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Intensities and half-widths for several H2O ν2 lines in the region 1500–1523 cm−1
JOURNAL
OF MOLECULAR
SPECTROSCOPY
111, 114-I 18 (1985)
Intensities and Half-Widths for Several Hz0 v2 Lines in the Region 1500-I 523 cm-’ V. MALATHY Naiional
DEVI,’
B. FRIDOVICH,
Oceanrc and Armospheric Dais.
G. D. .JONES, AND D. G. S. SNYDER’
.-ldministration,
and It@matron
Service.
National
Uhshinglotl,
Environmenral
Satellite.
D C. -70233
Intensities and half-widths have been measured. using a tunable diode laser, for several water vapor lines in the v2 spectral region between 1500 and I573 cm-‘. Where possible. results have been compared with previously published values. D 1985Academx PKSS. inc. INTRODUCTION
Water vapor plays a critical role in determining the radiative transfer properties of the earth’s atmosphere. Water vapor spectral lines are ubiquitous in the infrared; therefore, a precise knowledge of the parameters of these spectral lines-positions, intensities, half-widths, temperature dependence of half-widths, and pressure shiftsare required for any measurement program that requires that atmospheric transmittance be calculable. Examples are the deduction of atmospheric temperature profiles from satellite radiometric measurements, or the inference of stratospheric water content from remote measurements. High-resolution measurements, in the v2 band of water vapor, of intensity, halfwidth, and pressure shifts, have been reported in the recent literature (I-8). Some of these investigations were performed using tunable diode lasers (I, 2, 7). Although the determination of the various spectral line parameters are best done with the very high resolution of tunable diodes, the amount of data, and the spectral coverage, in any one study is usually very limited, owing to the narrow tuning range of the diodes. In this paper we report on diode laser measurements of intensities and half-widths for several lines in the uZ band, in the spectral region 1500-1523 cm-‘. The results are compared with literature values when appropriate. EXPERIMENTAL
DETAILS
The diode laser spectrometer used in this investigation has already been described in some detail (9). We repeat a very concise description here. The system consists of a commercial tunable diode laser (Laser Analytics, Inc.) whose modes are sorted by a 3.5-m focal length vacuum grating monochromator. The beam exiting the monochromator is collimated and then split by an aluminized grid evaporated onto
’ Current 23185. 2Current 0022-2852/85
address:
Department
address:
Naval Coastal
of Physics,
$3.00
Copyright 0 1985 by Academic Press, Inc. All rights of reproduction in any form reserved.
The College of William
Systems Center,
and Mary. Williamsburg,
Code 4130. Panama
114
City. Florida
32407.
Virginia
H,O v2: 1500-1523
cm-’
115
a CaF2 substrate. One beam passes through a 7.62-cm (3”) temperature-controlled Ge &talon, while the other beam passes through the sample cell, or cells. Each of the above beams is then focused onto independent HgCdTe detectors. The detector outputs go to two lock-in amplifiers (Princeton Applied Research Model 124A). The diode beam is chopped, with a tuning fork chopper, at 400 Hz at the entrance slit of the monochromator. We use a time constant, on the lock-in amplifiers, of 0.3 sec. A data system (Digital Equipment Corporation MNC 1 l/23) samples the lock-in outputs every 0.1 set and stores digital values on a hard disk for later analysis. Since these experiments were conducted in a spectral region containing strong water vapor lines, extra care was required to minimize background absorption, especially that which could occur at low pressure inside the monochromator tank. The monochromator tank was continually pumped with a 15.24-cm (6”) diffusion pump. All optics external to the vacuum tank are housed in rigid plastic enclosures which are continuously flushed with dry nitrogen, supplied from a large LN2 tank. The water vapor samples used for the measurements were prepared in the following way. A few milliliters of distilled water were placed into a small chamber, made by sealing one arm of a Pyrex and Teflon valve. The glass manifold which connected the water vapor source to the cell to be filled was evacuated to about 1O-6 Torr. The valve to the water was then slowly opened and the water was allowed to boil vigorously for a few seconds to outgas it. The valve was closed and the manifold was again evacuated. The manifold was then isolated from the vacuum pump, and the valve to the water source was opened so that the manifold and sample cell were filled with water vapor. The water source valve was again closed. After some time, during which the cell and manifold walls could come to equilibrium with the vapor, the manifold and cell were slowly pumped down to the desired pressure, as indicated on an MKS Baratron gauge. When the gauge showed a steady pressure, the cell valve was closed and the cell was moved from the sample preparation system and inserted into the optical beam. The stability of the water vapor sample was assessed by looking at the spectra of repeated scans. as displayed from digital data, on a CRT. The central transmittance, r(O), usually changed by less than 1.5%. During the 15-20 min required for a sequence of four to six measurements on one line, the measured equivalent widths remained fairly constantwithin 2% of each other. The sample cells were Pyrex and either 10.88, 2 1.4 1, or 50.5 cm long, with CaF,! windows. Water vapor pressures used ranged from a few hundred milliTorr to several Ton-, depending on the parameter being measured. A summary of sample characteristics is given in Table I. Sample temperatures were measured using precision thermistor beads affixed externally to the cell walls. ANALYSIS
Line intensities were determined from consistent with cell length and adequate recorded at two or more pressures, and pressure. Since the pressures ranged from taken into account when computing the
spectral scans made at the lowest pressure minimum transmittance. Each line was several repetitive scans were made at each about 0.4 to 3.5 Torr, self-broadening was intensity. For those transitions whose self-
116
MALATHY
DEW
ET AL.
