Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 39: Metal substrates: Solid-liquid interfaces
O 39.9: Vortrag
Mittwoch, 25. März 2009, 17:00–17:15, SCH A315
Variation of the electrode potential with elastic strain — •Maxim Smetanin1, Dominik Kramer1, Senthilnathan Mohanan2, Ulrich Herr2, and Joerg Weissmueller1,3 — 1Forschungszentrum Karlsruhe, Institut für Nanotechnologie,Karlsruhe — 2Universitat Ulm, Institut für Mikro- und Nanomaterialien, Ulm — 3Universität des Saarlandes, Technische Physik, Saarbrucken
A fundamental parameter in electrochemistry, the electrode potential,E, is intricately related to the solids Fermi energy and to its work function in vacuum. How does E at the metal-electrolyte interface vary when the electrode is subjected to an elastic tangential deformation with strain e? This is of interest in relation to strain effects on the metals band structure, which can affect catalytic processes, to corrosion science, and to recent attempts to understand the response of the surface stress, f, of metals to changes in the superficial charge density, q. The connection to surface stress rests on a Maxwell relation, df/dq=dE/de. While the left-hand-side has been studied in several experiments,we know of no quantitative experiment exploring the right-hand side. Our approach is to use a small cyclic strain of a thin-film gold electrode along with sensitive potential monitoring. We found that the potential varies linearly with the strain; the response parameter is negative. In 10 mM HClO4, for quasi-static straining dE/de=-1 V, whereas the value converges to -1.8 V at frequencies around 100Hz. The sign agrees with early predictions, the magnitude is in good agreement with recent results from density functional theory for Au(111) in vacuum and with experimental results for df/dq in electrolyte.