X-ray and neutron scattering studies of the structure of water at a hydrophobic surface

The structure of water in contact with a hydrophobic surface, namely, activated carbon, is studied using both x-ray and neutron scattering techniques. The structure factors and the corresponding radial distribution functions are determined for several levels of hydration, at room temperature and down to 77 K. At high water content (similar to 200%), the properties of water are very similar to those of bulk water; in partially hydrated samples (<50%), the molecular structure exhibits change of its local environment within particular a distortion at the level of the second neighbors, and water does not crystallize when the temperature is lowered. (C) 1996 American Institute of Physics.