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O: Oberflächenphysik

O 47: Organic films IV

O 47.5: Vortrag

Freitag, 31. März 2006, 12:15–12:30, PHY C213

Comparative UHV-STM study of adsorption structures formed from a family of oligo-(phenylene ethynylenes) with systematical variation of geometry and functional groups — •Christian Bombis¹, Carsten Busse¹, Siegrid Weigelt¹, Martin Noergaard¹, Martin Knudsen², Kurt V. Gothelf², Eva Rauls¹, Bjoerk Hammer¹, Flemming Besenbacher¹, and Trolle R. Linderoth¹ — ¹Department of Physics and Astronomy, and iNANO, University of Aarhus, 8000 Aarhus C, Denmark — ²Department of Chemistry, and iNANO, University of Aarhus, 8000 Aarhus C, Denmark

Using scanning tunneling microscopy we have systematically explored the influence of the geometry of molecules and the chemical nature of their functional groups on formed adsorbate structures. For this purpose we utilized compounds from a family of organic molecules, oligo-(phenylene ethynylenes), which have been deposited on the Au(111) surface under ultra high vacuum conditions. The elementary member of this family consists of a highly conjugated linear backbone functionalized with aldehyde, hydroxyl and bulky tert-butyl groups while compounds with bent and three-spoke geometries represent geometrical variants. The study with systematic variation of the endgroup chemistry supports the hypothesis, that only in the case, where intermolecular hydrogen bonds can form, does a more open network phase form instead of a close packed structure held together by non-specific Van-der-Waals interactions. Theoretical modelling based on the DFT-B method is currently being performed to further illuminate this observation.