The relationship between quartz thermoluminescence, photo-transferred thermoluminescence, and optically stimulated luminescence

The effects of green light stimulation on the thermoluminescence (TL) of a sedimentary quartz from the Kimberley region of Western Australia are reported. The loss of TL at 310°C and the concomitant growth and decay of the photo-transferred TL (PTTL) at both 110 and 160°C are presented for optical stimulation of up to 200 s in a Risø TL/OSL reader. The optical decay lifetime for the 110°C peak was about 130 s, and we deduce that this decay probably arises from optical stimulation of electrons rather than loss of recombination centres. A linear correlation was found between the loss of TL from the rapidly bleaching peak at 310°C (following a natural (N) + 43 Gy dose) and the integrated optically stimulated luminescence (OSL), for stimulation at 125°C and for stimulation times between 0.1 and 100 s. For another N + 43 Gy sample, the OSL signal decreased by about 20% with increasing preheat temperature from 220 to 280°C, after correction for thermal activation of luminescence centres (monitored by an additional experiment). The TL signal associated with this OSL (i.e. the TL lost as a result of optical stimulation) decreased by about 30% with preheat temperature. For repeated 0.1 s stimulation at 25°C, there was a linear relationship between the OSL, and the PTTL at 110°C obtained after each stimulation. The effects of different doses and stimulation times on this relationship are reported, and the implications for dating protocols using the OSL signal are discussed.