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

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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.