Line mixing in Raman scattering spectra of CO2 modelled by a non-Markovian Energy-Corrected Sudden approach

• Published in: Molecular physics Vol. 110; no. 17; pp. 2077 - 2089
• Main Authors: Daneshvar, L., Buldyreva, J.
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis Group 01.09.2012; Taylor & Francis Ltd; Taylor & Francis
• Subjects: Carbon dioxide; far wing; frequency-dependent relaxation matrix; high pressure; line mixing; non-Markovian ECS approach; Physics; Raman spectra; Studies
• ISSN: 0026-8976; 1362-3028
• DOI: 10.1080/00268976.2012.683458

Non-Markovian Energy-Corrected Sudden modelling of room-temperature CO 2 Raman scattering spectra up to the far wing is revisited and completed for gas densities between 1 and 45 amagat. The model parameters are fitted on an extended set of low-pressure isolated line widths including very high values of the rotational quantum number J and well reproduce the decreasing of line broadening for the experimentally studied J-values. From calculations of the absolute-intensity rototranslational spectrum at 23 amagat, it is shown that the traditional adiabaticity factor of De Pristo gives a more coherent description of low-pressure line widths and high-pressure wing intensities than the two-parameter factor of Birnbaum-Cohen. A simple qualitative correction of the ECS-modelled intensities for the induced and cross allowed-induced scattering appears to be insufficient to match the experimental data in the spectral wing. Theoretical spectral shapes are also calculated for the O-Q-S branches of vibrotational ν 1 and 2ν 2 Raman bands and compared to experimental results in the density range 1-45 amagat.