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The ν1 and ν1 + ν2 − ν2 infrared absorption bands of H12CP
JVURNALOF MOLECULAR SPECTROSCOPY 69, 319-32.5 (1978)
The
v1
and VI +
v2 -
v2
JEAN-MARC D@artement
de Chimie,
Infrared
Absorption
Bands of Hl*CP
GARNEAU AND ALDEE CABANA
llnicersit& de Skerbrooke,
Skerbrooke,
Quzbec, Canada JlK
ZRI
The vibration-rotation spectrum of HCP was recorded in the region of the ~1 band with a resolution of about 0.035 cm-l. All the data available were combined to calculate spectroscopic constants for the OOOO, IOOO,Olr”O, Olr’O, llreO, and 11’10 states. INTRODUCTION
Methinophosphide, the phosphorus analog of hydrocyanic acid, was first prepared by Gier (I), who showed, from a study of its infrared spectrum in the solid state, that the molecule is linear. Tyler (2) who later measured two microwave transitions for each of the H”CP and Dr*CP molecules and one for each of the corresponding r3C isotopes confirmed that structure. A very extensive spectroscopic study of gaseous HCP and DCP was reported by Johns d al. (3). Several electronic transitions have been analyzed in that investigation which included also some infrared data for the ~1, ~2, and 2~2 bands of HCP and for the ~1 band of DCP. However, many of the infrared data have been obtained under conditions of low resolution and I+, the CP stretching vibration, was not observed, although the appropriate region was scanned. Johns et al. (4) have investigated the millimeter wave spectra. They found nine pure rotational transitions for each molecule in its ground vibrational state and four transitions for DCP in the 7~~= 1 level. We have undertaken a comprehensive study of the high resolution infrared absorption spectrum of HCP and DCP. We report here a first part of this study obtained with much improved resolution and wavenumber accuracy. EXPERIMENT.%L
METHOD
The molecule was prepared with the reactor used by Johns et al. (3,4) and the method originally proposed by Gier (I). About three parts of acetylene to one of HCP were formed in the reaction, A small proportion of diacetylene was also formed but CO2, which was present in the sample obtained by Johns et al. (3), was not found in our sample. Attempts to remove the acetylene have failed. Therefore the spectra reported here were recorded using the mixture. Although several transitions of acetylene occur in the spectral region investigated in this study they do not interfere badly with the transitions of interest. Methinophosphide is rather unstable at room temperature but may be kept at least several months if stored at liquid nitrogen temperature. The spectra were all obtained at room temperature and low pressure (0.6 to 0.8 Torr of the 319 0022-2852/78/0692-0319$02.00/O Copyright @ 1978 by Academic Press, Inc. .X1 rights of reproduction in any form reserved.
GARNEAU
320
AND
CABANA
1 I
_
n
I
,110
‘n P30
I
-~-Iu
II, PPO
$~~:r_----
.
-..__-__ I
FIG. 1. Absorption spectrum of the ~1 spectral region of HCP. The spectrum was obtained with a path length of 24 m, a pressure of 0.8 Torr, and a sample containing HCP and &Hz in a ratio of about 1 to 6 The full width at half-height of isolated lines was 0.035 cm-1 or slightly less.
mixture) under which conditions the half-life of HCP was of the order of 30 to 40 hr, thus allowing plenty of time for recording high quality spectra. Four separate spectra were obtained with the high resolution infrared spectrometer at the Universid de Sherbrooke. That spectrometer is equipped with a 30-line/mm Bausch and Lomb echelle blazed at 63’ with dimensions 100 X 200 mm. A liquid nitrogen cooled lead sulfide detector was used. The spectra, occurring in the 19th order of the grating, were scanned in the spectral region extending from 3260 to 3160 cm1 with a resolution of 0.035 cm-’ or slightly better. The calibration was made using the 2 + 0 absorption line data of CO reported by Guelachvili (5). These lines occurred in the 25th order of our grating. The relative accuracy of strong unblended lines was as high as 0.0015 cm-1 while, for slightly blended or weaker lines, the accuracy was of the order of 0.003 cm-‘.
