Nagasaka Masanari, Yuzawa Hayato, Kosugi Nobuhiro
Institute for Molecular Science , Myodaiji, Okazaki 444-8585, Japan.
SOKENDAI (Graduate University for Advanced Studies) , Myodaiji, Okazaki 444-8585, Japan.
J Phys Chem B. 2017 Dec 7;121(48):10957-10964. doi: 10.1021/acs.jpcb.7b09789. Epub 2017 Nov 20.
Interaction between water molecules and alkali metal ions in aqueous salt solutions has been studied by the oxygen K-edge soft X-ray absorption spectroscopy (XAS) in transmission mode. In the measurement of several alkali halide aqueous solutions with different alkali chlorides (Li, Na, and K) and different sodium halides (Cl, Br, and I), the pre-edge component arising from the hydration water molecules shows a blue shift in peak energy as strongly depending on cations but not on anions. In the temperature dependent measurement, the pre-edge component arising from water molecules beyond the first hydration shell shows the same behavior as that of pure liquid water. On the other hand, the pre-edge component arising from water molecules in the first hydration shell of Li ions is not evidently dependent on the temperature, indicating that the hydration water molecules are more strongly bound with Li ions than the other water molecules. These experimental results are supported by the results of radial distribution functions of the first hydration shell and their temperature dependence, evaluated by molecular dynamics simulations.
通过透射模式下的氧 K 边软 X 射线吸收光谱（XAS）研究了盐水溶液中水分子与碱金属离子之间的相互作用。在测量几种含有不同碱金属氯化物（Li、Na 和 K）以及不同卤化钠（Cl、Br 和 I）的碱金属卤化物水溶液时，由水化水分子产生的前缘成分在峰值能量上表现出蓝移，强烈依赖于阳离子而非阴离子。在温度依赖性测量中，来自第一水化层之外水分子的前缘成分表现出与纯液态水相同的行为。另一方面，锂离子第一水化层中水分子产生的前缘成分明显不依赖于温度，这表明水化水分子与锂离子的结合比其他水分子更强。这些实验结果得到了通过分子动力学模拟评估的第一水化层径向分布函数及其温度依赖性结果的支持。
