Characterization of particles created by laser-driven hydrothermal processing

This study aims to identify, using various characterization techniques, the changes suffered by glassy materials as result of being subjected to laser-driven hydrothermal processing (LDHP). The overarching goal of the research was to verify if LDHP was more or less likely to comminute elements such as Fe and Ti. LDHP is an innovative technique used for the dissolution of submerged materials for subsequent chemical analysis. Two naturally occurring glasses, obsidian and tektite, were used as example targets in this study. Characterization of sample materials before and after laser processing was conducted through multiple techniques such as optical microscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray spectroscopy. Examination of the untreated base material, in bulk and crushed form, established a baseline for comparison to particles created by laser processing of the same material. The analytical methods employed here provided data on micrometer- and nanometer-sized particles, including their crystal structure, microstructure, and chemical composition. The bulk and crushed obsidian and tektite samples contained inclusions rich in several transition elements, most notably iron or titanium. Analysis of liquid media collected after laser processing of bulk obsidian and tektite samples revealed fine particles rich in the same elements. Qualitative evidence suggests that the laser-driven hydrothermal process preferentially partitions the transition metals in to the submerged liquid from the mostly amorphous silica matrix thus selectively enriching the supernate.