Correlation between multiple ionization and fragmentation of C60 in 2-MeV Si2+ collisions: Evidence for fragmentation induced by internal excitation

Fragment ions from C60 induced by 2 MeV (v=1.7 a.u.) Si2+ impacts are measured in coincidence with the number distributions of secondary electrons under conditions of single-electron loss and single-electron capture collisions. Multifragmentation, leading to disintegration of cage structure, is found to occur at surprisingly low charge states of r≅3. Also, we find that mass distributions of fragment ions are nearly the same for loss and capture collisions provided that the number of electrons ejected, due to electronic energy deposition from an incident ion, are the same. Present results indicate evidently that the internal excitation, rather than the charge state r of transiently formed prefragmented parent ions C60r+**, plays the essential role in C60 fragmentation in fast heavy ion collisions