title: Water diffusion in nanoporous glass: an NMR study at different hydration levels.
abstract: By pulsed field gradient nuclear magnetic resonance measurements, we investigated the translational diffusion of water confined in the 200 A diameter pores of a sol-gel silica glass. The experiments, performed as a function of the hydration level, showed an enhancement of the self-diffusion coefficient when the water content corresponds to one or fewer monolayers. An explanation for this occurrence has been given in terms of a two-phase process involving a fast molecular exchange between the liquid and the vapor phase. Moreover, in partially filled pores, the surface water diffusion coefficient was measured, and was 4 times lower than the diffusion of liquid confined water in saturated spaces.
authors.affiliation: Department of Physics, University of Messina, C.da Papardo, S.ta Sperone 31, P.O. Box 55, 98166 S. Agata, Messina, Italy. majolino@unime.it
authors.forename: Domenico
authors.initials: D
authors.lastname: Majolino
authors.forename: Carmelo
authors.initials: C
authors.lastname: Corsaro
authors.forename: Vincenza
authors.initials: V
authors.lastname: Crupi
authors.forename: Valentina
authors.initials: V
authors.lastname: Venuti
authors.forename: Ulderico
authors.initials: U
authors.lastname: Wanderlingh
mesh_terms: D004058:Diffusion; D005898:Glass / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D049329:Nanostructures / Q000737:chemistry*; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D012822:Silicon Dioxide