General Orientation Dependence of Rayleigh and Raman Scattering and Scattering by Linear Molecules in Arbitrary Electronic States*

Abstract

Modern angular-momentum techniques are used to study a few refined aspects of the conventional Raman effect—aspects not easily accessible in the old days of Placzek, who used mainly direction cosines and circular coordinates. The intensity at an arbitrary direction of observation (specified by three instead of one Euler angles, ϕs,θs,ψs), of scattering by random molecular systems, has been derived. In the limit of ϕs=ψs=0, θs=π/2−Θs=Φs, it reduces to that of Placzek. The intensity of the Rayleigh and Raman scattering by uniformly oriented molecules (in solid matrices or in molecular crystals) has also been derived. It is illustrated for oriented molecules with cylindrical symmetry. The Raman scattering by rotating linear molecules in arbitrary electronic states has been investigated. The general formulas derived are usable also in electronic Raman effects.