Ablation and spallation of gold films irradiated by ultrashort laser pulses

By extending molecular-dynamics simulation to the experimental micrometer length scale, we observed the complete dynamics of gold films subjected to ultrashort (1 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 μm) 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.