Non-destructive depth profiling of oxidized surface of stainless steels by synchrotron radiation excited X-ray photoelectron spectroscopy

Yamamoto, Hiroyuki; Esaka, Fumitaka  ; Sasase, Masato*

Initial surface oxidation of stainless steels was investigated by energy-tunable synchrotron radiation excited X-ray photoelectron spectroscopy (SR-XPS). Depth profiling with a few nm range using excitation energies between 1800 and 3700 eV was performed for the steels before and after oxidation at 373, 473, 673, 873 and 1073 K. The result for the steel oxidized at 473 K indicated that the formation of Fe oxides on the surface is dominant in the initial stage of oxidation. By further oxidation above 873 K, significant increases in the ratios of Cr oxides to Fe oxides were observed, suggesting the formation of Cr oxide layers more than a few nm on the steels. These results imply that SR-XPS is a powerful tool for non-destructive depth profiling with nm depth.