Optical Breakdown in Liquid Suspensions and Its Analytical Applications

Abstract

Micro- and nanoparticles persist in all environmental aquatic systems and their identification and quantification are of considerable importance. Therefore, the application of Laser-induced breakdown to aquatic particles is of interest. Since direct application of this method to water samples is difficult, further understanding of the breakdown is needed. We describe several optical techniques for investigation of laser breakdown in water, including Mach-Zehnder interferometry, shadow, and Schlieren diagnostic. They allow for studying the time dependent structure and physical properties of the breakdown at high temporal and spatial resolutions. Monitoring the formation of microbubbles, their expansion, and the evolution of the associated shockwaves are described. The new understanding is that the plasma column in liquids has a discrete nature, which lasts up to 100 ns. Controlling the generation of nanoparticles in the irradiated liquids is discussed. It is shown that multivariate analysis of laser-induced breakdown spectroscopy allows for differentiation between various groups of suspended particulates.