Berlin 2005 – scientific programme

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O: Oberflächenphysik

O 6: Grenzfl
äche fest-flüssig

O 6.4: Talk

Friday, March 4, 2005, 11:30–11:45, TU EB407

In Situ Observation of Adsorbates Diffusion on Au(111) using Electrochemical Video-STM — •Koji Suto and Olaf Magnussen — Institut für Experimentelle und Angewandte Physik, Universität Kiel, Kiel, Germany

The diffusion and interaction of molecular adsorbates on solid-liquid interface is an important fundamental subject of surface physics, due to its relevance for numerous surface processes, e.g. catalytic reactions, growth, or the formation of self-assembled adlayers. This time we report investigation of adsorbates motion at metal electrode - liquid electrolyte interfaces by an electrochemical Video-STM, capable of recording up to 30 images per sec and with atomic scale resolution. Full coverage of sulfate adlayers were observed to form well defined structure of ( √3 × √7 ) on Au(111)-(1 × 1) surfaces at 0.8 V vs. SCE in sulfuric acid solution as reported before [1], which fluctuated strongly in slightly negative potential region due to pronounced migration of the adsorbates between neighboring domains. 1,4-butanedithiol, a strong chemisorbed organic species, were found to migrate individually on the reconstructed Au(111) surface (at 0.3 V vs. SCE) at low coverage in acidic solution. The diffusion process could not be described by simple hopping migration, but involved rotational motion and translational motion of the adsorbates on the surface.

[1] O. M. Magnussen, J. Hageboeck, J. Hotlos, R. J. Behm, Faraday Discuss., 94 (1992) 329.