In situ video-STM studies of dynamic processes at electrochemical interfaces

Atomic-scale dynamic processes during Cu(100) dissolution/deposition in pure and Cu-containing 0.01 M HCl solution were studied in situ by high-speed electrochemical STM (video-STM). Direct observations of the equilibrium fluctuations at atomic kinks in the steps on the crystal surface due to the local removal/addition of atoms reveal the same anisotropic behavior found previously in Cu-free electrolytes, caused by the influence of the ordered (2 x 2) Cl adlayer on the kink structure. A first quantitative analysis of these fluctuations and interpretation in terms of a local current exchange density was attempted. In addition, observations on the nucleation of vacancy- or ad-rows at terrace corners and within the Cu steps are presented and the relevance of these processes for the macroscopic current density is discussed.