Simulation of OSL pulse-annealing at different heating rates: Conclusions concerning the evaluated trapping parameters and lifetimes

Abstract

Pulse annealing has been the subject of several studies in recent years. In its basic form, it consists of relatively short-time optically stimulated luminescence (OSL) measurements of a given sample after annealing at successively higher temperatures in, say, 10°C increments. The result is a decreasing function with a maximum OSL at low temperatures and gradually decreasing to zero at high temperature. Another presentation is that of the percentage OSL signal lost per annealing phase, associated with minus the derivative of the former curve, which yields a thermoluminescence (TL)-like peak. When the heating is performed at different heating rates, the TL various heating rates (VHR) method can be utilized to evaluate the trapping parameters. Further research yielded more complex pulse-annealing results in quartz, explained to be associated with the hole reservoir. In the present work, we simulate numerically the effect, following the experimental steps, in the simpler form when no reservoir is involved, and in the more complex case where the reservoir plays an important role. The shapes of the reduction-rate curves resemble the experimental ones. The activation energies found by the VHR method are very close to the inserted ones when the retrapping probability is small, and deviate from them when retrapping is strong. The theoretical reasons for this deviation are discussed.