High Frequency Interaction-Induced Anisotropic Rototranslational Light Scattering Spectra of Gaseous Carbon Dioxide

The anisotropic rototranslational scattering of carbon dioxide gas is studied theoretically at 294.5 K, in the frequency range 10-470 $cm^{-1}$, at a density of 1.026254 mole/litre. The anisotropic double differential cross-section for scattered light is calculated theoretically using new site-site Morse-Morse-Morse-spline-van der Waals intermolecular potentials with the parameters fitted to the different thermophysical and transport properties. Our theoretical calculations take into account multipole contributions from the first- and second-order dipole-induced dipole, first-order dipole-induced octopole and first-order dipole-dipole-quadrupole light scattering mechanisms as well as their cross contributions. The irreducible spherical form for the induced operator of these light scattering mechanisms was determined. The high frequency wings are discussed in terms of the collision-induced rotational Rayleigh effect and estimates for the dipole-octopole polarizability $E_4$, is obtained and checked with the ab initio theoretical value. Good agreement is obtained at moderate frequencies between the theoretical and experimental spectra. When an exponential contribution $exp(-ν//ν_{0})$, with $ν_0 = 115 cm^{-1}$ is considered to model very short-range light scattering mechanism, good agreement is found over the whole frequency range.