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O: Fachverband Oberflächenphysik

O 54: Electronic structure II

O 54.9: Vortrag

Mittwoch, 24. März 2010, 17:00–17:15, H33

Nanoporous supramolecular networks: From quantum confinement to caged rotators — •Florian Klappenberger — Physik Department E20, TU München, Germany

Making use of molecular self-assembly of dicarbonitrile-sexiphenyl (NC2Ph6) molecules, we confine the surface state of the Ag(111) surface with various nanoporous networks and investigate their properties by means of low-temperature scanning tunneling microscopy/spectroscopy and electronic structure calculation. The case of a hydrogen-bonded chiral Kagome superstructure induces a complex dichotomous electronic tessellation. An analysis employing a boundary element method based on Greens functions indicates a uniform repulsive scattering potential for the molecular building blocks. In a Co-directed metal-organic honeycomb network employing the same molecules, Co atoms scatter clearly different from the organic linkers with slight attractive potential for electrons at the Fermi energy, thus with strongly altered character than isolated Co adatoms. Further evaporation of NC2Ph6, acting as guest molecules, leads to the self-assembly of three-winged supramolecular units within the honeycomb pores and to further confinement of the surface state electrons. Thermal activation induces rotation of the trimeric unit and thus produces a dynamic quantum confinement. A temperature-dependent study yields the rate of the motion of the self-assembled rotor and shows various modes of motion.