Dielectric function of Cu, Ag, and Au obtained from reflection electron energy loss spectra, optical measurements, and density functional theory

Pairs of reflection electron energy loss spectra recorded at different incident energies are decomposed to give the energy loss distribution in individual inelastic collisions at the surface and in the bulk of the solid. The resulting single scattering loss distributions are fitted to a Drude-Lindhard model for the dielectric function in the spectral range between the near visible and soft x-ray regions. Good agreement is found between the retrieved optical constants, density functional theory calculations, and optical measurements, rendering this type of analysis promising for the investigation of surface plasmons and determination of optical constants of individual nanostructures.