title: Multiple ionization and fragmentation of negatively charged fullerene ions by electron impact
abstract: Cross sections for the electron-impact multiple ionization and fragmentation of negatively charged fullerene ions C(-)(n) ( n = 60, 70) to C(q+)(n-m) ( q = 1,2,3 and m = 0,2,4) have been measured for electron energies up to 1 keV. In the case of pure ionization all threshold energies are about 10 eV higher than the values expected. This shift, however, is not observed for the fragment ions. The experimental data indicate that there is no strong electron-electron interaction between the incident electron and the attached electron. A novel ionization mechanism is proposed which can be expected to be valid for all negatively charged molecular or cluster ions which are able to shield the attached electron from the incident electron.
authors.affiliation: Institut fur Ionenphysik, Leopold Franzens Universitat, A-6020 Innsbruck, Austria.
authors.initials: P
authors.lastname: Scheier
authors.initials: D
authors.lastname: Hathiramani
authors.initials: W
authors.lastname: Arnold
authors.initials: K
authors.lastname: Huber
authors.initials: E
authors.lastname: Salzborn