The fragile-to-strong dynamic crossover transition in confined water: nuclear magnetic resonance results.
By means of a nuclear magnetic resonance experiment, we give evidence of the existence of a fragile-to-strong dynamic crossover transition (FST) in confined water at a temperature T(L)=223+/-2 K. We have studied the dynamics of water contained in 1D cylindrical nanoporous matrices (MCM-41-S) in the temperature range 190-280 K, where experiments on bulk water were so far hampered by crystallization. The FST is clearly inferred from the T dependence of the inverse of the self-diffusion coefficient of water (1D) as a crossover point from a non-Arrhenius to an Arrhenius behavior. The combination of the measured self-diffusion coefficient D and the average translational relaxation time tau(T), as measured by neutron scattering, shows the predicted breakdown of Stokes-Einstein relation in deeply supercooled water.
Mallamace
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Dipartimento di Fisica and CNISM, Universita' di Messina, Vill. S. Agata CP 55, 98166 Messina, Italy. francesco.mallamace@unime.it
Broccio
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Corsaro
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Faraone
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Wanderlingh
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Liu
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Mou
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Chen
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