Simulation of the effect of resolution between thermoluminescence peaks on the initial rise method of analysis

Abstract

The initial rise (IR) method is an essential and accurate method for the evaluation of the activation energies of electron levels responsible for the individual glow peaks of a complex thermoluminescence (TL) glow-curve. The main drawback of the method is the reduction of its accuracy when the degree of peak overlapping within the glow curves increases. In the present work detailed simulations are performed to investigate the dependence of the accuracy of the IR method on the resolution parameter R between two or more successive peaks. During the simulations, the amount of peak overlapping is varied by keeping the parameters of one peak fixed, while varying the parameters of the rest of the peaks. Specifically, a two-peak TL glow curve is studied by (a) varying the activation energy E while keeping the frequency factor s constant and (b) by varying s while keeping E constant. In addition, a five-peak glow curve is analyzed by varying both E and s. In the case of a glow curve consisting of two peaks, the simulations show a strong correlation between the value of the parameter R and the success of the initial rise method. The simulations produce plateaus in the E values, which are always followed by a decrease in the effective activation energy E. These plateaus and the corresponding R values can be used as a reliable indicator of the accuracy of the IR method. In the case of a glow curve consisting of five successive peaks, the simulations show that the plateaus in the E values correlate strongly with the value of the resolution parameter R. In most cases simulated in this paper, the IR method is found to produce valid results, even in some cases of relatively strongly overlapping peaks.