Estimation of activation energy using skewness of TL data as symmetry parameter in peak shape method

Abstract

The retrapping and recombination mechanism of charge carriers in a thermoluminescence (TL) process governs the shape of a glow curve. In peak shape method the shape of a glow curve is exploited through various symmetry parameters to estimate activation energy. In statistical sense, skewness is a measure of distribution asymmetry of a dataset and hence may be useful to reflect the shape of a TL curve through its asymmetry. In this work, we investigate the applicability of skewness as a symmetry parameter and propose a new set of peak shape relations in terms of skewness of the data to extract activation energy from an isolated TL peak. The applicability of present method is verified by employing it to the TL peaks simulated in General Order Kinetics (GOK) and One Trap One Recombination centre (OTOR) equations. The present method yields consistent results for all the glow curves except for highly saturated cases with heavy retrapping. This limitation is investigated by studying the dependence of skewness on the ratio of retrapping to recombination probabilities. Finally, the present peak shape formulae are tried on experimental TL curves reported in literature and the results are quite satisfactory. The present peak shape coefficients are listed explicitly so that they can be used to estimate activation energy using skewness of isolated peaks deconvoluted from experimental TL data.