| AVS 60th International Symposium and Exhibition | |
| In Situ Spectroscopy and Microscopy Focus Topic | Friday Sessions |
| Session IS+AS+SP-FrM |
| Session: | Evolving In Situ Microscopic and Spectroscopic Techniques and Applications |
| Presenter: | K. Kristiansen, University of California, Santa Barbara |
| Authors: | K. Kristiansen, University of California, Santa Barbara M. Valtiner, Max Planck Institut fur Eisenforschung GmbH, Germany X. Banquy, Universite de Montreal, Canada G.W. Greene, University of Deakon, Australia J.N. Israelachvili, University of California, Santa Barbara |
| Correspondent: | Click to Email |
We present a newly designed electrochemical Surface Forces Apparatus (EC-SFA) that allow control of surface potential and interfacial electrochemical reactions with simultaneous measurements distances between apposing surfaces (with 0.1 nm resolution), normal interaction forces (with nN resolution), and friction forces (with μN resolution). We will describe three applications of the EC-SFA:
(1) Oxide growth of a gold surface. Applying a high positive electrical potential on a metal surface will lead to an oxide growth. Using the EC-SFA we compared the measured thickness of the anodic gold oxide layer and the charge consumed for generating this layer which allowed the identification of its chemical structure as a hydrated Au(OH)3 phase formed at the gold surface at high positive potentials.
(2) The evolution of the friction forces at a metal-ceramic contact as a function of the applied electrochemical potential.
(3) The phenomenon of “pressure solution”. We have found an intimate relationship between dissolution rate and the surface potential difference across interfaces of dissimilar materials that are immersed in brine solution. For example, using the EC-SFA we have visualized and measured the dissolution of silica glass surfaces close to a gold electrode surface, which is on the order of 0.1 nm/hr. This is similar to geological samples of sandstones.
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