Direct Measurements of Line-Mixing Coefficients in the ν1+ ν2QBranch of CO2

✍ Scribed by R. Berman; P. Duggan; P.M. Sinclair; A.D. May; J.R. Drummond

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 295 KB
• Volume: 182
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1006/jmsp.1996.7226

✦ Synopsis

High-resolution measurements of the (n 1 / n 2 ) Q branch of pure CO 2 were made using a difference frequency spectrometer with resolution of 5 1 10 05 cm 01 and a signal-to-noise ratio of 2000:1. Lines Q(2) through Q(32) were measured with up to 14 lines in a single spectrum. The analysis of the branch has been performed on data taken at 301 K and pressures less than 11 kPa. The spectra were analyzed on a line-by-line basis within the Rosenkranz approximation of weak overlap [P. W. Rosenkranz, IEEE Trans. Antennas Propagation AP-23, 498 (1975)]. The lineshape profile included Doppler broadening and Dicke narrowing [R. H. Dicke, Phys. Rev. 89, 472 (1953)] using a modified hard collision model [S. G. Rautian and I. I. Sobel'man, Sov. Phys. Uspekh. 9, 701 (1967)] with line mixing. For each line the broadening, Dicke narrowing, and line-mixing coefficients were determined. The broadening coefficients are in good agreement with measurements of lines belonging to different CO 2 bands. Our measured line-mixing parameters are compared to those predicted by a relaxation matrix which was calculated from an exponential power gap (EPG) law [L.