Bound Exciton Resonance in Raman Cross Sections in CdS

Abstract
We present the first direct and conclusive evidence of bound exciton resonance in phonon Raman scattering from solids. The observed enhancement in the 1LO scattering cross section at the I1 bound exciton in CdS is a factor of ∼ 30 for the sample with the highest impurity content. In contrast to 1LO, the 2LO scattering cross section shows no enhancement near bound excitons. An explanation of this behavior is suggested.