3aPA15. Hydrophobic hydration: Water structure around nonpolar solutes and its relevance to a new mechanism for sonoluminescence.

Session: Wednesday Morning, December 4

Time: 11:35

Author: Michael E. Paulaitis
Location: Dept. of Chemical Eng., Johns Hopkins Univ., Baltimore, MD 21218
Author: Andrea Prosperetti
Location: Johns Hopkins Univ., Baltimore, MD 21218


A clear picture of water structure surrounding simple, nonpolar solutes, such as xenon or argon, has emerged over the past decade from molecular simulations. A confirmation of these results is provided by their ability to explain the unusual temperature dependence of hydrophobic hydration as reflected in pure water by the density maximum observed at 4 (degrees)C and the isothermal compressibility minimum at 50 (degrees)C. The two factors that determine water structure around simple, nonpolar solutes are: (1) the small size of water molecules and the directional hydrogen-bonding nature of water, and (2) the fact that water molecules can also adopt ``straddling'' configurations around small solutes in order to maximize the number of hydrogen bonds with neighboring waters of hydration. These preferred configurations give rise to strong solute-water orientational correlations. The presentation will show the importance of these strong solute-water correlations in understanding the molecular nature of hydrophobic hydration and their possible relevance for a new hypothesized mechanism for sonoluminescence. [MEP supported by the National Aeronautics and Space Administration and the National Science Foundation, AP by the Office of Naval Research.]

ASA 132nd meeting - Hawaii, December 1996