A Study of the Electronic Band Spectrum of the Carbon-13 Modification of Carbon-Monoxide

99 Pages·5.392 MB·English

by  Mcculloh, Kenneth E

a study of the stmfmmc m m spectrum of the
CARBON-13 MODIFICATION OF CARBON MONOXIDE
%
Kenneth Everett McC ulloh
A dissertation submitted In partial fulfillment of the
requirements for the degree of Doctor of Philosophy,
In the Department of Chemistry and Chemical
Engineering in the Graduate College of
the State University of Iowa
June 1951
ProQuest Number: 10666203
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A0KH0WLED9EMSKT3
1 wish to acknowledge ©y deist of gratitude to
Professor aeorg© &lockl©r, director of this research,
whose long-standing interest in the problem of the heat
of sublimation of carbon prompted the undertaking herein
reported* His advice and guidance have been a source of
inspiration*
Information imparted by a number of friends
and associates has been most beneficial to me in this
work. To Ur* 0-. M. Mat lack, for many suggestions re­
garding applications of vacuum technique* to Dr. A* 1
Popov, Dr. R. IS* Keller and Mr* M. Honma, for advice
and assistance in the use of the spectrograph* and to
Mr* R* E* Ferguson, for inviting my attention to the
method for preparing carbon dioxide, sincere appreciation
is expressed*
Much of the credit for construction of apparatus
can be attributed to Mr* H* CK Hwnamaker and to Mr. Paul
Harper* Their skillful work and expert advice have been
a source of satisfaction*
The present form of the following pages is a
manifestation of the generosity of Mrs* Dorothy Hay, who
has fulfilled a promise of long duration t© type this
document. I am also pleased t© express my appreciation
to her husband, Dr* Robert F, Ray, who has assisted in
some of the more arduous parts of this work* His friend­
ship has sustained my courage and interest since under­
graduate days*
Finally, i t is a pleasure to record my gratitude
to my wife Sylva for her constant encouragement and
understanding and her assistance in the disinterment of
content from ill-expressed original drafts, in the pre­
paration of figures, and in the final checking of this
dissertation*
11
or commas
table
Chapter pag®
X INTRODUCTION » * , « * » * * • « . « » * » * # * * 1
XX THE STRUCTURE AMD ANALYSIS OF ELECTRONIC
BAUD SPECTRA................... 5
The Quantum Theory of Band Spectra » , « . . Ul
General Statement Ul
Origins of Band Spectra , « . « » * » » Ui
Energy Levels ©f Diatomic Molecules « * 0\
?
Classification of Molecular States * ♦ * O
Transitions and Selection Rules . # . .
Perturbations and Predissociations * * * H ©
O
Methods and Notation in Spectral Analysis * • HH
Rotational Structure of Electronic Bands HM
Vibrational Structure of Electronic
Band Systems • » * » » * * * » * . * . * Ui
H K
The Isotope Effect in Band Spectra . • # HC
XXX HISTORY OF THE CARBON MONOXIDE SPECTRUM ................ H

The 0l%X$ Spectrum ................ *-» 4
~
Electronic States and Band Systems * * ♦ H$
*
The Angstrom Bands « # • fig ©~
The Fourth Positive Group . • * * « * • O©
I
Molecular Constants of cfeol6* ( , ft> ©y*t
The Cl30l® Spectrum * * , . # * * * * » » • « *0 ~
Applications to the Present Research • • * • I© <n
XV PRODUCTION AMD RECORDING OF THE SPECTRUM . . . » * ©

