Spectral emission from glow peaks in x-irradiated Al2O3

Spectral emission associated with the 214, 246, and 286 K glow peaks of Al2O3 reveals that in addition to the previously reported 330- and 410-nm emission, R-line (694.3 nm) emission also accompanies the glow. Of particular interest is the model which explains the appearance of each type of emission. Our data are qualitatively consistent with a model where trapped holes are thermally released and recombine with F centers and Cr2+ ions to yield 330-nm and R-line emission at 214 K, respectively. Furthermore, F centers are thermally destroyed near 260--290 K thereby producing excited F+ centers which emit 410-nm radiation. In addtiion, the electron released by the F center is captured by a Cr4+ ion converting it to Cr3+ in an excited state which ultimately produces R-line emission