Some quartz thermoluminescence spectra relevant to thermoluminescence dating

Abstract

A new high-sensitivity spectrometer was used to study the thermoluminescence spectra of several quartzes. It was found that natural quartz extracted from sediments, but otherwise untreated or given a gamma dose, yields two broad emission bands, one centred at 630 nm and the other extending from 350 nm to at least 550 nm. The dependence of the spectra on radiation dose were examined for both laboratory dose and natural dose, which differ by 9 orders of magnitude in dose rate, and no effect due to dose rate was observed. The dose responses of both emission bands were examined in the range 0–1600 Gy and were found to be highly non-linear and different. It is shown that the predose effect in the high temperature thermoluminescence peak is associated with the blue emission and not the red emission. For some sediment samples the presence of zircon in “quartz” extracts was readily identified by its spectrum; in some cases the zircon even dominated the thermoluminescence. Thus it is clearly necessary to remove the zircon if one wishes to study the thermoluminescence of the quartz. For a commercial quartz it was found that annealing at 700°C caused a dramatic spectral change and an increase in sensitivity, thus casting doubt on the applicability of thermoluminescence studies on annealed quartz to TL dating of natural quartz extracted from sediments.