Phonon-phonon interactions in the polarizarion dependence of Raman scattering

Abstract

We have found that the polarization dependence of the Raman signal in organic crystals can only be described by a fourth-rank formalism. The generalization from the traditional second-rank Raman tensor $\mathcal{R}$ is physically motivated by consideration of the light scattering mechanism of anharmonic crystals at finite temperatures, and explained in terms of off-diagonal components of the crystal self-energy. We thus establish a novel manifestation of anharmonicity in inelastic light scattering, markedly separate from the better known phonon lifetime.Comment: 31 pages, 17 figure