title: Interaction of evaporated nickel nanoparticles with highly oriented pyrolytic graphite: Back-bonding to surface defects, as studied by X-ray photoelectron spectroscopy.
abstract: Ni nanoparticle evaporation onto highly oriented pyrolytic graphite (HOPG), with low and high surface defect densities, has been studied in situ by X-ray photoelectron spectroscopic (XPS) techniques, including binding energy shifts, Auger parameters, and Wagner plots. Ni nucleates at defect sites, whether initially present or those introduced by Ar+ bombardment, with the formation of spherical nanoparticles, which adhere strongly through Ni/HOPG back-bonding. The variation of the C 1s peak intensity with Ni coverage suggests that the photoelectron emission yield may be enhanced at lower Ni coverages, due to Ni nanoparticle-induced electron localization and work function reduction at the HOPG surface, which is evidence of such back-bonding.
authors.affiliation: Regroupement Québécois de Matériaux de Pointe, Département de Génie Physique, Ecole Polytechnique, CP 6079, succursale Centre-Ville, Montréal, Québec H3C 3A7, Canada.
authors.forename: D-Q
authors.initials: DQ
authors.lastname: Yang
authors.forename: E
authors.initials: E
authors.lastname: Sacher