Contamination-mediated deformation of graphite by the scanning tunneling microscope

Abstract

We demonstrate that surface deformation mediated by contamination plays a major role in images of graphite obtained by a scanning tunneling microscope in air. Atomic resolution has been obtained with the surface compressed by as much as 100 \AA{}, where abnormally high atomic corrugations, up to 24 \AA{}, are observed. Calculation of the deformation profile reveals that the force necessary to deform the surface must be spread over several thousand square angstroms. The measured deformation is negligible in vacuum with a clean sample and tip, and the corrugation is 0.9 \AA{}.