Subpicosecond excimer laser ablation of thick gold films of ultra-fine particles generated by a gas deposition technique

The results of UV laser ablation of gold nanoparticle films on glass substr ates using femtosecond pulses are presented. Films of ultra-fine gold parti cles were prepared by an inert gas evaporation and deposition technique, re sulting in a well-defined log-normal particle size distribution of (7 +/- 1 ) nm. The pulse length of the laser was 500 fs at a wave-length of 248 nm. Ablation thresholds, ablation rates at different fluxes, and the morphology of the ablated structures are presented. For the nanoparticle films studie d an ablation rate five times higher than that of gold films prepared by th e conventional evaporation technique was found. The ablation thresholds and rates are supposed to depend on the particle size and also on the evaporat ion pressure. These results are explained by taking into account the energy transport properties of nanocrystalline and conventionally evaporated gold films.