Time-dependent diffraction studies of Au(100) electrode surface during deposition

Detailed X-ray diffraction studies that allow us to monitor the solid-liquid interface structure during electrodeposition with high time resolution are demonstrated using as an example the homoepitaxial growth on Au(100) electrodes in HCl solution at a deposition rate of similar to 4.2 ML/min. By measuring X-ray intensity curves I(t) after a potential step at different diffraction index L, time-dependent crystal truncation rods (CTR) can be obtained. In the potential regime of the unreconstructed Au(100) surface (0.35 V), the initial stages are well described by nucleation and growth of Au monolayer islands. For deposition onto the reconstructed surface at -0.2 V, CTRs and complementary grazing incidence diffraction studies reveal rapid formation of the hex reconstruction within the first 4 s after the potential step, followed by layer-by-layer growth.