Thermoelastic modeling of microbump and nanojet formation on nanosize gold films under femtosecond laser irradiation

A model of elasto-plastic flow combined with the two-temperature model in a two-dimensional approximation has been developed to describe microbump and nanojet formation observed recently on nanosize gold films irradiated by femtosecond laser pulses. It has been shown that the effect of microbump and nanojet formation is conditioned by the elastic characteristics, yield stress, and other properties that are unique for gold. The numerical results are in excellent agreement with the experimental data with respect to a number of parameters, particularly the threshold fluence for nanojet formation at the tops of microbumps, which occurs nearby and above the melting threshold. The analysis of properties for a number of materials is performed and some other materials are discussed as possible candidates for nanotexturing of thin films by femtosecond laser pulses.