Analysis of thermoluminescence and phosphorescence related to phototransfer in natural quartz

Abstract

Phototransferred thermoluminescence (PTTL) induced in natural quartz by 470 nm blue light is reported. The quartz was annealed at 500 °C for 10 min before use. The thermoluminescence (TL) measured at 1 °C s−1 following irradiation to 50 Gy shows six peaks labelled I–VI at 76, 134, 188, 250, 316, and 446 °C respectively. Prior to PTTL measurements, the peaks were each removed in turn by preheating the irradiated quartz in succession to 110, 170, 220, 290, and 410 °C. Peak I is reproduced, under phototransfer as peak P1, when any of peaks I–V has been removed. In contrast, peaks II and III are reproduced only after preheating to 220 or 290 °C to remove peaks I–III or I–IV respectively. Their corresponding PTTL peaks are labelled P2 and P3. Peaks IV-VI are not reproduced under PTTL. Kinetic analysis of the main PTTL peak, peak P1, the only one that could be analysed this way, shows that peak I follows first-order kinetics and has an activation energy of ~0.92 eV. The kinetic analysis is also complemented by phosphorescence related to phototransfer. The influence of illumination time on PTTL intensity was studied for PTTL peaks P1, P2, and P3 corresponding to various preheating temperatures. The illumination-time dependent profiles of PTTL intensity corresponding to P1, P2, and P3 are modelled using coupled first-order linear differential equations based on an acceptor and multiple donors as informed by experimental data.