Radiation-induced charge trapping and recombination process in natural topaz studied by TL, EPR and XRD

Thermoluminescence (TL) was combined with X-ray diffractometry and electron paramagnetic resonance (EPR) to identify charge traps and recombination centres in natural topaz and to help the understanding of the process of light emission in this solid. According to the results, colourless samples presented higher TL intensities than coloured samples, and they also exhibited the highest [OH]/[F] occupation factors. The thermal treatments were found to change the [OH]/[F] ratios since samples treated at about 400 degreesC present higher TL response and occupation factors. These results indicate that the OH(-) group is directly connected to the trapping centres in topaz. The EPR signal with g approximate to 2.02, due to (AlO(4))(0) centres, increases with the dose. From the TL and the EPR results, it was possible to confirm that the (AlO(4))(0) centre is the luminescent centre in topaz. (C) 2003 Elsevier B.V. All rights reserved.