Atom-by-Atom Filling of a Ag(111) Surface Vacancy
A vacancy on a Ag(111) surface, which is purposedly formed by tip-sample contact, is filled back with individual atoms. These atoms are extracted from the native surface by means of a controlled tip-crash . After filling the fourth atom, the surface vacancy disappears and the area is no longer distinguishable from the rest of the surface. Thus, the atoms used to fill the vacancy have to be silver atoms . If other atom types are used, the background contrast will be different. This experiment proves that previously extracted atoms from the native silver surface with the STM-tip are silver atoms.
(Courtesy: Saw-Wai Hla)
Shaping the future by controlling the atomic world...
 S.-W. Hla, K.-F. Braun, V. Iancu, A. Deshpande, “Single Atom Extraction by Scanning Tunneling Microscope Tip-Crash and Nanoscale Surface Engineering”, Nano Lett. 4 (2004) 1997-2001.