- Email: [email protected]
High-resolution near-infrared absorption measurements on the 7-0 vibration-rotation band of hydrogen iodide
JOURNAL
012 MULECULAR
SPECTROSCUI’Y
68, 329-3.10
High-Resolution Near-Infrared 7-O Vibration-Rotation
(1977 1
Absorption Measurements Band of Hydrogen Iodide
on the
Eighteen lines of the 7-O vibration-rotation absorption band of HI were photographed in the second order of the 4-m focal length Ebert-t>Fe spectrograph in our laboratory. This instrument uses a 20 X 10 cm, IZOO-grooves/mm grating and has a theoretical resolving power of 480 000 in the second order. .L multipath White-type absorption cell, 2 m long, with an absorption path length of 260 m was filled with HI at a pressure of 160 Torr. On account of the drop of the White cellgoldenmirrorsreflectingfactor in the 7-O band spectral range, exposure times varying between 4 and 6 hr were required when using Kodak 103 -4-F plates. The lines were measured relative to atomic lines of thorium in the manner described by Bernage and Niay (1). The essential features of this method lie in photographing on the same plate, the spectrum of HI, the fringes obtained with a %-cm-long Fabry-Perot interferometcsr and a black-body source, together with the spectrum of thorium obtained by a high-frequency discharge. In order to reduce random errors introduced by noise and spectrograph instabilities, six plates were photographed and measured. The average values for the observed wavenumbers (expressed in vacuum cm-l) are listed in Table I. The experimental uncertainties were estimated to be less than 0.030 cm- L for most lines. .i set of equilibrium molecular constants was determined by using all the available accurate measurcments (2-6j and fitting them with a least-squares routine applied to the term value expression 7’1?, .7) = l~,l,iZ~+ $) + I-20(8 + 5,’ + F3”(I’ + 4,” + I‘,“!_; + 4)’ + I’,,(Zl + +)” + J(J
+ l)[I’(I,
+ F,,CZ’ + t‘) + I’2,(? + 3,’ + ITs,C? + +)“I + J”(/
+ I )‘l’,j&
i I)
Each measurement, in the microwave, in the infrared, and in the visible regions was weighted with a weight factor proportional to the inverse of the square of its uncertainty. Owing to the lack of measurement on higher J-transition lines, the E 11 and I’lr molecular equilibrium constants were found not to be significant when compared to their uncertainties and, accordingly, were not introduced in the least squares. ‘l’.ULE \Favenumbers
(in Vacuum
J
R(J)
0
13 891.493
1 2 3 1 5 6
13 13 13 13 13 13
7 8 Y
13 893.220 13 883.290 13 870.811
UI~-~) of Observed
Transitions
in the 7 c
A’”
P(J)
0 Band
of HI A”
(11,
899.315 904.634 907.416 907.689 905.416 900.601
a The differences A (observed ol~scrvctl w:lvcnuml)er.
I
(2) (7) 1-21 f+iJ f+3J (-51 C--281 L-621 C-- IOOJ -
calculated)
(‘up) tight Q 19; i by .\cademic Pleas. ln~. All rights of reproduction in any form reserved.
in the last digits
13 13 13 13 13 13
868.273 852.928 835.079 814.738 791.92’ 766.584
C-13) (-2) (3) (5) (21) (0)
13 738.801 13708.552
C+ll! (2Yi
are given
in parentheses
after
car.h
330
NOTBS
TABLE II Mclecuiar Equilibriu~ll Constants
(in Vacuum cm-l) and Dunham’s Coefiicients
Molecular equilibrium constants obtained by least-squares routine
Dunham coeficients
2308.95907 -39.5722 -0.05874 -7.0595 x 10-S -7.7637 x lo-* 6.511932 -0.17124 2.898 X iOW
E-31
-1.69
Fue
-2.067317
2.4
x 10-Z
2.1 x 7.4 x 1.1 X 6 x 4.2 X 1 x 4 x
X lo-’
4.8 X 1O-6 5
x lo-”
2309.2 1288 5.63999615 x 10-a -2.553884 4.096165 - 5.2 17654 3.742839 3.686482 -2.444037
10-Z 10-z 10-s IO-” lo-” 10-4 10-s
wex B,=------= 2
Ye
6.5119759
AlSib 2 4.8 9.5 6.5 1.3 1.8 1.0 2.5
x x x X x x
10-z IO-8 10-d 10-a 10-z 10-l
8
x 10-b
x 10-T -__-
-. a AY
The Dunham coefficients yc, wc, and the a; (i < 6) were deduced by an iterative process from the values of equilibrium constants Y+ in the way described by Finlan and Simons (7). By using the variance-covariance matrix of the Yij used and numerical values for the partial derivatives a,e/aYij, we have estimated the standard deviations of the potential coefficients. The molecular constants Y
NIAY
P. BERNAGE C. COQUAN~ H. BOCQUET Laboraloire de Spectroscopic des MolLcnles Diatomiqnes, E.R.d . 303 Univetsitt? des Sciences et Techniqms dc Lille B.P. 36-59650 Vilicneme d’A scq, Frame Rcccivcd March 2, 1977