321
Y, Ah’D vi+ ~2 - YZBANDS OF H=CP
Two spectra were obtained with a path length of 8 m and afterward (2 days later) two additional spectra were obtained using the same sample but a path length increased to 24 m. The sample pressure was 0.8 Torr for all experiments. In each of these two pairs, one of the spectra was continuous and contained lines from the sample only while the other recorded immediately after was interrupted each time a calibration line had to be inserted in between two portions of the spectrum of HCP. The absorption lines of methinophosphide were found to be only slightly more intense in the spectrum obtained with the 24-m path length than in that obtained with the 8-m path length, showing that about one-half of the HCP molecules had disappeared in 2 days. The scan obtained with the 24-m path length shown in Fig. 1. ANALYSIS OF THE BAND AKD CALCULATION
OF SPECTROSCOPIC
CONSTASTS
Line assignment for both bands was straightforward. It followed directly either from the missing Q branch for the D-+-B+ band or from the weak Q branch at 3200.2601 cm-’ for the II c II band. The vacuum wavenumbers of the VI band are collected in Table I, those of (~1 + V# - v&e in Table II, and those of (VI+ ~z)rf - ve’f in Table TABLE I Observed and Calculated Wavenumbers in the ~1Band of H’*CP
0 1 2
3,218.2153 219.5415 220.8519
-17
0
+4'i +15
1 2
3
222.1582
'7
4
223.4587
+i
5
224.7525
0
6 7
22h.0485 227.3204
+82 -I?
8
228.5961
-4
2
1,?11.5599 "14.2176 21?.87?7
+19 -14 -10
2
"
2
J11.5221
9
129.8639
-9
10 I1
231.12h2 232.3806
-4 -13
110.1612
-30
(1 2
.'OS..ml? ?(17.43?1
+12 +Ih
2
2
?OA.O555
+Ih
0
l(l4.6h90
-in
2
2
X13.2791 2n1.8348
-18 -8
12
233.h273
-34
1
209.4432
-10
2
13
234.8753
+z5
I
19Y.0780
+15
2
14
236.ll21
+37
2
107.6633
+7
2
15
?37.3383
+R
2
19h.244U
+lO
.?
Ih 17
238.5646 239.7743
+50 -12
2 2
194.8179 193.3842
+9 -x
2 2
18 19
240.9094 242.1862
+47 -9
0 2
191.9450 ,90.5"11
-19 -7
2
?U 21
743.3826 i44.5732
-3 +12
187.594h
-14 -20
2 1
22
1
2
IRL).“i,l
245.7337
-210
II
186.1331
-13
23
246.9304
+
184.6636
-28
24
248.1077
+a7
I,
lXl.19.'3
3
1
25
249.2632
+19
2
lR1.7130
+A
26
250.4192
+25
2
180.2277
+I1
27 28
251.5640 252.6999
-14 -74
0
178.7349 177.2373
29 30
253.8420 "54.9714
-4 +7
31 I?
256.1043 ?57.?rthH
+I.?0 0
2 2 2
0 0
? 2 2
175.7349 17L.2230
ill -15
2 2
172.7117 171.19n2 lil".i,‘>i”
+2&S tlh
0
!I
I‘t !I
l,‘.,.“, irr ‘,918,
0
i .’ + ;
.’ I
322
GAKNEAU
AND
TABLE Observed
.I
CABANA II
and Calculated Wavenumbers of the II” +- II~ Components the ~1 + ~1 - VPBand of H’VP -__ -___
_-__
K(J)
"lobs
1, ohs-"talc
I'(J)
__r"
ohs-'talc
‘.ohs
104
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
a)
+44 +72 +51 -24 +58 +29 +39 +7 -34 -2 -7 +23 -10 +100 +46 +25 +1 -17 +9h -9 -50 +32 +95 -5 -3 -15 f39 +4X
3.202.9245 204.2404 205.5452 206.8382 208.1406 209.4255 210.7080 211.9798 213.2444 214.5099 215.7652 217.0175 218.2571 219.5045 220.7289 221.9502 223.1645 224.3730 225.5879 226.7744 227.9607 229.1527 230.3361 231.4965 232.6604 233.81b2 234.9718 136.1162
of
ua
104 0 0 0 0 0 0 1
.! ? 2 0 0 ? 0 0 2 0 0 I
3,197.6065 196.2442 194.9052 193.5443 192.1805 190.8194 189.4466 188.0628 186.6768 185.2848 183.8829 182.4790 181.0704 179.6514 178.2264 176.7998 175.3599 173.9165 172.4689 171.0174 169.5600 168.0946
+I6 -160 -47 -88 -97 -17 f7 -17 -3
0 0 c 0 0 0 2 7
+12 -11 +6
2 7
+37 +24 fll
1 1 7
+42 0 -18 -19 +1 +21
2 2
+20
1
1
7
1 0
-1 -1 and 2 is used when the estimated accuracy is 0.0015 cm 1 when it is 0.0030 cm 0 when a line is badly blended and omitted from tlw fit.