Spectroscopic Apparatus • O

General Considerations • * • * « « * » • O

The Spectrograph .................... • • * * * • ro
The Spectroscopic Emission Source » , •
Preparation of Carbon Dioxide * « • * « « * *
The Auxiliary Vacuum System
Procedure ....................
Exposure of Spectrograms * , « * » • • • * *
Determination of Exposure Times » . • •
Exposure of 013q1o Spectrograms » » * • 4?
ill
TABLE OF GOMTENTS
(Oontinued)
Chapter page
V ANALYSIS OP THE OWolS SPEOTHUM....................... 50
Preliminary Analysis , » .......................* * • 50
Description of Spectrograms 50
Preliminary Analysis of the Angstrom
Bands • • » • • • * • • • * • • * • * « 52
Preliminary Analysis of the Fourth
Positive Group • 55
Quantitative Measurement of Spectrograms . . 56
Standard Wavelengths * * * • • * » * * « 56
Comparator Readings * * * * * * * * * * 58
Computation of Wave Numbers * ......... 59
Detailed Analysis of the Angstrom Bands . * * 61
The 0-1 Sand * * . * . . . * ..................61
the 0-2 Band . * . ........................................ 64
The 0-5 Band..................................................66
The 0-4 Band * * * * . « * . * * * . * • 68
The 0-5 Band . . . . . 68
Determination of Band Origins and
Rotational Constants * • * * * • * * • • 71
Vibrational Analysis of the Fourth
Positive Group « • • * * • * • • • * « » * • ?8
Measurement and Assignment of Band Heads 78
Determination of Band Origins * . . * ♦ 80
Vibrational Levels and Constants * * * * * * 84
Vibrational Levels of C*3ol6 * * * * * * 84
Vibrational Constants of C^3q3.6 , * . * 85
Summary and Conclusions • * * * • * » * « * » 88
BIBLIOGRAPHY * * * * * * * * * * * . 90
iv
TABLE OF FIGURES
Figure page
1. The Discharge Tube ...................................* 36
2« Emlsalon Source .......................... 39
3, Emission Sourest Schematic, « • • • » • » * » » » 40
4* Angstrom Bands (Positive Enlargement) 33
5* Fourth Positive and "3AH Bands
(Positive Enlargement) • . • @3
v
TABLE OF TABLES
Table page
I Electronic State® of Carbon Monoxide « * • * • 18
IX Band Systems of Ql2Ql®. * * • . * . * * * * * • 19
III Molecular Constants of 26
IV Tredioted Constants of 0150l 6 ...................... 29
V Wave numbers In the 0-1 Angstrom Band * . . . * 62
VI Perturbations In 0-1 Angstrom Band 63
VII Wave Numbers in the 0-2 Angstrom Band » • • « • 65
VIII Wave Numbers in the 0-3 Angstrom Band • . • • * 67
IX Wave Numbers in the 0-4 Angstrom Band • * . • . 69
X Wave Numbers in the 0-5 Angstrom Band • • • • « . 70
XI §{*r)-P(<T) for 0-vw Progression of
Angstrom Bands • » » « * • • * * • * * * « * • 72
XII AaF(J) and F(J) for Upper State of
Angstrom Bands * * ............................... 73
XIII Origin® and Constants for Angstrom Bands * . . 75
XIV Rotational Constants * ........................ 76
XV QU) - F* (J) + Fw{ J) for Angstrom Band® . . • * 77
X7I Band Heads of the Fourth Positive Croup * * • . 79
XVII Band Origins of the Fourth Positive Croup • . * 82
XVIII Tam Values of Vibrational Levels of C150l6 . . 87
vi
1
Chapter I
INTRODUCTION
The questions surrounding the problem of the
heat of sublimation of carbon have not been settled to
the satisfaction of all investigators who have concerned
themselves with Its solution. Recent direct determinations
of this quantity from vapor pressure measurements{ by
Brewer» Cllies and Jenkins (6); Simpson, Thorn and
Winslow (42)| and by Marshall and Morton (32); have
agreed in yielding a value of about 170 fecal* per mole*
However, Long (31) has cited data that would support a
much lower value*
Another approach to this problem is connected
with attempts to fix the dissociation energy of carbon
monoxide* In a recent book Hersberg (21) has given the
relationship,
L(C) * B0(CO) * 85*§ fecal. , (I-l)
in which L(C) represents the heat of sublimation of carbon,
and Do(C0) Is the dissociation energy of carbon monoxide.
Most spectroscopic determinations of this
dissociation energy have been based upon attempts to
Interpret supposed predissociations in the spectrum of
2
carbon monoxide, reported by Coster and Brens (7), Schmid
and Ger© {5@)» and aero (14) (15)* By evaluating the
spectroscopic evidence in different ways* a number of
investigators have proposed several value© for this
dissociation energy* Herzberg (20) has arrived at the
value 9*14 e.v*| Geydon and Penney (12), 11*11 e*v*s
Hagstrum (18), 9*61 e*v.j and Glockler (16), accepting
the results of the vapor pressure measurements, has given
the value 11*08 e*v*, suggesting that most of the reported
predissociations are in reality only perturbations, and
supporting this suggestion with a scheme of potential
energy curves *
It should be emphasized that the values 11*08
or 11*11 e*v* for B0(OO) stand In excellent agreement
with the value 170 keal* for 1(0)* The only question
not completely answered Is whether there is any reliable
evidence for a lower value of D0(GO)*
In the final analysis, much of the controversy
is centered about a predissociation, reported by Gero
(14), in the A *7T electronic state of carbon monoxide
«*1
at 9*61 e*v* (77500 cm ) above the ground state* The
question la not entirely one of interpretation, but
partly on© of reality or non^reality of the supposed
anomalies* Apparently, no other investigator has been
3
able to reproduce 0©r©fs results. Furthermore, some of
the apparent Intensity anomalies In the fourth positive
bands supposedly affected by this predissociation might
well be the result of superposition of M3AW bands upon
the fourth positive bands In Question* This objection
has been raised by G&ydon (11)*
It should be pointed out that a ll ©f the
discordant opinion about the carbon monoxide spectrum has
12
been baaed upon the spectrum of 0 0 • However, this Is
not the only form in which the carbon monoxide molecule
occurs. The present availability of C1-* is sufficient
ix 16
to warrant investigation of the C ^0 spectrum.
In particular, considerations of the isotope
effect indicated to Professor Gloekler and the author
that the supposed predlssoclation at 9*61 e«v«, if
13 1^
real, should appear in C ^0 fourth positive bands
which would be more favorably situated with respect to
the **3AM bands.
Therefore, in order to open a new approach to
the solution of this problem, it was decided to begin an
i , id
Investigation of the electronic band spectrum of G JQ .
As an in itia l step in this investigation It was deemed
necessary to study the carbon isotope effect in the
spectrum experimentally, in order to locate and assign