Improving the accuracy of the initial rise method and extending its applicability to evaluate the order of kinetics of TL glow peaks.

Abstract

The classical initial rise method is limited to evaluate the activation energy for signal levels that do not exceed 10-15% of the maximum intensity. When it becomes necessary to include higher signal levels the associated error in the activation energy increases. In the present work we introduced a new correction factor for the activation energy obtained by the initial rise method in terms of the percentage of maximum intensity and the geometrical factor of the glow peak. The new expression reflects the dependence of the correction factor on the order of kinetics through the geometrical factor, especially when high signal levels are involved in the analysis. With this correction, the initial rise method can be applied to signal levels up to 70% of the maximum intensity with errors lower than those encountered in applying the classical method at low intensity levels (~10% of the maximum intensity). In addition, the order of kinetics was evaluated based on the difference between the corrected value of E and the one obtained by the initial rise method. The present procedure was applied to the glow curve of Li2 B4 O7 :Mn single crystal. The obtained parameters show very good agreement with curve fitting, peak shape methods and the published data on this material which supports the validity and reliability of the present approach.