Regensburg 2007 – scientific programme

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O: Fachverband Oberflächenphysik

O 17: Poster Session I (Nanostructures at Surfaces; Metal Substrates: Epitaxy and Growth; Methods: Scanning Probe Techniques; Phase Transitions)

O 17.11: Poster

Monday, March 26, 2007, 17:30–20:30, Poster C

Chemical bonding identification in metal-organic chains of trimesic acid on Cu(110) — Rishav Chopra, •Chariya Virojanadara, Thomas Classen, Giovanni Costantini, Ulrich Starke, and Klaus Kern — Max-Planck-Institut für Festkörperforschung, Heisenbergstr. 1, D-70569 Stuttgart

Functional groups of hydrocarbon molecules provide chemical selectivity, e.g. for sensing or biological interactions, or can serve as linking key for the development of molecular networks on surfaces. In this context, trimesic acid (TMA) with its carboxylic groups can interact in different ways with surfaces. In the present work the adsorption of TMA is investigated on Cu(110). Scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED) experiments show that molecular linking to Cu adatoms leads to ordered metal-organic chains. The detailed bond configuration of the molecule on the surface can be determined using X-ray photoelectron spectroscopy (XPS). Analysis of chemical shifts reveals that the link is provided by a dehydrogenation of the acid groups, i.e. carboxylate groups are connected via the oxygen atoms to the Cu substrate. At low coverage this takes place already at room temperature. A denser phase at higher coverage still contains carboxylic groups at room temperature. Dehydrogenation is only observed when the chain is fully developed after 220^∘C annealing. The oxygen-Cu coordination is different for the two phases and depends on the density of the molecular adsorbate.