Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan.
Phys Chem Chem Phys. 2014 Feb 28;16(8):3815-22. doi: 10.1039/c3cp54709d.
We report results of our experimental and theoretical studies on the Au concentration profile of Cu3Au(111) during oxidation by a hyperthermal O2 molecular beam at room temperature, using X-ray photoemission spectroscopy (XPS), in conjunction with synchrotron radiation (SR), and density functional theory (DFT). Before O2 exposure, we observe strong Au segregation to the top layer, i.e., Au surface enrichment of the clean surface. We also observe a gradual Cu surface enrichment, and Au enrichment of the second and third (subsurface) layers, with increasing O coverage. Complete Cu segregation to the surface occurs at 0.5 ML O surface coverage. The Au-rich second and third layers of the oxidized surface demonstrate the protective layer formation against oxidation deeper into the bulk.
我们报告了在室温下使用同步辐射（SR）和密度泛函理论（DFT）的超热 O2 分子束氧化时，对 Cu3Au(111) 中 Au 浓度分布的实验和理论研究结果。在 O2 暴露之前，我们观察到强烈的 Au 向表层的偏析，即清洁表面的 Au 表面富集。我们还观察到随着 O 覆盖度的增加，Cu 逐渐向表面富集，Au 向第二和第三（次表面）层富集。在 0.5 ML O 表面覆盖度时，Cu 完全向表面偏析。富 Au 的氧化表面的第二和第三层形成了对更深层氧化的保护层。
