Thermoluminescence of ice and its implications

Abstract

A set of six glow curves of hexagonal ice irradiated at 77 K with various doses of γ-rays have been subjected to rigorous analysis. It shows the presence of as many as 11 thermoluminescence (TL) peaks at 108.2 ± 1.7 K, 115.5 ± 1.4 K, 123.4 ± 3.6 K, 131.8 ± 2.5 K, 138.9 ± 2.2 K, 149.8 ± 1.2 K, 161.3 ± 0.9 K, 168.4 ± 0.8 K, 178.0 ± 0.8 K, 194.1 ± 0.8 K and 203.8 ± 3.9 K (for a heating rate of 0.05 K/s) with thermal activation energies of 0.29 ± 0.01 eV, 0.31 ± 0.01 eV, 0.34 ± 0.01 eV, 0.40 ± 0.00 eV, 0.40 ± 0.01 eV, 0.41 ± 0.01 eV, 0.69 ± 0.01 eV, 0.70 ± 0.00 eV, 0.70 ± 0.01 eV, 0.70 ± 0.01 eV and 0.70 ± 0.01 eV, respectively. The lifetime of electrons in the trap giving rise to the most intense TL peak of ice (161.3 ± 0.9 K) estimated from TL data at 273 K is ∼55 ns, while that at 77 K is ∼2.0 × 10 +18 years i.e. ice can be used for TL dating of icy bodies in the solar system. The physical basis of these findings have been provided keeping in mind the formation of H 0, O −, OH −, HO 2 - and trapped electrons that are known to be produced by irradiation of ice. The implications of these findings have been discussed.