Quantification of the excitation of Auger spectra by characteristic and by white X-radiation

Abstract

The spectra of X-ray excited electron emission contain photoelectron spectroscopy (XPS) lines and X-ray excited Auger electron spectroscopy (XAES) lines. In general, only the photoelectron spectra are used for a quantitative surface analysis of the specimens. In an earlier paper (H. Ebel, M.F. Ebel and H. Krocza, Surf. Interface Anal., 12 (1988) 137) we have shown that XAES gives complementary information to a quantitative analysis. An essential detail of a successful application of XAES is the quantification of the contribution of white radiation to the excitation of the Auger spectra. Of course, this problem only arises for instruments without a monochromator. The present paper describes an investigation of the spectral responses of X-ray tubes and also includes the influence of the tube window. Further calculations are dedicated to the ratio of Auger electrons excited by white and by characteristic X-radiation. The results provide evidence of the very pronounced influence of the choice of the X-ray tube window — material and thickness — on this ratio. The data resulting from our investigations can be applied to any other X-ray photoelectron spectrometer.