Comparison of nanosecond and femtosecond pulsed laser deposition of silver nanoparticle films.

Nanoparticle (NP) films of silver were prepared using nanosecond (ns) and femtosecond (fs) pulsed laser deposition (PLD) in vacuum. The flux and energy distribution of the ions in the plasma part of the ablation plume were measured using a Langmuir ion probe. The deposition energy efficiencies of ns and fs silver PLD were also compared. For equivalent thickness up to ∼3 nm the NPs made by ns-PLD are well separated and roughly circular, but for higher thicknesses the NPs begin to coalesce. For equivalent thickness up to 7 nm the fs films are comprised of well separated NPs, though the mean NP size and the surface coverage increase with equivalent thickness. The mean Feret diameter for both ns- and fs-PLD films increases with increasing equivalent solid-density thickness. The surface plasmon resonance peak was observed to red shift for both ns- and fs-PLD films as the equivalent solid-density thickness was increased from 1 nm to 7 nm.