The effect of confinement on water structure.

Neutron diffraction experiments with hydrogen isotope substitution on water confined in MCM41-S15 have been performed at temperatures of 300 and 210 K. Data are analyzed at a microscopic level using a revised version of the empirical potential structure refinement technique. It is found that the influence of the substrate on the water structure is not negligible and depends on the temperature: owing to the geometrical constraints and the symmetry breaking induced by the wall, comparison with the corresponding bulk phases is not straightforward and standard analysis should be replaced by a more suitable one.