Phototransferred thermoluminescence of annealed synthetic quartz: Analysis of illumination-time profiles, kinetics and competition effects

摘要

Phototransferred thermoluminescence (PTTL) induced from annealed synthetic quartz using 470 nm blue light is reported. The quartz was annealed at 900 degrees C for 10, 30 and 60 min prior to use. A glow curve of conventional TL measured at 1 degrees C s(-1) following irradiation to 200 Gy for the sample annealed for 10 min shows six peaks at 90, 122, 176, 210, 240 and 340 degrees C. The sample annealed for 30 min has peaks at 80, 110, 136, 196, 240 and 330 degrees C. Similarly, the sample annealed for 60 min also has six peaks at 80, 120, 134, 188, 235 and 340 degrees C. For ease of reference, these are labelled I-VI respectively. Peaks observed under PTTL are referred to as A1 onwards. Of the six peaks, only the first three are reproduced under phototransfer for the sample annealed for 60 min. When the duration of annealing is reduced to 10 min, PTTL is induced only at peaks A1 and A3. Interestingly, for the intermediate duration of annealing of 30 min, the only peak that appears under phototransfer is the first one, A1. For quartz annealed for 10 min, the PTTL appears as long as the preheating temperature does not exceed 560 degrees C. On the other hand, in the quartz annealed for 30 and 60 min, PTTL only appears for preheating to and below 450 degrees C. This shows that the occupancy of deep electron traps at temperatures beyond 450 or 560 degrees C is low in the said samples. The activation energy for peaks A1 and A3 was found to be about 0.68 eV. The PTTL peaks were studied for thermal quenching and peaks A1 and A3 were determined to be subject to this effect. The activation energy for thermal quenching was determined as 0.62 +/- 0.04 eV in analysis using peak A1. In all cases, the PTTL intensity goes through a peak as a function of illumination time. The experimental dependence of PTTL intensity on illumination time is modelled using sets of coupled linear differential equations based on systems of donors and acceptors whose number is determined by preheating temperature. Competition effects involved in the PTTL have been discussed.