We wish to report the observation of pure-rotational Raman scattering in a low-pressure CO2 electric discharge. The results were obtained by use of an argon-ion laser and a sensitive photon-counting detection system. The spectrum clearly shows pure-rotational Raman scattering originating in the 0110 vibrational state of CO2 superimposed on the ground-state pure-rotational Raman spectrum. In unexcited CO2 gas at a pressure of 40 torr, the pure-rotational scattering in the 0110 state has been observed photoelectrically. In addition, high-resolution photographic studies of this effect were carried out using an He–Ne laser and a sample pressure of 1 atm. The rotational constants deduced from this study are B0000 = 0.39027±0.000007 cm−1, D0000 = (12.9±0.3) × 10−8 cm−1, B0110c = 0.39065±0.00004 cm−1, and D0110c = (8.2±4) × 10−8 cm−1. These values are in good agreement with previous infrared measurements.
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Raman displacements are in cm−1. All entries are averages of Stokes and anti-Stokes shifts.
These lines were not used in the final determination of the constants. For an explanation see the text.
Weak or blended lines. Not used in the analysis.
Table III
Pure-rotational Raman displacements of CO2 in the 0110 state.a
B values are given in units of 10−5 cm−1. D values are given in units of 10−8 cm−1.
The labeling of the c and d levels of the 0110 state is that of Courtoy.11,12
G. Herzberg and L. Herzberg, J. Opt. Soc. Am. 43, 1037 (1953).
E. K. Plyler, L. R. Blaine, and E. D. Tidwell, J. Res. Natl. Bur. Std. (U. S.) 55, 183 (1955).
K. Rossmann, K. N. Rao, and H. H. Nielsen, J. Chem. Phys. 24, 103 (1956).
Courtoy’s values for B0000 and D0000 (column 5) were assumed.
Tables (4)
Table I
Population distribution of the CO2 vibrational levels at 300 and 750 K.
N0000/N
N0110/N
N0200/N
N1000/N
N0001/N
300 K
0.9190
7.4865×10−2
1.9318×10−3
1.1800×10−3
1.1758×10−5
750 K
0.4796
0.2666
4.0736×10−2
3.3446×10−2
5.2933×10−3
Table II
Pure-rotational Raman displacements of CO2 in the 0000 statea.
Raman displacements are in cm−1. All entries are averages of Stokes and anti-Stokes shifts.
These lines were not used in the final determination of the constants. For an explanation see the text.
Weak or blended lines. Not used in the analysis.
Table III
Pure-rotational Raman displacements of CO2 in the 0110 state.a
B values are given in units of 10−5 cm−1. D values are given in units of 10−8 cm−1.
The labeling of the c and d levels of the 0110 state is that of Courtoy.11,12
G. Herzberg and L. Herzberg, J. Opt. Soc. Am. 43, 1037 (1953).
E. K. Plyler, L. R. Blaine, and E. D. Tidwell, J. Res. Natl. Bur. Std. (U. S.) 55, 183 (1955).
K. Rossmann, K. N. Rao, and H. H. Nielsen, J. Chem. Phys. 24, 103 (1956).
Courtoy’s values for B0000 and D0000 (column 5) were assumed.