Optics and Spectroscopy, 2025 Volume 133, Issue 2,Pages 124–133(Mi os1590)
Spectroscopy and physics of atoms and molecules
The Q-branch spectrum of isotropic Raman scattering in pure nitrogen: modeling within the framework of classical impact theory at various temperatures and pressures
Abstract:
The complete relaxation matrix N$_2$ was obtained by the method of classical trajectories at eight temperatures in the range from 77 to 2400 K. The calculations used the the potential energy surface of the intermolecular interaction N$_2$–N$_2$ of high accuracy. The obtained results are applied to calculate the spectra of the Q-branch of isotropic Raman scattering of N$_2$ at pressures of 1, 5 and 10 atm using the efficient Gordon and McGinnis algorithm. The transformation of the Q-branch spectrum under temperature and pressure changes has been quantitatively traced, as well as the difference between the exact spectrum and the sum of isolated Lorentz lines when the interference effect is not taken into account. The calculated spectra are compared with the results of the EGL approximation model reproducing the experimental data.
Keywords:collision line-interference, classical impact theory, classical trajectory method, isotropic raman scattering, molecular nitrogen, various temperatures and pressures.
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