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O: Fachverband Oberflächenphysik

O 9: Nanotribology

O 9.7: Vortrag

Montag, 11. März 2013, 12:00–12:15, H42

Molecular friction at electrodes — Nikolay Podgaynyy, Sabine Wezisla, Shahid Iqbal, and •Helmut Baltruschat — Inst. f. Physikal. Chemie, 53117 Bonn, Roemerstr.164

Friction under ambient conditions often involves wet surfaces, and thus electrochemical interfaces. Yet measurements of friction at an atomic scale under electrochemical conditions are scarce.[1] We will present friction measurements performed on Au(111) single crystal electrodes and the effect of adsorbates on atomic stick-slip resolution. At the small normal load of 15 nN transition to atomic stick-slip resolution is observed, when sulfate is adsorbed on the surface. The reason for that transition could be a penetration of the tip in to the double layer. At the pzc on clean gold stick-slip behaviour does not show any transition or penetration effects. The adhesion on the force-distance curve disappear with a copper adsorption. However, with a monolayer of Cu on Au(111) a transition to stick-slip behavior is present, but without atomic resolution. Multiple slip was also observed. We will further report on the influence of the molecule orientation of pyridine adsorbed to Au(111). Molecular stick slip was also observed; the corrugation correlates with the molecule separation as determined by STM. [2]. [1]*M. Nielinger, H. Baltruschat, Physical Chemistry Chemical Physics 2007, 9, 3965.; F. Hausen, M. Nielinger, S. Ernst, H. Baltruschat, Electrochimica Acta 2008, 53, 6058. [2]*W. B. Cai, L. J. Wan, H. Noda, Y. Hibino, K. Ataka, M. Osawa, Langmuir 1998, 14, 6992.