Chapter 10 - Nanosecond pulsed laser-plasma interaction and its applications

Abstract

Over the last decade, laser ablation, as the cleanest and simplest technique with the highest product purity, has received a lot of attention. Since the invention of laser technology, laser ablation of solid materials has been investigated extensively because it has demonstrated enormous potential in laser-based material processing, such as thin film preparation, material cutting, device fabrication, surface cleaning, alloying, and synthesis of various categories of nanomaterials where wet chemical synthesis method generally fails. The laser ablation of solid in liquid is mainly used for the generation of nanoparticles of various sizes and shapes bypassing thermodynamics constraints. Various intermetallics, multicomponents, alloys, core-shell, oxides, and magnetic nanocomposites can be prepared by this method just by bypassing the thermodynamic constraint. Basically, laser ablation can take place in any medium, including liquid, gas, and vacuum. The most important difference between laser ablation of solids in vacuum or dilute gas and in liquids is that liquid confines the movement of the plasma plume and, therefore, the various nanoparticles formation processes, like generation, transformation, and condensation of the plasma plume, resulting from laser ablation of solids in liquid environments takes place under the conditions of the liquid confinement. This confinement effect from liquid greatly influences the thermodynamic and kinetic properties of the plasma plume, and hence produces different conditions of condensing phase formation from that of laser ablation of solids in vacuum or gas. Therefore, the understanding of fundamental aspects of the evolution of the plasma plume from laser ablation of solids in liquids is required for their potential applications in nanotechnology.