Origin of C60 surface reconstruction resolved by atomic force microscopy

Surface adsorption of C 60 affects its chemical and electronic properties. Numerous studies have reported observation of bright and dark fullerenes on metal surfaces that suggest extensive surface reconstruction; however, the underpinning mechanism of the reconstruction remains under debate. Here we report tip-functionalized noncontact atomic force microscope measurements which unambiguously reveal that C 60 fullerenes adsorb with three well-defined adsorption heights on the Cu(111) surface, consistent with theoretical reports of top-layer hollow sites, single-atom vacancies, and surface nanopits. Using single-molecule resolution Δ f ( z ) measurements we identify well-defined adsorption heights specific to each site, confirming the presence of a complex vacancy model for C 60 monolayers on metal surfaces