The spectroscopy of colour centres in ZnS and CaS

Some data about colour centres of unactivated and activated CaS and ZnS with various impurities are reported. The stimulation (excited absorption) spectrum of ZnS consists at LNT four groups of band: the band at 2.5–3 eV and complex stimulation bands at 1.6 eV, at 1 eV and at 0.5 eV. The structure of stimulation spectra of CaS is analogous: it consists of an intense band at 2–2.5 eV, and bands at 1.6–1.8 eV and 0.8–1.0 eV. At room temperature the low energy band (at 0.5 eV for ZnS and 0.8–1.0 eV for CaS) does not appear. The excited absorption bands appear at energies above 2 eV. The investigation of non-isothermal relaxation of stimulation permitted us to establish the temperature stability of these stimulation bands.