Characterization of iron/oxygen surface reactions by X-ray photoelectron spectroscopy

The initial stages of oxidation of clean, high-purity, iron foil have been studied using a Kratos ES 300 electron spectrometer with monochromatic X-radiation. Through careful observation of the Fe 2p peak profile, peak energy maximum, and peak satellite structure, it was possible to identify oxide species containing Fe (II) and Fe (III). The results indicated that iron was highly mobile in the Fe (II)/Fe (III) lattice at intermediate oxidation levels and that the iron ions in the octahedral sites of Fe 3 O 4 exhibited a rapid symmetric intervalence electron transfer of the type Fe (II) + Fe (III) → Fe (III) + Fe (II).