Hydrodynamic phenomena induced by laser ablation of metal into liquid

Abstract

Laser ablation in liquid (LAL) is a promising technique for manufacturing nanoparticles (NPs) required for modern technologies, but it is not fully understood. Deep understanding is necessary to optimize processes and decrease the high price of LAL NPs. Known studies are focused on either the bubble dynamics at late stages or ablation of material before bubble formation. Here, we consider the LAL throughout: from ablation and up to the bubble formation and inflation. Thus, we cover an extremely wide range of spatiotemporal scales, for which the roles of absorbed energy, pulse duration, and supercritical states are considered. Atom diffusion, hydrodynamic mixing due to Rayleigh-Taylor instability, and interplay between them are described. Liquid near the contact with metal is heated by dissipation in strong shock and due to a small but finite heat conduction from hot metal after laser energy deposition. Expansion and cooling of atomically mixed liquid and metal lead to condensation of metal atoms into NPs after pressure drops below the critical pressure for metal. Development of bubble takes place during the next stages of pressure decrease below the critical parameters for liquid and below ambient pressure in liquid. Thin hot layer of liquid near the contact expands by many orders of magnitude producing the inflating bubble.