In the TL glow curve, are the glow curve peaks at higher temperatures realated to the deeper traps? so the activation energies of these peaks must be more than the lower temperature peaks. is it true?
What is the relationship between activation energy and the type of trap and the maximum temperature peak?
In the TL glow curve, are the glow curve peaks at higher temperatures related to the deeper traps? so the activation energies of these peaks must be more than the lower temperature peaks
May be true in general but not always as other factors do influence the value of activation energy.
In general for simplicity
(beta E/Tm^2)=s*exp(-E/kT) so s the frequency factor has also important role. beta is heating rate. See standard book on TL kinetics/any review article. So s factor plays important role.
For simple relation, please see equation 2 in the link below
https://www.researchgate.net/publication/237822966_Effect_of_heating_rate_on_TL_glow_curves_-_Theoretical_and_experimental_studies
Article Effect of heating rate on TL glow curves - Theoretical and e...
In general, as the Tm increases, so must be the activation energy. Frequency factor is also important however this behaviour is not so strictly expected as in the cases of activation energies.
Finally, there is a chance that one (JUST ONE) TL peak at higher Tm yields lower activation energy than the previous. In that case, the peak at higher Tm might be a hole trap. However, this should be further established.
The activation energy of higher temperature peaks are not necessarily be higher than that of the lower temperature peaks.
Tha position of a glow peak (Tm) is a function of activation energy (E), heating rate (β) and frequency factor (s). For a constant heating rate, the Tm of a peak for low value of s can be found at higher temperature. In that case sometimes a high temperature peak can have low value of E.
J.M. Kalita.
In addition to all the previous comments, the activation energy and frequency values calculated from the analysis of glow-curve may not be true values. Most of the analytical methods used in the glow-curve analysis are based on the OTOR model (one trap and one recombination level). However, there is no existing TL material that is accurately described by this model. Thus, the computed activation energy and frequency factor values are, in fact, appearing (or effective) values and may not be true. For example, the calculated low activation energy value may be attributed to the competition effect of other deep traps.
@Sadek agree with you. However considering simplest model say Randall Wilikins or so will just provide some information about E and s. Although not accurate but works well as can be seen from half or mean lives of glow peaks exhibiting thermal fading only. may I request you to cite some examples of a single material where we get more than one peak and showing E and s values as per question. I guess TLD 100 LiF:MgTi being one such material.
@Atefeh Aghaei First and foremost you just think of the band diagram of OTOR.
First ask yourself why does a peak comes at a higher temperature?
This is due to the fact that you are giving more thermal energy to liberate the electron from the trap.
Secondly why does the trap require a higher thermal energy in comparison with the shallow trap?
The answer is that the trap is deep i.e. the activation energy of the trap is higher than the shallow one.
Lastly what will be the dependence of the frequency factor on the peak?
Since the material is the same basically the frequency factor will be constant( if you consider negligible thermal dependence).
Each trapping level gives an associated max glow peak and the area and peak height of each glow peak , & Tmax depend on E, S, heating rate , and radiation dose.
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