Observations of anisotropic electron scattering on graphite with a low-temperature scanning tunneling microscope

Low-temperature scanning tunneling microscopy was used to observe anisotropic (3-fold) scattering from point defects on a graphite surface. Such scattering from defects was theoretically predicted but is not typically apparent in room temperature scanning tunneling microscope images. This 3-fold scattering was previously observed only with C-60-functionalized tips. The occupancy of the density of electronic states of the tungsten probe tip is sharpened sufficiently at cryogenic temperatures to enable the electron scattering to be imaged.