Radiation defects in alkali metal sulfates

Spectroscopic methods were used to investigate the mechanisms of formation of electron-hole capture centers in KNaSO4 and LiNaSO4 crystals by irradiation with ultraviolet (UV) light and photons with energies of 4-6.2 eV at 80 K and 300 K. We were the first who showed experimentally that the direct irradiation by photons with an energy of 4-6.2 eV at 80 K forms in KNaSO4 and LiNaSO4 crystals electron-hole capture centers registered in the measurements of TSL (thermo stimulated luminescence) and recombination radiation. During irradiation by photons, the electrons in 1t1, 3t2, 1e, 2t2 orbitals of SO42−anion in the sulfate valence band are excited. From this state, the electrons recombine with the self-trapped hole (SO42−) radiatively or with formation of defects. Quantum chemical calculations modeling the decay of the anionic complex confirm energy possibility of such processes.