Neutron Scattering Study on Dynamics of Water Molecules Confined in MCM-41

摘要

Quasi-elastic neutron scattering(QENS)spectra of water-filled MCM-41 samples having different pore sizes(pore diameters:2.14 and 2.84 nm)were measured over the temperature range 200-298 K and analyzed by a model in which contributions of translational and rotational diffusions of water molecules are expressed by a linear combination of Lorentzian functions(Teixeira et al.,1985).The results indicated that the translational diffusion is decelerated by confinement and that the deceleration increases with a decrease in pore size.QENS spectra of water-filled MCM-41 samples having the same pore sizes(pore diameter:3.36 nm)but a different amount of the hydroxyl groups(0.7 and 2.6 OH'sm~2)were also measured over the temperature range 220-298 K.It was found that the vibrational amplitude of water molecules in MCM-41 increases with increasing amount of the surface hydroxyls,which implies that the hydrogen-bond network of confined water is distorted by interaction with the surface hydroxyls.