Electron paramagnetic resonance investigation on the hyperfine structure of the Eδ′ center in amorphous silicon dioxide

We report an experimental investigation by electron paramagnetic resonance (EPR) spectroscopy on the hyperfine structure of the Eδ′ center in γ-ray irradiated amorphous silicon dioxide materials. This study has driven us to the determination of the intensity ratio between the hyperfine doublet and the main resonance line of this point defect. This ratio was obtained for a variety of silica samples and compared with the analogous ratio obtained for the Eγ′ defect. The comparison definitively confirms that the electronic wave function involved in the Eδ′ center is actually delocalized over four nearly equivalent Si atoms.