New evidence for spatially correlated TC-LC mechanisms in thermoluminescence of LiF:Mg,Ti

New experimental investigations, consistent with the spatial coupling/perturbation between the trapping centres (TC) and luminescent centres (LC) giving rise to the peaks 5 and 4 thermoluminescence (TL) of LiF:Mg,Ti are discussed: (1) The glow peak widths of peaks 2 and 3 are constant as a function of Ti concentration, while the width of peak 4 decreases with a correlated increase in the width of peak 5. The dependence of glow peak shape on Ti concentration indicates that peaks 4 and 5 arise from a TC/LC spatially correlated extended defect. (2) The increased TL intensity of peak 5a following high ionisation density HCP irradiation compared to low ionisation density γ irradiation strongly suggests that peak 5a arises from the geminate recombination of a locally trapped e-h pair. (3) The observation that the optical bleaching conversion efficiency (CE) of peak 5a to peak 4 is measured to be 31 ± 0.5 and is three orders of magnitude greater than the CE of peak 5 to peak 4, is strong evidence for the unique structure of peak 5a - trap, i.e. peak 5a is due to a TC/LC structure which has captured an e-h pair, optical ionisation of the electron leads directly to the peak 4 TC.