Kinetics Analysis of TL Glow Curves

Abstract

This chapter deals with the kinetics analysis of TL glow peaks. Five methods of glow peak analysis are summarized. The purpose of glow curve analysis essentially is to find the activation energy E and the kinetic order b of the given glow peak. It is shown that the glow peaks shift to higher temperatures and get widened as b increases and trap occupancy (dose) decreases. However at b = 1 the glow peaks stay at the same temperature and retain their fixed shape irrespective of the trap occupancy. This property is exclusive to the first-order (FO) kinetics. It is therefore suggested that the first step in glow peak analysis should be to test whether the given peak shifts with trap occupancy (dose). If it retains the fixed temperature T m with dose change it should be assigned FO. Application of peak shape method in analyzing the experimental glow curves may face uncertainty in the shape due to the presence of weak satellites close to the main peak under study. Simulations show that a linear relation exists between E and T m for a given s/β, where s is the frequency factor and β is the heating rate. This trend is observed also in experimental samples. This implies that the value of the frequency factor s for the different glow peaks of a given sample may be same. It is found that due to the lacunae of general order (GO) kinetics model the found value of E by the glow curve fitting method is subject to error if the best fitted value of b is found to be different from 1 and 2.