Theory for the ultrafast ablation of graphite films.
The physical mechanisms for damage formation in graphite films induced by femtosecond laser pulses are analyzed using a microscopic electronic theory. We describe the nonequilibrium dynamics of electrons and lattice by performing molecular dynamics simulations on time-dependent potential energy surfaces. We show that graphite has the unique property of exhibiting two distinct 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.
Jeschke
H O
HO
Institut für Theoretische Physik der Freien Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
Garcia
M E
ME
Bennemann
K H
KH