Thermoluminescence of LiH Irradiated at Low Temperature

Abstract

Thermoluminescence (TL) of LiH irradiated by X-rays at 12 K was studied together with thermally stimulated current (TSC) and F center annealing. The TL curve consists of a prominent peak at 52 K, weak peaks at 82 K and around 170 K and a broad underlying peak that extends from 12 K to 200 K; the broad peak is composed of many peaks with slightly different activation energies. No TSC peak was observed below 80 K in spite of the presence of TL at low temperature. By annealing, the optical density of the F band formed by X-irradiation is decreased gradually up to 40 K and rapidly at about 55 K, but increased above 80K until 110 K. These results were interpreted as due to the recombination and the dissociation of the close pairs of an F center and an interstitial hydrogen atom separated by various distances. The formation of close pairs in LiH was attributed to the small space for the interstitial in LiH lattice and to the absence of π type orbitals in a crowdion type separation of the F center and the inters...