Interpretation of Very High Activation Energies and Frequency Factors in TL as Being Due to Competition Between Centres
- 1 June 1996
- journal article
- research article
- Published by Oxford University Press (OUP) in Radiation Protection Dosimetry
- Vol. 65 (1) , 17-20
- https://doi.org/10.1093/oxfordjournals.rpd.a031614
Abstract
Very high values, considered to be physically impossible, were reported for the activation energy E and the frequency factor s in some thermoluminescence (TL) peaks. In particular, peak 5 of LiF:Mg,Ti was reported to have E = 2.0-2.2 eV and s = 1020-1022 s-1. If a peak shape method or curve fitting of a TL peak is utilised, there is an inverse relation between the width and the activation energy. Thus, if for a given TL peak, competition causes a narrowing of the peak, the effective activation energy is larger than expected. This, in turn, will cause the effective s to be significantly larger than the original one. In this study a model of one trap and three centres is considered, and the relevant simultaneous differential equations solved. Concentrating on the second peak, which looks like a first order peak and is very narrow, results in E = 2.1 eV and s = 8 x 1020 s-1, for original parameters of E = 1.2 eV and s = 2.5 x 1011 s-1.Keywords
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