Analysis of Optical- and Inelastic-Electron-Scattering Data Parametric Calculations*†

With the use of a simple model for the complex frequency-dependent dielectric constant ∊(ω), the electron energy-loss function −Im[1/∊(ω)] was calculated with the model parameters being varied systematically in a physically reasonable range. The intensity as well as the position of structure in −Im[1/∊(ω)] are strongly influenced by the admixture of free-electron- and interband-transition contributions to ∊(ω). Where such admixture effects occur in real materials, it is not meaningful to attribute structure in −Im[1/∊(ω)] exclusively to plasmon excitation or to interband transitions.