Influence of hydrogen on paramagnetic defects induced by UV laser exposure in natural silica

TL;DR

This study investigates how hydrogen influences the behavior of paramagnetic defects in natural silica exposed to UV laser light, revealing that hydrogen-related reactions cause defect annealing and formation over hours.

Contribution

It provides new insights into the role of molecular hydrogen in defect dynamics in silica under UV irradiation, highlighting post-irradiation defect reactions involving hydrogen.

Findings

E' centers anneal over hours post-irradiation

H(II) centers grow due to hydrogen reactions

Reactions involve molecular hydrogen generated by radiolytic H0 dimerization

Abstract

Diffusion limited reactions of point defects were investigated in amorphous SiO2 exposed to UV laser light. Electron spin resonance and in situ absorption measurements at room temperature evidenced the annealing of E' centers and the growth of H(II) centers both occurring in the post-irradiation stage and lasting a few hours. These transients are caused by reactions involving molecular hydrogen H2, made available by dimerization of radiolytic H0.