broadening coefficients were not determined in this study, a nominal value of 0.3 cm-‘/atm was assumed when deriving the intensities. Intensities were determined from the measured equivalent widths. The equivalent widths were measured using a program which located the 100% transmittance line and then computed the integrated absorption. The program also calculated half-width (HWHH), central transmittance, and line position. Wing corrections were applied to these measured equivalent widths (10). These corrections typically ranged from 1 to 3%, depending on the sample pressures used. Using the corrected equivalent widths, intensities were found by interpolating in the tables of Jansson and Korb (11). The results obtained are summarized in Table II. The values obtained in this study are compared with those calculated by Camy-Peyret, Flaud, and Toth (8). Nitrogen-broadened and self-broadened half-widths for a few transitions were also determined using various pressures of H20, or H20 and N2 mixtures. A computer program was used to determine the half-width of the line, bv, at the square root of the minimum transmittance, r(O). The instrument function was negligibly small. This fact was determined by measuring the half-widths of several Doppler lines. The effective Doppler width, b’, was therefore assumed to be the same as bD, the theoretical half-width when calculating Lorentz half-widths. For broadened lines, the measured half-widths ranged from 0.006 to 0.009 cm-’ and were therefore assumed to be those of Voigt lines, bv. Values of bv and bD were used in the expression of Oliver0 and Longbothum (12) to derive the Lorentz half-width, bL, and the broadening coefficient, bf = bdp(atm). In deriving the nitrogen-broadening coefficient, bF(H20 - N2), self-broadening effects were also taken into consideration. The broadening coefficients were derived using the relation b,_ = b:(H*O - H,O)p(H,O)
+ b:(H,O - N&(Nz).
(1)
Again, a nominal value of 0.3 cm-‘/atm was used as the self-broadening coefficient for those transitions for which measurements were not performed in this study. Measured half-widths have been corrected for inaccuracies produced by mislocating the 100% transmittance line (13). The results of these measurements are given in Table III. RESULTS
AND
DISCUSSION
The results of the measurements made to determine line intensities are reported in Table II. The values in parentheses are one standard deviation of the measurements TABLE Parameters Parameter
Studied
and Sample Characteristics
Intensity
21.41, 10.08.
21.41
bf(H20
- Np)
10.88.
21.41.
pressure
0.4 - 3.5
50.5
- H20)
partial
Sample pressure (tiorr)
Absorption path (cm)
b;(H20
* The
I
of water
vapor
50.5
ranged
Sample temp.(K)
297
5 - 14
297
50 - 100*
297
from
0.2
to 2.5
tort-.
W
~2;
117
1500-1523 cm-’
TABLE II Intensities (cm-* atm-‘) for Select Transitions in the v2 Band of Hz0 (297 K) Wavenumber km-l)a
Rotational
J’
K:, K,'
J
~___
(( K:: KI: _
Present
Study
Ref.
