Kinetic characterization of the thermoluminescence of natural fluorite

The kinetic parameters of the two high-temperature glow peaks (peaks III and IV) in a fluorite obtained in a region of Nigeria has been determined in detail by using Chen's peak shape and initial rise methods. The values of these parameters calculated with these two methods are comparable. The orders of kinetics of the two peaks are found to be different from either the first or the second. The b values obtained ranged from 1.023 to 1.134 for peak III and from 1. 156 to 1.223 for peak IV. The E values ranged from 0.777 to 1.068 eV for peak III and from 1.328 to 1.428 eV for peak IV. The present values of kinetic parameters are compared with those from past studies on fluorite and the observed variations discussed. The electron lifetime in each of these traps, a parameter to dosimetry, was also determined. The value of lifetime obtained for peak III suggests that the peak may be a complex one, when it is viewed in relation to the thermoluminescence enhancement of this peak with storage time that has been reported. The two peaks were tested for quasi-equilibrium (QE) approximation because the general order model used assumed QE condition; it was found that for all the heating rates used peak IV was emitted under QE condition, while peak III was emitted under QE condition only at the smallest heating rates of 7 and 10degreesC/s used in this work. (C) 2003 Elsevier Ltd. All rights reserved.