Molecular Dynamics Simulation of the Laser-Induced Melting of an Al Nanofilm

A coupled computational technique, which combines the one dimensional two-temperature model and molecular dynamics, was used to study the melting dynamics of a nanoscale aluminum film irradiated by a femtosecond laser pulse. The model is capable of providing an atomic-level depiction of fast microscale processes in metals and gives an adequate description of laser light absorption, energy transfer, and fast electron heat conduction in metals. The simulation revealed that the electron temperature, lattice temperature, and laser induced pressure of the Al film were significantly different from those of Ni and Au films. The Al film melts globally soon after laser radiation and this is different from the Ni film, which goes through a step melting process. In addition, the Al film shows a much faster melting process than the Ni and Au films because of strong electron-phonon coupling. The melting time of the Al film by an ultrafast laser pulse is consistent with recent experimental observations, which supports the assertion that the laser induced melting of an Al film is a thermal process.