Pressure effects on N 2 –N 2 rototranslational Raman spectra predicted from leading spectral moments
Résumé
Non‐Markovian effects having a strong influence on far‐wing intensities of spectroscopic signatures by molecular gases are analyzed theoretically with the use of a non‐Markovian relaxation matrix derived for rapidly colliding linear rotators (J. Chem. Phys. 149, 044305 [2018]) for the benchmark case of rototranslational Raman spectra of molecular nitrogen recorded at high densities up to very far wings (Phys. Lett. A 157, 44 [1991]). This matrix is built here on the base of the translational‐spectrum model of Birnbaum and Cohen and the recently computed, from known potential energy surfaces, two leading classical spectral moments (J. Ram. Spectrosc. 2020, DOI: 10.1002/jrs.5923). Theoretical intensity computations, going beyond the commonly used impact approximation, give much less overestimated values in the far wing and constitute a promising tool for getting accurate theoretical description of broad‐band spectra.