PHOTOLUMINESCENCE STUDIES IN SC-CAF2 AND SC,CE-CAF2 CRYSTALS

Stokes and anti-Stokes W-visible luminescence was investigated in gamm a-irradiated Sc and Sc-Ce doped CaF2 crystals. Wideband Stokes lumines cence under laser or CW lamp excitation was measured: (1) at 380 nm (l uminescence decay time tau similar to 17 mu S) in Sc:CaF2 and Sc,Ce:Ca F2 crystals, attributed to SC2+ ions and (2) at 300 nm (tau similar to 40 ns) in Sc,Ce:CaF2 crystals, due to Sc-Ce aggregate centers. Anti-S tokes luminescence in the 250-350 nm spectral range with a 1 mu s life time can be explained by exciton luminescence.