Sensitization and desensitization of the luminescence yield of Al2O3 : C

The effects of optical and thermal treatments on the luminescence and therm oluminescence efficiencies were investigated in alpha-Al2O3:C crystals. Emi ssion bands appeared at 500, 410 and 330 nm with excitation maxima near 300 , 200 and 260 nm respectively. These bands are ascribed to the emission of interstitial Al-i(+) ions, F and F+ centers. Prolonged UV illumination with 200-220 nm light caused a notable increase in the luminescence yield of th e 410 and 330 nm luminescence bands, while the illumination with 300 nm had a reverse effect on these bands. Wavelengths of 260 and 300 nm were most e fficient for the optical bleaching of the PTTL.