Raman Scattering in Resonance with the Exciton Transition in Pure Polar Crystals

A study of the Raman scattering near resonance with the exciton transition in pure polar crystals is presented. The following conclusions are obtained, independently of the crystal symmetry: (I) The resonant Raman spectra should show multiphonon structures at energy multiples of the first-order peak. The repetition of the peaks depends on the strength of the exciton-phonon coupling. (II) For the case of large-radius excitons, these spectra should show the same peaks for any polarization of the light.