Quantitative X-Ray Photoelectron Spectroscopy Characterization of Magnesium Oxidized in Air

The ratio of the photoionization cross section of the transition to that of the O 1s electrons is determined as 2.16 ± 0.02 for the Al Kα X‐ray excitation. Application of this value is limited to oxidic Mg. Based on the above ratio, the photoionization cross section ratio of the Mg 2p electrons to the O 1s electrons, σ(Mg 2p)/σ(O1s) was determined to be 0.147 ± 0.005, which can be used for quantitative X‐ray photoelectron spectroscopy analysis of both oxidic and metallic states of Mg. Using the σ(Mg 2p)/σ(O 1s) thus determined, the surface compositions and film thicknesses were quantitatively determined of ( i ) a pure magnesium specimen immediately after scratching in laboratory air at room temperature, ( ii ) a specimen scratched and then aged in air for a month, and ( iii ) a specimen immediately after scratching in cyclohexane. A clear correlation between the composition and the thickness of surface film is observed, i.e. , thickness where [E] denotes molar composition of E.