We report highly efficient generation of propagating
plasmons by
electron beams in planar films, planar dielectric cavities,
metallic wires, and
nanoparticle waveguides. Electron-induced
plasmon excitation is investigated in (1)
gold thin films, both free-standing or supported on a
silica substrate, (2) gold-silica-gold planar cavities, (3)
gold nanowires, and (4)
gold nanoparticle arrays. We obtain excitation yields as high as 10(- 2)
plasmons per incoming
electron over the
visible and near-infrared range. Symmetric and antisymmetric
plasmon modes are found to be more easily excited in thick and thin films, respectively, and in particular leaky
plasmons in supported films are shown to be excited with very large probability exceeding one
plasmon per
electron. Generation of guided
plasmons in
metallic particle arrays is also proved to be attainable by aiming the
electron at one end of the waveguide. The
temporal evolution and spectral distribution of excited
plasmons are discussed as well. Our results provide full support for the application of
electron bombardment to excite propagating
plasmons with high efficiency, thus solving the standing problem of
plasmon generation at designated locations.
