A Three-stage Thermal Stimulation of Thermoluminescence (Tl)

Abstract

A three-stage thermal stimulation of thermoluminescence is studied. Three assumed conditions are applied to this model and the analytical expressions are compared with the numerical results. For condition 1: effective activation energy, Eeff ≈ E1 + E2 + E3, effective frequency factor, seff ≈ s2s3/p2 and effective retrapping probability coefficient, An,eff ≈ An. The expected Eeff is obtained. For condition 2: Eeff ≈ E1 + E2, seff ≈ (s1s2/p1)exp(E3/kT) and An,eff ≈ (p2/s3)exp(E3/kT)An. In this case, Eeff reduces from 'E1 + E2 + E3' to 'E1 + E2' as a result of the exponential temperature dependence on seff. For condition 3: Eeff ≈ E1, seff ≈ s1exp[(E2 + E3)/kT] and An,eff ≈ (p1p2/s2s3)exp[(E2 + E3)/kT]An. The obtained Eeff reduces from 'E1 + E2 + E3' to 'E1' as a result of the exponential temperature dependence on seff. From the first-order kinetics, the numerical results were found to be in very good agreement with the analytical expressions. From the second-order kinetics, the numerical results did not agree with analytical expressions and explanation has been offered. In the assumed conditions 2 and 3, the exponential temperature dependence on An,eff did not affect the shape of the TL peak provided the chosen trapping parameters were within the confine of the assumed conditions. Evaluation of life-time of the excited signal to determine its stability is considered.