XPS analysis of iron aluminum oxide systems

XPS spectra of FeO and AlO oxides are reported. The main emphasis is placed on the quantitative analysis of Ar ion reductive effects on FeO surfaces in terms of n/n atomic ratios achieved by use of the "First Principles Model". No Fe metal is found in etched FeO. Quantitative results show that the reduction: FeO -> 2 FeO+ 1 2O occurs in the etching conditions used. Evidence of this reduction is found in the photoelectron spectra of the pure oxide as well as in those of FeO+AlO mixtures. A quantitative approach is proposed to derive Ar-induced modifications at FeO surfaces in the mixtures. This approach permits the derivation of n/n changes on the basis of intensity ratio measurements I/I between the two oxide components in the O 1s band of the mixtures. The correlation of derived n/n atomic ratios is very high in a vast range of composition of the mixtures analyzed either in the as received condition and in the etched condition. A sensitivity factor for the Fe 2p transition is given: S = 2.50 (with respect to S taken as the unity), which applies to the VG Esca 3 MkII apparatus used in this work. Comparison with previous quantitative XPS analysis of FeO and AlO is presented. © 1986.