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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >ESR evidence for 2 coexisting liquid phases in deeply supercooled bulk water
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ESR evidence for 2 coexisting liquid phases in deeply supercooled bulk water

机译：ESR证据表明深度过冷的散装水中有两种液相共存

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Using electron spin resonance spectroscopy (ESR), we measure the rotational mobility of probe molecules highly diluted in deeply supercooled bulk water and negligibly constrained by the possible ice fraction. The mobility increases above the putative glass transition temperature of water, T_g = 136 K, and smoothly connects to the thermodynamically stable region by traversing the so called "no man's land" (the range 150-235 K), where it is believed that the homogeneous nucleation of ice suppresses the liquid water. Two coexisting fractions of the probe molecules are evidenced. The 2 fractions exhibit different mobility and fragility; the slower one is thermally activated (low fragility) and is larger at low temperatures below a fragile-to-strong dynamic cross-over at ≈225 K. The reori-entation of the probe molecules decouples from the viscosity below ≈225 K. The translational diffusion of water exhibits a corresponding decoupling at the same temperature [Chen S-H, et al. (2006) The violation of the Stokes-Einstein relation in supercooled water. Proc Natl Acad Sci USA 103:12974-12978]. The present findings are consistent with key issues concerning both the statics and the dynamics of supercooled water, namely the large structural fluctuations IPoole PH, Sciortino F, Essmann U, Stanley HE (1992) Phase behavior of metastable water. Nature 360:324-328] and the fragile-to-strong dynamic cross-over at ≈228 K [Ito K, Moynihan CT, Angell CA (1999) Thermodynamic determination of fragility in liquids and a fragile-to-strong liquid transition in water. Nature 398:492-494].
机译：使用电子自旋共振光谱（ESR），我们测量了在深度过冷的散装水中高度稀释且受可能的冰分数限制很小的探针分子的旋转迁移率。迁移率增加到假定的水玻璃化转变温度T_g = 136 K以上，并通过穿越所谓的“无人区”（范围150-235 K）而平滑地连接到热力学稳定区域，据信冰的均匀成核作用抑制了液态水。证明了探针分子的两个共存部分。这两个部分显示出不同的迁移率和脆弱性；较慢的一个被热激活（低脆性），并且在低温下更大，在≈225K以下时从脆弱到强烈的动态变化较大。探针分子的重新定向与≈225K以下的粘度解耦。水的平移扩散在相同温度下表现出相应的解耦作用[Chen SH，et al。 （2006）在过冷水中违反Stokes-Einstein关系的行为。美国国家科学院院刊103：12974-12978]。目前的发现与有关过冷水的静态和动力学的关键问题是一致的，即大的结构波动IPoole PH，Sciortino F，Essmann U，Stanley HE（1992）亚稳态水的相态。 Nature 360​​：324-328]和≈228K时易碎到强的动态交换[Ito K，Moynihan CT，Angell CA（1999）热力学确定液体中的易碎性和易碎到强的液体转变。水。自然398：492-494]。

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