  We studied dynamics of Au (001) surface in situ in 0.1 M HClO4 electrolyte
solution using both coherent x-ray scattering and scanning tunneling microscopy
(STM). The surface of Au (001) is known to reconstruct at cathodic potentials;
the reconstruction lifts at anodic potentials. In our in-situ STM experiments,
the measurements focus on time-dependent progressions of surface morphology
during slow potential sweep. In our in-situ coherent x-ray scattering
measurements, we demonstrate that the equilibrium surface dynamics are directly
measurable and the measured dynamics are consistent with morphological
evolution of the STM images. These experiments represent the first successful
application of coherent x-ray scattering to the study of electrochemical
interfaces in situ.
