Binding state information from XPS depth profiling: capabilities and limits

Depth profiling with X-ray photoelectron spectroscopy (XPS) in combination with ion sputtering is a useful tool especially for the investigation of conductive and semiconductive samples. Considering the in general comfortable possibilities for binding state determination by evaluation of peak shift and peak shape changes in XPS, it is in great request to get such information also from sputter depth profiling. The paper critically discusses for a wide spread of examples the possibilities of such a methodology especially in connection with data analysis procedures like factor analysis, but also the limitations occurring due to bombardment-induced damage. It is concluded that despite of that damage useful binding state information can be derived in many cases, however, the amount of distortion has to be checked critically in every case.