Thermoluminescence of LiF TLD-100: Glow-curve kinetics

Abstract

The thermoluminescence kinetics have been determined for the 13 glow peaks contained in the glow curves obtained from LiF TLD-100 after exposure to 60Co irradiations. The glow curves were constructed from measurements made with recently developed equipment for recording emission spectra at closely spaced temperature intervals. In addition, the recorded data has been subjected to all corrections needed to make it suitable for reliable kinetic analysis. The recorded emission spectra can be described by a single Gaussian-shaped band whose width and peak-energy parameters vary erratically with temperature or, alternatively, by resolving the observed spectra into three Gaussian-shaped bands whose parameters vary with temperatures in accord with theoretical expressions relating the emission-spectra peak energy and full width at half-maximum to the sample temperature. The kinetics and kinetic parameters were independently determined for the two most intense resolved emission bands. All peaks are described by first-order kinetics and the independently determined parameters are in very good agreement. The glow curves for the least intense component are also described by the same kinetics and parameters. Inasmuch as the single-band emission is a superposition of the three components, the same kinetics and parameters apply to the glow curve constructed from unresolved spectra. The identification number, nominal peak temperature in °C (for a heating rate of 10.3 °C/min), the activation energy E (eV), and preexponential factor s (sec−1) for the 13 peaks are as follows: (1) 1.62, 1.04, and 1014; (2) 94, 1.07, and 1013; (3a) 112, 0.987, and 1011; (3) 137, 1.05, and 1011; (4) 170, 1.54, and 4×1015; (5) 190, 2.20, and 1022; (5a) 210, 1.61, and 1015; (6) 235, 1.70, and 1015; (7) 260, 1.79, and 1015; (8) 285, 1.96, and 5×1015; (9) 315, 2.10, and 1016; (10) 345, 2.19, and 1016; (11) 370, 2.27, and 1016. The unusual value of s=1022 for the 190 °C peak, previously reported by other authors, was obtained during this study. However, it appears that this value can be obtained from relatively simple mechanisms and one of these is described.