GEOC 24 |
| Nothing is more fundamental to geochemistry than the processes by which minerals interact with water. Mineral surfaces themselves are generally too complicated to provide meaningful information about molecular-scale transformations, but much can be learned from nanometer-size aqueous clusters, which have stable and verifiable structures in water and for which various oxygen sites can be spectroscopically isolated. In this presentation, I review kinetic information available for oxygen-isotope exchange in these clusters. I show that the pathways for replacing an oxygen are often complicated and counterintuitive, yet some key reactive properties are sufficiently robust to make sweeping predictions. The rates of water exchanges, for example, follow a trend in reactivity that is predictable from the monomer complexes---in the near future, these rates could be calculated directly from knowledge of structures at mineral sites. In contrast, exchange pathways for hydroxyl and oxo bridges are exceptionally complicated and any understanding requires close coupling between experiment and simulation.
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Physical Chemistry of Soil and Aquifer Systems: A Symposium in Honor of Garrison Sposito
1:30 PM-5:10 PM, Sunday, 10 September 2006 Moscone Center -- Room 256, Oral
Division of Geochemistry |
