Pressure effects on N-2-N-2 rototranslational Raman spectra predicted from leading spectral moments

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.