THE NEA R INFRARED SPECTRA
OF
D E U T E R I U M C H L O R I D E A N D NITRIC O X I D E

by
Beverley Hall Van Horne

AN ABSTRACT
Submitted to the School for Advanced Graduate Studies
Michigan State University of Agriculture and
Applied Science in partial fulfillment of
the requirements for the degree of
D O C T O R OF PHILOSOPHY

Department of Physics and Astronomy
1957

Approved

Beverley H. Van Horne
ABSTRACT
The first (2-0) and second (3-0) overtone bands of DC1 have
been obtained with high dispersion in the 2. 4 and 1. 6 micron regions
The (3-0) band of Nitric Oxide at 1. 8 microns was obtained with
increased resolution and the molecular constants re-evaluated.
The molecular constants obtained for DC1 are:
DC 1 35

D C 1 37

B

5, 449~cm *

Ie

5. 1354 x 10"40g - c m 2

re

1. 274^
4 x 10”8c m

we
wgxe

5.432 cm.-*
5. 151^ x 10"40 g - c m 2
1. 274c
5 x 10~^c m

2144. 77 c m ” ^

2141, 82 c m *

26. 92 c m - *

26.99 c m ”*

0. 036 c m

*

0. 063 c m

*

The values for the rotational constants, B g , Ie> and r^ are
essentially in agreement with those obtained by Pickworth and
Thompson for the fundamental band.

These data also agree

with values calculated from the data for HC1.
The (3-0) band of N O was resolved sufficiently to obtain
good frequencies on all lines of

branches for both sub-

bands through J - 45/2 and 37/2 respectively.

The Q branches

were resolved but due to their overlapping only one line in the

and two lines in the

branches -were measurable.

The data

'was more reliable than previous work, largely because of a
Fabry-Perot fringe calibration system.

The molecular constants

obtained are listed as follows:
r2,

r T f 1/2)
<B o>eff

3/2>

1.6720 c m
1. 7 197 c m

Bo

1. 6958 c m

b3

1. 6433 c m

B

1. 7044 c m
.0174 c m
16. 422 x 10
1. 1509

-40

gm-cm'

x 10'° c m

THE N E A R INFRARED SPECTRA
OF
D E U T E R I U M C H L O R I D E A N D NITRIC O X I D E

by
Beverley Hall Van Horne

A THESIS
Submitted to the School for Advanced Graduate Studies of
Michigan State University of Agriculture and
Applied Science in partial fulfillment of
the requirements for the degree of

D O C T O R OF PHILOSOPHY

Department of Physics and Astronomy
1957

Approved

0 .

1 9 ..

—

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ACKNOWLEDGMENTS

The author wishes to express his sincere
thanks to Dr. C. D. Hause for his guidance and
encou r a g m e n t .

Indebtedness is also expressed

for his continual efforts to improve and enlarge
the usefulness of the vacuum infrared spectograph
which made this work possible.

It is through his

efforts also that grants were obtained from the
Research Corporation for the support of this
research.

The author wishes to express his

gratitude to the Research Corporation for their
grants which provided financial support for this
work over a period of two y e a r s .

TABLE OF CONTENTS

INTRODUCTION

page
1

General

1

Deuterium Chloride

1

Nitric Oxide

2

THEORY

4

Deuterium Chloride

4

Ground State

4

Vector Model and Energy Relations

5

Determination of Constants

5

Rotational

5

Vibrational

5

Nitric Oxide

7

Ground State

7

Vector Model and Energy Relations

7

Determination of Constants

9

Rotational

9

Vibrational

9

APPARATUS
V a c u u m Infrared Spectrograph

10
10

Optical Components

10

Sources

12

Detectors, Amplifiers,and Recorders

12

Page
interferometric Calibration System

13

Description of Components

13

Alignment and Use

15

Absorption Cells

17

E X P E R I M E N T A L DETAILS

18

Deuterium Chloride

18

2-0 Band

18

3-0 Band

18

Nitric Oxide

20

3-0 Band

20

R E S U L T S A N D DISCUSSION

23

Deuterium Chloride

23

Wave Numbers for 2-0 and 3-0 Bands

23

Vibrational and Rotational Constants

29

Band Origins for 2-0 and 3-0 Bands

29

Evaluation of B Qt B 2. and B 3

34

Evaluation of B e ,

36

Ig , and rg

Calculation of coe,coexe , ^ eYe

^6

Isotopic Relationships

37

Nitric Oxide
Wave Numbers of the 3-0 Band Line Intensities 39
Vibrational and Rotational Constants

42

Band Origins of T w o Substates

42

Evaluation of B Q and B^

48

Evaluation of B e , ocQ f le, and r£

52

Conclusion

55

BIBLIOGRAPHY

56

LIST O F F I G U R E S
Figure

Page

1.

Nitric Oxide (Hund's Coupling Case "a")

2.

Optical System of Spectrogr aph

11

3.

Block Diagram of Detection and Recording System
for V a c u u m Infrared Spectrograph

14

4.

3-0 Absorption Band of DC1 at 1. 64 microns

19

5.

3-0 Absorption Band of N O at 1. 8 microns

21

6.

Graph of 2-0 Band Origin for D C l ^

26

7.

Graph of 2-0 Band Origin for D C l ^

27

8.

Graphical Determinations of B Q for DC1

31

9.

Graphical Determination of B

32

for DCl^^

8

10.

Graphical Determination of B g for DC1 37

33

11.

Graph of the 3-0 Band Origins for N O

43

12.

Graphical Determination of B^(l) for N O

45

13.

Graphical Determination of B^(2) for N O

46

14.

Graphical Determinations of B Q for N O

47

15.

Graphical Determination of B g for N O

51

LIST O F T A B L E S
Table

Page

I

W A V E N U M B E R S F O R T H E 2-0 B A N D O F DC1

24

II

W A V E N U M B E R S F O R T H E 3-0 B A N D O F DC1

25

III

C O M B I N A T I O N S U M S F O R DC1

28

IV

COMBINATION DIFFERENCES FOR L O W E R
S T A T E O F DC1

30

R O T A T I O N A L C O N S T A N T S F O R DC1

35

VI

V I B R A T I O N A L C O N S T A N T S F O R DC1

35

VII

COMPARISON OF THE OBSERVED M O L E C U L A R
CONSTANTS WITH THOSE C A L C U L A T E D O N THE
BASIS O F A N ISOTOPIC SHIFT
38

VIII

I S O T O P E SHIFT

V

38

IX

W A V E N U M B E R S (P B R A N C H ) O F 3-0 B A N D O F NO 40

X

W A V E N U M B E R S (R, Q B R A N C H E S ) O F 3-0 B A N D 41

XI

C O M B I N A T I O N S U M S F O R 3-0 B A N D O F N O

44

XII

ORIGINS F O R T H E 3-0 B A N D O F N O

44

XIII

C O M B I N A T I O N D I F F E R E N C E S (BQ) 3-0 B A N D
OF NO

49

M O L E C U L A R C O N S T A N T S F O R NITRIC
O X I D E (B3)

50

M O L E C U L A R C O N S T A N T S F O R NITRIC
O X I D E (Bq)

50

XIV

XV

INTRODUCTION
General
The spectra of two diatomic molecules, deuterium chloride
and nitric oxide were studied in the near infrared by means of
a high resolution vacuum recording spectrometer.

