COLL 248 |
| Jing Zhang, Zhiqun Lin, Yingxi Zhu, and Steve Granick. Department of Material Science and Engineering, University of Illinois at Urbana-Champaign, 1304 W. Green St., Urbana, IL 61801 |
| A controversial issue in recent surface forces experiments is the viscosity of molecularly-thin aqueous films. Here, in experiments with deionized water and also water with added inorganic salts, we seek to resolve the experimental discrepancies by employing mica that is free of nanoparticulate deposits that are reported to result from use of a hot platinum wire. Based on avoiding all use of this method of sample preparation, it is possible to reconcile experiments between different laboratories. More substantively, we find that the effective viscosity of films 1-2 hydrated ions thick varies by orders of magnitude depending on the relative angle between the opposed mica sheets. The mica has pseudo-hexagonal crystal symmetry and the magnitude of the effective viscosity oscillates with the 60 degree period of the crystal lattice. The surface-induced structure of the confined aqueous films thus reflects the Moiré pattern of the crystal lattices that confine it. |
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Posters: Fundamental Research in Surface and Colloid Chemistry
6:00 PM-8:00 PM, Monday, March 29, 2004 Disneyland -- North Exhibit Hall, Poster
Division of Colloid and Surface Chemistry |