Surface electron energy loss line structure

For analysis, we used inelastic scattering cross sections calculated from REELS data. As already mentioned, this should, in principle, be superior to cross sections calculated from optical data because it also reproduces surface loss features such as surface plasmons. As the fine structure of K ( q, T) depends on the primary energy [108], we chose the energy of the primary electron beam to match the energy range of the Auger lines. In the subsequent analysis the depth profile in a first approximation was assumed to be a flat layer cut off at the characteristic depth of excitation dc... 

Additional structures in PE spectra can result from mul-tiplet splitting (Fig. 10b shows an example), which is discussed in more detail in Section II.H, plasmon losses, and even the X-ray source itself. Plasmon losses, which are of little analytical use, are observed in the PE and Auger spectra of clean metal surfaces, as shown in Fig. 10c for a clean aluminum surface. They result from collective oscillations in the conduction band excited by the outgoing electron which thereby suffers a discrete energy loss. The plasmon frequency and multiples thereof are observed as a characteristic series of peaks on the high binding energy side of the main core line. 

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