Thermally stimulated luminescence and conductivity - Theoretical models and their applicability to experimental results

In this paper computational glow curves are presented for commonly used models by varying the various parameters in the respective models. The characteristics of the computed glow curves are discussed in the following aspects: (i) temperature of maximum intensity, (ii) shape of the glow curve, (iii) kinetics order b, in particular the relevance of non-integral order and the condition causing it, (iv) pre-exponential factor s' and its dimensions, (v) possible relationship of empirical parameters (b and s') with the physical parameters, (vi) growth of intensity as a function of trap occupancy, (vii) pre-dose sensitization, (viii) applicability of different models to experimental results from some commonly studied materials, (ix) role of trapping/untrapping transitions and other physico-chemical processes during thermal stimulation of emission and (x) relevance of computerized fitting and deconvolution of experimentally obtained glow curves. The results of the study show that in general the glow peaks shift their position and undergo change in their shape when the trap occupancy (dose) is changed. The exceptions to this general behaviour occur only when the applicable value of kinetic order b is 1 at all trap occupancies. These theoretical glow curve behaviours are discussed in the perspective of those observed experimentally in most materials. It is concluded that among the various models in vogue, it is only the interactive trap system model which is commensurate with the experimental observations.