H(II) centers in natural silica under repeated UV laser irradiations

TL;DR

This study examines how H(II) centers in natural silica respond to repeated UV laser irradiation, revealing their destruction and regeneration dynamics to better understand defect behavior under laser exposure.

Contribution

It provides new insights into the kinetics and recovery processes of H(II) centers in natural silica during repeated UV laser irradiation cycles.

Findings

UV photons temporarily destroy H(II) centers

Re-irradiation causes re-growth of H(II) centers

Recovery kinetics depend on irradiation dose

Abstract

We investigated the kinetics of H(II) centers (=Ge'-H) in natural silica under repeated 266nm UV irradiations performed by a Nd:YAG pulsed laser. UV photons temporarily destroy these paramagnetic defects, their reduction being complete within 250 pulses. After re-irradiation, H(II) centers grow again, and the observed recovery kinetics depends on the irradiation dose; multiple 2000 pulses re-irradiations induce the same post-irradiation kinetics of H(II) centers after each exposure cycle. The analysis of these effects allows us to achieve a deeper understanding of the dynamics of the centers during and after laser irradiation.