Berlin 2008 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 32: Oxides and Insulators: Clean Surfaces
O 32.13: Vortrag
Dienstag, 26. Februar 2008, 16:00–16:15, MA 042
Surface Stress Variation as a Function of Charge for the Metal at Metal - Electrolyte Interface — •Maxim Smetanin1, Raghavan N Viswanath1, Dominik Kramer1, and Joerg Weissmueller1,2 — 1Institut für Nanotechnologie, Forschungszentrum Karlsruhe, Karlsruhe, Germany — 2Universität des Saarlandes, Saarbruecken, Germany
During the last decade, there has been considerable progress in measuring and understanding the capillary forces on metal surfaces. The present work revisits the question, what is the magnitude of the surface stress charge coefficient(SSCC) for the gold in an electrolyte near the potential of zero charge, in particular in respect to comparison to numerical computation. We report in-situ measurements of f(q) for planar gold electrodes in weakly adsorbing electrolytes, using a cantilever bending technique with optical detection. We used 40 nm thick, (111)-textured gold films on 100 *m thick (100)-oriented silicon wafers in aqueous NaF and HClO4. The films were characterized in respect to roughness (using a scanning probe microscopy) and to contamination (using Auger microscopy). Their pzc value was determined in 7 mM NaF using the minimum of the differential capacitance, it is ca. 0.20 V vs. SCE. The wafer bending results testify to an essentially linear f(q) near the pzc and electrode charging occurs mainly within the diffuse double layer at minimum influence of specific ions adsorption. SSCC was found to be of the order of -1.95 V for 7 mM NaF and -2.02 V for 10 mM HClO4.