Comparison of the low-energy decay mechanisms of C70+ and C70−

Low-energy multiple-collisional-excitation experiments have been performed on C70+ and C70− at the ClusterTrap apparatus. The ions are stored in a Penning trap where they are excited via radial dipolar excitation before undergoing collisions with neutral argon atoms. The dominant decay mechanism for C70+ (sequential loss of C2-units) is compared with the dominant decay process of C70− (thermionic electron emission). A simple model based on the decay rates of the clusters is found to be in reasonable agreement with the experimental data obtained for the fragmentation process of the cationic fullerenes. The same model, when applied to the anions is observed to be in less agreement with the experimental results.