Phonon-Phonon Interactions in the Polarization Dependence of Raman Scattering

We have found that the polarization dependence of Raman scattering in organic crystals at finite temperatures can only be described by a fourth-rank tensor formalism. This generalization of the second-rank Raman tensor stems from the effect of off diagonal components in the crystal self-energy on the light scattering mechanism. We thus establish a novel manifestation of phonon-phonon interaction in inelastic light scattering, markedly separate from the better-known phonon lifetime.
Funding Agencies|European Research Counsel [850041]; Swedish Research Council (VR) [2020-04630]; Belgian National Fund for Scientific Research (FNRS) [T.0072.18, T.0094.22, U.G001.19, O.005018F, O.00322]; French Community of Belgian (ARC) [20061]