,
III. Because of the resolution limit of this study the G doublets were resolved only for values of J” > 7. In order to get the best possible upper state constants, the constants for the 00’0 and 01’0 lower states were first determined from all available data. The ground state constants were determined from a simultaneous least-squares fit of the nine known pure rotational transitions (2,4) and the 78 infrared ground state combination differences calculated from measured frequencies of the ~1 and ~2 bands recorded in our laboratory. (The analysis of the v2 region, particularly of the three intense “hot” bands is not yet completed and will be reported later.) In this least-squares fit each datum was weighted by a factor inversely proportional to the square of the estimated uncertainty in the manner suggested by Pliva (6). It was found that the distortion constant H is not well determined because the fit did not contain transitions with high enough values of J. That constant was therefore set equal to zero. The calculated ground state rotational constants are given in Table IV. The constants for the 01’0 state were obtained from an analysis of the v2 band using the accurately determined ground state constants and are also given in Table IV. The &type doubling constant, q, of the 01’0 state was obtained from a simultaneous fit of expressions of the type :
[Q(J) - R(J -
l)]
+
2B”J
[Q(J) - P(J +
l)]
-
2B”(J
- 4D”J3 = qJ (J + 1) ; + 1) + 4D”(J
+ 1)s = qJ(J + 1).
~1 AND
~1 + ~2 -
There were 50 such combinations tions has been calculated taking the above expressions. It should but that the R(J)- or P(J)-type proposed by a series of workers
AVR~J, = R(J)., -
- R(J),,
(D1rlro - Zir14[(J
323
OE’ H’V?
in the fit. The weight assigned to each of these combinainto account the uncertainties of each of the terms in be noted that each Q(J)-type transition was used twice transitions were used only once. Using the notation (7) q is defined as: q
The &type doubling constant which are derived below:
VP BANDS
=
B,/
-
IL,.
in the 11’0 state was calculated - Bl~~~d[(J -I- l)(J
= (huO i- l)(J
i- 2) -
l]? -
using the expressions
+ 2) -
11
(Boluo - Bol~eo)[J(J + 1) -
l]
+ (D 31110- Dc,11eo)[.7(/+ 1) Leaving out the terms involving duces to: AVR(J)
+
A similar expression,
qa'o[J(J
the differences
+
1)
using the P(J)
AVPW = P(J),/ AVPV) +
-
11
=
- -__
qll'o[(J
components,
+
l)(J
+
2)
constants
-
11.
is also derived:
- J’(J).q
q,IdJ:J(J
+
1) -
11
TABLE Observed
in the distortion
=
qnv,[J(J
-
1) -
11.
III
and Calculated Wavenumbers of the nf + JI’ Components the ~1 + YZ- v2 Band of HYX’
___
__. ~______~_______-._~_-___
1,2”2.!4245 204.2404 ZOj.545?
_ -,i -ill,
0 0
-Jlil
(1
?Oh.tlh??
+17
ii
JOB.1569
-1 i -,,L
(1
"09.4433 L10.7358 11?.01.'0 .!13."861 .'14.5452 215.8117
I,
+I4
I
-ill
.' ?
+li -54 +1-
?17.0hh7
+'i.?
ii
.!18.3063
-II: -77
0
L14.5426 120.7839 1?2.01?6 "23.23b8 J24.44b4
1
- I +14 +4Y + i
.' 0 .!