T w o rota­

tion -vibration bands of deuterium chloride were examined; the
2-0 and the 3-0 bands, at 2. 4 and 1. 6 microns respectively.
One band of nitric oxide, the 3-0 band at 1. 8 microns was obtained
at higher resolution than previously and the constants re-evaluated.
In 1953 Pickworth and Thompson^ re-examined the fundamen­
tal band of deuterium chloride at 5 microns.

This had previously

been obtained under low resolution by Hardy, Barker, and Dennison

2

in 1932.

The work of Pickworth and Thompson gave more

reliable rotational constants since they were able to obtain with
good resolution lines out to J - 16.

The present work includes

results of an investigation of the first and second overtone bands
of DC1 at 2. 4 and 1. 6 microns respectively.
In 1939, Nielsen and Gordy 3, and Gillette and Eyster 4 pub­
lished the results of investigations of the fundamental of nitric
oxide.

Gillete and Eyster

4

gave a complete analysis of the obser­

ved structure and obtained the vibrational and rotational constants
of the molecule.

In 1955 Nichols, Hause and Noble

5

analyzed

the first (2-0), and the second (3-0) overtone bands and obtained

-2-

the molecular constants.

The envelope of the third overtone

(4-0) was also obtained and its origin determined.

A comprehensive

survey of all previous work on the ground state of NO, including
the results from the electronic bands, is given by Nichols. ^
More recently, Shaw

7

has re-examined the fundamental at 5. 3

microns with increased resolution and re-evaluated the molecular
constants.
The present work includes a re-examination of the 3-0 band
at 1. 8 microns.

The purpose of the investigation was to search

for evidence of lambda-type doubling in the infrared spectrum.
The magnitude of the expected splitting could be predicted from
the micro-wave studies of Burrus and Gordy 8 , and of Gallagher,
Bedard, and Johnson. ^ The doublet separation of the 2 tT(l/2)(
J = 1/2

J = 3/2 line as observed by them was 355 Mc/sec.

(0. 012 c m

^).

Although the direct splitting would not be observ­

able even with the increased resolving power available, its presence
presumably might be detected by combination defects employing
the Q branches.

Unfortunately the intensity falls off so rapidly

in the component showing observable doubling, C~ff\ /2)» that
this could not be verified.
The 3-0 band of N O was, however, obtained with better

-3-

resolution than previous studies and so was analyzed and the
vibrational and rotational constants re-evaluated.
The work on each molecule will be discussed separately.

-4THEORY

Deuterium Chloride
Deuterium chloride, a diatomic molecule ’
with an even n u m ­
ber of electrons (18), has a ground state of the ^ ^\

type.

This

is a state of zero resultant spin angular m o m e n t u m and zero
orbital angular momentum.
For such a simple molecule the non-rigid rotating vibrator
becomes an acceptable model.

The total energy of the molecule

(expressed in wave numbers) m a y be written as the sum of three
terms; the electronic energy, vibrational energy, and rotational
energy.
T - T ej -f- T Vik

T rot

eq 1

The rotational energy or term value for the rotational motion
is given by:
F(J) = B v J(J+ 1) - D v J 2 (H-1)2

eq 2

where J is the rotational quantum number, and :
B v = B e - OCe (v-t- 1/2),

Be =

h
8 7T^ Ie c ,

Ie =/ /re

ecls 3

D v r centrifugal stretching constant
The subscripts indicate the dependence of the rotational constants
upon the state of vibration.

-5-

The anharmonic approximation is necessary for the vibra­
tional energy.

The term value is given by:

G (v) = LOe (v -+*1/2) -fiJexe (V -f-1/2)2h- «A>eye (v + 1/2)3

. .eq 4

For a vibration-rotation band in the infrared no change occurs
in the electronic state.

The frequency (in c m “l) emitted or

absorbed is given by
V = G '(v) - G" (v) -b F ’(J) - F" (J)

eq 5

where the single prime refers to the upper state and the double
prime to the lower state.
Performing the indicated subtraction of the G terms one
obtains:
2^ G (v' -v") - iOe - 2 LGexe (v -t*1) -+■3 OJGye (v^+ 2v ■+ 13/ 12) ..eq 6
The rotational transitions for ^2* states are governed by the
selection rule,

^ J : T 1, resulting in two branches called the

P and R branches.
If thevibrational change, j£,G, is indicatedby

-j/0 , the band

origin, the observed frequencies are given by:
U - t £ + ( B v ,+ B v „ ) m . (Bv , - B v „ + D' - D " ) m 2 - (D' + D " ) m 3

m = ^1, +2, T 3, ....

..

eqs 7

When m = -J or -1, -2, etc. , one obtains the P branch; P(l),
P(2), etc. . When m = J-f-1 or +1, -f-2, etc. , one obtains the R
branch; R(0), R(l), etc. . The P and R branches form a single

series with a missing line at the band origin corresponding
to m

- 0.

Since the vibrational intervals are m u c h larger than
♦

the rotational intervals energywise, a vibration-rotation band
is observed as rotational fine structure in the region correspond
ing to the vibrational energy change.

-7 -

THEORY
Nitric Oxide
Nitric oxide is the only stable diatomic molecule having
an odd number of electrons.

Thus the resultant spin, S, and

its projection on the internuclear axis,
This spin vector combines with

, must be half-integral.

A, the projection of L,

the

orbital angular m o m e n t u m vector, on the internuclear axis, in
either of two directions resulting in a ground state of two components.

aA

These substates are

2

7Ti/2 and

?
773 j2^, indicating

value of 1.

Modes of coupling of the electronic orbital angular m o m e n ­
tum, L, and spin, S, with rotation, N, of the molecule about an
axis perpendicular to the inter-nuclear axis were first considered
by Hund^.

In Hund's case "a" the interaction of electronic motion,

both spin and orbital, with nuclear rotation is weak, while the
coupling of electronic motion with the internuclear axis is strong.
This is shown in the vector schematic of Figure 1.

Expressions

for the energy of the molecule in intermediate coupling cases
were first derived by Hill and VanVleck

11
. Since N O approaches

case "a" coupling it is possible to expand these expressions and

-8-

\

NITRIC

OXIDE

(HUND'S

FIGURE

I.

COUPLING CASE "a")

-9-

obtain adequate relations for the energies of the substates.
These are as follows:
Tj - T e - A/2 + Gj (v) + B v (l)/4 + B V (1)J(J+1)

( 7Ti/2)

-D v (1)J2(J-»-1)2+ ...eqs 8
<27r3/2>

T 2 = T e + A / 2 + G 2(v ) + 7 B v(2)/4-»-Bv(2)J(J-t-l)
-D v (2)J2(J + 1)2 .......

