On Light Scattering by Polyatomic Fluids

"Scattering equations" are derived which relate the spectrum of the light scattered from a polyatomic fluid to the spectral functions of the fluctuating spherical (scalar) and anisotropic parts of the electric permeability tensor. The influence of a constant external (electric or magnetic) field is considered. For a gas of linear molecules, it is shown that the fluctuations leading to the depolarized Rayleigh light scattering are fluctuations of the mean (2nd rank) tensor polarization of the rotational angular momenta of the molecules. Furthermore, the fluctuations associated with the rotational Raman scattering are expressed by fluctuaions of the mean values of (2n d rank) tensor operators which induce transitions between the rotational levels of a molecule.