012 MULECULAR
SPECTROSCUI’Y
68, 329-3.10
High-Resolution Near-Infrared 7-O Vibration-Rotation
(1977 1
Absorption Measurements Band of Hydrogen Iodide
on the
Eighteen lines of the 7-O vibration-rotation absorption band of HI were photographed in the second order of the 4-m focal length Ebert-t>Fe spectrograph in our laboratory. This instrument uses a 20 X 10 cm, IZOO-grooves/mm grating and has a theoretical resolving power of 480 000 in the second order. .L multipath White-type absorption cell, 2 m long, with an absorption path length of 260 m was filled with HI at a pressure of 160 Torr. On account of the drop of the White cellgoldenmirrorsreflectingfactor in the 7-O band spectral range, exposure times varying between 4 and 6 hr were required when using Kodak 103 -4-F plates. The lines were measured relative to atomic lines of thorium in the manner described by Bernage and Niay (1). The essential features of this method lie in photographing on the same plate, the spectrum of HI, the fringes obtained with a %-cm-long Fabry-Perot interferometcsr and a black-body source, together with the spectrum of thorium obtained by a high-frequency discharge. In order to reduce random errors introduced by noise and spectrograph instabilities, six plates were photographed and measured. The average values for the observed wavenumbers (expressed in vacuum cm-l) are listed in Table I. The experimental uncertainties were estimated to be less than 0.030 cm- L for most lines. .i set of equilibrium molecular constants was determined by using all the available accurate measurcments (2-6j and fitting them with a least-squares routine applied to the term value expression 7’1?, .7) = l~,l,iZ~+ $) + I-20(8 + 5,’ + F3”(I’ + 4,” + I‘,“!_; + 4)’ + I’,,(Zl + +)” + J(J
+ l)[I’(I,
+ F,,CZ’ + t‘) + I’2,(? + 3,’ + ITs,C? + +)“I + J”(/
+ I )‘l’,j&
i I)
Each measurement, in the microwave, in the infrared, and in the visible regions was weighted with a weight factor proportional to the inverse of the square of its uncertainty. Owing to the lack of measurement on higher J-transition lines, the E 11 and I’lr molecular equilibrium constants were found not to be significant when compared to their uncertainties and, accordingly, were not introduced in the least squares. ‘l’.ULE \Favenumbers
(in Vacuum
J
R(J)
0
13 891.493
1 2 3 1 5 6
13 13 13 13 13 13
7 8 Y
13 893.220 13 883.290 13 870.811
UI~-~) of Observed
Transitions
in the 7 c
A’”
P(J)
0 Band
of HI A”
(11,
899.315 904.634 907.416 907.689 905.416 900.601
a The differences A (observed ol~scrvctl w:lvcnuml)er.
I
(2) (7) 1-21 f+iJ f+3J (-51 C--281 L-621 C-- IOOJ -
calculated)
(‘up) tight Q 19; i by .\cademic Pleas. ln~. All rights of reproduction in any form reserved.
in the last digits
13 13 13 13 13 13
868.273 852.928 835.079 814.738 791.92’ 766.584
C-13) (-2) (3) (5) (21) (0)
13 738.801 13708.552
C+ll! (2Yi
are given
in parentheses
after
car.h
330
NOTBS
TABLE II Mclecuiar Equilibriu~ll Constants
(in Vacuum cm-l) and Dunham’s Coefiicients
Molecular equilibrium constants obtained by least-squares routine
Dunham coeficients
2308.95907 -39.5722 -0.05874 -7.0595 x 10-S -7.7637 x lo-* 6.511932 -0.17124 2.898 X iOW
E-31
-1.69
Fue
-2.067317
2.4
x 10-Z
2.1 x 7.4 x 1.1 X 6 x 4.2 X 1 x 4 x
X lo-’
4.8 X 1O-6 5
x lo-”
2309.2 1288 5.63999615 x 10-a -2.553884 4.096165 - 5.2 17654 3.742839 3.686482 -2.444037
10-Z 10-z 10-s IO-” lo-” 10-4 10-s
wex B,=------= 2
Ye
6.5119759
AlSib 2 4.8 9.5 6.5 1.3 1.8 1.0 2.5
x x x X x x
10-z IO-8 10-d 10-a 10-z 10-l
8
x 10-b
x 10-T -__-
-. a AY
The Dunham coefficients yc, wc, and the a; (i < 6) were deduced by an iterative process from the values of equilibrium constants Y+ in the way described by Finlan and Simons (7). By using the variance-covariance matrix of the Yij used and numerical values for the partial derivatives a,e/aYij, we have estimated the standard deviations of the potential coefficients. The molecular constants Y
NIAY
P. BERNAGE C. COQUAN~ H. BOCQUET Laboraloire de Spectroscopic des MolLcnles Diatomiqnes, E.R.d . 303 Univetsitt? des Sciences et Techniqms dc Lille B.P. 36-59650 Vilicneme d’A scq, Frame Rcccivcd March 2, 1977