Quartz OSL emission spectra and the role of [AlO4]° recombination centres

Synthetic crystalline quartz, with known concentrations of Al and alkali ions was used in this study. The wavelength-resolved OSL spectra were measured after different periods of optical stimulation, and more than one emission band were detected. A composite peak centred at 380 nm is seen; this is similar to the emission band for the 110 °C TL peak, that has been associated with the [AlO4]° recombination centres. A direct correspondence between OSL signal intensity and the alkali ion concentration was observed; the signal intensity in bulk crystalline “swept out” quartz, i.e. quartz submitted to electro-diffusion, was found to be much lower than that from the ‘unswept’ quartz. These data suggest that alkali ions play an important role in the OSL phenomenon. Based on the data presented here and the existing TL studies it is inferred that OSL and the 110 °C and 325 °C TL peaks share a common recombination centre. This emission is assigned to electron recombination at Al centres with a trapped hole, [AlO4]°. A preliminary phenomenological model of TL and OSL is proposed, which is based on a spatial association between the OSL and the 110 °C TL trap.