Phototransferred thermoluminescence from natural quartz annealed at 1000 °C: Analysis of time-dependent evolution of intensity and competition effects

Abstract

Phototransferred thermoluminescence (PTTL) related to multiple acceptors and donors in natural quartz is reported. A glow curve measured at 1 °C s−1 after beta irradiation to 300 Gy has four peaks labelled I, II, III, and IV at 70, 124, 170, and 298 °C respectively. Preparatory to measurement of PTTL, these peaks were removed in turn by preheating to 100, 140, 250 and 500 °C. PTTL is observed for peak I after any of these preheating temperatures. This means that peak I is reproduced, under phototransfer, when any of peak I, II, III or IV has been removed. Peak II is only reproduced after preheating to 250 °C to remove peaks I, II and III. Peak II does not re-appear after any preheating beyond 250 °C. Peak III re-appears under phototransfer following preheating to either 250 or 500 °C. No PTTL was observed for peak IV at all. The behaviour of peaks II and IV are suggestive of competition effects that merit investigation. This is addressed in this report. The dependence of PTTL intensity on the duration of illumination is studied for all PTTL peaks corresponding to various preheating temperatures. Peak I shows an initial increase in intensity followed by a decrease with illumination for preheating to 100, 140 and 500 °C. However when the sample is preheated to 250 °C, the intensity decreases monotonically. The PTTL intensity for peaks II and III go through a slow and extended growth up to 1500 s before the onset of any decrease. The change of intensity with illumination time is modelled using coupled first-order linear differential equations on the basis of systems of acceptors and donors whose number depends on the preheating temperature.