Photoinduced emission and thermoluminescence in topaz

Topaz has been demonstrated to be useful for dosimetric application. This mineral exhibits a satisfactory thermoluminescent (TL) response to radiation. In previous studies we analyzed the natural topaz samples from Minas Gerais, Brazil, by TL, infrared and X-ray diffraction techniques, with the aim of obtaining an explanatory model for the process of light emission of this mineral. Thermal treatments and irradiations do not produce significant changes in the TL emission. TL spectra exhibit a broad band with a maximum TL intensity at 420 nm in all the samples. In order to better understand the physical processes involved in the light emission of the topaz, we analyzed the photoinduced fluorescence of natural (as received) and thermally treated samples in powder form. The photoinduced emission of topaz was found to be similar to that of other silicates. In the UV–visible range there are intense emission bands between 350 and 550 nm, with a maximum intensity at 435 nm. The intensities are different for each sample.