High-frequency interaction-induced rototranslational wings of anisotropic nitrogen spectra

The anisotropic rototranslational scattering spectra of nitrogen gas at high frequency up to 700 cm−1 for several temperatures and from low densities are analyzed in terms of new site-site (M3SV) intermolecular potential and interaction-induced pair polarizability models, using quantum spectral shapes computations. Our theoretical calculations take into account multipole contributions from the mean value and anisotropy of the dipole-dipole polarizability tensor α, two independent components of the dipole-octopole polarizability tensor E and dipole-dipole-quadrupole hyperpolarizability tensor B. The high-frequency wings are discussed in terms of the collision-induced rotational Rayleigh effect and estimates for the dipole-octopole polarizability |E4| are obtained and checked with recent ab initio theoretical value. Good comparison is found in the frequency range 0-400 cm−1 between the theoretical and experimental spectra. When an exponential contribution [exp(−ν/ν0)] with ν0 = 425 cm−1 is considered to model very short-range light scattering mechanisms at room temperature, good agreement is found over the whole frequency range.