Numerical simulation of ejected molten metal-nanoparticles liquefied by laser irradiation: Interplay of geometry and dewetting

TL;DR

This paper presents a continuum-level simulation approach to model the ejection of molten metal nanoparticles caused by laser irradiation, highlighting the effects of geometry, wetting, and inertia, and validating results against experiments and molecular dynamics.

Contribution

It introduces a detailed continuum model for nanoparticle ejection, demonstrating control over ejection direction through initial shape and wetting properties, and validates the approach with experimental and molecular dynamics data.

Findings

Inertial effects significantly influence nanoparticle ejection.

Initial geometry and wetting properties can control ejection direction.

Continuum simulations match experimental and molecular dynamics results.

Abstract

Metallic nanoparticles, liquefied by fast laser irradiation, go through a rapid change of shape attempting to minimize their surface energy. The resulting nanodrops may be ejected from the substrate when the mechanisms leading to dewetting are sufficiently strong, as in the experiments involving gold nanoparticles [Habenicht et al., Science 309, 2043 (2005)]. We use a direct continuum-level approach to accurately model the process of liquid nanodrop formation and the subsequent ejection from the substrate. Our computations show a significant role of inertial effects and an elaborate interplay of initial geometry and wetting properties: e.g., we can control the direction of ejection by prescribing appropriate initial shape and/or wetting properties. The basic insight regarding ejection itself can be reached by considering a simple effective model based on an energy balance. We validate our computations by comparing directly with the experiments specified above involving the length scales measured in hundreds of nanometers, and with molecular dynamics simulations on much shorter scales measured in tens of atomic diameters, as in [M. Fuentes-Cabrera et al., Phys. Rev. E 83, 041603 (2011)]. The quantitative agreement, in addition to illustrating how to controlling particle ejection, shows utility of continuum-based simulation in describing dynamics on nanoscale quantitatively, even in a complex setting as considered here.