Ions in water: The microscopic structure of concentrated hydroxide solutions
Ions in water: The microscopic structure of concentrated hydroxide solutions
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DOI：
10.1063/1.1899147
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发表时间：
2005-05-15
影响因子：
4.4
通讯作者：
Soper, AK
中科院分区：
文献类型：
--
作者：
Imberti, S;Botti, A;Soper, AK
通过蒙特卡罗模拟（经验势结构细化）分析氢氧化物水溶液的中子衍射数据，溶质浓度范围为每 12 个水分子 1 个溶质到每 3 个水分子 1 个溶质，以确定较小碱金属离子存在下 OH- 的水合壳层。事实证明，至少在如此高浓度的液相中，H+ 和 OH- 之间的对称性论证不能用于确定氢氧化物水合壳层。 K+ 水合层中的水分子的偶极矩与 K+-水氧导向器成约 45 度，而不是像 Li+ 和 Na+ 水合层那样呈放射状。与其他阳离子-水氧函数相比，K+-水氧径向分布函数显示出较浅的第一最小值。溶质对水-水径向分布函数的影响显示出对水结构的影响相当于水压力的增加，具体取决于离子浓度和离子半径。带电溶质存在下水结构的变化以及不同阳离子的水合壳之间的差异用于对观察到的阳离子迁移率进行定性解释。 (c) 2005 年美国物理研究所。
Neutron-diffraction data on aqueous solutions of hydroxides, at solute concentrations ranging from 1 solute per 12 water molecules to 1 solute per 3 water molecules, are analyzed by means of a Monte Carlo simulation (empirical potential structure refinement), in order to determine the hydration shell of the OH- in the presence of the smaller alkali metal ions. It is demonstrated that the symmetry argument between H+ and OH- cannot be used, at least in the liquid phase at such high concentrations, for determining the hydroxide hydration shell. Water molecules in the hydration shell of K+ orient their dipole moment at about 45 degrees from the K+-water oxygen director, instead of radially as in the case of the Li+ and Na+ hydration shells. The K+-water oxygen radial distribution function shows a shallower first minimum compared to the other cation-water oxygen functions. The influence of the solutes on the water-water radial distribution functions is shown to have an effect on the water structure equivalent to an increase in the pressure of the water, depending on both ion concentration and ionic radius. The changes of the water structure in the presence of charged solutes and the differences among the hydration shells of the different cations are used to present a qualitative explanation of the observed cation mobility. (c) 2005 American Institute of Physics.