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 (less than or similar to 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 mu 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.