 l 9 l D- 0 1
5060.730
21 .
l 0
-1C 56 3.00
0,2C510-01
5111.691
op
i:
- 1 9 36 9. 0 0
0. 1 4 010- 01
5162.390
23,
l c
-19178.00
:. 19950-0?
5214.309
24 .
i:
- 1999 0.0 0
C. 22 70 0-0?
5205.930
25,
l c
- 1 380 5.C C
C 14 080-0 l
5317.736
1 3 ,
11
-21771.28
0 9 59660-0?
4607.781
1 4 ,
11
-21503.28
C. 22 34 0- 01
4t 30 .4 54
l
11
-21288,29
3 3 0-21
$697. 421
16 ,
11
- 2 1 C 7 C 2 d
JO 1 3590-01
4 7 44.671
1 7,
11
-2'367.28
084000-07
4792.192
1 3 .
11
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0 o 44 7D 0- :?
4 33V.9 71
19,
11
-2 0458.28
:.1730^-01
4 3 87 .9 96
23 ,
11
2"' 253.8
2. 19330-0 t
49 36. 2 53
21 ,
11
-? C 6 1 3 *> 8
4 <~-84.726
2 ,
11
- 1 966 7.2d
G 3 8 y ?1' 0 5
5033 4 01
? i,
11
- 1 9 c 7 6 2 8
.7377 0-0 >
50 82.261
24,
11
- 1 94 8 8.28
, 1 7 32 0-0 1
5131.>89
2 5,
i i
-19302.28
J.ll900-0l
5 1 80 o 4 66
1 3 .
l 2
- ? > 2 1 3 6 7
S 33 1 9 D- 3 1
4 5 01 7 32
1 4,
l 2
- .? 1 99 5.6 7
C.2 4 690 01
4546.749
l ,
l 2
-21780.67
, rK 390- : e
4591e 22 ?
1 *5,
l 2
-2 1 5t 3.6 7
- 7 1 6 50-0r
4 6 36.3*4
1 7.
l ?
-21355.l7
0, 9 0 7 0"'- 02
4 6 31 72 0
1 <.
I 2
- > l l 6 3
' >0370- 0 l
4727,71i
Chlorine Anion Franck-Condon Overlap Factors (con't)
QT**3
QT**4
RC
R**2C !
Phase
: 1 7 VO
1 2
037 19 0
1 .
>. 232 1
6. ?rt.2
_
J,3 3770
1 1
0.63080
15
2.2760
5. 1 7' <

3c 60
1 0
G. 1 8 550
15
.2639
5.157?
3.10430
l ?
C.20940
l 6
r> 2 6 3 3
5. t 2 4c
-
j e 1 9 7 fcO
1 2
0.39250
1 6
2.2575
5.0919

i 8 0 70
1 2
35530
1 6
2.2518
5. 36 9 c
-
0,74330
1 l
0.14440
1 6
22464
5. 04 3 7
f
1 5090
1C
C. 2 9060
1 4
22462
5 C 2 1 2
-
).3 7640
1 1
07 1740
1 5
2.2332
4. 99 l ?
-
0.ll300
l 2
0.22260
16
2.2284
4,9667

0.12 730
1 2
C ? 3 7 7 0
1 6
2.2234
4.9427
-
0 .5 ? 8 4 D
1 1
0.9 7680
l 5
2.2 188
4.9200
4
O. 96 390
08
0. 1 764 0
1 3
2 .2547
4.9848
-
:. i: -9 6 o
1 1
C.23270
15
2.2959
5. 2t 20
-
0.38070
1 1
0.73660
l 5
2.2903
5.2505
-
0. 1 6390
1 2
3.34 080
l 6
22841
5.21*3

0.2 3 3 7 D
1 2
0.48090
l 6
2.2780
5. 1 894
-
0. 1 5950
l 2
C .3248 0
16
2.2721
5.1612

C73790
1 1
C.6 8 130
15
2.2666
5. 1327
-
G .7 0080
1 0
G13990
1 5
?2583
5. 1136
-
0. 9 I860
1 1
0.18150
1 6
2.2542
5.0827

0. 1 5150
1 2
0. 30030
1 6
2.2489
5.0577
-
o o i o i e o
l 2
0l9720
16
2.2437
5.0326

