| Abstract: | Bleaching by sunlight results in rapid reduction of optically-stimulated luminescence, e.g. by a factor of 300 in 15 min for one of the several samples of quartz so far tried. However, if the bleached sample is stored before measurement the signal partially recovers, suggesting the possibility that the observed natural luminescence from a young sediment sample may contain a significant contribution from this component. Recuperation is accelerated if the sample is warmed during storage: after 5 min at 220°C the recuperation levels in the samples of quartz studied were equivalent to the order of one gray. Recuperative effects are also observed in zircon. We suggest that the effect is associated with phototransfer into shallow light-insensitive traps during bleaching, with subsequent thermal redistribution into the traps responsible for the initial luminescence. Investigation of recuperation gives a useful insight into the mechanisms upon which optical dating relies. |
