AVS 50th International Symposium
    Surface Science Wednesday Sessions
       Session SS+NS-WeA

Paper SS+NS-WeA9
Manipulating Single Metal Atoms with the Scanning Tunnelling Microscope

Wednesday, November 5, 2003, 4:40 pm, Room 328

Session: Perspectives and New Opportunities
Presenter: K.-F. Braun, Freie Universit@um a@t Berlin, Germany
Authors: K.-F. Braun, Freie Universit@um a@t Berlin, Germany
K.H. Rieder, Freie Universit@um a@t Berlin, Germany
K. Flipse, Eindhoven University of Technology, The Netherlands
S.-W. Hla, Ohio University
Correspondent: Click to Email
Scanning tunnelling microscopy has been used to manipulate single atoms, small molecules as well as larger molecules and parts of it. Lateral manipulation can be applied to position atoms for the construction of artificial assemblies on desired atomic sites. Although manipulation techniques have been used on a variety of systems only little is known about the interaction forces between microscope tip and adparticle. Here we present a detailed study of the lateral manipulation of Au and Ag atoms on Ag(111) and Ni(111) surfaces. We describe a complete picture of how single Ag atoms move on the various potential energy landscapes of a Ag(111) surface during a quantum corral construction by using an STM tip at 6 K. The threshold tunnelling resistance and tip-height to move the Ag atom across the surface are experimentally measured as 210  19 k and 1.3  0.2 Å. The experimental atom manipulation signals reveal remarkably detailed atom movement behaviour dependent on the surface crystallographic orientation and offer atomic-level tribology information.@footnote 1@ Manipulation experiments with Au atoms on the same Ag(111) surface show a voltage dependent threshold resistance above 100 mV. Possible current and field effects will be discussed. Measurements on Au atoms on a Ni(111) surface display even a long-ranged repulsive interaction for voltages below -300 mV. The influence of the electronic surface structure on the manipulation will be discussed. Electrons injected in the antibonding levels of the atom-surface system can weaken the bond to allow lateral manipulation at high voltages as well as desorb the atom.@footnote 2@ @FootnoteText@@footnote 1@S.W. Hla, K.-F. Braun, K.H. Rieder, Phys. Rev. B, Rapid Comm., accepted (2003). @footnote 2@K.-F. Braun, K. Flipse, K.H. Rieder, in preparation (2003).