0. 14070
1 1
0.26980
15
2.2399
5.009?
-
0 a 1554D
l 1
2.29520
1 5
2.2303
4.9804
-
Ce 9363D
1 1
J 1 761 0
1 6
2.2262
4.9574
4
.71393
1 1
8. 15510
1 6
2.3111
5.34 17
4
0 a 222 20
1 2
v, *4 7 770
16
2.JO 46
5.312C
-
0.25400
l 2
C. t>4 07 0
1 5
2.2983
5 28 1 8

31272D
1 2
: 2 6 8 1 0
1 6
2.2922
5.2520
-
Oo 763 30
l 0
0.15930
15
22862
5.2148
4
0. 390 70
1 1
2. 80720
15
2.2803
5.204a
4
0.14310
1 2
C.30 300
l o
2.2745
5.1746

Co 1 6 070
l 2
C.32560
1 6
2 .2689
5. 14 74
4
0.60170
1 1
2. 1 2 070
16
2. 2636
5.1206
-
C .6977i0
06
C13350
l 3
?2394
5. 1375
-
2. 60 0 3D
1 1
0.11810
16
2.25 1 6
5.0727
4
3. 1?52D
1 2
3.24980
1 6
2.2466
5. 04 7f>
-
Oo 8*630
l I
0l653 D
16
2. 24 l 6
5. C2 ? 9
4
0. 276 ID
l 2
0.61320
16
2. 32 50
5.4 06 3
4
2- ? 6 ? 7 D
1 2
?.57790
l c
2.3185
5. 37 c. 7

J,93 4 OD
1 l
G20 34 0
16
2.3123
5.3424
4
> 7 1 8 9J
08
6.15510
1 3
232 C 7
5.5164
4-
3 3 3 7 9 U
1 1
;l8330
1 6
?.>006
5.2Q55
-
Go 19260
1 2
0.4 0 78 0
1 6
2.29 45
5, 26 5 1
4


44
resonator. All gratings used were blazed at 500 nm. Either a 1200
line/mm PTR (64) or Bausch and Lomb grating (65) was employed for
these studies. The general characteristics of these gratings are
presented in Table 2. In a few studies a 600 line/mm grating obtained
from Edmund Scientific (66) was also used. The grating selected
was mounted on a Burleigh SG-101 Star Gimbal Mount and SG-305 Mount
Base (67). This assembly was fixed to a rotating base driven by a
motor-turned lead screw/lever arm assembly.
At the ion cell, the laser cavity optical element was a copper
mirror attached physically to and contacting electrically the end
plate of the trapped ion cell. Visual inspection of this mirror
indicated that it was of low quality and the surface was in poor
condition. Replacement of the copper mirrorwith a reconditioned 90%
reflecting A1 mirror did not markedly improve the laser output.
Wavelength selection is determined solely by the dispersive
cavity element, the diffraction grating. Since the grating drive
was uncalibrated, a beamsplitter on the optical axis split a fraction
of the incident light to a monochromator for spectral analysis.
An American Instrument Company Model 1-8401 monochromator (68) and
and Instruments SA J-Y H20 0.5 meter monochromator (69) were used.
Both were periodically calibrated versus Hg lines and the 632.8 nm
line of a HeNe laser.
Following wavelength determination at a particular grating angle,
a GenTec ED 200 Joulemeter (70) was positioned to intercept the
fraction of the beam split to the monochromator. The joulemeter


41
Table 1. Laser Dyes and Observed Lasing Wavelength Regions
Dye
Observed Useful Wavelength Range (nm)
LD 423
No activity
LD 440
No activity
LD 450
No activity
LD 460
445-465
LD 473
Extremely weak
LD 480
470-485
LD 490
470-510
Coumarin 540
510-550
Fluorol 555
No activity
Rhodamine 6G
575-605


57
output is read into the KIM-1 in three 4-bit parts through the four
8-bidirectional-channel MUX's. The data direction registers configure
PBO and PA5-PA7 as KIM-1 inputs. PA1-PA3 select the A/D channels.
Channel one selects the least significant four bits of the conversion,
channel two the next four significant bits, and channel three the four
most significant bits. The conversion result is recombined and
stored by the A/D read software.
The interface provides a pulse to the laser trigger electronics
for program-defined counter states. In a preliminary version of the
software a latch was set (1) during the read sequence prior to that
for which the laser was to be fired. The latch output was AND'ed
with the free pulse of the ensuing pulse sequence to provide the
laser trigger pulse. The latch input was then reset (0) to prevent
laser triggering by successive pulse sequences. This technique is
cumbersome and a simplified scheme has been implemented in which the
trigger pulse is generated by software immediately after the interrupt
pulse is received. This scheme results in nontrivial simplification
of the software.
The IRQ is provided by the free pulse for automatic triggering
and by an debounced pushbutton for manual triggering. Both inputs
are conditioned by a pair of Schmitt triggers, which feed into a
one-shot pulse generator to produce a sharp, clean IRQ pulse at the
microprocessor.
The output of the laser photodetector is buffered and amplified
(x50) and the level held by a peak detector. The pulse is used


