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Site-specific surface chemical interactions govern numerous scientific and technological fields including catalysis, thin film growth, and tribology. Full control over design processes in these fields requires quantitative, site-specific elaboration of the surface energy field. Until now, such information has only been theoretically accessible. In this talk, we present an atomic force microscopy-based approach to experimentally obtain this data and illustrate its application by imaging the three-dimensional surface energy field of graphite with picometer and millielectronvolt resolution. Graphite has been chosen due to its importance as a solid lubricant as well as model system for multilayer graphene. We show that from the three-dimensional energy data, sets of normal as well as lateral force maps can be created that allow a detailed characterization of the distance-dependent surface-probe interactions. Within these maps, the positions of all atoms are identified, and differences between atoms at unequal sites are quantified. The results suggest that the origin of graphite's excellent lubrication properties may lay in a remarkable localization of the lateral forces. In addition, simultaneously recorded energy dissipation maps provide important complementary information that allows a further characterization of lattice sites. |
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