Ultrafast ring-opening fragmentation dynamics of C6 H63+ induced by electron-impact ionization

The fragmentation dynamics of triply charged benzene [(C6H6)3+] induced by 260 eV electron-impact ionization are investigated using a multiparticle coincidence momentum spectrometer. By measuring three fragment ions and one outgoing electron in quadruple coincidence, we identify the complete three-body dissociation channels of CH2+ + C2H3+ + C3H+, CH3+ + C2H2+ + C3H+, and C2H2+ + C2H2+ + C2H2+. We determine the projectile-energy-loss spectra, Dalitz plots, Newton diagrams, momentum correlation maps, and kinetic-energy release for each fragmentation channel. The analysis of these spectra is supported by an ab initio molecular dynamics simulation, which provides a molecular movie of the dissociation process. Our study reveals sequential mechanisms for all three dissociation channels of (C6H6)3+ trication, i.e., an ultrafast ring-opening reaction followed by two subsequent Coulomb-explosion processes.