Berlin 2005 – wissenschaftliches Programm
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O: Oberflächenphysik
O 55: Epitaxie und Oberfl
ächenreaktionen
O 55.4: Vortrag
Mittwoch, 9. März 2005, 11:30–11:45, TU EB107
Static and Dynamic Self-Organization of Dendron Monolayers on Graphite Monitored with Scanning Tunneling Microscopy — •B. A. Hermann1, L. Merz2, L. J. Scherer3, C. E. Housecroft3, and E. C. Constable3 — 1Dept. of Physics / CeNS, LMU Munich and WMI,Walther-Meissner-Str. 8, 85748 Garching, Germany — 2on leave from: Inst. of Physics, Uni. Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland — 3Dept. of Chemistry, Uni. Basel, Spitalstrasse 51, 4056 Basel, Switzerland
The direct imaging of chemical species at molecular and submolecular levels allows to probe self-organized structures using scanning tunneling microscopy (STM). The evaporation of solutions of bipyridine-dendrons and dendron wedges on graphite give highly ordered monolayers.
The near atomic resolution of the 1st and 2nd generation bipyridine dendron permits us to assign conformers, which spontaneously and rapidly form molecular domains under ambient conditions. Within a molecular domain, only one conformer is present and domains of different conformers are observed side by side. No preference for one conformer was observed.
The long-chain alkyl-decorated Fréchet-type dendron wedges initially form a pattern based on trimeric units, organized into hexagonal host structures with a pseudo-unit cell of seven molecules, one of which remains highly mobile. Over time, it changes into a dimeric pattern. The chirality arising from the adsorption of the dendrons onto the surface is discussed.