Photoluminescence activity, in as-grown or γ-irradiated high-purity synthetic silica samples, was investigated in the vacuum ultra-violet region. An emission band was found which was centered at 4.4eV, was excited within the absorption band at 7.6eV and which exhibited a strong temperature-dependence. These features, together with the very fast decay time (2.3ns at 10K), made this emission distinguishable from the well-known iso-energetic bands which were detected in O-deficient or γ-irradiated silica. The results were consistent with the occurrence of a change in the structure of a point defect, from the single O vacancy which was responsible for absorption at 7.6eV, to the 2-fold coordinated Si which gave rise to photoluminescence at 4.4eV.

Experimental Evidence of Different Contributions to the Photoluminescence at 4.4eV in Synthetic Silica. R.Boscaino, M.Cannas, F.M.Gelardi, M.Leone: Journal of Physics - Condensed Matter, 1999, 11[3], 721-31