OXYGEN-DEFICIENT CENTERS IN SILICA GLASSES - A REVIEW OF THEIR PROPERTIES AND STRUCTURE

This report is a review and discussion of the results of investigations of the oxygen-deficient centers (ODC) in silica glasses obtained by the authors and other researchers. The spectroscopic characteristics of intrinsic and impurity ODCs in silica glasses are reviewed and models of the centers are suggested and discussed. New and original results are also presented from experiments on the formation of photo-induced color centers and the destruction of the ODCs in pure and Ge-doped silica glasses under UV laser irradiation at wavelengths similar to 248 nm. These results are interpreted in terms of the ODCs being an assembly of defects of the 'oxygen vacancy'-type, which differ from each other in their local structure. It is also noted that the processes of thermo-, cathode- and gamma-luminescence take place through the ODCs, namely their T-1 states.