Gamma-ray irradiation effects on the optical properties of KHSeO4 single crystals

Potassium hydrogenselenate KHSeO4 single crystals were successfully grown by the solution growth technique. The structure of the grown crystals was confirmed by XRD diffraction spectrum to be the structure of the desired KHSeO4 single crystal. The crystals were irradiated by different doses of gamma-irradiation in the range 0.4-2.4 kGy and the optical absorption spectra were recorded along the a-, b- and c-axes. The optical inter-band transitions were of the indirect allowed ones and the optical energy gap E-g was determined along the three crystallographic directions. The effect of the irradiation on the optical energy gap is reported along the principle crystallographic directions. Urbach rule suggested the formation of Urbach tail and the effect of irradiation on this band tail is reported. These observations are attributed to the radiation-induced defects on the bulk crystal.