STM Observations of the Underpotential Deposition and Stripping of Pb on Au(111) under Potential Sweep Conditions

We report the observation of electrochemical deposition and stripping of a monolayer of Pb on the surface of Au(111) using an in situ scanning tunneling microscope. Sequential STM scans taken during slow (1 mV/s) potential sweeps show that the Pb layer forms by initial growth at Au step edges followed by Pb island nucleation on Au terraces. When the potential sweep is reversed to remove the Pb monolayer, the surface is restored to a state similar to the original, but the details of the Au topography are modified.