0
~.____
1500.54631
9
3
7
9
4
6
0.0207(l)
0.0215
1501.84607
7
2
6
7
3
5
0.1750(93)
0.1678
1507.44275
0
17
0
2
6
0.1076(4)
0.0907
1507.48437
0
3
6
a
4
5
0.1738(98)
0.1586
1507.79965
6
5
2
6
6
1
0.0666(14)
0.0731
1507.82170
6
5
1
6
6
0
0.0218(9)
0.0244
1507.85200
7
5
3
7
6
2
0.0188(7)
0.0204
1507.97297
7
5
2
7
6
1
0.0572(10)
0.0613
1508.02191
0
5
4
8
6
3
0.0313(13)
0.0348
1508.23059
9
5
5
9
6
4
0.0048( 1)
0.0052
1508.29276
10
5
6
10
6
5
0.0056(Z)
0.0060
1508.34263
9
4
6
9
5
5
0.0119(3)
0.0118
1508.49059
0
5
3
8
6
2
0.0103(2)
0.0116
1509.53108
8
4
5
8
5
4
0.0799(28)
0.0830
1509.62267
5
4
2
5
5
1
0.0854(44)
0.0907
1509.66336
9
5
4
9
6
3
0.0132(12)
0.0158
1515.77900
0
4
4
8
5
3
0.0296(6)
0.0279
7 6
2 2
5' 4
0.0667(47)
0.0610
1523.63459
; Ref. 15 Ref. a Unresolved:
’
Intensity
Assignmentb
ti2170 upper
line,
H2160
lower
1
line
in the units of the last digit quoted. The present results are compared with those calculated by Camy-Peyret and F’laud, which are given in the last column. The mean difference in the two sets of values is 6.3%. However, it should be noted that the results reported in Table II were made on relatively weak transitions. Although very strong absorption lines were observed in the spectral region studied in this work, no intensity measurements are reported for those transitions. Since the absorption paths used were large, the sample pressures required would have been too small to be measured with confidence. Measurements on these strong lines would indeed be useful for testing the accuracy of the calculated line intensities over a wider range of intensity values. Table III summarizes the broadening coefficients obtained in this study. The values given in parentheses are the standard deviation of the measurements in the last digit. The self-broadened half-widths are smaller than those reported by Benedict et al. (14). The values for nitrogen-broadened half-widths agree with similar measurements for u2 band lines in the region 1650- 1700 cm-’ reported in Ref. (7). A ratio of 4.8 + 0.4 is obtained for the self- to nitrogen-broadened half-width.
MALATHY
118
DEVI ET AL.
TABLE III Self- and Nitrogen-Broadening Coefficients (cm-’ atm-‘) for Some Y* Band Lines of Hz0 (297 K) Wavenumber
(8)
RotatfonalAssignment J' K; K;
J' K; K;
1498.80354
111
2
2
1498.87509
6
0
6
6
15
1500.54631
9
3
7
9
4
6
0.313(4)
(crnl)
(9)
bf(H2C-H20) bf(H2D-N2)
(8)/(9)
0.094(l)
0
0.077(6) 0.064(5)
4.9
1508.23069
9
5
5
9
6
4
0.218(7)
1508.29276
10
5
6
10
6
5
0.239(5)
1508.34263
9
4
6
9
5
5
0.320(9)
1508.55917
4
2
3
5
14
1514.98777
6
3
4
6
4
3
0.313(81
0.071(8)
4.4
1515.77899
8
4
4
8
5
3
0.383(11)
0.075(l)
5.1
0.091(2)
ACKNOWLEDGMENTS The authors are grateful to Dr. C. Camy-Peyret and Dr. J.-M. FIaud of the Laboratoire de Physique Moleeulaire et d’optique Atmospherique, Orsay, France, for reading the manuscript and making many
valuable suggestions. RECEIVED:
December 6. 1984 REFERENCES
1. R. S. ENG, P. L. KELLEY, A. MOORADIAN,
A. R. CALAWA, AND T. C. HARMAN, Chem. Phys. Lett. 19, 524-528 (1973). 2. R. S. ENG, P. L. KELLEY, A. R. CALAWA, T. C. HARMAN, AND K. W. NILL, Mol. Phys. 28, 653664 (1974). 3. J.-M. FLAUD, C. CAMY-PEYRET, J.-Y. MANDIN, AND G. GUELACHVILI, Mol. Ph.vs. 34, 413-426 (1977). 4. Y. S. CHANG AND J. H. SHAW, J. Quartz. Spectrosc. Radiat. Transfer 18, 491-499 (1977). 5. J.-Y. MANDIN, J.-M. FLAUD, AND C. CAMY-PEYRET, J. Quant. Spectrosc. Radiat. Transfer 23, 351370 (1980). 6. J.-Y. MANDIN, J.-M. FLAUD, AND C. CAMY PEYRET, J. Quant. Spectrosc. Radiat. Transfer 26, 483494 (1981). 7. J. A. MUCHA, Appl. Spectrosc. 36, 141-147 (198 1). 8. J.-M. FLAUD, C. CAMY-PEYRET,AND R. A. TOTH, “Water Vapor Line Parameters from Microwave to Medium Infrared,” Pergamon, New York, 198 I. 9. V. MALATHY DEVI, B. FRIDOVICH,G. D. JONES,AND D. G. S. SNYDER,J. Mol. Spectrosc. 105, 6 l-
69 (1984), and references cited therein. 10. R. A. TOTH, R. H. HUNT, AND E. K. PLYLER, J. Mol. Spectrosc. 38, 107-l 17 (1971). II. P. A. JANSSON AND C. L. KORB, J. Quant. Spectrosc. Radiat. Transfer 8, 1399-1409 (1968). 12. J. J. OLIVEROAND R. L. LONGBOTHUM,J. Quant. Spectros. Radiat. Transfer 17, 233-236 (1977). 13. B. FRIDOVICH,J. Mol. Spectrosc. 105, 53-60 (1984). 14. W. S. BENEDI~ AND L. D. KAPLAN, J. Quant. Spectrosc. Radiat. Transfer 4, 453-469 15. G. GUELACHVILI,J. Opt. Sot. Amer. 73, 137-150 (1983).
