Collective excitations in the electron energy loss spectra of C 60

The results of a joint experimental and theoretical investigation of the collective excitations in the energy loss spectra of the C-60 fullerene are presented. A variation of the shape of the electron energy loss spectrum has been observed experimentally as the scattering angle increases. This variation is described within the frame of a new theoretical model which treats the fullerene as a spherical shell of a finite width and accounts for the two modes of the surface plasmon and for the volume plasmon as well. It is shown that at small angles the inelastic scattering cross section is determined mostly by the excitation of the symmetric mode of the surface plasmon, while at larger angles the excitation of the antisymmetric surface and volume plasmons becomes prominent.