Maxima in the thermodynamic response and correlation functions of deeply supercooled water
Maxima in the thermodynamic response and correlation functions of deeply supercooled water
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DOI：
10.1126/science.aap8269
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发表时间：
2017-12-22
期刊：
影响因子：
56.9
通讯作者：
Nilsson, Anders
中科院分区：
文献类型：
--
作者：
Kim, Kyung Hwan;Spah, Alexander;Nilsson, Anders
飞秒 X 射线激光脉冲用于探测在真空中冷却至 227 开尔文的微米大小的水滴。从低动量传递区域的 X 射线散射中提取等温压缩性和相关长度。这些热力学响应和相关函数的温度依赖性显示水的最大值为 229 开尔文，重水的最大值为 233 开尔文。此外，我们观察到液体在相似的温度下四面体结构的生长最快。这些观察结果表明维多姆线的存在，该线被定义为从深度过冷状态中正压力的临界点发出的最大相关长度的轨迹。两种同位素之间等温压缩系数最大值的差异表明了核量子效应的重要性。
Femtosecond x-ray laser pulses were used to probe micrometer-sized water droplets that were cooled down to 227 kelvin in vacuum. Isothermal compressibility and correlation length were extracted from x-ray scattering at the low-momentum transfer region. The temperature dependence of these thermodynamic response and correlation functions shows maxima at 229 kelvin for water and 233 kelvin for heavy water. In addition, we observed that the liquids undergo the fastest growth of tetrahedral structures at similar temperatures. These observations point to the existence of a Widom line, defined as the locus of maximum correlation length emanating from a critical point at positive pressures in the deeply supercooled regime. The difference in the maximum value of the isothermal compressibility between the two isotopes shows the importance of nuclear quantum effects.