Ablation of solids under femtosecond laser pulses

We study the basic mechanisms leading to ablation by femtosecond laser pulses using molecular dynamics and a simple two-dimensional Lennard-Jones model. We demonstrate that the ablation process involves three different mechanisms as a function of deposited energy. In particular, it can result from mechanical fragmentation, which does not require the system to cross any metastability or instability line. The relevance of homogeneous nucleation and vaporization for the description of ablation in this regime is also established.