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arXiv · 2009.07722

Supercooled water confined in a metal-organic framework

Jonas K. H. Fischer·Pit Sippel·Dmytro Denysenko·Peter Lunkenheimer·Dirk Volkmer·Alois Loidl
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Abstract

Within the so-called "no-man's land" between about 150 and 235 K, crystallization of bulk water is inevitable. The glasslike freezing and a liquid-to-liquid transition of water, predicted to occur in this region, can be investigated by confining water in nanometer-sized pores. Here we report the molecular dynamics of water within the pores of a metal-organic framework using dielectric spectroscopy. The detected temperature-dependent dynamics of supercooled water matches that of bulk water as reported outside the borders of the no-man's land. In confinement, a different type of water is formed, nevertheless still undergoing a glass transition with considerable molecular cooperativity. Two different length scales seem to exist in water: A smaller one, of the order of 2 nm, being the cooperativity length scale governing glassy freezing, and a larger one (> 2 nm), characterizing the minimum size of the hydrogen-bonded network needed to create "real" water with its unique dynamic properties

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Jonas K. H. Fischer, Pit Sippel, Dmytro Denysenko, Peter Lunkenheimer, Dirk Volkmer, Alois Loidl. 2020-09-16. Supercooled water confined in a metal-organic framework. https://doi.org/10.1038/s42005-020-0363-x

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