Interface atom mobility and charge transfer effects on CuO and Cu2O formation on Cu3Pd(111) and Cu3Pt(111).

ABSTRACT

We bombarded [Formula see text] and [Formula see text] with a 2.3 eV hyperthermal oxygen molecular beam (HOMB) source, and characterized the corresponding (oxide) surfaces with synchrotron-radiation X-ray photoemission spectroscopy (SR-XPS). At [Formula see text], CuO forms on both [Formula see text] and [Formula see text]. When we increase the surface temperature to [Formula see text], [Formula see text] also forms on [Formula see text], but not on [Formula see text]. For comparison, [Formula see text] forms even at [Formula see text] on Cu(111). On [Formula see text], [Formula see text] forms only after [Formula see text], and no oxides can be found at [Formula see text]. We ascribe this difference in Cu oxide formation to the mobility of the interfacial species (Cu/Pd/Pt) and charge transfer between the surface Cu oxides and subsurface species (Cu/Pd/Pt).