XPS study of oxides formed on the surface of high-purity iron exposed to air

Angle-resolved XPS and micro-XPS have been used for characterizing reaction products consisting of oxide and oxyhydroxide formed on the surface of high-purity iron exposed to air at room temperature for a long time. Angle-resolved measurements of O 1s XPS spectra have shown that an oxyhydroxide layer covers a native oxide layer in the nanometric thickness range formed on the iron surface. Moreover, imaging by micro-XPS has indicated that fine reaction products, which are oxyhydroxides, are heterogeneously formed on the iron surface by exposure to air for a long time. Based on these results, it is considered that initial oxidation occurs on the iron surface uniformly, and the fine reaction products nucleate at some areas and grow during further air exposure. Copyright © 2000 John Wiley & Sons, Ltd.