The B v (i) and the D v (i) appearing in these equations are effec­
tive values and are related to the actual rotational constants of
the molecule by the following relations:
B v

= <B V 1 +

B V 2 )/Z

D V

= <D V l -<- d v 2 ) / 2

e9 s 9

Allowed frequencies emitted or absorbed by the molecule are
given in general by the difference between two expressions for
T| or T^ (AS = 0).
tion has occur^d.

If the T g terms differ, an electronic transi­
Different v's refer to the vibrational energy

change, different J's to the rotational energy change.

For the

3-0 band of the vibration-rotation spectrum of N O the electronic
state, the ground state, does not change, v assumes the values of
0 and 3, and J assumes half-integral values beginning with either
1/2 or 3/2.

Observed frequencies are governed by the selection

rule A J = 0, * 1.

-10-

APPARATUS
Spectrograph
The vacuum infrared spectrograph used in this work was
built and previously described by Noble
operates at f/5.

This instrument

(See Figure 2) For the work with deuterium

chloride it was equipped with a Bausch and L o m b 15000 line per
inch grating blazed at 1. 5 microns.

A Baird Associates phase

sensitive amplifier and chopper system was installed.

The

chopper generator which operates at a frequency of 450 cycles
per second was placed inside the vacuum tank just in front of
the entrance slit.

The detector was a lead sulfide Ektron (Kodak)

cell and for the work with DC1 was placed directly in back of the
exit slit.

Various other refinements were made in the mounting

of the optical elements.

A 100 watt zirconium concentrated arc

was used as a source.
During the course of the work further improvements were
made on the spectrograph.

Most important of these was the

installation of a Fabry-Perot etalon to allow simultaneous record­
ing of fringes for calibration.

This is described separately below.

For the work with the 3-0 band of N O the multiple traverse cell

-11

TdJ> 0>
-ft P

O X;

Q> CO
o o

Q. E

c

CL
XI

CO
jO

CL

o

a>

Fig ur e 2

OPTICAL. S Y S T E M O F S P E C T R O G R A P H

- 12-

was used and in order to obtain sufficient radiation through the
system a 300 -watt concentrated zirconium arc source was used.
A new narrower lead sulfide detector was installed for increased
resolution.

A Bausch and L o m b grating, 6" by 8M, with 10000

lines per inch was also installed.

This has a theoretical resolv­

ing power in the first order of 60, 000.

It is blazed at 39° or

about 3 microns and was used in the second order for the investi­
gation of nitric oxide.

-13-

FRINGE CALIBRATION S Y STEM
In the work with deuterium chloride a Fabry-Perot etalon
with a 3 m m .
entrance slit.
apart.

spacer was placed in parallel light in front of the
This gave equally spaced fringes about 1. 6 c m

^

The actual value of this constant fringe separation was

secured from the super position of known second-order argon
emission lines on all runs.

These same lines were used as refer­

ence points when superimposed on the DC1 records.

Later, the

present system was built which incorporates the Fabry-Perot
etalon into the optical system of the spectrograph and places it
inside the vacuum tank.

By means of a two-pen L and N strip

chart recorder the calibration Fabry-Perot fringes were recorded
simultaneously with the spectra.

Figure 2 shows a rough sketch

of the optical system with the fringe system incorporated.

The

block diagram shown in Figure 3 gives the relationship of the
associated pre-amps, amplifiers, and power supplies.
In order not to interfere with the infrared signal the incoming
light from a 100-watt concentrated arc lamp was brought into
the entrance slit low and the mirror at the exit slit was placed
above the position of the infrared signal.

The Fabry-Perot etalon

-14-

W
E-i

co

>s_,

r1
CO

a

z
i
—i
Q
pel

o

m

u
w
Q
Z
<
CO

Z

o
►—I

H
u
w
H
W
Q
(j-t
O

1H
On

<

pti

a

O
pel
EH

U
w
cu
to
Q
W
Pd
<
Pd
Oh
£
D
u
<:

>
fM

<
Pd
a
<
i
—i

o

450 cps

w
u
o
n
CQ

<u
3
0/)
Oh
•p H

-15-

v^as placed on an adjustable mount in parallel light from the
exit beam.

Suitable collimating lenses were employed and the

b e a m emerged from the last lens, through the wall of the tank
to a 1PZ1 photomultiplier just outside the tank window.

It was

found necessary to completely shield this photomultiplier from
all stray light, and to build a low noise level preamp.

A special

regulated power supply for the photomultiplier high voltage supply
was also found desirable.

To reduce the number of orders received,

optical filters were placed in front of the photomultiplier.

In

the 1.8 micron region a light yellow filter was very satisfactory.
Alignment of the Fabry-Perot fringe system for m a x i m u m
modulation is done visually.

The photomultiplier is replaced by

a magnifying eye-piece and a mercury arc placed at a point back
of the exit slit such that it was plainly visible through the system.
The position of the line with respect to the fringe pattern was
adjusted by moving the adjustable base of the etalon.

When the

image is seen in the central zone of the Fabry-Perot fringes and
centered the modulation will be a maximum.

The mercury arc

is then removed and the eyepiece replaced by the photomultiplier.
With the zirconium arc in operation final adjustments were made

-16-

on the photomultiplier by observing the recorder signal and peaking
the system from this signal.

With proper adjustment a modula­

tion of 80% or better was available.
The regular arc source supplied known argon emission lines
in most regions.

These were superimposed on the infrared record

and together with the adjacent fringes provided an excellent
calibration.

Thus the measurements were independent of paper

stretch or gear irregularities.

The measured number of fringes

and fractions thereof between any two known argon lines yield
a constant for the fringe separation in wave numbers per fringe.
Being adjacent to the spectrum to be measured the accuracy of
line frequency determination was greatly enhanced.
This completed system of calibration was utilized for the
run of the 3-0 band of nitric oxide.

-17-

ABSORPTION CELLS
For the 2-0 band of DC1 it was only necessary to use a sample
glass cell 40 cm. long.

This consisted of a glass tube about

6 centimeters in diameter with provisions for clamping the end
windows securely and a side tube with a stopcock for filling.
The 3-0 bands of DC1 and N O both were obtained by use of a
multiple traverse absorption cell of the White type.13 This cell
was built by Nichols^ who describes its construction details.
Its mirrors are about 6" in diameter and have a 35 cm. separation.
The f-number of this cell is f/5 and it was designed to match the
relative aper^tture of the spectrograph.
with over 100 traversals.

This cell has been tested

However the signal after so many

reflections is so weak that for practical work only 40 traversals
were used.

If 30 traversals are chosen the absorption path length

of 30 x 35 centimeters gives about 11 meters of absorption path.

-18-

E X P E R I M E N T A L DETAILS

Deuterium Chloride

The gas -was prepared by the use of acetyl chloride.
reaction was:

C H ^ C O C L 4-D^Q - ■» C H ^ C O O D + DCL.

