Time resolved luminescence of quartz from Nigeria

The influence of optical bleaching on lifetimes and luminescence intensity in the slow component of optically stimulated luminescence of natural quartz from Nigeria

“…The sample was analyzed for feldspar, which usually occurs concurrently with natural quartz, using a JEOL superprobe 733 electron microprobe (JEOL company, Japan) as in a previous study using the same material [16]. The analysis determined the percentage of oxides of Si, Al, Ca, Na and K in the sample with a lower limit of detection (LLD) in each case of 0.017, 0.013, 0.012, 0.018 and 0.013, respectively.…”

“…The relevant formulae for the latter case as well as general theoretical models for the analysis of time-resolved luminescence spectra including computer-simulated and experimental aspects have been reported recently by Chithambo [24,27]. The methods used for evaluating lifetimes and various kinetic parameters from quartz experimental data [10,[14][15][16]22] thus discussed, are based on a simple model consisting of one electron trap and one kind of recombination centre with emission involving electron transition through the conduction band just like in discussions of optically stimulated luminescence by McKeever and Chen [28] and Chen and Leung [29]. However, in typical timeresolved optical stimulation measurements, the stimulating light pulse is brief (of the order of nanoseconds to several microseconds) such that the reduction in trapped charge due to optical stimulation in that time is negligible and as a result retrapping is also assumed to be negligible [27].…”

The dependence of luminescence lifetimes on additive irradiation in natural sedimentary quartz: sands from Santa Elina, Brazil

“…This dose-dependent feature is in contrast to that observed in other varieties of sedimentary quartz [2] where lifetimes are independent of irradiation dose unless the quartz is annealed at high temperature prior to measurement. Indeed, a barely palpable decrease in lifetime with dose that is observed in some volcanic quartz is enhanced if the quartz is annealed at temperature near 500 o C or greater before use [10]. To emphasize this point, results are shown in Fig.…”

“…The model allows for intercentre hole transition during annealing but a consideration of relative hole-capture probabilities of the centres is indispensable in some cases e.g. [10]. With regards to Fig.…”

“…Since this sample is sedimentary without an annealing step before use, the concentration of holes in secondary centres will be comparatively negligible explaining the initial importance of centre C A . If it can be assumed that the hole-capture probability of each of the secondary centres is greater during irradiation as done for a similar scenario but in annealed quartz [10], then the subsequent decrease in lifetime can be understood as being caused by the preferential hole trapping at the secondary hole centres but with little re-trapping at the primary centre C A . Thus increasing radiation enhances the dominance of the shorter lifetime hole centres seen as a decrease in luminescence lifetimes with irradiation dose.…”