Oxidation‐induced nanostructures on Cu{100}, Cu(Ag) and Ag/Cu{100} studied by photoelectron spectroscopy

Initial surface oxidation and nanoscale morphology on Cu{100}, Cu(Ag) and Ag/Cu{100} have been investigated in situ by X‐ray photoelectron spectroscopy (XPS), X‐ray induced Auger electron spectroscopy (XAES) and the inelastic electron background analysis as a function of oxygen exposure at 3.7 × 10 −2 and 213 mbar pressures at a surface temperature of 373 K. Relative Cu 2 O concentrations have been quantified by analysis of the peak shape of the XAES Cu LMM transition. The surface morphology of Cu 2 O islands and the Ag layer has been characterized by inelastic electron background analysis of XAES O KLL and Ag 3d transitions. Oxygen‐induced segregation of Cu, as well as the subsequent Cu 2 O island formation on Cu(Ag) and Ag/Cu{100} surfaces, has been investigated quantitatively. Our results indicate that Ag has a clear inhibitive effect on the initial oxidation and Cu 2 O island formation on Cu(Ag) and Ag/Cu{100} surfaces. The Cu 2 O islands are also observed to remain highly strained on Ag/Cu{100} even at higher O 2 exposures. The results suggest that strained Cu 2 O islands eventually penetrate through the buried Ag layer, and in conjunction with segregating Cu atoms enable the oxidation to proceed at a similar rate to or even faster than on the unalloyed Cu surface. Copyright © 2007 John Wiley & Sons, Ltd.