I have studied TL peaks of different minerals and found that peak shifts towards high temperature when we increase heating rate /??? what is logical reason to it and secondly is it possible for materials to show opposite response if yes any example ???? does this behavior ll b different for synthetic materials????
TL glow curve is the total light output determined by the trapped charges i.e. proportional to the absorbed dose. For a low heating rate e.g 1oC/s the sample will be heated at some temperature for a longer time which means that the trap is earlier (lower temperature) emptied resulting in a lower glow peak max temperature Tm.
For a high heating rate e.g 2oC/s the sample will be heated at the same temperature for a half time than 1oC/s which means that the trap is not emptied fully and charges continue to emit luminescence for longer time, resulting the glow peak max temperature Tm to reach at higher temperature.
Mathematically this can be described as.
Consider a first-order peak. The maximum condition is
βE/kTm^2=s*exp(-E/kTm).
This can be written as:
β=(ks/E)Tm^2*exp(-E/kTm).
Please Also study these two articles explaining the effect of change in Tm of glow curve with change in heating Rate.
" The shift of the thermoluminescence peak maximum temperature versus heating rate, trap filling and trap emptying: Predictions, experimental verification and comparison"
"Heating rate effects on the TL glow-peaks of three thermoluminescent phosphors"
please also go through
https://www.researchgate.net/post/What_is_the_physical_explanation_for_the_shift_in_TL_peak_with_change_in_heating_rate2
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