Radiation defects in sulfates of alkali and alkaline-earth metals creating at excitation by ultraviolet photons

X-ray luminescence, photoluminescence, and vacuum ultraviolet spectroscopy have been used to study the nature of intrinsic luminescence and the formation of electron-hole trapping centers in a LiNaSO₄ crystal in a broad spectral range at a temperature of 15-300 K. Based on the measurement of the spectrum of creation of intrinsic luminescence and recombination radiation at electron-hole trapping centers, the minimum energy of creation of electron-hole pairs is estimated, which determines the width of the band gap in the new model of the band structure, LiNaSO₄. It is assumed that the appearance of intrinsic luminescence and the formation of capture centers are associated with low-energy transitions from the 1t1 orbitals of the valence band of the anionic complex to the s-state of the cation in the conduction band. (paper)