The
This

reaction was carried out in a vacuum to help eliminate H^O.
The 2-0 band was obtained by using a 40 c m absorption cell.
This was filled to a pressure of 35 c m Mercury and gave a
m a x i m u m absorption of approximately 20%.

For the 3-0 band

it was necessary to use a multiple traverse cell of the White 13
type.

An adjustment of the cell for 30 traversals and a gas

pressure of 15 cm.
meter atmospheres.
was about 15%.

Mercury gave a total absorption path of 2
The m a x i m u m absorption for this band

In each case a 100-watt concentrated arc was

used as a source.
Calibration was obtained by the use of Fabry-Perot fringes.
A n etalon with a 3 - m m spacer was placed in parallel light in
front of the entrance slit, giving equally spaced fringes about
1. 6 c m -^ apart.

The actual value of this constant fringe separa­

tion was secured from the superposition of known second-order
argon emission lines on all runs.

These same lines were used

as reference points when superimposed on the DCL. records.
Figure 4 shows a portion of the 3-0 band and a tracing of the fringe
pattern used in calibration.

3-0

Absorption

of

Figure

Bond

D Cl

ot

164

p

-19-

-20-

E X P E R I M E N T A L DETAIL

Nitric Oxide

The nitric oxide gas used was from a tank obtained from
the Matheson Gas Company.

A purity of 99 percent was claimed

and thus it was used direct from the supplied tanks.

The multi­

ple traverse cell described above was set for 24 traversals and.
filled with N O to an approximate pressure of 25 cm, of Mercury.
This gave about 2. 8 meter-atmospheres of absorbing path.
300 watt zirconium concentrated arc source was used.

A

This

gave adequate signal and a m a x i m u m absorption of approximately
30 percent was realized in the P and R branches of the 3-0 band.
Several records of the 3-0 band were obtained and of these
three were chosen and complete measurements of the line fre­
quencies were obtained.

These records were run at the grating

rotation speed of 1. 25 minutes of arc every 60 sec.

The two

sets of data from the runs with the narrowest slit widths--less
than 50 microns --were chosen.

These are listed as the records

of March 11th and March 12th.

Figure 5 shows a similar faster

run through the 3-0 band taken for illustration purposes and of
lower resolution than those measured.

-LI-

3

-22-

Each of the records was a simultaneous record of the 3-0
band of N O and of Fabry-Perot fringes spaced an equal number
of wave numbers apart.

Two argon emission lines appeared

superimposed on the N O record.

These lines were 12112. 20

A° (5502. 54 cm~^) and 9122. 966A° (5479. 171 c m -^) and were
23. 37 c m -^ apart.

The number of calibration fringes between

these two argon lines was carefully measured to the nearest
0. 02 of a fringe.

The measurements on the spectral lines were

made using this measured constant of the wave numbers between
fringes.

The constant used for the measurement of frequencies

was 0. 5361 c m -* per fringe.

-23-

R E S U L T S A N D DISCUSSION

Molecular Constants of Deuterium Chloride

The observed frequencies of DC1 are shown for the 2-0
band in Table 1 and for the 3-0 band in Table 2.

All lines showing

evidence of any disturbance from close neighbors or overlapping
were rejected.

In all cases the frequencies listed are averages

from two records.
DC1

It should be noted that overlapping of the

35 .
37
isotopic species lines with the DC1
lines prevented

accurate determination of the position of several of the lines.
The frequencies of all such lines have been indicated in paren­
theses as approximate values.
The molecular constants were obtained by standard graphical
and least squares methods.

Typical graphical determinations

of the band origins are given for the 2-0 band in Figures 6 & 7.
As mentioned in the foregoing all the origins were verified by
a least squares fit to the data.

The ordinates of Figures 6 & 7

are plotted as suggested by Herzberg^ on a much expanded
scale.

This is obtained by subtracting 2(B'-B")avJ2 from the

combination sums.

The combination sums used in the origin

plots are given in Table III.

The relationship shown in the

plots is expressed by the equation
R(J-1)+P(J) - 2(B'-B”)avJ2 = 2 \JQ - 2 A(B'-B")J2.

eq. 10

-24TABLE I
2-0 BAND LINE POSITIONS

DC1

35

R-branch______________
J

0
1
2
3
4
5
6
7
8
9
10
11
12

Observed_____ Calculated
4138,88
4148 a80
4158.24
4167.22
4175,70
4183,80
4191,33
4198,46
4205.13
4211„27
4216.97
4222,20
4226.87

(cm"1 )

4138.91
4148.80
4158.23
4167.20
4175,72
4183.77
4191.35
4198.46
4205.10
4211.26
4216.94
4222.14
4226.84

P-branch
Observed

Calculated

4117,74
4106,57
4094.92
4082.81
4070.24
4057.26
4043.84
4030.00
4015.79
4 0 0 1 o10
3986,04

4117.78
4106.55
4094,88
4082.77
4070.23
4057,25
4043,85
4030.02
4015.77
4001.10
3986.02

4111.88
4100.72
4089.09
4077,05
4064.50
4051.61
4038.27
4024.49
4010.29
3995 o72
3980,59

4 1 1 1 o93
4100 u73
4089..10
4077,04
4064,54
4051„61
4038 o26
4024 .49
4010,30
3995.70
3980,68

PCI37

0
1
2
3
4
5
6
7
8
9
10
11

4133.03
4142,90
4152.34
4161.28
4169,80
4177,75
4185.35
4192.44
4199.03
(4205.13)^
(4211.29)

4132,99
4142.85
4152.26
4161.22
4169.72
4177.76
4185,33
4192.44
4199.08
4205.24
4210.93

a These lines overlapped by R(8)

and R(9) of PCI

35

-25TABLE II
3-0 BAND LINE POSITIONS

DC1

35

R-branch
_J

Observed

0
1
2
3
4
5
6
7
8
9
10
11

(6123.05)
6132.38
6141.13
6149.27
(6156.55)
6163.46
6169.45
6174.74
6179.39
(6183.23)
6186.67
6189.25

P-branch
Calculated
6122.91
6132.36
6141.13
6149.23
6156.65
6163.39
6169.44
6174.80
6179.47
6183.44
6186.71
6189.28

PCI

0
1
2
3
4
5
6
7
8

6114.24
(6123.99)
(6132,35)
(6141.13)
6147.98
6154.64
6160„80
(6166.14)
(6170.76)

(cm 1)

6114*. 37
6 1 2 3 i78
6132.52
6140;59
6147;98
6154 %68
6160 a70
6166.03
6170,67

Observed

Calculated

(6102.15)
(6090.70)
6078.49
6065.69
6052.23
(6038.09)
6023.43
6008.07
5992.20
(5975.69)
5958.23

6102.01
6090.56
6078.45
6065.68
6052.27
6038.19
6023.48
6008.12
5992.12
5975.48
5958.21