125.6340 -26.8518 L'Z8.0511
-'OO -,I +I6
1
'29.2397 .!JO.4177
+22 -I3 -1
0 I
?l -,i + u -I,;
? 1 I/
231.5934 232.7642 ?33.92.'? ?JS.O7Yh .!lh.?.'wl
I
-___.
of
1-J.
this re-
324
GARNEAU
AND
CABANA
TABLE Spectroscopic
IV
Constants
(cm-l)
of HYP*
oo"o
0
0.6663?73?(17)
h.998(?4)
loo0
3?16.89066(42)
0.6631487(25)
6.954(28)
olleo
674.69919(49)
0.6659701(2?)
OllfO
674.6994(10)
0.6675999(31)
llleo
3874.9710(11)=
0.6628454(71)
lllf0
3874.9745(16jd
0.6644888(83)
7.045(19) a 7.126(17) 7.080(97) b
* Uncertainties a)
401lo
are one standard deviation
=
1.61937(59) X lO-3 cm-l
=
1.6450(21) X lO-3 cm-l
b,
%llO
c)
This is the sum
d)
of the v. obtained
7.07(11)
and are in units of the last digit cited.
for the the OlleO + 00'0 band [674.69919(49)cm-'1
and the u. obtained
for the llleO + OlleO band [3200.2718(10)cm~1~.
This is the similar
sum
band
far the OlfO + 00'0 band [674.6994(10)cm-11
and the llfO 1 OllfO
[3200.2751(12)~"-'1.
In obtaining the qlllo constant, using the expressions just derived, the constants in the lower state, 01’0, have been fixed to their known values. There were 30 such combinations in the fit for q1110,each of which had been weighted in the manner described previously. The lists of wavenumbers given in Tables I-III are weighted averages from the four different spectra that have been recorded and are the wavenumbers used in all of our fits. The upper state constants for both the vl band or the vr + v2 - vz band, also reported in Table IV, were obtained with the lower state constants fixed at the values previously determined. The rotational levels were represented by expressions of the type : F(J) = B[J(J and each vibration-rotation
+ 1) - 1”] - D[J(J
transition
by:
v = vg + F’(J) More explicitly
each R(J)
R(J) + B”[J (J + 1) -
transition
+ 1) - 2212,
- F”(J).
of the II + II band was expressed by:
l] - D”[J (J + 1) -
1-J”
=v~+B’[(.7+1)(.J+2)-1]-D’[(J+1)(.J+2)-1]~ and each P(J) P(J)
+ B”[J(J
by: + 1) -
l] - D”[J(J
+ 1) -
1-J
= v. + B’[J(J
- 1) -
1) - D[J(J
- 1) -
11”.
These equations were solved for the coefficients v,,, B’, and D’ by the method of least squares with the coefficients for the lower states fixed at the values obtained previously.
Y, AND Y, + ~2 - ~2 BANDS OF HnCP
325
CONCLUSION In this paper improved sets of spectroscopic constants have been obtained for the ground, the 10’0, the Ol’“o, and the Ol”O states. Spectroscopic constants for the 11W1 and for the 11’0 states are reported for the first time. Other data have already been collected in our laboratory particularly in the ~2, v3, and 2v~ spectral regions. They are now being analyzed and will be reported later. ACKNOWLEDGMENTS The authors are grateful to J. W. C. Johns of NRC who provided us with the sample used in this investigation. We acknowledge helpful suggestions from Claude PCpin with regards to the least-squares programs necessary to this study. This research was supported by the “Ministere de I’Education du Quebec, programme FCAC” and by the National Research Council of Canada. RECEIVED: August 5, 1977 REFERENCES 1. 2. 3. 4. 5. 6. 7.
T. E. GIER, J. Amer. Chem. Sec. 83, 1769 (1961). J. K. TYLER, J. Chem. Phys. 40, 1170 (1964). J. W. C. JOHNS,H. F. SHURVELL,AM) J. K. TYLER, Cunad. J. Phys. 47,893 (1969). J. W. C. JOHNS,J. M. R. STONE,ANDG. WINNEWISSER,J. &fol. Spectrosc. 38,437 (1971). G. GUELACHVILI,Opt. Cornman. 8, 174 (1973). J. PL~VA,J. Mol. Spectrosc. 23, 228 (1967). J. M. BROWN,J. T. HOUGEN,K.-P. HUBER, J. W. C. JOHNS, I. KOPP, H. LEFEBVRE-BRION,A. J. MERER, D. E. RAMSAY,J. ROSTAS,.UD R. N. ZARE,J. Mol. Spectrosc. 55, 500-503 (1975).
