Direct observation of the diffusion layer during copper electrodeposition

Eight snapshots of the computer-processed diffusion layer maps at different times during the copper electrodeposition in 0.2 mol dm−3 CuSO4 solution are exhibited. A full sequence is available in Video 1. The evolution of the diffusion layer during copper electrodeposition is automatically presented by the use of a system integrating optical interferometric technique and image/video processing methods, which may have many potential applications in the control of the chemical engineering processes.Figure optionsDownload as PowerPoint slideHighlights
• The evolution of the diffusion layer during copper electrodeposition is presented.
• The diffusion coefficient of cupric ion in 0.2 M CuSO4 solution is evaluated.
• The method is visualized and has no external effect on chemical reactions.
• The system may have applications in the control of chemical engineering processes.

Electrodeposition of metals is widely used in microsystem technologies as it offers a means for an exact and easy control of the deposition parameters. The observation of the diffusion layer during the electrodeposition is fundamental for the understanding and controlling of the dynamic processes. In this paper, a Mach–Zehnder interferometer is employed to visually present the dynamic behavior of the diffusion layer during the electrodepostion processes of copper. Digital image/video processing methods are used to analyze the interferograms in real time, which allow to obtain the whole processes of the evolution of the diffusion layer at the solid/liquid interface. The experimental results are validated with the theoretical model deduced by Amatore and co-workers (C. Amatore, S. Szunerits, L. Thouin, J. Warkocz, J. Electroanal. Chem. 500 (2001) 62–70). This measurement system combining the interferometric technique and video processing methods provides a powerful way to monitor the diffusion layer during chemical reactions. It has many potential applications in the control of the chemical engineering processes.