6093 o65
6082.15
6070,07
(6057,08)
(6044.10
6029:84
(6015.41)
(5999.98)

6093;53
6082.11
6070.04
6057:31
6043:92
6029:89
6015;20
5999.88

37

-26-

IO

CM

ro

O
Q

O

lO

V.O
0)
u
3
tJO

00
OJ

•rH

rin
&
00

r

*

<M
CO

(Dd-(i-nd

<\J

00

27

-

Band

D Cl

-

2-0

Figure

CJ

a

m

in

in

§

§

00

pm

? * (Dd” - (i-o a

00
&
00

- 28-

TABLE III
COMBINATION SUMS FOR DC1

J2
1
4
9
16
25
36
49
64
81
100
121

J2
1
4
9
16
25
36
49
64
81
100
121

(2-0)DCl35
8256.62 cm ^
8255.37
8253.16
8249.99
8245.94
8241.06
8235.17
8228.46
8220.92
8212.37
8202.99

(3-0)DC1
12225.20
12223.08
12219.62
12214.96
12208.78
12201.55
12192.88
12182.81
12171.59
12158.92
12144.90

(2-0)DC137
8244.91
8243.62
8241.43
8238.33
8234.30
8229.36
8223.62
8216.93
8209.32
8200.85
8191.88

(3-0)DC137
12207.89
12206.14
12202.36
12198.21
12192.08
12184.48
12176.21
12166.12

-29-

The Y-intercepts give the origins, and the slopes are propor­
tional to the needed added correction,
difference of the B-values chosen.

^<B' -B"). the average

This furnishes an additional

check on the value of the rotational constants obtained from the
combination differences.
Final values of the rotational constants ’
were obtained from
combination differences.

While a least squares fit to these data

was obtained for each of the constants as a final value, a graphical
determination was also made in each case.

Figure 8 shows such

a graphical determination of the B q values of the two species
plotted from the data shown in Table IV of the combination
differences for the lower state.
The B v values thus obtained are plotted against v, the
vibrational quantum number, to give B e , the equilibrium rotational
constant.

Such a plot is shown in Figure 9 for the DC1

cule and in Figure 10 for DC1

37

35

mole-

. The relation is expressed by

the equation
Bv - Be

®Ce (v -+■1/Z)
'.

eq.
^ 3a

The values for B^ are taken from the results of Pickworth and
Thompson.

The slope of the line determines oce > a measure of the

dependence of B v on the vibrational state .

-30-

TABLE IV

B Q COMBINATION DIFFERENCES

PCI

J
1
2
3
4
5
6
7
8
9
10

(2-0)
32.31
53.88
75.43
96.98
118.44
139.96
161.33
182.67
204 03
225.23

2F"

35

(3-0)
32.35
53.89
75.44
97.04
118.46
140.03
161.38
182.54
203.70
225.00

PCI
1
2
3
4
5
6
7
8
9
10

32.31
53.81
75. 29
96. 78
118.19
139.48
160.86
182.15
203.31
224.54

2F"

2F " ( A v e r a g e )
32.33=
53.88?
75.43
97.01
118.45=
139.99=
161.35=
182.60
203.87
225„12

37

32.09
53.92
75.27
97.03
118.14
139.23
160.82
—
—

—

32.20=
53.86
75.28=
96 ,90 =
118.16=
139.35
160.84
(182c15)
(203.31)
(224054)

-31-

DCL35
ro

B0= 5.3930 cm-1
O
00
OJ

CM

DCL37

CM

B0= 5.376s cm
Q
00
CM

CD

Li.
CM

L

Figure 8

-

o>

32

-

p

CVJ
to

in

IOk Q

CD

L_____

CM

ro

CM
in

I
Figure 9

-

33-

CD

IQlsQ

<

<

oih

CJl

—
01

F i g u r e 10

OJ
ro

-34-

Convergence and low intensity in the R-branch of the 2-0
band, and to a still greater extent in the 3-0 band, prevented
the measurement of any lines in this branch beyond J - 12 and
J = 1 1 respectively.

Since the combination differences which

are used in determining the rotational constants could not go
beyond these J-values it was not possible to secure accurate
values of D e, the centrufugal stretching constant.

The data,

however, at least as far as J=10, indicated no significant change
in this constant from the value given by Pickworth and Thompson. ^
The value of

and

^

given in Table V are those from

Pickworth and Thompson. ^ The remainder of this table summarizes
the results for the rotational constants and the band origins.
It includes the equilibrium moments of inertia, I , and the
O
equilibrium separation, r . The value of re=l. 274q x 10”° c m
and 1.274^ are in excellent agreement with the value obtained
by Mills, Thompson, and Williams*^ for HC1; re =l- 274^. x 10‘^cm,
The atomic masses used to obtain re were m^=l. 008142 and
m D =2. 0 147 35 and are taken from DuMond and Cohen

1R

. The

isotopic masses of chlorine due to Segre^ are m^.^35 = 34. 980175
and

= 36- 977624.

Using the rotational constants listed

£n Table V, the frequencies of the lines were calculated by

-35-

TABLE V
ROTATIONAL CONSTANTS FOR DC1

d 35 c l

d

37 c l

(2-0)

■%>=
4128.57 cm -1
o

(2-0)

jJo= 4122.68 cm -1

(3-0)

V 0 = 6112.79

(3-0)

-j/o = 6104.28

B

©

=

5.449

•CL =

B

o

e

.1 1 2 _

«

5.432..
1

-

.111„

(De =

1.374 x 10 4 )

(D e

(|5=

6

( ( 3 = 6

T

I

x

10- 7 )

=

C
TOC
^“ 40 gm-cm 2
5.135^
x t10

=

1.274.

x

10

cm

I

1.36. x 10 4 )
6
x

10- 7 )

- 5.151 6 x 10 ^ g m - c m 3

e

r = 1. 274(_ x 10
e
5

-8

TABLE VI
VI B R ATIONAL CONSTANTS
d

35 c l

d

= 2144.77 cm

C*3 X =
e

coe y e =

26 .92
.036

-1
e

3 'c l
= 2141.82 cm

M ? Xe =
*>ey e =

26.99
063

-1

cm

-36-

substitution in the following equation:
V=

m -(B’- B M ^ D ' - D " ) m 2
~(D' -h D " ) m 3 + (D'-D")m4 +

eq. 7

These are given in Tables I and II along with the observed
value s.
Since the publication of the above, the work on DC1 in the
submillimeter microwave region by Cowan

Gordy 17 yields

for D C l ^ , B e = 5. 4484 and re = 1. 27462 and for DCl^y,
Be
„ - 5. 4324 and r0 = 1. 27463 x 10-3 cm.