The
v1
and VI +
v2 -
v2
JEAN-MARC D@artement
de Chimie,
Infrared
Absorption
Bands of Hl*CP
GARNEAU AND ALDEE CABANA
llnicersit& de Skerbrooke,
Skerbrooke,
Quzbec, Canada JlK
ZRI
The vibration-rotation spectrum of HCP was recorded in the region of the ~1 band with a resolution of about 0.035 cm-l. All the data available were combined to calculate spectroscopic constants for the OOOO, IOOO,Olr”O, Olr’O, llreO, and 11’10 states. INTRODUCTION
Methinophosphide, the phosphorus analog of hydrocyanic acid, was first prepared by Gier (I), who showed, from a study of its infrared spectrum in the solid state, that the molecule is linear. Tyler (2) who later measured two microwave transitions for each of the H”CP and Dr*CP molecules and one for each of the corresponding r3C isotopes confirmed that structure. A very extensive spectroscopic study of gaseous HCP and DCP was reported by Johns d al. (3). Several electronic transitions have been analyzed in that investigation which included also some infrared data for the ~1, ~2, and 2~2 bands of HCP and for the ~1 band of DCP. However, many of the infrared data have been obtained under conditions of low resolution and I+, the CP stretching vibration, was not observed, although the appropriate region was scanned. Johns et al. (4) have investigated the millimeter wave spectra. They found nine pure rotational transitions for each molecule in its ground vibrational state and four transitions for DCP in the 7~~= 1 level. We have undertaken a comprehensive study of the high resolution infrared absorption spectrum of HCP and DCP. We report here a first part of this study obtained with much improved resolution and wavenumber accuracy. EXPERIMENT.%L
METHOD
The molecule was prepared with the reactor used by Johns et al. (3,4) and the method originally proposed by Gier (I). About three parts of acetylene to one of HCP were formed in the reaction, A small proportion of diacetylene was also formed but CO2, which was present in the sample obtained by Johns et al. (3), was not found in our sample. Attempts to remove the acetylene have failed. Therefore the spectra reported here were recorded using the mixture. Although several transitions of acetylene occur in the spectral region investigated in this study they do not interfere badly with the transitions of interest. Methinophosphide is rather unstable at room temperature but may be kept at least several months if stored at liquid nitrogen temperature. The spectra were all obtained at room temperature and low pressure (0.6 to 0.8 Torr of the 319 0022-2852/78/0692-0319$02.00/O Copyright @ 1978 by Academic Press, Inc. .X1 rights of reproduction in any form reserved.
GARNEAU
320
AND
CABANA
1 I
_
n
I
,110
‘n P30
I
-~-Iu
II, PPO
$~~:r_----
.
-..__-__ I
FIG. 1. Absorption spectrum of the ~1 spectral region of HCP. The spectrum was obtained with a path length of 24 m, a pressure of 0.8 Torr, and a sample containing HCP and &Hz in a ratio of about 1 to 6 The full width at half-height of isolated lines was 0.035 cm-1 or slightly less.
mixture) under which conditions the half-life of HCP was of the order of 30 to 40 hr, thus allowing plenty of time for recording high quality spectra. Four separate spectra were obtained with the high resolution infrared spectrometer at the Universid de Sherbrooke. That spectrometer is equipped with a 30-line/mm Bausch and Lomb echelle blazed at 63’ with dimensions 100 X 200 mm. A liquid nitrogen cooled lead sulfide detector was used. The spectra, occurring in the 19th order of the grating, were scanned in the spectral region extending from 3260 to 3160 cm1 with a resolution of 0.035 cm-’ or slightly better. The calibration was made using the 2 + 0 absorption line data of CO reported by Guelachvili (5). These lines occurred in the 25th order of our grating. The relative accuracy of strong unblended lines was as high as 0.0015 cm-1 while, for slightly blended or weaker lines, the accuracy was of the order of 0.003 cm-‘.
