High-resolution electron energy loss spectroscopy is used to study the electronic properties of thin Ag layers on Ni (111). In addition to the ordinary surface plasmon at 3.8 eV, we observe a broad feature at 7–8 eV, whose nature is investigated as a function of scattering geometry and primary electron beam energy. Loss measurements unambiguously indicate that this mode has spectral components from both free-electron Ag plasmonic excitations (free-electron surface plasmons and multipole plasmons) and single-particle transitions.
14 Jun 2013
Volume: 25 Issue: 30 Pages: 305001
Journal of Physics: Condensed Matter