Abstract: | It is shown by means of investigation of both optical absorption spectra and Roentgen K-lines of chromium doped in LiKSO4, LiNaSO4, and Li2SO4 · H2O crystals, that X-irradiation results in change of the impurity charge in a following way: Cr3+ + h → Cr4, Cr4+ + h → Cr5+. |