Inelastic interactions between an electron and a clad cylindrical system were investigated using the dielectric response theory. By solving the Poisson equation and applying the boundary conditions, these interactions were formulated in terms of the surface, interface and volume excitations. Formulas of the differential inverse inelastic mean free path ͑DIIMFP͒ were derived for electrons moving parallel to the axis of such a cylindrical structure. A sum-rule-constrained extended Drude dielectric function with spatial dispersion was applied to the calculations of the DIIMFP for a Si cylindrical tube or a Si cylinder clad in a SiO 2 film. For the Si tube, it was found that surface excitations occurred as electrons moved near either the inner or outer surface of the tube and either inside or outside Si. Whereas, volume excitations arose only for electrons moving inside Si. Surface excitations increased, or volume excitations decreased, as electrons moved closer to the surface. For the Si cylinder clad in the SiO 2 film, inelastic interactions were contributed from volume, surface, and interface excitations. Calculated results showed that the relative importance of these excitations depended on the electron distance from the surface or interface of the cylindrical system, the radius of the Si cylinder, and the thickness of the SiO 2 film.

A reverse Monte Carlo method for deriving optical constants of solids from reflection electron energy-loss spectroscopy spectra When a charged particle moves parallel and close to a solid surface, it suffers an energy loss arising from the induced potentials caused by the interactions between the charged particle and the surface. For the fast moving charged particle, the induced potentials could be affected by the electromagnetic retardation effect. In the present work, the retardation effect on the induced potentials was studied using a dielectric function with spatial dispersion for an electron of high energy moving parallel to the solid surface. Appropriate boundary conditions and the Lorentz gauge were employed to calculate the induced potentials by solving Maxwell equations in the Fourier space using the dielectric response theory. Analytical formulas of the differential inverse inelastic mean free path ͑DIIMFP͒, inelastic mean free path ͑IMFP͒, and stopping power ͑SP͒ were derived by considering the retardation effect using relativistic energy and momentum conservation relations and applying the extended Drude dielectric function with spatial dispersion. The DIIMFP, IMFP, and SP were calculated for electron moving parallel to the Cu surface with different electron energies. Results calculated with the retardation effect were compared to corresponding data without the retardation effect.