TY - JOUR

T1 - Dynamical properties of confined supercooled water

T2 - An NMR study

AU - Mallamace, Francesco

AU - Broccio, Matteo

AU - Corsaro, Carmelo

AU - Faraone, Antonio

AU - Liu, Li

AU - Mou, Chung Yuan

AU - Chen, Sow Hsin

PY - 2006/9/13

Y1 - 2006/9/13

N2 - We report a set of dynamical data of confined water measured in a very deeply supercooled regime (290-190K). Water is contained in silica matrices (MCM-41-S) which consist of 1D cylindrical pores with diameters d ≤ 14,18 and 24. When confined in these tubular pores, water does not crystallize, and can be supercooled well below 200K. We use the NMR technique to obtain the characteristic proton relaxation time-constants (the spin-lattice relaxation time-constant T1 and the spin-spin relaxation time-constant T2) and a direct measurement of the self-diffusion coefficient in the whole temperature range. We give evidence of the existence of a fragile-to-strong dynamic crossover (FSC) at TL ≤ 225K from the temperature dependence of the self-diffusion coefficient. A combination of the NMR self-diffusion coefficient with the average translational relaxation time, as measured by quasi-elastic neutron scattering, shows a well defined decoupling of transport coefficients, i.e. the breakdown of the Stokes-Einstein relation, on approaching the crossover temperature TL.

AB - We report a set of dynamical data of confined water measured in a very deeply supercooled regime (290-190K). Water is contained in silica matrices (MCM-41-S) which consist of 1D cylindrical pores with diameters d ≤ 14,18 and 24. When confined in these tubular pores, water does not crystallize, and can be supercooled well below 200K. We use the NMR technique to obtain the characteristic proton relaxation time-constants (the spin-lattice relaxation time-constant T1 and the spin-spin relaxation time-constant T2) and a direct measurement of the self-diffusion coefficient in the whole temperature range. We give evidence of the existence of a fragile-to-strong dynamic crossover (FSC) at TL ≤ 225K from the temperature dependence of the self-diffusion coefficient. A combination of the NMR self-diffusion coefficient with the average translational relaxation time, as measured by quasi-elastic neutron scattering, shows a well defined decoupling of transport coefficients, i.e. the breakdown of the Stokes-Einstein relation, on approaching the crossover temperature TL.

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U2 - 10.1088/0953-8984/18/36/S04

DO - 10.1088/0953-8984/18/36/S04

M3 - Article

AN - SCOPUS:33748892679

SN - 0953-8984

VL - 18

SP - S2285-S2297

JO - Journal of Physics Condensed Matter

JF - Journal of Physics Condensed Matter

IS - 36

M1 - S04

ER -