321
Y, Ah’D vi+ ~2 - YZBANDS OF H=CP
Two spectra were obtained with a path length of 8 m and afterward (2 days later) two additional spectra were obtained using the same sample but a path length increased to 24 m. The sample pressure was 0.8 Torr for all experiments. In each of these two pairs, one of the spectra was continuous and contained lines from the sample only while the other recorded immediately after was interrupted each time a calibration line had to be inserted in between two portions of the spectrum of HCP. The absorption lines of methinophosphide were found to be only slightly more intense in the spectrum obtained with the 24-m path length than in that obtained with the 8-m path length, showing that about one-half of the HCP molecules had disappeared in 2 days. The scan obtained with the 24-m path length shown in Fig. 1. ANALYSIS OF THE BAND AKD CALCULATION
OF SPECTROSCOPIC
CONSTASTS
Line assignment for both bands was straightforward. It followed directly either from the missing Q branch for the D-+-B+ band or from the weak Q branch at 3200.2601 cm-’ for the II c II band. The vacuum wavenumbers of the VI band are collected in Table I, those of (~1 + V# - v&e in Table II, and those of (VI+ ~z)rf - ve’f in Table TABLE I Observed and Calculated Wavenumbers in the ~1Band of H’*CP
0 1 2
3,218.2153 219.5415 220.8519
-17
0
+4'i +15
1 2
3
222.1582
'7
4
223.4587
+i
5
224.7525
0
6 7
22h.0485 227.3204
+82 -I?
8
228.5961
-4
2
1,?11.5599 "14.2176 21?.87?7
+19 -14 -10
2
"
2
J11.5221
9
129.8639
-9
10 I1
231.12h2 232.3806
-4 -13
110.1612
-30
(1 2
.'OS..ml? ?(17.43?1
+12 +Ih
2
2
?OA.O555
+Ih
0
l(l4.6h90
-in
2
2
X13.2791 2n1.8348
-18 -8
12
233.h273
-34
1
209.4432
-10
2
13
234.8753
+z5
I
19Y.0780
+15
2
14
236.ll21
+37
2
107.6633
+7
2
15
?37.3383
+R
2
19h.244U
+lO
.?
Ih 17
238.5646 239.7743
+50 -12
2 2
194.8179 193.3842
+9 -x
2 2
18 19
240.9094 242.1862
+47 -9
0 2
191.9450 ,90.5"11
-19 -7
2
?U 21
743.3826 i44.5732
-3 +12
187.594h
-14 -20
2 1
22
1
2
IRL).“i,l
245.7337
-210
II
186.1331
-13
23
246.9304
+
184.6636
-28
24
248.1077
+a7
I,
lXl.19.'3
3
1
25
249.2632
+19
2
lR1.7130
+A
26
250.4192
+25
2
180.2277
+I1
27 28
251.5640 252.6999
-14 -74
0
178.7349 177.2373
29 30
253.8420 "54.9714
-4 +7
31 I?
256.1043 ?57.?rthH
+I.?0 0
2 2 2
0 0
? 2 2
175.7349 17L.2230
ill -15
2 2
172.7117 171.19n2 lil".i,‘>i”
+2&S tlh
0
!I
I‘t !I
l,‘.,.“, irr ‘,918,
0
i .’ + ;
.’ I
322
GAKNEAU
AND
TABLE Observed
.I
CABANA II
and Calculated Wavenumbers of the II” +- II~ Components the ~1 + ~1 - VPBand of H’VP -__ -___
_-__
K(J)
"lobs
1, ohs-"talc
I'(J)
__r"
ohs-'talc
‘.ohs
104
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
a)
+44 +72 +51 -24 +58 +29 +39 +7 -34 -2 -7 +23 -10 +100 +46 +25 +1 -17 +9h -9 -50 +32 +95 -5 -3 -15 f39 +4X
3.202.9245 204.2404 205.5452 206.8382 208.1406 209.4255 210.7080 211.9798 213.2444 214.5099 215.7652 217.0175 218.2571 219.5045 220.7289 221.9502 223.1645 224.3730 225.5879 226.7744 227.9607 229.1527 230.3361 231.4965 232.6604 233.81b2 234.9718 136.1162
of
ua
104 0 0 0 0 0 0 1
.! ? 2 0 0 ? 0 0 2 0 0 I
3,197.6065 196.2442 194.9052 193.5443 192.1805 190.8194 189.4466 188.0628 186.6768 185.2848 183.8829 182.4790 181.0704 179.6514 178.2264 176.7998 175.3599 173.9165 172.4689 171.0174 169.5600 168.0946
+I6 -160 -47 -88 -97 -17 f7 -17 -3
0 0 c 0 0 0 2 7
+12 -11 +6
2 7
+37 +24 fll
1 1 7
+42 0 -18 -19 +1 +21
2 2
+20
1
1
7
1 0
-1 -1 and 2 is used when the estimated accuracy is 0.0015 cm 1 when it is 0.0030 cm 0 when a line is badly blended and omitted from tlw fit.
