title: Atom transfer and single-adatom contacts.
abstract: The point contact of a tunnel tip approaching towards Ag(111) and Cu(111) surfaces is investigated with a low temperature scanning tunneling microscope. A sharp jump to contact, random in nature, is observed in the conductance. After point contact, the tip-apex atom is transferred to the surface, indicating that a one-atom contact is formed during the approach. In sharp contrast, the conductance over single silver and copper adatoms exhibits a smooth and reproducible transition from tunneling to contact regime. Numerical simulations show that this is a consequence of the additional dipolar bonding between the adatom and the surface atoms.
authors.affiliation: Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, D-24098 Kiel, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Limot
authors.forename: J
authors.initials: J
authors.lastname: Kröger
authors.forename: R
authors.initials: R
authors.lastname: Berndt
authors.forename: A
authors.initials: A
authors.lastname: Garcia-Lekue
authors.forename: W A
authors.initials: WA
authors.lastname: Hofer