Spectrally resolved thermally stimulated luminescence of irradiated anion-defective alumina single crystals

Thermally stimulated luminescence (TSL) spectra in the 313-580 K temperature range have been studied in anion-defective alumina crystals (named in literature as Al2O3:C) exposed to different irradiation doses. The TSL curve features two peaks with the maxima at Tm1=437 K and Tm2=565 K. The TSL spectrum of the first peak contains the emission of F centers and the R line of Cr3+ impurity ions. The absence of the emission of F+ centers indicates that electron traps are responsible for the first dosimetric TSL peak. The TSL spectrum of the second peak features emission bands of F, F+ centers, R line as well as a wide band centered at 550 nm and associated with the formation of aggregate centers (F2 and F22+) under irradiation. Possible excitation mechanisms of the TSL emission bands that involve both electron and hole traps related to anion vacancies and impurities are discussed.