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

Low-temperature scanning tunneling microscopy was used to observe anisotrop ic (3-fold) scattering from point defects on a graphite surface. Such scatt ering from defects was theoretically predicted but is not typically apparen t in room temperature scanning tunneling microscope images. This 3-fold sca ttering was previously observed only with C-60-functionalized tips. The occ upancy of the density of electronic states of the tungsten probe tip is sha rpened sufficiently at cryogenic temperatures to enable the electron scatte ring to be imaged.