Scanning tunnelling microscopy (STM) has been used to observe a misori
entation of a graphite layer that is buried several layers below the s
urface. A nanoscale periodic pattern superimposed on the atomic graphi
te lattice has been observed. The appearance of the superperiodic feat
ures in the STM image is shown to be clearly tip-sample distance depen
dent. We suggest that a subsurface misorientation, several layers deep
, causes a nanoscale moire pattern, which can propagate to the surface
and contributes to the STM image. This result is rather surprising as
STM is thought to be unable to image bulk defects. (C) 1998 Elsevier
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