The spectral and decay properties of photoluminescence emissions, ranging from 3.5 to 5.0eV, were investigated in as-grown and irradiated silica. Experimental studies were made of ultra-violet (5.0eV) absorption, of the emission and excitation spectra of the stationary photoluminescence, and of the decay times of the transient photoluminescence emission at room temperature and 10K. The results showed that  irradiation led to the appearance of a photoluminescence band, centered at 4.37eV, which could be excited at 5.0 and 6.8eV. This band was very similar to the photoluminescence band that was peculiar to non-irradiated O-deficient natural silica. Nevertheless, small but significant differences between the 2 bands could be deduced from the experimental data. The results were consistent with an energy level scheme which involved 2 singlet-singlet transitions. The small differences between the 2 photoluminescence bands were tentatively attributed to the presence of different dynamic environments around the intrinsic and irradiation-induced centers.

R.Boscaino, M.Cannas, F.M.Gelardi, M.Leone: Physical Review B, 1996, 54[9], 6194-9