Regensburg 2007 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 44: Poster Session II (Semiconductors; Oxides and Insulators: Adsorption, Clean Surfaces, Epitaxy and Growth; Surface Chemical Reactions and Heterogeneous Catalysis; Surface or Interface Magnetism; Solid-Liquid Interfaces; Organic, Polymeric, Biomolecular Films; Particles and Clusters; Methods: Atomic and Electronic Structure; Time-resolved Spectroscopies)

O 44.1: Poster

Mittwoch, 28. März 2007, 17:00–19:30, Poster C

A Novel Approach to Measure the Step Line Tension and the Step Dipole Moment on Vicinal Au(001) Electrodes — •Guillermo Beltramo, Harald Ibach, and Margret Giesen — Forschungszentrum Jülich, Institut für Bio- und Nanosysteme IBN 4, D 52425 Jülich, Germany

The step line tension plays a crucial role in the electrochemical deposition and dissolution of metals, and in particular, in the creation of nanostructures and their dynamical properties. In the present work, we introduce a new method to measure the step line tension on metal electrodes, using a theoretical model proposed by Ibach and Schmickler [1]. Vicinal Au(11n) and Au(001) electrodes were investigated by impedance spectroscopy in weakly adsorbing electrolytes. Within the limits of error the shift in the potential of zero charge is proportional to the step density of the electrode surfaces and we determine a dipole moment per step atom of about 6.10⁻³ eÅ for all electrolytes. The line tension of the steps is then calculated from the difference between the surface tension of the stepped and the step free surfaces. In accordance with [1], the step line tension decreases (roughly linear) with the electrode potential in absence of specifically adsorbed ions. Furthermore we are able to give an estimation of the step capacity. The results will be discussed with respect to a recent theoretical model [2].

[1] H. Ibach and W. Schmickler, Physical Rev. Lett. 91 (2003) 016106.

[2] H. Ibach et al., J. Electroanal. Chem. 544 (2003) 13.