Platinum nanoparticles growth by means of pulsed laser ablation

Platinum nanoparticles were deposited onto Highly Oriented Pyrolitic Graphite (HOPG) substrate by laser ablating a Pt target at room temperature into a vacuum chamber. By varying the helium background pressure (from 10(-5) to 0.5 Torr) and the target-to-substrate distance (from 3 to 6 cm), we were able to explore a large range of kinetic energies (i.e., from similar to4 to similar to130 eV/atom) of the Pt ablated neutrals species impinging on the HOPG substrates. Thus, the effect of the kinetic energy on the size and the surface density of Pt nanoparticles has been investigated ex-situ by means of scanning tunneling microscopy (STM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The pulsed laser deposition technique is shown to produce Pt nanoparticles (of which diameter in the 1-4 nm range) with a relatively narrow size distribution. While the size of the PLD Pt nanoparticles is shown to be mainly influenced by the number of laser pulses, their shape is found to be more sensitive to kinetic energy of the Pt ablated species.