Structural relaxation of E' gamma centers in amorphous silica

TL;DR

This paper investigates two variants of E' gamma centers in amorphous silica, revealing their structural differences, thermal interconversion, and potential energy configurations through experimental paramagnetic resonance analysis.

Contribution

It provides the first experimental evidence of two distinct E' gamma center variants and their thermally induced interconversion in amorphous silica.

Findings

Identified two distinguishable E' gamma variants by their resonance line shapes.

Discovered a thermally activated interconversion with an energy barrier of about 34 meV.

Suggested the existence of a stable and a metastable structural configuration.

Abstract

We report experimental evidence of the existence of two variants of the E' gamma centers induced in silica by gamma rays at room temperature. The two variants are distinguishable by the fine features of their line shapes in paramagnetic resonance spectra. These features suggest that the two E' gamma differ for their topology. We find a thermally induced interconversion between the centers with an activation energy of about 34 meV. Hints are also found for the existence of a structural configuration of minimum energy and of a metastable state.