Konovalov A. Components of reflection electron energy loss spectra of Al, In and Ge films

The thesis is devoted to the experimental investigation of electron interaction processes of medium energies (100-1000 eV) in the surface region of Al, Іn and Ge film targets by reflection electron energy loss (REEL) spectroscopy. A new approach is proposed for the quantitative study of REEL spectra. It is based on the simultaneous analysis of a set of spectra measured at different geometries of the experiment. Within the approach two methods for determination of REEL spectrum components have been developed, not based on models of electron interactions in a solid. The components have been obtained for Al, Іn and Ge REEL spectra measured at different angles of incidence, exit and scattering of electrons in the primary electron energy range 300-800 eV. Shape analysis of the components in the range of single energy loss has shown that the surface plasmon dispersion is positive for the Іn film and negative for the Al and Ge films. A multipole surface plasmon peak is revealed in the components of REEL spectra of the Al and Ge films. Angular dependences of peak intensities of single and double energy losses, normalized on the peak intensity of elastic reflected electrons, have been determined for different values of primary electrons energy. For Іn and Ge REEL spectra it is found that normalized intensities of the peaks concerned with excitation of volume plasmons essentially depend on an electron scattering angle in a complicated nonmonotonic manner. The selection of the electron scattering angle can fundamentally change the character of dependences of the normalized volume plasmon peak intensities on primary electron energy. For REEL spectra of Al film it was possible to estimate the normalized peak intensity of multipole surface plasmon. This intensity weakly depends on angles of electron incidence and exit and decreases with the increase of primary electron energy.