Theory for the ultrafast ablation of graphite films - art. no. 015003

The physical mechanisms for damage formation in graphite films induced by f emtosecond laser pulses are analyzed using a microscopic electronic theory. We describe the nonequilibrium dynamics of electrons and lattice by perfor ming molecular dynamics simulations on time-dependent potential energy surf aces. We show that graphite has the unique property of exhibiting two disti nct laser-induced structural instabilities. For high absorbed energies (>3. 3 eV/atom) we find nonequilibrium melting followed by fast evaporation. For low intensities above the damage threshold (>2.0 eV/atom) ablation occurs via removal of intact graphite sheets.