Dresden 2006 – wissenschaftliches Programm

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O: Oberflächenphysik

O 7: Surface reactions I

O 7.7: Vortrag

Montag, 27. März 2006, 12:45–13:00, WIL C207

Two-dimensional polymeric network formed via a surface reaction — •Carsten Busse^1,2, Sigrid Weigelt¹, Kurt V. Gothelf³, Christian Bombis¹, Thomas Strunskus², Christof Wöll², Flemming Besenbacher¹, and Trolle R. Linderoth¹ — ¹Department of Physics and Astronomy, and iNANO, University of Aarhus, DK-8000 Arhus C, Denmark — ²Lehrstuhl für Physikalische Chemie I, Ruhr-Universität Bochum, D-44780 Bochum, Germany — ³Department of Chemistry, and iNANO, University of Aarhus, DK-8000 Aarhus C, Denmark

Molecular assemblies on surfaces are often held together via weak forces (van-der-Waals interaction, hydrogen bonding). In order to form more stable, covalently bond structures, we explored chemical reactions between adsorbed molecules. A tri-aldehyde with a large, conjugated backbone was deposited under UHV-conditions in submonolayer coverage on Au(111). The resulting 2D-islands were exposed to a background pressure of a reactive di-amine. After annealing to 450 K, STM reveals the formation of a network structure that consists of large (molecular mass up to 6 kDA) polymer-like macromolecules. We were able to study the connectivity and the varying local binding patterns with sub-molecular resolution. The structure of the macromolecules leads to the conclusion that a chemical reaction between the aldehyde and the amine takes place. Increasing the initial tri-aldehyde coverage leads to a dense, monolayer-high polymer film covering the whole surface. Changing the structure of the educts leads to very similar reactions. We obtained additional information on this process by XPS and NEXAFS.