Electronic excitation of C 70 in the gas phase by electron energy loss spectroscopy

Abstract

Electron energy loss spectroscopy of the C 70 molecule in the gas phase, with angular analysis, has been investigated in the intermediate energy range (from excitation thresholds up to 80 eV above threshold). The occurrence of a ‘plasmon like’ process, different from the one-electron dipole-allowed excitations, has been detected based on a different angular behaviour. Optically forbidden transitions appear only weakly and are observed at 1.9 and 4.8 eV. In contrast to the case of C 60, a small vibrational excitation, possibly resonant in character, has been observed around 2 eV incident energy. Variations in the cross sections and angular behaviour of the main excitation processes observed are presented.