Line mixing in Raman scattering spectra of CO2 modelled by a non-Markovian Energy-Corrected Sudden approach
Abstract
Non-Markovian Energy-Corrected Sudden modelling of room-temperature CO2 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 ν1 and 2ν2 Raman bands and compared to experimental results in the density range 1-45 amagat.
- Publication:
-
Molecular Physics
- Pub Date:
- September 2012
- DOI:
- 10.1080/00268976.2012.683458
- Bibcode:
- 2012MolPh.110.2077D
- Keywords:
-
- line mixing;
- carbon dioxide;
- Raman spectra;
- far wing;
- non-Markovian ECS approach;
- frequency-dependent relaxation matrix;
- high pressure