(1964).
OF MOLECULAR
SPECTROSCOPY
111, 114-I 18 (1985)
Intensities and Half-Widths for Several Hz0 v2 Lines in the Region 1500-I 523 cm-’ V. MALATHY Naiional
DEVI,’
B. FRIDOVICH,
Oceanrc and Armospheric Dais.
G. D. .JONES, AND D. G. S. SNYDER’
.-ldministration,
and It@matron
Service.
National
Uhshinglotl,
Environmenral
Satellite.
D C. -70233
Intensities and half-widths have been measured. using a tunable diode laser, for several water vapor lines in the v2 spectral region between 1500 and I573 cm-‘. Where possible. results have been compared with previously published values. D 1985Academx PKSS. inc. INTRODUCTION
Water vapor plays a critical role in determining the radiative transfer properties of the earth’s atmosphere. Water vapor spectral lines are ubiquitous in the infrared; therefore, a precise knowledge of the parameters of these spectral lines-positions, intensities, half-widths, temperature dependence of half-widths, and pressure shiftsare required for any measurement program that requires that atmospheric transmittance be calculable. Examples are the deduction of atmospheric temperature profiles from satellite radiometric measurements, or the inference of stratospheric water content from remote measurements. High-resolution measurements, in the v2 band of water vapor, of intensity, halfwidth, and pressure shifts, have been reported in the recent literature (I-8). Some of these investigations were performed using tunable diode lasers (I, 2, 7). Although the determination of the various spectral line parameters are best done with the very high resolution of tunable diodes, the amount of data, and the spectral coverage, in any one study is usually very limited, owing to the narrow tuning range of the diodes. In this paper we report on diode laser measurements of intensities and half-widths for several lines in the uZ band, in the spectral region 1500-1523 cm-‘. The results are compared with literature values when appropriate. EXPERIMENTAL
DETAILS
The diode laser spectrometer used in this investigation has already been described in some detail (9). We repeat a very concise description here. The system consists of a commercial tunable diode laser (Laser Analytics, Inc.) whose modes are sorted by a 3.5-m focal length vacuum grating monochromator. The beam exiting the monochromator is collimated and then split by an aluminized grid evaporated onto
’ Current 23185. 2Current 0022-2852/85
address:
Department
address:
Naval Coastal
of Physics,
$3.00
Copyright 0 1985 by Academic Press, Inc. All rights of reproduction in any form reserved.
The College of William
Systems Center,
and Mary. Williamsburg,
Code 4130. Panama
114
City. Florida
32407.
