Abstract
Characteristics of luminescence lifetimes and luminescence intensity obtained from time resolved spectra of quartz from Nigeria are presented. The luminescence was pulse-stimulated at 11μs width at 470nm. Samples used consisted of unannealed quartz as well as samples annealed at 500°C, 600°C, 700°C, 800°C and 900°C. The luminescence lifetimes and luminescence intensities were studied as a function of annealing temperature, irradiation dose and measurement temperature. It was found that there is a decrease, although non-monotonic, in the luminescence lifetime with change in annealing temperature from 20 to 900°C. In addition, lifetimes extracted from time resolved spectra of unannealed samples as well as ones annealed at 500°C and 600°C are initially independent of irradiation dose but do later decrease with further irradiation. Regarding the luminescence intensity it was observed that in general, the intensity passes through a peak as the measurement temperature is increased from 20 to 200°C with slight differences in the detailed pattern dependent on preheating. Activation energies for thermal quenching and thermal assistance evaluated from temperature-dependent changes of luminescence lifetime and luminescence intensity are given. The results are discussed in terms of a model consisting of three luminescence centres with probability of hole trapping during irradiation being highest for the luminescence centre associated with the least lifetime.
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