Optical bleaching of the 375 °C TL peak, [GeO4/Li+]0 EPR center and OSL signal in irradiated natural quartz

Abstract

The effect of exposure of quartz samples to blue (470 ± 30 nm) and UV (365 ± 10 nm) light has been studied. Thermoluminescence, TL, Electron Paramagnetic Resonance, EPR, and Optically Stimulated Luminescence, OSL, have been considered.Looking at the OSL signal, while a reduction of the slow component is indeed induced by the UV exposure, a similar effect is observed, although with lower efficiency, under blue light exposure. Therefore, no conclusions can then be drawn as regards the effects induced on the OSL signal upon a change in the excitation wavelength.The effect of the UV and blue light exposure on the so called Slowly Bleachable Peak, SBP [1], observed by TL at 340°C, heating rate 5°C/s, is presented. It is noticed a decrease of the SBP induced by UV exposure while no effect is caused by blue light exposure. A similar behaviour is detected when looking at the EPR signal of the [GeO 4 /Li + ] 0 center, that is reduced by the UV light, while no effect is seen after exposure to blue light.These results suggest that one of the electron sources originating the SBP can be identified as the [GeO 4 /Li + ] 0 center.

Thermoluminescence properties and new insights on the UV-vis absorption features of colorless quartz after γ-ray irradiation

“…Since the absorption bands at 345 nm and 450 nm are both involved in electron traps at 110 °C, 238 °C, 325 °C and 375 °C, the attenuation of the absorption intensities of these bands may be related to the photosensitive traps at 110 °C and 325 °C. 17,19,20,39 These experimental results can be explained as follows: when the sample is exposed to blue light, electrons in photosensitive traps (at 110 °C and 325 °C) can be released, and then recombine with the hole trapped at the [AlO 4 /h + ] 0 centers, this reduces the absorption centers [AlO 4 /h + ] 0 generated by previous irradiation, i.e. the absorption intensity of the bands decreased.…”

“…This recombination process is accompanied by the emission of photons. 9,16–21 (ii) The second one is related to electron traps that give rise to a signal above 200 °C in the TL glow curve. The signal spectrum is relatively wide and asymmetric between two sides of the short and long wavelengths.…”

“…[AlO 4 ] 0 ) act as hole traps. 9,16,17,19,21–23 (iii) The last band is related to traps with temperatures from 200 to 280 °C, and above 350 °C. The spectral intensity in this band is usually much less intense than other emission bands.…”