Growth dynamics of pulsed laser deposited Pt nanoparticles on highly oriented pyrolitic graphite substrates

Abstract

Platinum nanoparticles were grown by pulsed laser deposition (PLD) on highly oriented pyrolitic graphite substrates and characterized by scanning tunneling microscopy. Unexpectedly, as the nominal Pt thickness $(t)$ is increased from $0.1\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}20\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$, the mean diameter $({d}_{m})$ of the Pt nanoparticles follows the power law ${d}_{m}\ensuremath{\propto}{t}^{1∕Z}$ with a dynamic exponent $Z=4.7\ifmmode\pm\else\textpm\fi{}10\phantom{\rule{0.2em}{0ex}}%$. This growth law is found to be valid for incident kinetic energy $({K}_{E})$ of the ablated species involved in the growth process ranging from $4\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}130\phantom{\rule{0.3em}{0ex}}\mathrm{eV}∕\mathrm{at.}$ We also show that the shape of isolated Pt nanoparticles can be greatly influenced by ${K}_{E}$. Our results point out that PLD Pt nanoparticles nucleate and grow on the substrate rather than being formed in the ablation plume.