,
III. Because of the resolution limit of this study the G doublets were resolved only for values of J” > 7. In order to get the best possible upper state constants, the constants for the 00’0 and 01’0 lower states were first determined from all available data. The ground state constants were determined from a simultaneous least-squares fit of the nine known pure rotational transitions (2,4) and the 78 infrared ground state combination differences calculated from measured frequencies of the ~1 and ~2 bands recorded in our laboratory. (The analysis of the v2 region, particularly of the three intense “hot” bands is not yet completed and will be reported later.) In this least-squares fit each datum was weighted by a factor inversely proportional to the square of the estimated uncertainty in the manner suggested by Pliva (6). It was found that the distortion constant H is not well determined because the fit did not contain transitions with high enough values of J. That constant was therefore set equal to zero. The calculated ground state rotational constants are given in Table IV. The constants for the 01’0 state were obtained from an analysis of the v2 band using the accurately determined ground state constants and are also given in Table IV. The &type doubling constant, q, of the 01’0 state was obtained from a simultaneous fit of expressions of the type :
[Q(J) - R(J -
l)]
+
2B”J
[Q(J) - P(J +
l)]
-
2B”(J
- 4D”J3 = qJ (J + 1) ; + 1) + 4D”(J
+ 1)s = qJ(J + 1).
~1 AND
~1 + ~2 -
There were 50 such combinations tions has been calculated taking the above expressions. It should but that the R(J)- or P(J)-type proposed by a series of workers
AVR~J, = R(J)., -
- R(J),,
(D1rlro - Zir14[(J
323
OE’ H’V?
in the fit. The weight assigned to each of these combinainto account the uncertainties of each of the terms in be noted that each Q(J)-type transition was used twice transitions were used only once. Using the notation (7) q is defined as: q
The &type doubling constant which are derived below:
VP BANDS
=
B,/
-
IL,.
in the 11’0 state was calculated - Bl~~~d[(J -I- l)(J
= (huO i- l)(J
i- 2) -
l]? -
using the expressions
+ 2) -
11
(Boluo - Bol~eo)[J(J + 1) -
l]
+ (D 31110- Dc,11eo)[.7(/+ 1) Leaving out the terms involving duces to: AVR(J)
+
A similar expression,
qa'o[J(J
the differences
+
1)
using the P(J)
AVPW = P(J),/ AVPV) +
-
11
=
- -__
qll'o[(J
components,
+
l)(J
+
2)
constants
-
11.
is also derived:
- J’(J).q
q,IdJ:J(J
+
1) -
11
TABLE Observed
in the distortion
=
qnv,[J(J
-
1) -
11.
III
and Calculated Wavenumbers of the nf + JI’ Components the ~1 + YZ- v2 Band of HYX’
___
__. ~______~_______-._~_-___
1,2”2.!4245 204.2404 ZOj.545?
_ -,i -ill,
0 0
-Jlil
(1
?Oh.tlh??
+17
ii
JOB.1569
-1 i -,,L
(1
"09.4433 L10.7358 11?.01.'0 .!13."861 .'14.5452 215.8117
I,
+I4
I
-ill
.' ?
+li -54 +1-
?17.0hh7
+'i.?
ii
.!18.3063
-II: -77
0
L14.5426 120.7839 1?2.01?6 "23.23b8 J24.44b4
1
- I +14 +4Y + i
.' 0 .!
125.6340 -26.8518 L'Z8.0511
-'OO -,I +I6
1
'29.2397 .!JO.4177
+22 -I3 -1
0 I
?l -,i + u -I,;
? 1 I/
231.5934 232.7642 ?33.92.'? ?JS.O7Yh .!lh.?.'wl
I
-___.
of
1-J.
this re-
324
GARNEAU
AND
CABANA
TABLE Spectroscopic
IV
Constants
(cm-l)
of HYP*
oo"o
0
0.6663?73?(17)
h.998(?4)
loo0
3?16.89066(42)
0.6631487(25)
6.954(28)
olleo
674.69919(49)
0.6659701(2?)
