Molecular dynamics study of the short laser pulse ablation: quality and efficiency in production

The ablation mechanism of solids due to a short laser pulse energy deposition is a complex phenomenon, which depends on both the laser input parameters and the material properties. In particular, when moving toward pico-second and even femto-second pulses, the irradiated material can be driven to extreme conditions, when its properties are not strictly defined and a number of transient inter-related processes determining a further material's evolution are occurring simultaneously on the nanoscale. Some of the processes were successfully studied experimentally and resulted in numerous publications. The difficulties of the experimental measurements, however, and often the impossibility to isolate those processes for their detailed study, make theoretical investigation beneficial. Here, we are targeting the determination of the working ablation regimes in technological terms of quality and production. The utilized atomistic-continuum model combines the advantages of the molecular dynamics method in description of the laser-induced non-equilibrium phase transition processes at atomic level with the ability of the two temperature model in the continuum description of the photo-excited free carrier's dynamics. On the example of Al and Au metal targets, the model is applied to study the ablation regimes induced with laser irradiation of different fluences and pulse durations. The obtained photo-thermal and photo-mechanical modes are related with quality and production terms from the point of industrial applications.