Virginia
H,O v2: 1500-1523
cm-’
115
a CaF2 substrate. One beam passes through a 7.62-cm (3”) temperature-controlled Ge &talon, while the other beam passes through the sample cell, or cells. Each of the above beams is then focused onto independent HgCdTe detectors. The detector outputs go to two lock-in amplifiers (Princeton Applied Research Model 124A). The diode beam is chopped, with a tuning fork chopper, at 400 Hz at the entrance slit of the monochromator. We use a time constant, on the lock-in amplifiers, of 0.3 sec. A data system (Digital Equipment Corporation MNC 1 l/23) samples the lock-in outputs every 0.1 set and stores digital values on a hard disk for later analysis. Since these experiments were conducted in a spectral region containing strong water vapor lines, extra care was required to minimize background absorption, especially that which could occur at low pressure inside the monochromator tank. The monochromator tank was continually pumped with a 15.24-cm (6”) diffusion pump. All optics external to the vacuum tank are housed in rigid plastic enclosures which are continuously flushed with dry nitrogen, supplied from a large LN2 tank. The water vapor samples used for the measurements were prepared in the following way. A few milliliters of distilled water were placed into a small chamber, made by sealing one arm of a Pyrex and Teflon valve. The glass manifold which connected the water vapor source to the cell to be filled was evacuated to about 1O-6 Torr. The valve to the water was then slowly opened and the water was allowed to boil vigorously for a few seconds to outgas it. The valve was closed and the manifold was again evacuated. The manifold was then isolated from the vacuum pump, and the valve to the water source was opened so that the manifold and sample cell were filled with water vapor. The water source valve was again closed. After some time, during which the cell and manifold walls could come to equilibrium with the vapor, the manifold and cell were slowly pumped down to the desired pressure, as indicated on an MKS Baratron gauge. When the gauge showed a steady pressure, the cell valve was closed and the cell was moved from the sample preparation system and inserted into the optical beam. The stability of the water vapor sample was assessed by looking at the spectra of repeated scans. as displayed from digital data, on a CRT. The central transmittance, r(O), usually changed by less than 1.5%. During the 15-20 min required for a sequence of four to six measurements on one line, the measured equivalent widths remained fairly constantwithin 2% of each other. The sample cells were Pyrex and either 10.88, 2 1.4 1, or 50.5 cm long, with CaF,! windows. Water vapor pressures used ranged from a few hundred milliTorr to several Ton-, depending on the parameter being measured. A summary of sample characteristics is given in Table I. Sample temperatures were measured using precision thermistor beads affixed externally to the cell walls. ANALYSIS
Line intensities were determined from consistent with cell length and adequate recorded at two or more pressures, and pressure. Since the pressures ranged from taken into account when computing the
spectral scans made at the lowest pressure minimum transmittance. Each line was several repetitive scans were made at each about 0.4 to 3.5 Torr, self-broadening was intensity. For those transitions whose self-
116
MALATHY
DEW
ET AL.
broadening coefficients were not determined in this study, a nominal value of 0.3 cm-‘/atm was assumed when deriving the intensities. Intensities were determined from the measured equivalent widths. The equivalent widths were measured using a program which located the 100% transmittance line and then computed the integrated absorption. The program also calculated half-width (HWHH), central transmittance, and line position. Wing corrections were applied to these measured equivalent widths (10). These corrections typically ranged from 1 to 3%, depending on the sample pressures used. Using the corrected equivalent widths, intensities were found by interpolating in the tables of Jansson and Korb (11). The results obtained are summarized in Table II. The values obtained in this study are compared with those calculated by Camy-Peyret, Flaud, and Toth (8). Nitrogen-broadened and self-broadened half-widths for a few transitions were also determined using various pressures of H20, or H20 and N2 mixtures. A computer program was used to determine the half-width of the line, bv, at the square root of the minimum transmittance, r(O). The instrument function was negligibly small. This fact was determined by measuring the half-widths of several Doppler lines. The effective Doppler width, b’, was therefore assumed to be the same as bD, the theoretical half-width when calculating Lorentz half-widths. For broadened lines, the measured half-widths ranged from 0.006 to 0.009 cm-’ and were therefore assumed to be those of Voigt lines, bv. Values of bv and bD were used in the expression of Oliver0 and Longbothum (12) to derive the Lorentz half-width, bL, and the broadening coefficient, bf = bdp(atm). In deriving the nitrogen-broadening coefficient, bF(H20 - N2), self-broadening effects were also taken into consideration. The broadening coefficients were derived using the relation b,_ = b:(H*O - H,O)p(H,O)
+ b:(H,O - N&(Nz).
(1)
Again, a nominal value of 0.3 cm-‘/atm was used as the self-broadening coefficient for those transitions for which measurements were not performed in this study. Measured half-widths have been corrected for inaccuracies produced by mislocating the 100% transmittance line (13). The results of these measurements are given in Table III. RESULTS
AND
DISCUSSION
The results of the measurements made to determine line intensities are reported in Table II. The values in parentheses are one standard deviation of the measurements TABLE Parameters Parameter
Studied
and Sample Characteristics
Intensity
21.41, 10.08.
21.41
bf(H20
- Np)
10.88.
