Berlin 2008 – scientific programme
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O: Fachverband Oberflächenphysik
O 18: Poster Session I - MA 141/144 (Atomic Wires; Size-Selected Clusters; Nanostructures; Metal Substrates: Clean Surfaces+Adsorption of Organic / Bio Molecules+Solid-Liquid Interfaces+Adsorption of O and/or H; Surface or Interface Magnetism; Oxides and Insulators: Clean Surfaces)
O 18.58: Poster
Monday, February 25, 2008, 18:30–19:30, Poster F
STM analysis of the fluctuations at 2D phase boundaries between ordered and disordered organic adlayers — •Thomas Waldmann, Harry E. Hoster, and R. Jürgen Behm — Institute of Surface Chemistry and Catalysis, Ulm University, D-89069 Ulm, Germany
The dynamic equilibrium between distinct 2D phases of organic molecules on Ag(111)-oriented films on Ru(0001) at room temperature are studied by time resolved STM. As recently found, the parallel chain structure (PCS) [2] formed by a bis(terpyridine) derivative (2,4’-BTP)[1] can be produced coexistent with a disordered 2D molecular adlayer [2]. At the boundaries between both phases a continuous exchange of molecules takes place with equal rates. At room temperature, these fluctuations are too fast for direct STM-observation, even at scan rates of 5 images s−1. Adapting the approach previously applied to analyse the step dynamics at metal surfaces [3], we evaluated the displacement of the phase boundary in single scan lines as a function of time. The results are discussed in comparison with 2D phase equilibria observed at other coverages [4] and with metal step fluctuations.
[1] C. Meier, U. Ziener, K. Landfester, P. Weihrich, J. Phys. Chem. B 109, 21015 (2005)
[2] M. Roos, H.E. Hoster, A. Breitruck, R.J. Behm, Phys. Chem. Phys. 9, 5672 (2007)
[3] M. Giesen, S. Baier, Atomic transport processes on electrodes in liquid environment, J. Phys.: Condens. Matter 13, 5009 (2001)