Formation of copper oxide surface structures via pulse injection of air onto Cu(111) surfaces

We have investigated the Cu(111) surface after controlled injection of air by Auger electron spectroscopy (AES) and scanning tunneling microscopy (STM). During deposition, the temperature of the copper substrate was kept at room or elevated temperature. AES spectra show that mainly oxygen is adsorbed on the copper surface. STM images display the initial stages of oxidation of Cu(111), which are governed by the restructuring of the surface where Cu atoms from the step edges and terraces are incorporated into the growing surface oxide. The nucleation and growth of the oxide are strongly influenced by the substrate temperature during air injection as well as by the oxygen coverage. Depending on the coverage, different kinds of oxide or oxide-precursor islands are observed. The surface oxides produced at higher temperature exhibit ordered structures, which are ascribed to a strained Cu(2)O(111) lattice that coincides with the Cu(111) substrate.