Thermoluminescence from within large defect complexes

Thermoluminescence was originally modelled in terms of highly localised point defects with independent trapping and recombination sites. Neither concept is now throught to be appropriate and data are presented which indicate the scale of defect complexes, within which thermoluminescence occurs where long range interactions are often evident. The present views are strongly supported by data from thermoluminescence emission spectra. For example, the glow peak temperatures of emission from different rare earth ions depend on the dopant, implying that the trap and recombination centre are spatially linked. In LaF3 there are examples of peak shifts of up to 18 K which depend directly on the ionic radii of the rare earth ions. Similar data from other systems are noted, all of which underpin models of thermoluminescence generated by internal charge transfer within very large defect complexes.