Plasmon excitations in photo- and electron impact ionization of fullerenes

Abstract

We study collective electron excitations (also referred to as plasmons) in the C60 fullerene in the processes of photoionization and electron inelastic scattering. To reveal the contribution of collective electron excitations, we utilize the plasmon resonance approximation. It is shown that within this framework the photoionization cross section is described as a sum of two contributions, which represent two coupled modes of the surface plasmon. The electron energy loss spectra of C60 are described by three contributions, namely by the two modes of the surface plasmon and the volume plasmon. The results of calculations are in good agreement with experimental data on photoionization and electron inelastic scattering of C60. We show that the collective excitations play a significant role in the ionization process and provide a dominant contribution to the spectra.