Thermocapillary effects in driven dewetting and self-assembly of pulsed laser-irradiated metallic films

TL;DR

This paper develops a dynamical model for molten metallic films irradiated by pulsed lasers, analyzing how heat transfer and laser parameters influence film stability, dewetting patterns, and nanostructure formation.

Contribution

The study introduces a new 3D long-wave evolution PDE model incorporating heat transfer effects for laser-irradiated metallic films, with analytical and numerical analysis of stability and pattern formation.

Findings

Heat production increases stability of the film.

Interference heating induces spatially periodic rupture.

Model aligns qualitatively with experimental nanostructure observations.

Abstract

In this paper the lubrication-type dynamical model is developed of a molten, pulsed laser-irradiated metallic film. The heat transfer problem that incorporates the absorbed heat from a single beam or interfering beams is solved analytically. Using this temperature field, we derive the 3D long-wave evolution PDE for the film height. To get insights into dynamics of dewetting, we study the 2D version of the evolution equation by means of a linear stability analysis and by numerical simulations. The stabilizing and destabilizing effects of various system parameters, such as the peak laser beam intensity, the film optical thickness, the Biot and Marangoni numbers, etc. are elucidated. It is observed that the film stability is promoted for such parameters variations that increase the heat production in the film. In the numerical simulations the impacts of different irradiation modes are investigated. In particular, we obtain that in the interference heating mode the spatially periodic irradiation results in a spatially periodic film rupture with the same, or nearly equal period. The 2D model qualitatively reproduces the results of the experimental observations of a film stability and spatial ordering of a re-solidified nanostructures.