Ionization and fragmentation of CCl{sub 2}F{sub 2}, CClF{sub 3}, CF{sub 4}, and CHF{sub 3} by positron impact

The fragmentation patterns of the halomethanes CCl{sub 2}F{sub 2}, CClF{sub 3}, CF{sub 4}, and CHF{sub 3} have been studied by positron impact, in the energy range from threshold to around 50 eV. These data were obtained using a quadratic potential time of flight mass spectrometer, coupled with a Penning trap and a LINAC-based positron source. The present data for positrons are compared with results for electron and photoionization from other works.