106
reached with the current laser source and does not contribute further
to the discussion of these results.
The spectrum for the photoreduction of Cl^ exhibits
significant, complex structure not observed in previous studies (75,
92, 97, 98, 99). Studies employing polarized incident radiation have
identified the two transitions observed for chlorine anions as the
2 + 2 + 2 2 +
zn - X e transition at approximately 365 nm and the n *- Xi
9 u J g u
transition peaked at 750 nm (75,92,97). For chlorine the spin-
orbit splitting of the state was not observed (97). The photo-
induced decrease of the Cl^ intensity observed in this study cannot
be explained in terms of transitions to the dissociative excited
states of the anion. The wavelength range covered by this work
corresponds to the region of the long wavelength tail of the ultra
violet transition (365 nm). In this range, the photodissociation
of the molecular chlorine anion occurs with a lower probability and
photodetachment processes from excited vibrational levels of the
chlorine molecular anion may be observed.
Computation of Franck-Condon Factors
The anticipated transitions are those occurring from a
vibration-rotation manifold of the £u state of the anion to the
vibration-rotation manifold of the neutral ground state ^e* The
relative intensities of the individual lines in such a spectrum
depend upon the relative values of the Franck-Condon (FC) overlap
factors, in conjunction with rotational parameters, for a constant
electric dipole transition moment. FC factors may be obtained if


Copyright 1983
by
Ronald 0. Daubach


BIOGRAPHICAL SKETCH
Ronald 0. Daubach was born in Belleville. Illinois, on August
12, 1952. He graduated from Althoff Catholic High School in 1970
and Knox College in 1974. He attended the University of Florida
from 1974 to 1983. During the final three years of this period,
he worked as a research associate with the Magnetohydronamic Energy
Center, Mississippi State University, Starkville, Mississippi. On
August 22, 1981, he married Joni Meno. He is currently employed
with the Magnetohydronamic Energy Center.
212


Appendix III. Microcomputer Programs (continued)
Data Analysis Storage Subroutine (continued)
Address Label Op Code Mnemonic
C8
INY
E8
INX
EO 40
CPX #40

90 F6
BCC F6
84 43
STY 43

60
RTS
Comment
Shift the results to the
permanent storage area
PO


19
Natural cyclotron frequency, 00/2-n
Radius of cyclotron orbit, r
Drift frequency, fi /2tt
Drift velocity, v Trapping frequency, o^/2ir
Observed cyclotron frequency, \/2t\
24.4 kHz
214 Hz
0.2 mm
0.27 m/sec
153.6 kHz
152 kHz
where v =v =v is 2 x 10^ m/sec. The motion of the ion proceeds as
x y
follows: during the period of one complete oscillation of the guiding
center along the magnetic field line (Twj ~ 40 us) the ion will have
completed six rotations about the guiding center (T^ ~ 6us) and the
guiding center will have drifted along an electrostatic equipotential
line and perpendicular to the magnetic field axis a distance of
approximately 0.01 mm.
Ion Motion in an RF Electric Field
An rf electric field takes the form
E_j(t) = Ej sin (a) t) i
(11)
for a field linearly polarized in the x-direction. A linearly
polarized rf field may be decomposed into counterrotating circularly
polarized fields
and
E1 E1
E j(t) = ~y sin (u^) i -j- cos (w-jt) j
(12)


82
Table 4. Variation of ICR Operating Parameters During Studies to
Maximize Formation of the Nitrite Ion from Nitromethane.
Parameter
Range
Resolution
Electron Energy3
1.8 18 eV
2 eV
Sample Pressure^
4xl0-7 1x10^ mm Hg
lxlO"7 lxl0-5 mm
Grid Pulse
8 ms 25 ms
5 ms
Detect Delay
0 300 ms
1 ms
Detect Widthc
5 ms
Not varied
Marginal Oscillator
Level
50 100 mV
10 mV
QA true estimate of the electron energy is obtained by subtracting
the trapping plate potential of 1.50 v.
^The background sample pressure was 2-4 x 107 mm Hg.
c
Detect width and marginal oscillator level are related, however, over
the range of marginal oscillator levels attempted detect width did
not require change.


