Pressure-Broadening and Cross-Relaxation Rates of Rotation–Inversion Transitions in the ν4Band of NH3Perturbed by CO2

✍ Scribed by H. Aroui; A. Picard-Bersellini; M. Chevalier; M. Broquier; S. Gherissi

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 148 KB
• Volume: 176
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1006/jmsp.1996.0073

✦ Synopsis

Measurements of pressure-broadening and cross-relaxation rates of rotation-inversion transitions in the n 4 band (1470-1600 cm 01 ) of NH 3 perturbed by CO 2 are reported. Pressure-broadening parameters were measured at a low pressure of CO 2 (0-180 Torr). At high pressure, the two lines of the doublet broaden as the pressure is increased, but with a markedly lower rate than at low pressure, until they overlap. Such an effect is due to collision cross-section relaxation between the two lines of the inversion components of the doublet. Detailed modeling of the spectral lines permits us to determine pressure-broadening coefficients for 41 transitions, and cross-relaxation parameters for 10 doublets. The results show a decrease of the pressure-broadening parameters with the J quantum number. We compared our results with other previous measurements obtained in the far-infrared and n 2 regions, and for several foreign gases such as He, H 2 , and N 2 .