Thermoluminescence and optical absorption measurements were carried out on Eu+-doped crystals which had been irradiated with monochromatic ultra-violet light (200 to 300nm) or X-rays at room temperature. Marked similarities were found between the thermoluminescence glow curves of crystals which had been irradiated with ultra-violet light or X-rays, and it was suggested that the low-energy ultra-violet radiation produced the same defects as those produced by X-rays. The thermoluminescence glow curves comprised 6 peaks at: 337, 383, 403, 435, 475 and 509K. Thermal annealing of previously irradiated crystals revealed a clear correlation between the glow peak at 383K and the F-center thermal bleaching process. The excitation spectrum for each thermoluminescence glow peak was investigated, and this showed that low-energy radiation led to the formation of F centers.

R.Pérez-Salas, R.Meléndrez, R.Aceves, R.Rodriguez, M.Barboza-Flores: Journal of Physics - Condensed Matter, 1996, 8[27], 4983-92