Photon emission from silver particles induced by a high-energy electron beam - art. no. 205419

Photon emission spectra from submicron silver particles induced by an elect ron beam have been measured using a light detection system combined with a 200-kV transmission electron microscope. Multiple peaks appear in the spect ra associated with collective plasmon excitations produced in the particles by the incident electrons. The wavelengths of these peaks are observed to shift towards larger values with increasing particle diameter, as predicted by Mie theory. Moreover, photon maps have been obtained in a scanning mode and they indicate that those peaks correspond to the multipole modes of el ectromagnetic oscillations in metallic spheres (Mie resonances). The spectr al shape of the emission and the dependence on particle size, impact parame ter, and electron energy are well explained from theoretical calculations o f the photon emission probability derived from a fully retarded analytical treatment of the interaction of fast electrons with metallic spheres.