Controlled vertical manipulation of single CO molecules with the scanning tunneling microscope: A route to chemical contrast

Abstract

A reliable procedure for controlled vertical transfer of single CO molecules between a Cu(111) surface and a scanning tunneling microscope tip and vice versa is demonstrated. It is shown that with a tip having a single CO molecule at its apex, chemical contrast is achieved allowing distinction of adsorbed CO molecules and oxgen atoms, which look very similar to the bare metal tip.