Dresden 2003 – wissenschaftliches Programm

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O: Oberflächenphysik

O 24: Postersitzung (Epitaxie und Wachstum, Oxide und Isolatoren, Elektronische Struktur, Oberfl
ächenreaktionen, Adsorption an Oberfl
ächen, Organische Dünnschichten)

O 24.62: Poster

Mittwoch, 26. März 2003, 14:30–17:30, P1

Investigation of Hourglass-Shaped Dendrimers with STM — •Isabelle Widmer, Meike Stöhr, Leo Merz, Hans-Joachim Güntherodt, and Bianca A. Hermann — Institut für Physik, Universität Basel, Klingelbergstr. 82, CH-4056 Basel

It is still widely believed that only flat and stiff molecules have good self-organization properties on surfaces. In the here presented study, an alkoxyl-substituted dendritic compound (hourglass-shaped dendrimer) with a chiral core moiety was investigated.

Samples of the hourglass-shaped dendrimer were prepared by solution-casting on an HOPG substrate and studied with STM. The molecules were found to form a spontaneous ordering (i.e. not induced by the STM tip). This could be attributed to the flexibility of the center piece, which allows the alkyl chains to lie flat on the HOPG surface. Although the measurements were conducted at room temperature in air, submolecular resolution could be achieved. The molecules show self-organization in double rows. Furthermore, different domains, which were aligned with an angle of approximately 60^∘ with regard to each other, as well as regions in which the ordered phase coexisted with an unordered No-dq2D gasNo-dq phase were observed.

These results will be compared with earlier measurements of the same dendritic compound at the solid-liquid interface.