THE EFFECTS OF PHOTOELECTRON DIFFRACTION ON QUANTITATIVE X-RAY PHOTOELECTRON-SPECTROSCOPY

Although not discussed in most reviews of quantitative x-ray photoelectron spectroscopy (XPS), diffraction of the photoelectrons leaving a single crystal can lead to potential errors of a factor of two or more in the calculated surface composition. A series of experimental measurements has been made to demonstrate the magnitude of the diffraction effects. These results are used as the basis for a discussion of the influence of crystalline effects on quantitative XPS. If the full solid angle of modern electron spectrometers is used, the potential errors are relatively small and can be minimized by adopting suitable procedures. If the acceptance angle of the analyser is restricted for angular-resolved or for small-area measurements, the potential errors are substantial and great care is required to avoid them.