Search results for "Oxygen deficiency"
showing 3 items of 3 documents
Optically active oxygen-deficiency-related centers in amorphous silicon dioxide
1998
Abstract The spectroscopic properties, structure and interconversions of optically active oxygen-deficiency-related point defects in vitreous silica are reviewed. These defects, the E′-centers (oxygen vacancies with a trapped hole or 3-fold-coordinated silicons), different variants of diamagnetic `ODCs' (oxygen-deficiency centers), and their Ge-related analogs play a key role in the fiber-optic Bragg grating writing processes. The controversy surrounding the structural models for the Si- and Ge-related ODCs is discussed and the similarity between the bulk and surface point defects in silica is emphasized. The possible interconversion mechanisms between 2-fold-coordinated Si, neutral oxygen …
EXCITONS, LOCALIZED STATES IN SILICON DIOXIDE AND RELATED CRYSTALS AND GLASSES
2000
The excitons, localized states in crystalline and glassy silicon dioxide, germanium dioxide were studied by photoluminescent and photoelectric experimental methods. Results were compared with analogous investigations of related crystals, such as aluminum and gallium orthophosphates, and of related glasses, such as silica, sodium silicates, germanates, lead and phosphates glasses. Special attention was made to the influence of oxygen deficiency on localized states of glasses, in general, and to the nature of the 7.6 eV band in reduced silica, in particular.
The landscape of the excitation profiles of the αE and β emission bands in silica
1999
Abstract We report data about the relevance of the conformational heterogeneity in determining the optical properties of oxygen deficiency point defects in natural silica samples. The spectral profiles of the photoluminescence emissions at about 4.2 eV (α E band) and at about 3.15 eV (β band), and the efficiency of the intersystem-crossing mechanism connecting them appear modified by a fine tuning of the excitation energy within the B 2β absorption band. Moreover, the relative excitation optically spectra indicate the presence of optically distinguishable contributions to the emission profile. The reported data are attributed to a distribution of centers that maps into a spectral inhomogene…