CHAPTER VI
SUMMARY
The investigation of negative ions has proved a complex,
difficult and perplexing problem. The rewards associated with
performing such investigations have increased with the recognition
of the significance of negative ions to a variety of scientific
concerns. In this work, an ion cyclotron resonance mass spectrometer
was employed as a negative ion source, containment device, and detector.
Since the ions chosen for this study were known to exhibit small
cross-sections for the transitions of interest, a tunable, flash-
lamp-pumped dye laser system with a high output per pulse was employed.
The possibility of time-resolved effects on negative ion spectra
was investigated. In this study, no effects were observed but this
in itself confirms the results of studies attributing structure to
effects other than simple internal excitation.
This experimental technique allowed the observation of structure
in the photodetachment cross-sections of the halogen molecular anions,
Cl2 and This structure was attributed to vibronic transitions
between the ground state of the ankln and the neutral. The adiabatic
electron affinity of chlorine is derived fron the assigned transitions,
as 2.36 eV. This electron affinity has an error associated with the
peak assignment of +0.27 and -0.32 eV. In the case of the bromine anion,
the absence of structure due to the anion in the photodetachment
150


11
velocity perpendicular to the field, Vg ,must be nonzero for this
interaction, significantly, the frequency of gyration is independent
of the actual magnitude of the velocity component. Therefore, ions
of identical charge-to-mass ratios circulate about the magnetic field
lines at a single natural cyclotron frequency regardless of the
distribution of velocity components, Vg^. The component, Vg remains
significant since the radius of gyration, r, retains a functional
dependence on vg
r
_ V0J_
qB (2)
The motion of a charged particle in the presence of uniform and
static electric and magnetic fields, E and B, respectively, is
governed by the Lorentz force law,
F = q(E + v x B) (3)
where v^ is the particle velocity. This equation is readily soluble
for the assumed field conditions for the equations of motion of the
particle (44). For the simplified field conditions in which E. and B
are mutually perpendicular, the equations of motion dictate a
trochoidal path, the superposition of the cyclotron motion and the
drift of the center of the cyclotron orbit perpendicular to both
fields (Figure 1). The separation of the complex trajectory of the
particle into the cyclotron and drift components is a useful
modification for the analysis and visualization of ion motion in
complicated electrostatic fields. The center of the cyclotron motion
is referred to as the "guiding center" and the separation of motions
is called the 'guiding center or "drift approximation (45).


ACKNOWLEDGEMENTS
The author thanks Dr. John R. Eyler for his instruction,
assistance, and direction in this research effort. In addition,
the patience and concern of Dr. Eyler in all stages of this research
and manuscript preparation are gratefully acknowledged.
The stimulation provided by fellow graduate students was
valuable. Particular thanks are extended to Dr. L. Morgenthaler,
R. J. Doyle,and D. A. Atherton. The design of the microcomputer
interface was initially generated by Dr. Ed Voigtman without
whose assistance no subsequent progress would have been possible.
The construction of the apparatus used in this work involved
the efforts of many. The professional workmanship of Mr. Art Grant,
Mr. Ed Whitehead, Mr. Rudy Strohschein, Mr. James Chamblee,and
Mr. Robert Dugan is thankfully commended.
The author thanks Ms. Constance Miller for the patient and
careful preparation of this dissertation.
The impetus to accomplish when the desire lagged was provided
by the love, concern,and devotion of Joni Meno Daubach which is
deeply appreciated.
Funding for this research has been provided by the Division
of Sponsored Research and the Department of Chemistry.


