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SYOF: Organische Festkörper

SYOF 5: Poster Session

SYOF 5.8: Poster

Tuesday, March 27, 2001, 17:00–19:00, Aula S3

Self-assembly of 6-(4-phenylazo-phenoxy)-hexanethiol on Au(111) — •Stefan Mannsfeld, Tobias W. Canzler, Torsten Fritz, and Karl Leo — Institut für Angewandte Photophysik, Technische Universität Dresden, 01062 Dresden

Self-assembled monolayers of a photochromic model substance (6-(4-phenylazo-phenoxy)-hexanethiol) were prepared on Au(111) surfaces. Their structure was analyzed by two complementary methods: First, we employed FTIR-spectroscopy in reflection geometry (so-called grazing-angle FTIR). From the absence of the two CH₂-related stretching modes (which are clearly visible in reference spectra taken from KBr pellets) we conclude that our thin film samples are highly ordered and that the alkyl chains are oriented almost perpendicular to the substrate plane. Second, those integral measurements were complemented by local structural investigations using STM. Despite the inherently large tunneling resistance of the rather extended molecule (length being approximately 20 Å), we succeeded in identifying two different crystalline phases, characterized by almost identical lattice parameters but different molecular contrast. Finally, we compare our results to previous studies of other authors.