Properties of quartz TA – OSL signal with a peculiar decay shape for SAR TA – OSL applications

Abstract

A rapidly decaying curve shape, similar to the conventional optically stimulated luminescence (OSL) curve, is observed when thermally assisted (TA –) OSL signal from quartz is measured at a steady elevated temperature. In some cases, a peculiar shape consisting of one flat signal is yielded. The effects of thermal assistance and dose applied on the features of this peculiar type of curve were studied using quartz samples collected from Anatolia, Turkey. The results indicated the absence of the initial rapidly decaying part of the conventional OSL for this peculiar curve of TA-OSL for all stimulation temperature and dose ranges attributed within this work. The intensity of the flat decay curve signal was observed to be dependent on both stimulation temperatures and doses. It was demonstrated that for this specific signal, thermally assisting activation energy of almost 1 eV stands as a prevalent feature, indicating that this TA – OSL signal with flat shape originates from very deep traps with activation energy under the conduction band of the order of 3 eV. This suggests that such a trap could provide signal with adequate stability for dating back to a million years, or even more. The dose response linearity for high attributed doses strongly supports the application of Single Aliquot Regenerative TA – OSL for equivalent dose estimations. However, the high recuperation values, of the order of 30%, indicating possible underestimation of the equivalent doses, along with recycling ratio values of around 1.25, stand as drawbacks that limit the use of such TA – OSL signal in single aliquot regenerative protocols for equivalent dose estimations.