Simulated Structure Modifications in Silica Subjected to UV-Laser Irradiation

The structural modifications of silica glass, α-quartz and stishovite subjected to UV-laser irradiation are investigated using molecular dynamics simulations with a modified van Beest-Kramer-van Santen potential. Laser energy deposition is approximated by converting photon energy to kinetic energy of a Si-O pair via the two-photon process. The structural and transport properties of the irradiated silica are characterized. For isobaric-isothermal irradiation (ambient conditions) with absorbed fluences of up to 200 mJ cm-2, silica glass undergoes radiation-induced densification, but α-quartz and stishovite recover original structures with negligible defects. For constant energy and volume (ambient density) irradiation up to 1.1 mJ cm-2 (absorbed), glass, quartz and stishovite melt directly into liquid