The values found

compare very well with these recent microwave values.
The position of band origins here obtained together with
that of the fundamental provided sufficient information to enable
solution for the three vibrational constants: cO^^^X^and

y e-

Substituting into the expression for the vibrational energy,
G(v) -uJ& (v + l/2) - W e X e (v + l/2)2+ w ey e (v + l/2)3+

.. ..eq. 4.

for the various vibrational states and subtracting successive
equations yields three difference equations of the form,
G (v’-v") =

-2

< e (v + 1) -l-3c<Je y e (v"Z + 2v" -*-13/12)+.. . eq. 6

The results of solving these three equations are given in Table VI.
The assumption of identical electron configurations for the
HC1 and DC1 isotopic forms makes the isotope shift a function

-37-

of m a s s alone.

The justification for this is shown in Tables

VII and VIII where the expected values of the constants and band
positions calculated from the isotope shift are compared with the
observed values.

If

is defined as the ratio of the square roots

of the reduced isotopic masses,
and B g as

0 varies as

,CcAx~
^ C as

,

. The frequency shift can be expressed with

sufficient accuracy using only the first two vibrational constants
by the equation from Herzberg^ as follows:
A if - (1- f*

" 6Jexe ^

The results are shown in Table VIII.

J

v

"

£^>exe (

0q‘

1

The agreement is within

experimental error.
For the constants which are accurately determined the
variation occurs in the 5th place which is probably all that can
be expected from the data.

The individual frequencies through­

out the two regions are felt to be good to t 0. 05 c m -^.
undertainty in the values for B e is i 0. 0005 c m “l.

The

1

1

-38-

Table VII
d

D

Calculated

2144.77

B

_35_,t

35 c l - h 35 c l

Observed

>eXe

Isotope Shift

o

37

2141.61cm"1

26.99

5.449.

Table VIII

d

26.84

5.432,

o

1

Isotope Shift

35 c l -

d

CL

Calculated

2141.82

26. 77

5. 4 4 9

5.433

o

(Al))

37 c l

Observed

Calculated

to
i
o

Band

Observed

2 1 4 4 . 4 7 c m -1

26. 9 2

CL - D

5. 89cm ^

5.84cm ^

+ .05

3-0

8. 51

8. 52

- .01

d

35 c l -

h

35 c l

1539.98cm_ 1

1539.49cm ^

+ .49

3-0

2234.19

2233.41

+

00

2-0

-39-

R E S U L T S A N D DISCUSSION
Molecular Constants of Nitric Oxide

The ground state of the N O molecule is a

V7~ state and

thus the 3-0 rotation-vibration band at 1. 8 microns consists of
t^o sub-bands corresponding to energy transitions in the
2 7 T (1/2) and 2 T T (3/2) sub state s.

separate P, Q, and R branch.

Each sub .-band has a

The separation of the two sub­

states is only about 1Z3. 8 c m - ^.

The Q branches are therefore

crowded and their detail not resolved, except that it was possible
to measure the first line of the Q(l/2) branch and the first two
of the Q(3/2) branch.
The lines of the two substates in the R branch were well
resolved as far as J = 11/12, but beyond this J value the two
species merged to the extent that only a single frequency was
obtainable for R branch lines from J = 13/2 to J = 45/2.

(see

Figure 5. ) The lines of the P branch diverge and were farther
apart so that the frequencies of the lines of each substate were
easily obtained.

These are given in Table IX and those of the

R and Q branch are shown in Table X.

-40 -

TABLE IX

J + 1/2
P1
l2_

Wave Numbers From
Record of Mar. 11
**

2

4
4

5528.21

6

5524.42

7

5520.54
5516.51

5516.57

5512.34

5512.42

5508.20

5508.17

5503.84

5503.82

5499.38
5494.85

5494.90

5490.26

5490.30
**

14

5483.09

5478.08

5478.12
**

**
**

17

5473.00
5470.73

5470,66

18

5483.06
5480.65

5480.68

17

5487.94*
5485.50

5485.55
15
16

**

**

13

16

5497.3 5

5497.41

12

15

5501.93

5501.96
5499.41

14

5506.34

5506.46

11
13

5510.77

5510.76

10
12

5515.04

5515.05

9
11

5519.11

5519.14

8
10

5523.19

5523.24
5520.54

9

5527.11

5527.14
5524.45

8

5530.88

5530.89

5
7

5534.65
5531.94

5528.30

6

**

18
5465.54

-1
**

**
5531.97

5

cm

5535.49

553 5. 58
3

19

5539.04
**

2
3

Wave Numbers From
Record of Mar. 12

**
5465.54

**Lines obscured by H 00 ljLnes
L
* H 20 line at 5488.20 cm

-41-

TABLE X
WAVE NUMBERS FOR 3-0 BAND OF NO
J + 1/2
1

Wave Numbers From
Record of Mar. 11
5548.92

2
2

5551.54
5551.98

3
3

5554.63
5555.01

4
4

5557.64
5557.89

5
5

5560.42
5560.66

6
6
7*
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23

5563.28*
5563.28
5565.86
5568.33
5570.73
5572.99
5575.15
5577.19
5579.14
5581.00
5582.77
5584.38
5585.88
5587.34
5588.63
5589.85
5590.94
5591.90
5592.81

Wave Numbers From
Record of Mar. 12
5548.95 cm-1
5551.55 cm -1
5551.99
5554.64
5554.99
5557.60
5557.86
5560.43
5560.66
5563.14
5563:27
5565.81
5568.34
5570.70
5572.93
5575.13
5577.20
5579.14
5580.95
5582.74
5584.32
5585.89
5587.34
5588.60
5589.83
5590.95
5591.89
5592.82

*The two R components were unresolved
from this line on through higher J value.
1/2

Qi Q:

Wave Numbers F r o m
Record of Mar. 12.
5544. 09 c m

-1
5543. 24 c m
5542.94

-

1

-42-

In general the intensities of lines in the P and R branches
showed that the
stronger than 2

-/l
^(l/2) state lines were from 20 to 5Q percent
(3/2) lines of corresponding J value.

In

contrast to this the stronger lines of the Q branch are those
of the

7T (3/2)

substate.

This result agrees with the

intensities calculated from the Honl and London formulae quoted
by H e rzberg^ on page 422.
The molecular constants were found by graphical methods
as described above and these results checked by the method
of least squares.

The graphical determination of the band

origins are shown in Figure 11.

The combination sums used

in plotting the origins are shown in Table XI.

The 3-0 band

origins thus found are listed in Table XII and compared with
those previously found by Nichols, Hause, and Noble

5

and

4

Gillette and Eyster .
Figure 12 shows a graphical determination of B^(l), the
rotational constant for the upper state of the

7f(1/2) state.

Figure 13 shows the plot of B 3(2), for the 2 7V<3/2) state.
And Figure 14 gives the plots for the values of B q for each
component. It is to be noted that the vertical scale here is

-

43

-

cm '
55443-0

5543-

5542H

554H

BAND

ORIGINS

Comp.

