A LEED and RHEED Investigation of Cu on Au(111) in the Underpotential Region

The structure of Cu adsorbates, deposited electrochemically up to one monolayer onto Au(111) at underpotentials, has been investigated using LEED and RHEED after transfer of the gold electrode from the electrochemical cell into an UHV chamber. Before electrochemical deposition, the gold surface was thoroughly cleaned in the UHV‐chamber by argon bombardment and subsequent annealing. The Cu adsorbate is then found to yield a (√3 × √3)R30° superstructure at medium coverages, which is in clear contrast to the growth behaviour for Cu evaporated in UHV onto a bare Au(111) surface, where pseudo‐morphic growth is observed from the very beginning.