Real-space observations of long-range electronic perturbations caused by defects have been made with scanning tunneling microscopy. The defects are isolated adsorbed molecules on the surface of graphite. These defects perturb the charge density, giving periodic oscillations similar to Friedel oscillations. The oscillations have a wavelength radical3 times that of the graphite lattice, and the symmetry of the oscillations reflects the nature of the defect.

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We have used the atomic force microscope as a nanoindenter to both doped and undoped polycarbonate to probe the dependence of adhesion on topography and material inhomogeneities. Adhesion measurements at the same position are repeatable to 2%. The magnitude of the adhesion is found to decrease as the local curvature on the surface increases. Spatial adhesion maps of doped polymers show structure that is not apparent in surface topography. The spatial resolution of the measurement is at least 300 Å.

Tilt boundaries have been observed on the (0001) surface of graphite by scanning tunneling microscopy (STM). Rotation angles about the c axis of 6.5°, 8°, and 19° were found, indicating no preferential orientation of grains in the basal plane of graphite. The grain boundary region between crystallites appears disordered with a width varying between 10 and 100 Å. Moiré patterns are observed near grain boundaries when multiple tips scanning over different grains contribute to the image simultaneously. Such images support the theory that multiple isolated tips, occasionally hundreds of angstroms apart, can contribute to STM images.

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