Dresden 2006 – scientific programme

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O: Oberflächenphysik

O 9: Organic films I

O 9.5: Talk

Monday, March 27, 2006, 16:00–16:15, TRE Phys

Molecule-molecule vs. molecule-substrate interactions in 2D oligopyridine networks — •H.E. Hoster¹, M. Roos¹, Ch. Meier², A. Breitruck¹, B. Pluhar¹, M. Seyfried¹, K. Tonigold¹, and R.J. Behm¹ — ¹Abt. Oberflächenchemie und Katalyse, Universität Ulm, 89069 Ulm — ²Abt. Organische Chemie III, Universität Ulm, 89069 Ulm

Oligopyridines vapor deposited onto single crystallines surfaces form highly ordered 2D networks with a geometry mainly determined by the coverage. We have analysed such networks on HOPG, Au(111), and Ag(111)-like adlayers on Ru(0001). Variations of the substrate in some cases alter details within the structures such as intermolecular distances or aspect ratios of unit cells, while in other instances certain molecular arrangements are only found on one type of surface. We assume the local constellations of the molecules and as a consequence also the unit cells of the resulting superstructures to be dominated by intermolecular interactions via hydrogen bonds. On the other hand, both the 2D networks and the planar single molecules appear to prefer certain lateral alignments with respect to the substrate, as obvious in closer analyses of domain orientations and STM-images showing molecular adlayers with the Au(111) herringbone reconstruction shining through. This points towards a significant contribution of the adlayer/substrate interface to the overall energy, which causes an adaptation of the respective 2D-layer to the respective substrate up to a repetitive occupation of equivalent adsorption sites, i.e., a commensurate or at least quasi-epitaxial layer.