论文标题
离子对解离动力学在水性预淘汰层中
Ion Pair Dissociation Dynamics in an Aqueous Premelting Layer
论文作者
论文摘要
使用分子动力学模拟和重要性采样方法，我们研究了在冰及其蒸气之间的界面自发形成的水性预塑料中氯化钠的热力学和动力学。我们揭示了时间尺度的层次结构，这些层次尺度表征了该系统的松弛动力学，跨越了离子运动的皮秒，到与液体晶体界面波动相关的10s-100s纳米秒的10s-100s。我们发现离子会扭曲两个局部接口，从而产生导致离子优先驻留在层中间的离子的恢复力。虽然离子对解离在热力学上是有利的，但这些结构和动态效应导致其速率通过整层的数量级而变化，而最大速率与相应的体积值显着降低。在预言层中离子的溶剂化环境与散装液体中的溶剂化环境不同，该溶剂是由水分子缓慢重组和冰与其熔体之间的水结构所主导的。
Using molecular dynamics simulations and methods of importance sampling, we study the thermodynamics and dynamics of sodium chloride in the aqueous premelting layer formed spontaneously at the interface between ice and its vapor. We uncover a hierarchy of timescales that characterize the relaxation dynamics of this system, spanning the picoseconds of ionic motion to the 10s-100s of nanoseconds associated with fluctuations of the liquid-crystal interface in their presence. We find that ions distort both local interfaces, incurring restoring forces that result in the ions preferentially residing in the middle of the layer. While ion pair dissociation is thermodynamically favorable, these structural and dynamic effects cause its rate to vary by over an order of magnitude through the layer, with a maximum rate significantly depressed from the corresponding bulk value. The solvation environment of ions in the premelting layer is distinct from that in a bulk liquid, being dominated by slow reorganization of water molecules and a water structure intermediate between ice and its melt.
