XPS Studies of Anodic Surface Films on Copper Electrodes

X‐ray photoelectron spectroscopy was employed to study surface films generated by anodic electrochemical oxidation of copper in solutions at . A simple and efficient, low‐cost transfer system is described which allows electrochemical manipulation and transfer of specimens into the vacuum analysis chamber under an inert atmosphere. Copper covered with oxygen and oxide species was found to be hydrophilic. Sputter depth profiles revealed the nature and extent of the surface films withdrawn from solution. An adherent liquid electrolyte film of ca. 0.3 μm thickness dried out upon emersion of the electrode and formed an approximately 30Å thick overlayer of , , and on underlying electrochemically formed anodic layers of the order of 40Å. Two oxidation states, and , could be well resolved, each occurring at their respective equilibrium potential.