Characteristics of LM-OSL from several different types of quartz

We present Linear-Modulation OSL (LM-OSL) curves from several different typ es of quartz, including sedimentary quartz, bulk rock crystal and synthetic quartz. The LM-OSL method consists of linearly increasing the intensity of the stimulation light while continuously monitoring the OSL emission from the sample. With this technique, one obtains peaks of luminescence intensit y versus time (Bulur, 1996) in which the position of the peak is inversely related to the photoionization cross-section of the trap. The shape of the LM-OSL curve is directly related to the shape of the conventional OSL decay curve in which the stimulating light source is maintained at constant inte nsity (so-called Continuous-Wave OSL, or CW-OSL). In the latter, the OSL fr om the traps with the highest photoionization cross-section decays most rap idly with stimulation time, while OSL from those traps with smaller photoio nization cross-sections is characterized by longer decay times. In this pap er, data are presented comparing the CW-OSL and LM-OSL curves for several d ifferent quartz types with particular focus on the changes in the shapes of each of these curves with sample type pre-heat temperature, acid measureme nt temperature. Several different LM-OSL components are found for each samp le, each with different photoionization cross-sections, but a universal beh avior for quartz is not observed; each sample is different. From the depend ence upon pre-heat temperature, features associated with shallow traps can be identified. Traps which empty very rapidly can be observed more easily i n the LM-OSL curves than in the conventional CW-OSL curves, and the tempera ture dependence of the photoionization cross-section for the various compon ents can be clearly discerned. (C) 2000 Elsevier Science Ltd. All rights re served.