Ablation and spallation of gold films irradiated by ultrashort laser pulses

Abstract

By extending molecular-dynamics simulation to the experimental micrometer length scale, we observed the complete dynamics of gold films subjected to ultrashort $(\ensuremath{\lesssim}1\text{ }\text{ps})$ laser irradiation, culminating in cavitation then ablation of the melt at the front, and crack nucleation then spallation at the rear side of the sample. For thick films $(>0.5\text{ }\ensuremath{\mu}\text{m})$ ablation and spallation are spatially separated; whereas for thin films, they merge into a unique damage process, which leads to a dependence of ablation threshold on film thickness. This work provides insights into thermomechanical dynamics of irradiated metal films, including coupling-decoupling of ablation and spallation processes, and opens up a field of direct comparison between experiment and atomistic simulations.