Comparison of Energy-Loss Functions from Reflection Electron Energy-Loss Spectroscopy Spectra with Surface and Bulk Energy-Loss Functions: in Case of Cu

Abstract

Effective energy-loss functions (EELFs) are derived from experimental reflected electron energy-loss spectroscopy (REELS) spectra measured at different primary energies for copper using an extended Landau approach. The peak profiles of EELFs are between those of the surface and bulk energy-loss functions. Fine structures overlapping on an elastic peak and corresponding to interband transitions are obtained. It is found that the plasmon peak at 7–9 eV shifts to a higher energy with an increase in primary energy; this is because peak consists of the surface and bulk plasmon excitations at ∼7 eV and ∼8.3 eV, which overlap each other to be observed as a single peak. The double peak structure at 15–30 eV results from the synergistic action of collective oscillations including the participation of d-band electrons and high-energy band–band transitions. The excitation and ionization of 3p inner-shell electrons form two other humps at ∼57 eV and ∼77 eV. A Monte Carlo simulation using EELFs has been applied to reproduce the experimental REELSs with considerable success.