Temperature dependences of spectral and kinetic characteristics of photoluminescence of alkali and alkaline-earth metal chromate crystals

Based on the results of temperature studies of spectral and kinetic characteristics, a study is made to determine the influence of the structure of different types of luminescence centers (LC) formed in chromate crystals on the processes of relaxation and radiationless deactivation of excitation energy. It is shown that "isolated" LC are characterized by simple temperature quenching of luminescence above the barrier. It is established that several excited states take part in the radiation of complex LC. The possibility of radiationless transitions between them with a change in spin is due to spin-lattice relaxation, which, as calculations showed, is described for different types of LC by the "van Vleck" or "defect" mechanisms.