CONTRIBUTIONS OF SCATTERING OF POLARITONS BY PHONONS TO EMISSION OF RADIATION BY SOLIDS

A brief discussion of the coupled exciton-photon (polariton) fields is given. Probabilities per unit time associated with the scattering of polaritons by acoustical and optical phonons are calculated to terms of first order in the exciton-phonon interaction. Results applicable to cadmium sulfide at 77°K are obtained. Two phonon-assisted emission bands are found. One is positioned approximately one longitudinal optical (LO) phonon below the exciton-photon resonance energy EA, and is due to the inelastic scattering of polaritons above the knee of the lowest-lying polariton branch to states below the knee with the simultaneous creation of LO phonons. The second band is positioned very close to EA and is also due primarily to LO-phonon scattering. © 1969 The American Physical Society.