Hydrogen-Related Paramagnetic Centers in Ge-Doped Sol-Gel Silica Induced by γ-Ray Irradiation |
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Authors: | S Agnello R Boscaino F La Mattina S Grandi A Magistris |
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Institution: | (1) Department of Physical and Astronomical Sciences, University of Palermo, and INFM, Via Archirafi 36, Palermo, I-90123, Italy;(2) Department of Physical Chemistry, University of Pavia, and INFM, Via Taramelli 16, Pavia, I-27100, Italy |
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Abstract: | We have studied the generation mechanisms of H(II) paramagnetic centers in Ge-doped silica by investigating up to 104 mol ppm sol-gel Ge-doped silica materials. We have considered materials with the same concentrations of Ge but that are produced
by two different densification routes that give rise to different concentrations of Ge-related oxygen deficient centers (GeODC(II)).
These centers are characterized by an optical absorption band at ∼5.2 eV (B2β band) and two related emissions at ∼3.2 eV and ∼4.3 eV. The GeODC(II) content was estimated by absorption and emission measurements.
The H(II) centers were induced by room temperature γ-ray irradiation and their concentration was determined by electron paramagnetic
resonance measurements.
The comparison between the two kinds of materials, obtained by different preparations, shows that the GeODC(II) concentration
increases with the Ge content and is enhanced by vacuum densification. The comparison of irradiated samples shows that beyond
the already known process of conversion of preexisting GeODC(II) into H(II) centers, another generation process of H(II) centers
is effective that involves irradiation induced GeODC(II). |
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Keywords: | sol-gel glasses aerogel germanium doping germanium defects photosensitivity |
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