OllfO
674.6994(10)
0.6675999(31)
llleo
3874.9710(11)=
0.6628454(71)
lllf0
3874.9745(16jd
0.6644888(83)
7.045(19) a 7.126(17) 7.080(97) b
* Uncertainties a)
401lo
are one standard deviation
=
1.61937(59) X lO-3 cm-l
=
1.6450(21) X lO-3 cm-l
b,
%llO
c)
This is the sum
d)
of the v. obtained
7.07(11)
and are in units of the last digit cited.
for the the OlleO + 00'0 band [674.69919(49)cm-'1
and the u. obtained
for the llleO + OlleO band [3200.2718(10)cm~1~.
This is the similar
sum
band
far the OlfO + 00'0 band [674.6994(10)cm-11
and the llfO 1 OllfO
[3200.2751(12)~"-'1.
In obtaining the qlllo constant, using the expressions just derived, the constants in the lower state, 01’0, have been fixed to their known values. There were 30 such combinations in the fit for q1110,each of which had been weighted in the manner described previously. The lists of wavenumbers given in Tables I-III are weighted averages from the four different spectra that have been recorded and are the wavenumbers used in all of our fits. The upper state constants for both the vl band or the vr + v2 - vz band, also reported in Table IV, were obtained with the lower state constants fixed at the values previously determined. The rotational levels were represented by expressions of the type : F(J) = B[J(J and each vibration-rotation
+ 1) - 1”] - D[J(J
transition
by:
v = vg + F’(J) More explicitly
each R(J)
R(J) + B”[J (J + 1) -
transition
+ 1) - 2212,
- F”(J).
of the II + II band was expressed by:
l] - D”[J (J + 1) -
1-J”
=v~+B’[(.7+1)(.J+2)-1]-D’[(J+1)(.J+2)-1]~ and each P(J) P(J)
+ B”[J(J
by: + 1) -
l] - D”[J(J
+ 1) -
1-J
= v. + B’[J(J
- 1) -
1) - D[J(J
- 1) -
11”.
These equations were solved for the coefficients v,,, B’, and D’ by the method of least squares with the coefficients for the lower states fixed at the values obtained previously.
Y, AND Y, + ~2 - ~2 BANDS OF HnCP
325
CONCLUSION In this paper improved sets of spectroscopic constants have been obtained for the ground, the 10’0, the Ol’“o, and the Ol”O states. Spectroscopic constants for the 11W1 and for the 11’0 states are reported for the first time. Other data have already been collected in our laboratory particularly in the ~2, v3, and 2v~ spectral regions. They are now being analyzed and will be reported later. ACKNOWLEDGMENTS The authors are grateful to J. W. C. Johns of NRC who provided us with the sample used in this investigation. We acknowledge helpful suggestions from Claude PCpin with regards to the least-squares programs necessary to this study. This research was supported by the “Ministere de I’Education du Quebec, programme FCAC” and by the National Research Council of Canada. RECEIVED: August 5, 1977 REFERENCES 1. 2. 3. 4. 5. 6. 7.
T. E. GIER, J. Amer. Chem. Sec. 83, 1769 (1961). J. K. TYLER, J. Chem. Phys. 40, 1170 (1964). J. W. C. JOHNS,H. F. SHURVELL,AM) J. K. TYLER, Cunad. J. Phys. 47,893 (1969). J. W. C. JOHNS,J. M. R. STONE,ANDG. WINNEWISSER,J. &fol. Spectrosc. 38,437 (1971). G. GUELACHVILI,Opt. Cornman. 8, 174 (1973). J. PL~VA,J. Mol. Spectrosc. 23, 228 (1967). J. M. BROWN,J. T. HOUGEN,K.-P. HUBER, J. W. C. JOHNS, I. KOPP, H. LEFEBVRE-BRION,A. J. MERER, D. E. RAMSAY,J. ROSTAS,.UD R. N. ZARE,J. Mol. Spectrosc. 55, 500-503 (1975).