Coulombic and non-Coulombic fragmentation of highly charged benzene

Triple coincidence techniques have been used to measure the kinetic energies released (KER) upon fragmentation Of C6H6q+ (q greater than or equal to 4) molecules that are formed in collisions of benzene with 120 keV Ar8+ ions. The measured KER spectrum, which shows definitive structure rather than a continuous profile, is simulated using a simple Coulomb explosion model that accounts for all the permutations and combinations of states from which these fragment ions can be produced from the precursor molecular ion. The simulated spectrum correlates very well with the measurements but for disagreement in the low-KER regime that is attributed to non-Coulombic fragmentation pathways. Thus, in a single spectrum, both non-Coulombic and Coulombic regimes are accessed.