By pulsed field gradient nuclear magnetic resonance measurements, we investigated the translational diffusion of water confined in the 200 Å 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.
Water diffusion in nanoporous glass: An NMR study at different hydration levels
MAJOLINO, Domenico;CORSARO, CARMELO;CRUPI, Vincenza;VENUTI, Valentina;WANDERLINGH, Ulderico
2008-01-01
Abstract
By pulsed field gradient nuclear magnetic resonance measurements, we investigated the translational diffusion of water confined in the 200 Å 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.Pubblicazioni consigliate
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