Asymmetry in the Raman cross section from large temperature variation

Abstract

We show that in the presence of large temperature gradients the second-order Raman cross sections can show asymmetry around the optical-phonon frequency. This skewness as a function of Raman frequency is proportional to the temperature gradient and is traced to the form of the accoustical-phonon occupation. It thus provides an additional mechanism for this asymmetry in addition to the usual spatial variation considered previously.