X-ray Scattering from Ag (001) and Ag (111) Surfaces in Electrochemical Environments: Dynamics and Structure*

We have investigated the Ag (001) and Ag (111) single crystal surfaces in weak electrolyte using a combination of x-ray Crystal Truncation Rod (CTR) experiments to determine structural information and X-ray Photon Correlation Spectroscopy (XPCS) to examine the nano-scale dynamics. Our structural measurements confirm earlier potential dependent measurements of H$_2$O over the Ag (111) surface [1], and also show that the Ag (001) H$_2$O interface behaves in an analogous fashion. The XPCS dynamics data reveal how the surface evolves, in real-time, relative to the point of zero charge. Both the CTR and XPCS data were collected at different applied potentials. By comparing the CTR data with the XPCS data, along with ex-situ Atomic Force Microscopy (AFM), we will investigate relationships between the dynamics of the Ag surface and the distribution of H$_2$O molecules above the crystal surface. [1] M. F. Toney et al. Nature 368, 444 (1994).