LAUSR

Abstract We have investigated multiple ionization and fragmentation of 1,1,1,2-tetrafluoroethane (CF3–CH2F) in charge-changing collisions with 580-keV C+. By measuring the number of emitted electrons in each collision, we obtained the charge state (r) distribution of multiply ionized CF3–CH2Fr+* ions transiently formed as intermediate states prior to fragmentation. The mean charge states of CF3–CH2Fr+* in single-electron (1e)-capture, 1e-loss, and double-electron-loss collisions were determined to be 1.9, 3.2, and 4.0, respectively. Time-of-flight mass spectra of the product ions from CF3–CH2Fr+* were obtained as a function of r from coincidence measurements with the number of emitted electrons. Production of specific fragment ions and variation of the fragmentation patterns were systematically revealed up to r = 4. For example, it was found that proton emission becomes the dominant decay process from multiply ionized CF3–CH2Fr+. The results also show that coincidence measurements can distinguish ion species with the same mass-to-charge ratio but different charge states. The characteristic features of the fragmentation processes of CF3–CH2Fr+* were investigated by the correlation among the product ions for r ≥ 2. C+ and C2+ fragment ions are emitted to the same side as H+ even at r = 2, reflecting the structural feature of the asymmetric location of the heavier atoms (F) in the molecule.