A COMPARATIVE REFLECTION ELECTRON-ENERGY LOSS STUDY OF C-60 AND GRAPHITE

Electronic excitations of solid C60 have been studied using the reflection EELS technique with a 0.2 eV energy resolution. A comparison with graphite revealed an overall similarity of the spectral gross features, while significant differences were observed in the fine details, mainly at low loss energies. A similar dominant plasmon was observed in C60 at a slightly shifted energy of 23.2 eV. For C60, in contrast to graphite, a clear energy loss onset was found at 1.7 eV and up to 6 eV six loss peaks were clearly observed. It was found that minima in the loss spectrum fit well with reported optical transitions. This observation supports an interpretation which attributes a significant collective character to the loss peaks.