0000000000162583
AUTHOR
C. Oproiu
Structure of amorphous SiO 2 nanoparticles probed through the E′ γ centers
We report an experimental investigation by electron paramagnetic resonance (EPR) spectroscopy on the properties of the E′ γ centers induced by β-ray irradiation in nanoparticles of amorphous SiO 2 (fumed silica) with mean diameters from 7 up to 40 nm. We found that the E′ γ centers are induced in all the fumed silica types in the dose range 4-400 kGy. They are characterized by an EPR line shape similar to that observed in common bulk silica materials independently on the particle diameter. Moreover, the E′ γ center concentration decreases on decreasing of the particle size for each given dose. Our findings are interpreted in terms of a shell-like model of nanoparticles in which it is assume…
Comparison of &#x03B3; and &#x03B2;-ray irradiation effects in sol-gel Ge-doped SiO<inf>2</inf>
We report an experimental study on the comparison between the γ or β ray induced Ge related point defects in Ge doped silica. Silica samples doped with ∼2.2 1017 Ge atoms/cm3 produced with the sol-gel technique have been irradiated. The effects of the irradiation have been investigated by optical absorption, photoluminescence and electron paramagnetic resonance spectroscopy in order to evaluate the generation and the dependence on dose of the Ge(1), E'Ge, Germanium Lone Pair Center (GLPC) and H(II) point defects. No relevant differences between the concentrations of γ or β ray induced Ge(1) and E'Ge point defects have been observed. In addition, it is found that both irradiations are able t…
Formation of optically active oxygen deficient centers in Ge-doped SiO2 by γ- and β-ray irradiation
Abstract We report an experimental study on the comparison between the γ- or β-ray induced Ge related point defects in Ge-doped silica. Silica samples doped with ∼2.2 1017 Ge atoms/cm3 produced with the sol–gel technique have been irradiated with γ-ray or with β-ray. The effects of the irradiation have been investigated by optical absorption, photoluminescence and electron paramagnetic resonance spectroscopy in order to evaluate the generation and the dependence on dose of the Ge(1), E’Ge, GLPC (Germanium lone pair center) and H(II) point defects. No relevant differences between the concentrations of γ- or β-ray induced Ge(1) and E’Ge point defects have been observed and, in addition, it ha…