Luminescence and optically detected ESR in a-As2S3

Luminescence with decay time of about 10 nsec and the Stokes-shift of about 0.84 eV was found in a-As2S3 by the excitation at the absorption edge at 4.2 K. The peak position of the luminescence depended on the excitation energy and the luminescence remembered the polarization of light of the excitation. The experimental data can be explained by assuming that the luminescence and the absorption edge are due to localized excitons. Photo-structural change is discussed according to the exciton model. In addition, ESR of centers of the luminescence observed by Kolomiets et al. was optically detected. (orig.)