Photo-multidetachment and Fragmentation of C$_{60}^-$

Absolute single-photon multi-detachment and fragmentation cross sections of C$_{60}^-$ fullerene anions have been measured as a function of energy with the merged ion-photon beam apparatus at the ALS. Multiple electron ejection was substantial at all photon energies, allowing product charge states up to C$_{60}^{3+}$ to be measured. We argue that $q$-fold detachment spectra of C$_{60}^-$ relate directly to $q$-fold ionization of neutral C$_{60}$, except the loosely bound excess electron of C$_{60}^-$ results in a significant change of the energy scale and increase of the absolute cross section, with otherwise little change in the structure. Fragmentation into cations of C$_{58}$ and C$_{56}$ was also studied. We conclude from the determination of appearance thresholds that fragmentation occurs at significantly lower photoexcitation energies in C$_{60}^-$ than in C$_{60}$.