TIME-INTEGRATED OPTICAL-EMISSION STUDIES OF PLUMES GENERATED FROM LASER-ABLATED GERMANIA GLASS

The optical emission from plumes induced by ArF laser irradiation of GeO2 was characterized as a function of laser fluence, distance from the target surface, and ambient O2 Pressure. Dispersion of the light emitted by the plume in a vacuum revealed emission from both neutral and singly ionized Ge atoms as well as neutral O atoms. The spatial variation showed that the ion concentration decreased exponentially from the target surface while the neutral atom number density reached peak intensities at distances of almost-equal-to 1.5-2.5 cm from the target surface. Interactions between the plume constituents and the ambient molecular oxygen increased the excited Ge atom and Ge ion populations in the plume and, most notably, significantly enlarged the excited O atom concentration over that produced directly from the ablation process.