INTERACTION OF FREE-ELECTRONS WITH C-60 - IONIZATION AND ATTACHMENT REACTIONS

Electron impact ionization and attachment to C-60 has been studied as a function of electron energy using a crossed molecular beam-electron beam double focusing mass spectrometer system. It was possible to determine absolute ionization cross section functions (up to 80 eV) for the reactions C-60 + e --> C-60(+), C-58(+), C-56(+) and C-54(+), respectively. The huge kinetic shifts observed for the appearance of the various fragment ions are interpreted in terms of RRKM theory yielding a corresponding dissociation energy for C-2 evaporation of (7.1 +/- 0.4) eV. The attachment cross section curve observed for the production of C-60(-) exhibits a strong zero energy resonance and evidence of equally strong autoscavenging processes up to energies of 14 eV.