Study on growth mechanism of thin films during electrodepostion at two-liquid interface by measuring interfacial tension

到目前为止，这项研究的首席投资人和同事们观察到了两种不相容液体之间的界面处薄膜的二维生长。他们将界面应用于电化学制备薄膜。然而，目前还没有弄清楚为什么薄膜优先在界面方向生长。我们试图阐明两种不相容液体界面处薄膜的生长机理。在这项研究中，我们重点研究了电沉积薄膜过程中界面张力的变化。首先，我们用Whilhelmy方法测量了电沉积锌膜过程中醋酸丁酯与硫酸锌界面的界面张力。结果表明，薄膜生长前沿附近的界面张力降低，表明这种降低可以引起界面上的Marangoni对流，从而使锌离子迅速向生长前沿迁移。为了确定电沉积过程中界面处Marangoni对流的演化，我们应用纹影法和Mach-Zehnder干涉法观察了薄膜电沉积过程中界面附近液体的运动。结果，我们看到了薄膜生长前沿附近的电解液漩涡。我们认为这个涡旋是由Marangoni对流引起的。最后，我们尝试应用涟漪光散射技术来测量两种不相容液体之间的界面张力。我们制作了一套测量系统，并成功地测量了水和乙醇的表面张力。然而，我们不能得到足够强的涟漪强度来估计液体之间的界面张力。因此，我们需要对系统进行改进，以获得良好的涟漪信号。

So far the head investor of this study and coworkers observed two dimensional growth of a thin film at the interface between two immiscible liquids. They applied the interface to prepare thin films electrochemically. However, it has not yet clarified why the films grow preferentially in the interfacial direction. We tried to elucidate growth mechanism of the films at the interface between two immiscible liquids. In this study we focused on the change in interfacial tension during electrodeposition of thin films. First, we applied Whilhelmy method to measure the interfacial tension during electrodeposition of zinc films at the interface between n-butyl acetate and ZnSO_4. As a result, we confirmed that the interfacial tension decreased around the growth front of the film, suggesting that this decrease can induce Marangoni convection along the interface, which can generate rapid transportation of Zn^<2+> to a growth front of the film. In order to confirm evolution of Marangoni convection at the interface during electrodeposition, we applied Schlieren method and Mach-Zehnder interferometry to observe the motion of liquids around the interface during the electrodeposition of a thin film. As a result, we visualized vortex of the electrolyte in the vicinity of growth front of the film. We believe that this vortex is caused by Marangoni convection. Finally, we tried to apply ripplon light scattering technique to measure interfacial tension between two immiscible liquids. We made a system for the measurement, and succeeded in measure surface tensions of water and ethyl alcohol. However, we could not get strong intensity of ripplon enough to estimate interfacial tension between the liquids. Therefore, we need to improve the system to get good signals by ripplon.