Bresme Fernando, Chacón Enrique, Tarazona Pedro, Tay Kafui
Department of Chemistry, Imperial College London, London, United Kingdom.
Phys Rev Lett. 2008 Aug 1;101(5):056102. doi: 10.1103/PhysRevLett.101.056102.
We investigate the water-oil interface using molecular dynamics simulations of realistic models of alkanes and water. The intrinsic density profiles are computed using a methodology that removes the smoothing effect of the capillary waves. We show that at 300 K the intrinsic width of the gap separating the oil and water phases spans little more than one water molecule diameter, and undergoes very weak short-ranged fluctuations, indicating that the water-oil interface is a rigid molecular structure at ambient temperature. Only near the drying transition (above 500 K for dodecane), the gap features uncoupled fluctuations of the oil and water surfaces, as expected in a typical drying structure. We find that the intrinsic structure of water next to the oil phase is remarkably similar to the bare water-vapor interface.
我们使用烷烃和水的真实模型的分子动力学模拟来研究水-油界面。本征密度分布是使用一种消除毛细波平滑效应的方法计算得出的。我们表明，在300 K时，分隔油相和水相的间隙的本征宽度仅略大于一个水分子直径，并且经历非常微弱的短程波动，这表明水-油界面在环境温度下是一种刚性分子结构。仅在接近干燥转变时（十二烷在500 K以上），该间隙具有油表面和水表面的非耦合波动，这在典型的干燥结构中是预期的。我们发现油相旁边水的本征结构与裸露的水汽界面非常相似。
