HIGH-FREQUENCY INTERACTION-INDUCED ROTOTRANSLATIONAL WINGS OF ISOTROPIC NITROGEN SPECTRA

The isotropic rototranslational scattering of nitrogen gas is studied in the frequency range 300-600 cm-1, both theoretically and experimentally, at a density of 41 and 169 amagat. The isotropic double differential cross-section for scattered light is calculated theoretically considering first- and second-order dipole-induced dipole, first-order dipole-dipole-quadrupole, and dipole-induced octopole light scattering mechanisms as well as their cross contributions. The irreducible spherical form for the induced operator of these light scattering mechanisms was determined. Good comparison is found in the frequency range 300 450 cm-1 between the theoretical and experimental double differential cross-sections. When an exponential contribution [exp(-nu/nu0)] with nu0 = 118 cm-1 is considered to model very short-range light scattering mechanisms good comparison is found over the whole frequency range.