Energy-Dependent State-Density Corrugation of a Graphite Surface as Seen by Scanning Tunneling Microscopy

We performed scanning-tunneling-microscopy (STM) experiments on cleaved graphite surfaces. STM clearly distinguishes between the inequivalent carbon sites, and yields an energy selective density-of-states corrugation in qualitative agreement with recent theory. A lateral resolution of better than 2 Å was achieved. The experiments further confirm directly the atomic flatness of some thousand ångstrom size areas of cleaved graphite.