5544.11 cnrf

Comp. 2

5543.44crrf

oo

oc

|C\1

5540

100
2
F i g u r e 11

-44-

TABLE XI
COMBINATION SUMS

2 -.25

R-^J-1)

+

March 11
2
6

12
20
30

42
56
72
90

110
132
156
182

210
240
272
306
342

—

R 2 (J-1)

11086.186
11085.521
11084.781
*11083.655
*11082.423
*11080.911
*11079.093
*11077.190
*11074.949
*11072.563

—

-

—

11056.620
11052.878

—

4 P 2 CJ )

March 11

11087.992
11087.477
11086.979
11086.068
11085.082
11083.806
11082.315
11080.681
11078.894
11076.772
11074.516
11072.054
11069.401
11065.907
11063.386

11087.564
11086.979
11086.191
*11085.109
*11083.816
*11082.433
*11080.750
*11078.895
*11076.810
*11074.568
*11072.087
*11069.443
*11066.549
*11063.444
—

P X (J)
Marchl2

March 12
1 1 0 8 6 .1 9 7 c m
11085.521
11084.701
11083.623
11082.245
11080.851
11079.110
11077.040
11074.864
11072.478
—

—
—
—

—
—

*11067.080**
11064.007
11060.812
11057.317

—

—

—

—

*Lines of this branch were not resolved from
this point on through lines of higher J value.
*Near H g O line
TABLE XII
3-0 BAND ORIGINS

vna
3-0 (1)
3-0 (2)

h

NHN

G SE

5544. 1 1 c m " 1

5544. 2 8 c m -1

5544 .2 1 c m “ ^

5543.44

5543.69

5543.35

-45-

CM

COMPONENT I
CVJ

1.6201

c m '1

ro

SCO

O
lO

ro

1.0

SOD
Q.

0/0

0.5

vhM/2
*
20
F i g u r e 12

-46-

IQ.

OJ

B3

1.5

IO

COMPONENT
I. 6 6 0 4

2

cm*1

o

lO

CD
fO

ro

JCD

J + l/2
F i g u r e 13

-47-

B,

0.3

Comp. I

00 0.2

B0(l) = 1.6720

cm-1

i o

O

0

CM °
Is^ - 0.1
* -

r%
a

°

Q

®

®

o o

o

O — q ---- q-

® —

o

0.21-

<3
0.3

Bo Comp. 2

00 0.2 +

Bo(2)= 1.7197 cm"1

3 o.i
(7)
r-

0

^-°

j

o

Q
° ~ 0

o

O

0

o

°

o

i

= CJ 2
Li_
C\J

J+l/2

<d .3
I

I

i

1

I

I

I

I

|

I

10
F i g u r e 14

|

I

I

I

1___ |___ I__

15

-48-

greatly exaggerated by subtracting from the second differences
a value equal to 4B q (J -f- 1/2).

The average combination differ­

ences used for this plot are given in Table XIII.

The rotational

constants for nitric oxide are listed in Tables XIV and XV.
Table XIV lists the values of

obtained and for comparison

the results quoted from Nichols, Hause and Noble

3

are included.

Table X V lists the results for B Q and includes three recent resuits.

The values of Palik and Rao 1ft from the pure rotational

spectra, the microwave results of Burrus and Gordy

Q

and the
Q

still more recent work of Gallagher, Bedard, and Johnson7
(Bq (1) = 1. 67 196), are especially to be noted.

The values

obtained for this constant agree very well with this recent work.
Figure 15 is a plot of the values of B v obtained against
v-t-1/2 in order to determine B e, the equilibrium rotational
constant.
and Noble

The value of B^ was taken from Nichols, Hause,
5

7
and B ^ value is that of Shaw . The value of B e

thus obtained (1. 7044 c m -1) is in very good agreement with the
recent work of Gallagher and Johnson
B

o

= 1. 69578.

Using the value of

a B e = 1. 7045 cm" ^.

who §ive a value of
just obtained this yields

-49-

T A B L E XIII
i.

J

A

tt"

* 2F 1

~

(Ma r. IB
3/2
5/2
7/2
9/2
11/2
13/2
15/2
17/2
19/2
21/2
23/2
25/2
27/2
29/2
31/2
33/2
35/2
J

13. 34cm" 1
2 0.00
26. 71
33.45
40. 13
46. 71
53.44
60. 16
66.91
73,58
80. 26
86.89
93. 59
100.32

A

F"
2 1

A 2F 2

(Mar. 12)
13. 4 6 c m ”1
20 06
26. 78
33.44
40. 12
46. 76
53.47
60. 15
66.86
73. 55
80. 28
86.94
93. 64
100.29

(Mar, 11)

2 0 .66c m -1
27. 54
34. 36
41. 33
48. 10
55.04
62 00
68 77
75. 59

'C' 'i*

89. 26
96. 08
102.88
109.74

96.05
102.88

^ 2F 1
(Average)
3/2
5/2
7/2
9/2
11/2
13/2
15/2
17/2
19/2
21/2
23/2
25/2
27/2
29/2
31/2

F"
2 2

(Mar. 12)

2 0 .65cm ^
27.49
34.40
41.27
48.23
55. 10
61 .87
68.77
75. 59

113.. 59
120.35

vV

A

13. 4 0 c m ” 1
20. 03
26.. 74
33.44
40. 13
46. 74
53.46
60. 15
66.88
73. 56
80 2 7
86.92
93. 62
100.31
;[<*
Lines missing due to H ^ O

=!«
-v»

V

-fi

't'

"I’**

"i"

*2 F2
(Average)
1

20.66 c m 1
2 7,52
34. 38
41 30
48. 10
55. 07
61. 93
68.77
75. 59
-

89.26
96. 06
102.88
109.74

-50-

TABLE XIV
ROTATIONAL CONSTANTS FOR N O
Infrared and Electronic Values

V 1)
1.6201
1.6150
1.6193
1.6199

M

2>

B.
1.6438
1.6408
1.6422
1.6414

1 .6664
1.6660
1.6651
1.6629

Source
*(3-0)Infrared VH & H
(3-0)Infrared NHN
E l e c tronic(gver.7 bands)
Electronic (0-3)

* Results of this investigation

TABLE X V
B

Infrared and Electronic Values

o________ ________________________________

B (1)
B (2)
o '__________ o
1.6720
1.6680
1.6762
1.6706
1.6696
1.6703
1.6706
1.6733
1.6720
1.67198

B

Source
Q_____________________

♦Infrared (3-0) VH & H
(3-0)NHN
(2-0) NHN
I nfr a r e d (3-0
2-0)NHN
Infrared (1-0) G & E
Electronic 1-0, 2-0
Electronic 0-0,1-0
Infrared(1-0)Shaw
Palikand Rao-Pure Rotat.
Burrus.and Gordv.
_______ (microwave)
* fusing the B Q (2) value from G &E

1.7197
1.7222
1.7207
1.7224
1.7200
1.7182
1.7239
1.7200
1.7198

1.6959
1.6951
x 1.6985
1.6965
1.6948
1.6943
1.6973
1.6966
1.6959
(1.6951

♦Results of this investigation

-51-

Be =

1 .7 0 4 4

cmT1

cm.
oce=

0 .0 1 7 4

cmr1

I.70--

1. 68- -

B. ( S H A W )

Bo (N H N )
I.66--

I.64--

V + 1/2
1.5

3.5
F i g u r e 15

-52-

It is to be noted that greater weight was given to the values of
B Q and

obtained in this present work.

