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

Abstract

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 | E 4| 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/ ν 0)] with ν 0 = 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.