ORIGIN OF THE 430 K TL PEAK IN THERMOCHEMICALLY REDUCED ALPHA-AL2O3

Thermo- and optically stimulated processes are studied in reduced alph a-Al2O3 excited by X rays or UV light. It is shown that the 430 K TL p eak and OSL band at 2.7 eV is caused by release of electrons from trap s followed by recombination mainly at F+ centres and resulting in F ce ntre emission. Traps responsible for the composite 430 K TL peak and i nduced 2.7 eV absorption band are caused by several kinds of defects o f an electronic nature. Production of free electrons by selective UV e xcitation in the region of the absorption of F centres results in effe ctive filling of all kinds of traps responsible for the 430 K TL peak, whereas free electrons and holes produced by X ray excitation competi tively recombine via various localised electronic states, which result s in lowered efficiency of the accumulation of the light sum and selec tive filling of different kinds of traps, responsible for the 430 K TL peak.