The value of

here is lower than the value of Gillette and Eyster

used

(0. 0180 c m -^).

It is in agreement with the value of ©Ce calculated from the results
of Fletcher and Begun

22

on N

IS
O for the fundamental.

This gives

a value of B e slightly lower than the value recently published
by Gallagher and Johnson 19 .
Values Ie and re together with the above constants are listed
in Table XVI.
The molecular coupling constant, A, was first determined by
Jenkins, Barton, and Mullikan

20

yielding a value of 124.4 c m

from electronic band spectra
This value was used by microwave

o
investigators, Gallagher, Bedard, and Johnson . More recently
Beringer, Rawson, and Henry

21

have used 123. 8 c m

that this m a y be in error by as much as 0. 5 c m

-1

and state

Although A

cannot be obtained directly from the infrared data, it is of interest
to check the consistency of the value 123. 8 with the infrared data.
This was done as follows:

Using the expression

(Bv> eff = B „ * B v2/ 0 ( A - 4 B v)J 1/2 + D v

...eq. 12

and substituting present experimental values for (Bv) e£f

-53-

from each species and the value for B v we obtain some measure
of the reliability of A by checking the equality.
_

A _________

B vy j A (A-4BV) J 1

(ByJeff-By

123. 4 c m - ^

. 0240 c m -^

.0239 c m

123. 8

.0239

.0239

124. 2

.0238

.0239

F r o m the results it is obvious that the value of A is at least as
good as 123. 8 4

0.4 c m

*

-54-

T A B L E XVI
M O L E C U L A R CONSTANTS OF NO

(B0)eff

(Z"7f /2)
1

1. 6720 c m

(B0)eii(Z'jf3/2)

1.7197 c m

Bq

1. 6958 c m

B^

1. 643 3 c m

B

1.7044 c m

€Ce

Ie
re

•0174 c m
16. 422 x 10"40 g m - c m
1.15096 x 10~J* c m

2

CONCLUSION

The use of a Fabry-Perot etalon incorporated into the
spectrograph to give calibration fringes simultaneously with
the record has greatly increased the accuracy with which the
frequency of any absorption line m a y be determined.

For

the work on the 3-0 band of nitric oxide the accuracy of frequency
determination is better than

. 04 c m -^.

This increased accuracy has resulted in more dependable
rotational constants and changes slightly the previously
published values of the equilibrium constants for the molecule.
The major change occurred in

This work gives

the former value was

This new value is thought

.0 180 c m -^.

= .0174 c m -^;

to be m o r e valid for two reasons; first, the rotational constants
from which it was derived are consistent with recent micro­
wave values; and secondly, this value is consistent with the
value obtained from recent measurements of Fletcher and
B e g u n

o n

th e

f u n d a m e n t a l

M e a s u r e m e n t s

in

t h i s

r e g i o n

o f

th e

w o u l d

o f

th e

o v e r t o n e

b e

o f

i s o t o p i c

b a n d s

o f

m o l e c u l e ,

th e

is o t o p e ,

N 15 0 1lA
D .
N

^

0

^

,

i n t e r e s t .

In addition to the above we are able to show that the
molecular constant, A = 123. 8 cm" * can not be varied by more
than

0.4 cm'^ and remain consistent with the infrared

frequencie s.

-56-

BIBLIOGRAPHY

Pickworth, J. , and H. W. Thompson. The fundamental
vibration-rotation band of deliterium chloride. Proc.
Roy. Soc. (London) 218, 37 (1953).
2.

Hardy, J. D. , E. F. Barker, and D. M. Dennison. The
infrared spectrum of H^Cl. Phys. Rev. 42, 279 (1932).

3.

Neilsen, A. H. , and W. Gordy. The infrared spectrum and
molecular constants of nitric oxide. Phys. Rev. 56,781 (1939).

4.

Gillette, R. H. , and E. H. Eyster. The fundamental rotationvibration band of nitric oxide. Phys. Rev. 56, 1 113 (1939).

5.

Nichols, N. L. , C. D. Hause, and R. H. Noble. Near infrared
spectrum of nitric oxide. Jour. Chem. Phys. 23, 57 (1955).

6. Nichols, N. L. The near infrared spectrum of nitric oxide.
Ph. D. Thesis, Michigan State University (1953).
7.

Shaw, J. H. Nitric oxide fundamental.
Phys. 24, 399 (1956).

Jour. Chem.

8. Burrus, C. A. , and W. Gordy. One-to-two millimeter wave
wave spectroscopy III. N O and DI. Phys. Rev. 92,
1437 (1953).
~
9.

Gallagher, J. J. , F. D. Bedard, and C. M. Johnson.
Microwave spectrum of N ^ O ^ . Phys. Rev. 93, 729 (1953).

10.

Herzberg, G. Spectra of Diatomic Molecules , ed. 2,
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11.

Hill, E. and J. H. VanVleck "On the Quantum Mechanics of
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Phys. Rev. _32, 250 (1928).

12.

Noble, R. H. A vacuum spectrograph for the infrared
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-57-

13.

White, J. U. Long optical paths of large aperature.
J. Opt. Soc. Am. 32,, 285 (1942).

14.

Mills, I. M. , H. W. Thompson and R. L. Williams. The
fundamental vibration-rotation band of hydrogen chloride.
Proc. Roy. Soc. (London) 218, 29 (1953).

15.

DuMond, J. W. M. , and E. R. Cohen.
25, 691 (1953).

Rev. Mod. Phys.

16 . Segre, E. , editor, Experimental Nuclear Physics .

John Wiley and Sons, Inc. , N e w York, 1954 p. 746.
17.

Cowan, M. J. and W. Gordy. Submillimeter wave spectros
copy. Bui. Am. Phys. Soc. Apr. 25, 1957 Paper Q A I O
p. 212.

18.

Palik, E. D. and K. N. Rao. Pure rotational spectra of
CO, NO, and N ^ O between 100 and 600 microns.
Jour. Chem. Phys. 25, 1174 (1956).

19.

Gallagher,J. J. and C. M. Johnson. Uncoupling effects in
the microwave spectrum of nitric oxide. Phys. Rev.
103, 1727 (1956).

20 . Jenkins, F. A. , H. A. Barton and R. S. Molliken.

beta bands of nitric oxide.

The
Phys. Rev. 30 , 152, (1927)

21.

Beringer, R. , E. B. Rawson and A. F. Henry. Microwave
resonance in nitric oxide: lambda doubling and hyper fine
structure. Phys. Rev. 94, 343 (1954).

22

Fletcher, W. H. , and G. M. Begun. Fundamental of N
Journ. Chem. Phys. 27, 579 (1957).

.

15

O.