A nomalous lon transport on liquid/liquid Interface

两种互不相容的液体之间的界面是一个非常奇特的反应场。当水相中含有金属离子时，通常可以在位于界面上的阴极周围观察到二维金属沉积。研究了镀层形状与外加过电位的关系。过电势越低，界面形成二维盘，而过电势越高，界面上就形成了分形图。当电极电势接近平衡电势时，电化学反应的速度由电子转移决定。然而，势能向远离平衡点的区域移动，速度受传质的限制。每次碰撞都会在电极反应前沿的顶部形成一个还原的金属原子。在这种情况下形成了分形体，这表明离子在界面上的运动速度远远快于体相中法向表面的运动速度。这种反常现象的解释是，分子在界面上的取向与本体中的取向有很大不同。界面处空间电荷区分子的取向受静电场的控制。由于溶剂分子的单轴取向，界面的折射率是各向异性的。然后，激光的偏振方向作为界面之间施加的电势的函数而旋转。

The interface between two mutually immiscible liquids is a very exotic reaction field. When an aqueous phase contains a metallic ion, the two dimensional metal deposition is commonly observed around the cathode whose top is located on the interface. The relationship between the shape of the deposit and the applied over potential was investigated. The lower over potential forms two dimensional disk but the higher over potential made a fractal pattern on the interface. When the electrode potential locates close to the equilibrium potential, the rate of the electrochemical reaction is governed by the electron transfer. However, the potential moves towards the region far from the equilibrium, the rate is restricted by the mass transfer. Every collision made a reduced metal atom on the top of the reaction front of the electrode. The fractal shape is formed on this occasion, which suggests that the speed of the ion movement on the interface is much faster than the one of the normal direction toward the surface in the bulk. This anomaly has been explained by the fact that the orientation of the molecule at the interface is much different from the ones in the bulk. The orientation of the molecules in the space charge region at the interface is controlled by the electrostatic field. The refractive index of the interface is anisotropic due to the uniaxial orientation of the solvent molecules. Then the polarization direction of the laser light is rotated as a function of the applied potential between the interface.