ROOM-TEMPERATURE EFFECTS OF UV-RADIATION IN KBR-EU2+ CRYSTALS

Thermoluminescence and optical absorption measurements have been carri ed out in KBr:Eu2+ crystals irradiated with monochromatic UV light (20 0-300 nm) and x-rays at room temperature. For UV- and x-irradiated cry stals strong similarities between the thermoluminescence glow curves h ave been found, suggesting that the low-energy UV radiation produces t he same defects as produced by x-irradiation in this material. The the rmoluminescence glow curves are composed of six glow peaks located at 337, 383, 403, 435, 475 and 509 K. Thermal annealing experiments in pr eviously irradiated crystals show clearly a correlation between the gl ow peak located at 383 K and the F-centre thermal bleaching process. A lso, the excitation spectrum for each thermoluminescence glow peak has been investigated, showing that the low-energy radiation induces the formation of F centres.