We have carried out a scanning tunneling microscopy barrier-height (STM-BM)
imaging of a reconstructed Au(111) surface and found that the BH locally d
ecreases on herringbone reconstruction ridges, or Shockley dislocations. Th
e observed lowering of the BH can be explained by the formation of an elect
ric dipole at a dislocation core, which was theoretically predicted by Cott
rell et al. (Philos. Mag. 44 (1953) 1064) in their theory on the electric i
nteraction between solutes and dislocations.