Ionization and fragmentation of fullerene ions by electron impact

Absolute cross sections have been measured for the first time for the electron-impact single ionization of the fullerene ions ${\mathrm{C}}_{60}^{+}$, ${\mathrm{C}}_{60}^{2+}$, ${\mathrm{C}}_{60}^{3+}$, and ${\mathrm{C}}_{70}^{+}$ as well as for double ionization of ${\mathrm{C}}_{60}^{+}$ ions at electron energies ranging from threshold up to 1000 eV. It is found that the cross sections ${\mathrm{\ensuremath{\sigma}}}_{1,2}$ for ${\mathrm{C}}_{60}^{+}$ and ${\mathrm{C}}_{70}^{+}$ ions coincide within error bars and, furthermore, that at energies greater than 60 eV the cross section ${\mathrm{\ensuremath{\sigma}}}_{2,3}$ for ionization of ${\mathrm{C}}_{60}^{2+}$ ions is larger than ${\mathrm{\ensuremath{\sigma}}}_{1,2}$. In addition, cross sections for fragmentation ${\mathrm{C}}_{60}^{+}$\ensuremath{\rightarrow}${\mathrm{C}}_{56}^{+}$ and for fragmentation ionization ${\mathrm{C}}_{60}^{+}$\ensuremath{\rightarrow}${\mathrm{C}}_{56}^{2+}$ are presented.