Interface atom mobility and charge transfer effects on CuO and CuO formation on CuPd(111) and CuPt(111)

Tsuda, Yasutaka   ; Gueriba, J. S.*; Makino, Takamasa*; Dio, W. A.*; Yoshigoe, Akitaka ; Okada, Michio*

We bombarded CuPd(111) and CuPt(111) 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 300 K, CuO forms on both CuPd(111) and CuPt(111). When we increase the surface temperature to 500 K, CuO also forms on CuPd(111), but not on CuPt(111). For comparison, CuO forms even at 300 K on Cu(111). On CuAu(111), CuO forms only after 500 K, and no oxides can be found at 300 K. 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).