Initial stages of CuAu(111) oxidation

CuAu(111)酸化の初期過程

津田 泰孝*; 牧野 隆正*; 橋之口 道宏*; 岡田 美智雄*; 岡 耕平*; Dio, W. A.*; 笠井 秀明*; 吉越 章隆 ; 寺岡 有殿

Tsuda, Yasutaka*; Makino, Takamasa*; Hashinokuchi, Michihiro*; Okada, Michio*; Oka, Kohei*; Dio, W. A.*; Kasai, Hideaki*; Yoshigoe, Akitaka; Teraoka, Yuden

The Au-4f SR-XPS spectra were measured at 70 with respect to the surface normal for CuAu(111) at O-coverages of 0.0 ML, 0.28 ML, and 0.48 ML. At 0.0 ML, both the Au-4f and Au-4f XPS peaks of CuAu(111) were clearly separated into the bulk and the surface components. With increasing O-coverage, the surface component decreased and disappeared at 0.48 ML. At the same time, the interface component newly developed, which indicates increase of Au atoms situated between the topmost Cu-O layer and the third metallic layer. This suggests Cu segregation to the surface and Au rich layer formation in the interface layer. Moreover, the layer profiles at 0.00 and 0.48 ML were obtained quantitatively by analyzing separated Au-4f peak components measured at 0 and 70. The high concentration of Au atoms in the interface layer impedes the O-atom diffusion into bulk and the Cu-atom diffusion from the bulk.