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DS: Fachverband Dünne Schichten
DS 3: Metal Layers and Multilayers
DS 3.2: Talk
Monday, March 26, 2007, 09:45–10:00, H34
Reactive Surfaces under Electrochemical Control: Cl/Cu(100) — •Hubert Zajonz1, Helmut Dosch1, Peter Broekmann2, Sascha Huemann2, and Klaus Wandelt2 — 1Max-Planck-Institut für Metallforschung, Heisenbergstr.3, 70569 Stuttgart, and Institut für Theoretische und Angewandte Physik, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany — 2Institut für Physikalische und Theoretische Chemie, Universität Bonn, Wegelerstr. 12, 53115 Bonn, Germany
The surface structure of Cu(100) modified by chloride has been studied in an electrochemical environment by means of in-situ surface x-ray scattering with a particular focus on adsorbate and potential dependent surface relaxation effects. An extraordinary large Cu-Cl bond length of 2.63 Å is found for the c(2×2)-Cl phase on the basis of diffraction data analysis at positive potentials close to the on-set of the copper dissolution reaction. This finding points to a largely ionic character of the Cu-Cl interaction on Cu(100) with chloride particles likely retaining their full charge upon adsorption. In combination with the positive surface charging at these high potentials this ionic Cu-Cl bond is discussed as the origin of the observed 2.2 % outward relaxation between the first two copper layers. These results indicate that the bond between the first and the second copper layer is significantly weakened which seems to be the crucial prerequisite for the high surface mobility of copper-chloride species under electrochemical annealing conditions at these high potentials.