Integration of point-contact microscopy and atomic-force microscopy: Application to characterization of graphite/Pt(111)

The electrical current through the point-contact junction of an AFM tip is used to image the surfaces of bulk graphite (HOPG) and the surface of a gra phitized carbon monolayer on Pt(111) under ultra-high-vacuum (UHV) conditio ns. Lattice-resolved images are obtained simultaneously in topography, late ral friction, and contact current channels. Lattice resolution in current m aps persisted up to 0.9 mA and pressures of up to 5 GPa. In both bulk graph ite and the case of graphitized carbon monolayer on Pt(111), the current im ages show only one maximum per unit cell. In addition, the contact current images of the graphite monolayer reveal local conductivity variations. We o bserved local conductivity variations in the form of moire superstructures resulting from high order commensurability with the Pt lattice. [S0163-1829 (99)03248-8].