论文标题
超冷的水限制在金属有机框架中
Supercooled water confined in a metal-organic framework
论文作者
论文摘要
在所谓的“无人土地”之间，大约150至235 K之间，不可避免地会结晶散装水。可以通过将水限制在纳米尺寸的孔中来研究玻璃状冷冻和液体到液的水的液体到液体过渡。在这里，我们报告了使用介电光谱法在金属有机框架孔内水的分子动力学。所检测到的超冷水的温度依赖性动态与散装水相匹配，如无人土地边界外报道。在限制中，形成了不同类型的水，尽管如此，仍然经历了具有相当大的分子合作性的玻璃过渡。水中似乎存在两个不同的长度尺度：一个较小的尺度，是2 nm的顺序，是玻璃冷冻的合作长度尺度，以及一个较大的（> 2 nm），表征了创建“真实”水所需的氢键网络的最小尺寸，其独特的动态特性所需的“真实”水
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
