FACTOR-ANALYSIS OF FEM2,3VV SPECTRA OF OXIDIZING IRON - THE ROLE OF THE BACKGROUND IN THE EMERGENCE OF GHOST COMPONENTS

The influence of the (correction for the) background in AES spectra on the results of factor analysis (FA) was investigated. To this purpose a set of experimental spectra for the Fe M2,3 VV transition, obtained on the oxidation of pure iron, and sets of look-alike simulated spect ra, using a linear combination of two elastic components superimposed on background components, were analysed with FA after different types of treatment of the spectra prior to FA, e.g. differentiation or remov al of a particular type of background. In the sets of simulated spectr a the roles of a background due to the secondary electron cascade and that due to the inelastically scattered electrons were investigated se parately. It was observed that for both types of backgrounds additiona l principal components with respect to the two elastic components aris e, irrespective of the considered treatment of the spectra prior to FA . Results obtained for the experimental set and for the simulated sets with a background originating from the secondary electron cascade wer e very similar. In the simulated spectra, the origin of the additional components could be identified unambiguously as (an inadequate correc tion for) the background due to the secondary electron cascade. It is likely that the same origin applies to the additional (third) componen t emerging on FA of the set of experimental Fe M2,3VV spectra.