Influence of Spatial Dispersion on the Transmission Spectra of CdS Single Crystals

Abstract

Abstract Transmission spectra are measured on extremly thin CdS single crystals with high quality in the energy range of exciton transitions from 1.8 °K to room temperature. Analysing the characteristics of the exciton absorption lines such as lineshapes, halfwidths, and oscillator strenghts it is found that the line A n=1 , E ⊥ c shows at low temperatures some “anomalies”, which cannot be explained in a model with weak exciton‐photon coupling but are qualitatively well understandable in a polariton model with spatial dispersion. This is caused by the fact that at low temperatures the exciton‐photon interaction prevails over the exciton‐phonon interaction resulting in a weakly‐damped polariton.