Plasmon excitations in electron emission processes. Comparison between XPS and AES

The excitation of bulk and surface plasmons in the presence of a solid surface during the emission of electrons in X-ray photoemission spectroscopy (XPS) and in Auger electron spectroscopy (AES) is investigated. The modifications in the energy loss spectra as well as in the plasmon excitations due to the sudden creation of electron–hole pairs, electron transport phenomena and the presence of residual holes and furthermore the proximity of the surface are analysed. The results illustrate that, from a theoretical point of view, separation of extrinsic and intrinsic contributions could be ambiguous (in terms of independent processes) due to interference effects between the photoelectron and photohole present in both processes. A comparison of the results of our model with experimental spectra showed a good agreement.