COLL 514 |
| The composition of mineral-water interfaces play a significant role in governing/indicating the chemistry of the local aqueous environment. Using Lateral Force Microscopy (LFM), we have studied a model system exhibiting nanometer scale chemical inhomogeneity on an atomically flat surface, namely an ionic monolayer on a freshly cleaved, highly ordered CaMg(CO3)2 (dolomite) surface. Calibrated LFM measurements show distinct contrast between the ionic monolayer and the original substrate, while both surfaces appeared to be in the same ionic plane in the topographic images. From the observed increase in friction on the monolayer, we designed investigations to test the mechanism responsible for the friction contrast. Initial results suggest that the vertical stiffness of the monolayer is lower than the dolomite surface, giving rise to a larger contact area between the LFM tip and monolayer. These experiments also revealed negligible difference in the tip-surface adhesion, pointing to vertical stiffness as the determining mechanism for friction contrast. |
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Environmental Interfaces
2:00 PM-5:50 PM, Wednesday, 13 September 2006 Sir Francis Drake -- Empire Room, Oral
Division of Colloid & Surface Chemistry |