Berlin 2015 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 89: Inorganic/Organic Interfaces: Molecular Switches
O 89.12: Vortrag
Donnerstag, 19. März 2015, 17:45–18:00, MA 043
Force and conductance in a single molecule switch: SnPc on Ag(111) — Nuala Caffrey1, Kristof Buchmann2, Nadine Hauptmann2, Cesar Lazo1, •Paolo Ferriani1, Stefan Heinze1, and Richard Berndt2 — 1Institut für Theoretische Physik und Astrophysik, Christian-Albrecht-Universität zu Kiel, D-24098 Kiel, Germany — 2Institut für Experimentelle und Angewandte Physik, Christian-Albrecht-Universität zu Kiel, D-24098 Kiel, Germany
Transport in molecular electronic devices is ultimately determined by the properties of the interface between the metallic electrodes and the organic molecule. To understand the interface properties, the relation between structure and conductance needs to be assessed. The combined use of scanning tunneling and atomic force microscopy is an ideal technique as it allows to simultaneously measure interaction forces and conductance between a tip and an adsorbed molecule. Here, we apply it to study Sn-Phthalocyanine (Pc) on Ag(111). This molecule has a shuttle-cock shape and on a surface can acquire one of two possible conformations – either with the central metal atom pointing away from or towards the surface. We have performed conductance and force measurements on both molecular configurations as a function of tip-sample distance. First-principles calculations of the force and conductance curves agree well with the experiment. We find a non-trivial distance-dependence of the force curves which is explained based on the competition of forces acting on different atoms in the molecule.