Dynamics of confined water in porous alumina: neutron-scattering study

We report dynamics of water molecules contained in the pores of alumina gel as studied by the high-resolution quasi-elastic neutron scattering technique at room temperature and below. Some water molecules are found to be attached on the inner surfaces of the alumina gel (localized) and others undergo diffusion within the available space in the pores. The localization radius and the diffusion constant (Dloc) of water molecules performing local motion are obtained. The diffusion constant (Dt) and the residence time (τconf) of the water molecules diffusing inside the alumina-gel pores are also obtained. It is found that the diffusion constant and the residence time of water molecules in the pores are very much different to those of bulk water.