21.41.
pressure
0.4 - 3.5
50.5
- H20)
partial
Sample pressure (tiorr)
Absorption path (cm)
b;(H20
* The
I
of water
vapor
50.5
ranged
Sample temp.(K)
297
5 - 14
297
50 - 100*
297
from
0.2
to 2.5
tort-.
W
~2;
117
1500-1523 cm-’
TABLE II Intensities (cm-* atm-‘) for Select Transitions in the v2 Band of Hz0 (297 K) Wavenumber km-l)a
Rotational
J’
K:, K,'
J
~___
(( K:: KI: _
Present
Study
Ref.
0
~.____
1500.54631
9
3
7
9
4
6
0.0207(l)
0.0215
1501.84607
7
2
6
7
3
5
0.1750(93)
0.1678
1507.44275
0
17
0
2
6
0.1076(4)
0.0907
1507.48437
0
3
6
a
4
5
0.1738(98)
0.1586
1507.79965
6
5
2
6
6
1
0.0666(14)
0.0731
1507.82170
6
5
1
6
6
0
0.0218(9)
0.0244
1507.85200
7
5
3
7
6
2
0.0188(7)
0.0204
1507.97297
7
5
2
7
6
1
0.0572(10)
0.0613
1508.02191
0
5
4
8
6
3
0.0313(13)
0.0348
1508.23059
9
5
5
9
6
4
0.0048( 1)
0.0052
1508.29276
10
5
6
10
6
5
0.0056(Z)
0.0060
1508.34263
9
4
6
9
5
5
0.0119(3)
0.0118
1508.49059
0
5
3
8
6
2
0.0103(2)
0.0116
1509.53108
8
4
5
8
5
4
0.0799(28)
0.0830
1509.62267
5
4
2
5
5
1
0.0854(44)
0.0907
1509.66336
9
5
4
9
6
3
0.0132(12)
0.0158
1515.77900
0
4
4
8
5
3
0.0296(6)
0.0279
7 6
2 2
5' 4
0.0667(47)
0.0610
1523.63459
; Ref. 15 Ref. a Unresolved:
’
Intensity
Assignmentb
ti2170 upper
line,
H2160
lower
1
line
in the units of the last digit quoted. The present results are compared with those calculated by Camy-Peyret and F’laud, which are given in the last column. The mean difference in the two sets of values is 6.3%. However, it should be noted that the results reported in Table II were made on relatively weak transitions. Although very strong absorption lines were observed in the spectral region studied in this work, no intensity measurements are reported for those transitions. Since the absorption paths used were large, the sample pressures required would have been too small to be measured with confidence. Measurements on these strong lines would indeed be useful for testing the accuracy of the calculated line intensities over a wider range of intensity values. Table III summarizes the broadening coefficients obtained in this study. The values given in parentheses are the standard deviation of the measurements in the last digit. The self-broadened half-widths are smaller than those reported by Benedict et al. (14). The values for nitrogen-broadened half-widths agree with similar measurements for u2 band lines in the region 1650- 1700 cm-’ reported in Ref. (7). A ratio of 4.8 + 0.4 is obtained for the self- to nitrogen-broadened half-width.
MALATHY
118
DEVI ET AL.
TABLE III Self- and Nitrogen-Broadening Coefficients (cm-’ atm-‘) for Some Y* Band Lines of Hz0 (297 K) Wavenumber
(8)
RotatfonalAssignment J' K; K;
J' K; K;
1498.80354
111
2
2
1498.87509
6
0
6
6
15
1500.54631
9
3
7
9
4
6
0.313(4)
(crnl)
(9)
bf(H2C-H20) bf(H2D-N2)
(8)/(9)
0.094(l)
0
0.077(6) 0.064(5)
4.9
1508.23069
9
5
5
9
6
4
0.218(7)
1508.29276
10
5
6
10
6
5
0.239(5)
1508.34263
9
4
6
9
5
5
0.320(9)
1508.55917
4
2
3
5
14
1514.98777
6
3
4
6
4
3
0.313(81
0.071(8)
4.4
1515.77899
8
4
4
8
5
3
0.383(11)
0.075(l)
5.1
0.091(2)
ACKNOWLEDGMENTS The authors are grateful to Dr. C. Camy-Peyret and Dr. J.-M. FIaud of the Laboratoire de Physique Moleeulaire et d’optique Atmospherique, Orsay, France, for reading the manuscript and making many
valuable suggestions. RECEIVED:
December 6. 1984 REFERENCES
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