Recently a fingering morphology, resembling the hydrodynamic Saffman-Taylor instability, was identified in the quasi-two-dimensional electrodeposition of copper by M. Lòpez-Salvans et al. [Phys. Rev. Lett. 76, 4062 (1996)]. This thesis tries to elucidate the underlying mechanism by measuring the dispersion relation of the growing front.
The instability is accompanied by gravity-driven convection rolls at the electrodes, which are examined using particle image velocimetry. While at the anode the theory presented by Chazalviel et al. [J. Electroanal. Chem. 407, 61 (1996)] describes the convection roll, the flow field at the cathode is more complicated because of the growing deposit. In particular, the analysis of the orientation of the velocity vectors reveals some lag of the development of the convection roll compared to the finger envelope.
In thin-layer electrodeposition the dissipated electrical energy leads to a substantial heating of the ion solution. Measurements of the resulting temperature field by means of an infrared camera indicate, that its properties correspond closely with the development of the concentration field. In particular, we find that the thermal gradients at the electrodes act similar to a weak additional driving force to the convection rolls driven by concentration gradients.