200
8


209
67. Burleigh Instruments, Inc., Burleigh Park, Fishers, NY 14453.
68. American Instrument Co. (S-L-M Instrument Co.), 810 W. Anthony
Drive, Urbana, IL 61801.
69. Instruments SA, Inc., J-Y Optical Systems Div., 173 Essex Ave.,
Metuchen, NJ 08840.
70. Gen Tec Inc., 2625 Dalton, Ste-foy, Quebec, Canada G1P 359.
71. Spectra-Physics, Inc., 1250 W. Middlefield Road, Mountain View,
CA 94042.
72. L. Anders, J. Beauchamp, R. Dunbar, and J. Baldeschwieler, J.
Chem. Phys. 45, 1062 (1966).
73. M0S Technology, Inc., 950 Rittenhouse Road, Norristown, PA 19401.
74. S.J. Smith, Methods Exptl. Phys. 7a, 179 (1968).
75. 0.1. Asubiojo, H. L. McPeters, W. N. Olmstead, and J. I.
Brauman, Chem. Phys. Lett. 48, 127 (1977).
76. J.J. DeCorpo and J. L. Franklin, J. Chem. Phys. 54, 1885 (1971).
77. D. E. Milligan, M.E. Jacox, and W. A. Guillory, J. Chem. Phys.
52, 3864 (1970).
78. D. B. Dunkin, F. C. Fehsenfield, and E. E. Ferguson, Chem. Phys.
Lett. 15, 257 (1972).
79. B. M. Hughes, C. Lifschitz, and T. 0. Tiernan, J. Chem. Phys.
59, 3162 (1973).
80. C. Lifshitz, B. M. Hughes, and T. 0. Tiernan, Chem. Phys. Lett. 7,
469 (1970).
81. J. Berkowitz, W. A. Chupka, and D. Gutman, J. Chem. Phys. 55,
2733 (1971).
82. K. Lacmann and D. R. Herschbach, Bull. Am. Phy. Soc. 16, 213
(1971).
83. P. Warneck, Chem. Phys. Lett. 3, 532 (1969).
84. K. Smyth, Ph. D. dissertation, Stanford Univ., Palo Alto, CA
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61 1300 (1974).


Figure Page
19 Photodetachment of Cl-? 97
20 Photoproduction of Cl 100
21 Cl^~ Photodetachment Cross-Section as a Function
of Wavelength 103
22 Rydberg-Klein-Rees Potential Energy Curves for
C12 and C^" 112
23 The Negative Ion Mass Spectrum of a Mixture of
Chlorine/Bromine and Nitromethane 125
24 Photodetachment Spectrum of B^" 127
25 Negative Ion Mass Spectrum with BrCl" 133
26 Acetophenone Signal Intensity 138
27 Photoreduction of the Enolate Anion 140
28 Photodetachment of Acetophenone as a Function of
Wavelength at 150 ms Delay 144
29 Photodetachment of Acetophenone as a Function of
Wavelength at 200 ms Delay 146
30 Photodetachment of Acetophenone as a Function of
Wavelength at 250 ms Delay 148
vi i i


TABLE OF CONTENTS
Page
ACKNOWLEDGEMENTS iii
LIST OF TABLES vi
LIST OF FIGURES vi i
ABSTRACT ix
CHAPTER I INTRODUCTION 1
Historical and Scientific Interest in
Negative Ions 1
Electron Affinity 3
Experimental Techniques 5
Theoretical Techniques 6
Outline of Dissertation 9
CHAPTER II THEORY OF ION CYCLOTRON RESONANCE 10
Ion Motion in Static Fields 10
Ion Motion in an RF Electric Field 19
Ion Detection 25
CHAPTER III EXPERIMENTAL APPARATUS 31
Trapping Cell 31
Vacuum Apparatus 34
Optical Apparatus 39
Pulsed Electronics 46
Microcomputer 52
Microcomputer and Modifications 53
Microcomputer Interface Hardware 55
Microcomputer Software 58
Run Time Operation 59
Derivation of the Expression for the Photo
detachment Cross-Section 75
CHAPTER IV EXPERIMENTAL RESULTS AND DISCUSSION OF
THE HALOGEN ANION STUDIES 80
Chlorine Molecular Anion-Formation of Cl?. . 80
Photodetachment of Cl^ 95


65


136
and the large concentration of OH' which could be generated and
trapped at the ion cell.
Electron attachment to sulfuryl fluoride produces F" in a single-
step, dissociative attachment process. Nitrogen trifluoride also
produces considerable F~ upon electron impact, however, sulfuryl
fluoride generates F~ with markedly lower translational energy (121).
For this reason, F produced from surfuryl fluoride should produce
fewer excited state secondary anions upon proton abstraction and
SO2F2 was the source selected.
The enolate anion of acetophenone was efficiently produced
using both anionic bases by the reaction
The enolate anion signal level for optimum conditions with OH" is
reproduced in Figure 26. The negative ion mass spectrum of the
acetophenone/base mixtures contained only the precursor anion and
the acetophenone enolate anion (Figure 27).
Photodetachment of the Enolate Anion
The photodetachment of the enolate anion of acetophenone was
examined near threshold at differing delays between ion formation
and ion irradiation and detection. The experimental conditions
employed for the ion formation for each base are tabulated in Table
13. Laser irradiation preceded the detect pulse by 10 ms. The