Study of ultrashort laser ablation of metals by molecular dynamics simulation and experimental method

The dynamics of fs-laser ablation of monocrystalline copper has been investigated by molecular dynamics simulation and experimental method. A simulation model is developed by taking the laser energy absorption, the thermal transport of free electrons as well as the energy exchange between electrons and lattice into account. The propagation of laser-induced stress wave in the simulation model is studied. The velocity of stress wave is predicted to be nearly equal to sound velocity of copper 4400 m/s. The mechanisms of ablation responsible for individual atoms and clusters are analyzed as the thermal fluctuations in the kinetic energy and tensile stresses, respectively. The rates of ablation at different fluences obtained from molecular dynamics calculations support the experimental observations of two different ablation regimes.