0000000000022213
AUTHOR
I. M. Grigoriev
Helium and Argon Line Broadening in the nu2 Band of CH4
Abstract The spectra of the gaseous mixtures CH 4 –He and CH 4 –Ar were obtained in the spectral region 1400–1750 cm −1 with a resolution up to 0.003 cm −1 . Helium and argon pressure broadenings for the vibration–rotation lines of the ν 2 band of CH 4 have been estimated at room temperature for some lines in the P , Q , and R branches. These values were also calculated using the theoretical approach developed by Robert and Bonamy, extended to the case of tetrahedral molecules. The helium data have been found to be in a satisfactory agreement whereas a divergence of calculated and measured broadening coefficients has been evidenced in the case of argon. Simulations of the ν 2 band shapes of…
Estimation of line parameters under line mixing effect: the nu3 band of CH4 in helium
International audience; Spectra of CH4-He mixtures were measured in the P and R branch regions of nu3 vibration-rotation band at lower pressures of 0.26-1.0 bar and for the whole band at higher pressures up to 90 bar. The line broadening coefficients were found from lower pressure data for the lines of the P branch. These coefficients were calculated in the framework of the Robert and Bonamy semi-classical approach. In general, they agree with the experimental ones, but a small J-dependent deviation was observed. Line mixing effects were observed at all pressures. At higher pressures they were interpreted in terms of the adjusted branch-coupling model. At lower pressures line mixing effects…
Line parameters and shapes of high clusters: R-branch of the nu3 band of CH4 in He mixtures
International audience; The IR absorption spectra of CH4 in pure gas and in mixture with helium were studied in the region of nu3 band at higher J line clusters R(17)-R(22). The frequencies and intensities of rotation-vibration lines were estimated from the experimental spectra at Doppler shape conditions. The line frequencies and intensities were calculated and used for the attribution of overlapped lines in clusters. The calculated line intensities are close to the experimental values. The calculated frequency structure of the higher J manifolds are somewhat wider than the observed one. The shapes of helium-broadened line clusters were compared with those calculated accounting for line mi…