Exciton luminescence in krypton cryocrystals with an admixture of molecular deuterium

Abstract

Data on the VUV and UV cathodoluminescence spectra of the Kr-based solid solutions, Kr-D2, Kr-D2-O2, and Kr-Xe-O2, as functions of dopant concentration are presented. Introducing deuterium impurity into krypton crystals produces no new spectral features, which indicates that electron bombardment of these crystals does not cause excitation or dissociation of D2. The intensity of the intrinsic emission from the matrix increases substantially, the more so for higher concentrations of D2. The observed intensity increase is found to be caused by localization of matrix excitons within a limited volume of the crystal as they undergo quasielastic scattering by impurity deuterium molecules, which leads to a substantial reduction in the mean free path and diffusion length for the excitons, as well as to their faster self-localization. Possible mechanisms for luminescence quenching in pure krypton cryocrystals are discussed. It is shown that quenching is caused by annihilation of excitons as they interact among themselves or with other electronic excitations of the crystal.