Photochemical Behavior of Alkali Halide Crystals Containing OH−and SO4=Ions

Abstract

The irradiation with uv light of KCl crystals containing ${\mathrm{K}}_2$S${\mathrm{O}}_4$ produces three new absorption bands at 213, 236, and 258 mμ. Simultaneously, the absorption due to S${\mathrm{O}}_4^{=}$ ions in the infrared decreases. KCl crystals doped with KOH show on irradiation only the 236- and 213-mμ bands. A comparison of the absorbance at these wavelengths after irradiation with that due to the O${\mathrm{H}}^{-}$ and S${\mathrm{O}}_4^{=}$ ions prior to irradiation leads to the conclusion that the 236-mμ band is due to absorption by an oxygen species while that at 213 mμ comes from the photolysis of O${\mathrm{H}}^{-}$ ions which are present to some extent even in crystals which have not been doped with KOH. It is likely that the 213-mμ band is identical with the hydride band. KBr doped with ${\mathrm{K}}_2$S${\mathrm{O}}_4$ shows broadly similar results.