Multi-frequency ESR analysis of the E′_δ defect hyperfine structure in SiO₂ glasses

Author： Stesmans A. Jivanescu M. Afanas'ev V. V.

E-ISSN： 1286-4854|93|1|16002-16002

ISSN： 0295-5075

Source： EPL (EUROPHYSICS LETTERS), Vol.93, Iss.1, 2011-02, pp. : 16002-16002

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Abstract

A multifrequency electron spin resonance study of the E′_δ defect in six SiO₂ glasses irradiated by UV, VUV, or ⁶⁰Co γ-rays, points to an electronically rigid structure with no dynamic rearrangement occurring in the temperature range T ≥ 4.2 K. Reassuringly coinciding over all frequencies and T's applied, the average intensity ratio of the 100 G ²⁹Si hyperfine doublet to the central Zeeman signal points to delocalization of the unpaired spin over n = 4 or 5 equivalent Si sites, thus refuting the Si dimer model. A noteworthy revelation is that E′_δ is only observed in those (3) silica types studied also showing the Al E′ center in the as γ-irradiated state. This may signify some indirect role of charge compensators/traps in activating/stabilizing E′_δ centers, relevant to further theoretical modeling.