Fine Structure of the Infrared Absorption and Emission Spectra ofCu2+in ZnS and CdS Crystals

Abstract

Near-infrared absorption and emission spectra of ${\mathrm{Cu}}^{2+}$ as a substitutional impurity in ZnS and CdS crystals recorded at low temperatures are found to exhibit a pronounced fine structure. The optical transitions occur between energy levels which result from a splitting of the ${\mathrm{Cu}}^{2+}$ ground state by a crystal field of tetrahedral symmetry and the spin-orbit interaction. A small contribution of lower symmetry---possibly produced by Jahn-Teller effect---and an interaction of the center with vibration modes of the host lattice account for the occurrence of numerous lines. Crystal field and spin-orbit parameters were calculated for ${\mathrm{Cu}}^{2+}$ in ZnS and CdS crystals.