Observations of the Cu(1 × 1) adlayer on Au(111) in a sulfuric acid solution using atomic force microscopy

Atomic structures of an underpotentially deposited Cu adlayer on a Au(111) surface have been investigated using in situ atomic force microscopy. A Cu(1× 1) structure adlayer is atomically resolved just before starting the bulk deposition. We demonstrated that the first full Cu monolayer on Au(111) is a pseudomorphic (1× 1) layer in an aqueous sulfuric acid solution. We have confirmed that a Cu(5 × 5) phase adlayer has been induced by Cl −1 in the solution.