Radiation defects in alkali metal sulfates irradiated by ultraviolet photons.

In the present paper the formation of defects in LiKSO 4 andK 2 SO 4 crystals after excitation by 4–11 eV photons at the temperature of liquid nitrogen was studied by the methods of thermal activation and vacuum-ultraviolet spectroscopy. It is shown experimentally that electron-hole trapping centers are formed as a result of capture of electrons and holes by anion complexes S O 4 2 − created by the transition of electrons from 1t 1 ; 3t 2 ; e; 2t 2 orbitals in the valence band to the s-state of the cation in the conduction band. It is supposed that the formation of defects in LiKSO 4 and K 2 SO 4 crystals is caused by the dissociation of excited anion complexes, created by the transition of electrons from 1t 1 ; 3t 2 ; e; 2t 2 orbitals in the valence band to free, antibinding orbitals 4 t 2 ∗ and 3 a 1 ∗ in the conduction band. In this case, stable electron S O 3 − v a + e − and hole O 3 − trapping centers are formed. [ABSTRACT FROM AUTHOR]