title: Periodic Charging of Individual Molecules Coupled to the Motion of an Atomic Force Microscopy Tip.
abstract: Individual molecules at the edges of self-assembled islands grown on Ag(111) can be deliberately switched in their charge state with the electric field from a scanning-probe tip. Close to the threshold voltage for a charge state transition, periodic switching of the charge is directly driven by the cantilever motion in frequency-modulated atomic force microscopy (AFM), as can be deduced from the signature in the measured frequency shift. In this regime, the integrated frequency shift yields the tip-sample force that is due to a single additional electron. Further, the signature of the dynamic charging response provides information on the electronic coupling of the molecule to the substrate. In analogy to previous experiments on quantum dots, this may also be used in the future to access excited state properties of single molecules from AFM experiments.
authors.affiliation: †Institute of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany.
authors.forename: N
authors.initials: N
authors.lastname: Kocić
authors.affiliation: †Institute of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Weiderer
authors.affiliation: ‡Department of Chemistry and Biochemistry, University of Bern, 3012 Bern, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Keller
authors.affiliation: ‡Department of Chemistry and Biochemistry, University of Bern, 3012 Bern, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Decurtins
authors.affiliation: ‡Department of Chemistry and Biochemistry, University of Bern, 3012 Bern, Switzerland.
authors.forename: S-X
authors.initials: SX
authors.lastname: Liu
authors.affiliation: †Institute of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Repp
keywords: Single-electron tunneling; atomic force microscopy; charge sensing; level broadening; single molecule