REACTIONS OF CNFM+ IONS WITH C2F4 AND OTHER PERFLUOROCARBONS

The gas-phase reactions of CF+, CF2+, CF3+, C2F3+, C2F4+, C3F5+, and C 3F7+ with tetrafluoroethylene, C2F4, have been studied using a variabl e temperature-selected ion flow tube (VT-SIFT) instrument at 300 and 4 96 K. In addition, reactions of CF3+ with the perfluorocarbons C3F6, 2 -C4F8, and C-C4F8 have been studied at 300 and 496 K. Reaction rate co nstants and product branching fractions were measured. The reaction of CF+ With C2F4 is fast and produces the ions CF3+, C3F5+, and C2F4+. T he ion CF2+ reacts with C2F4 by nondissociative charge transfer at the collisional rate. The reaction of CF3+ with C2F4 proceeds slowly by a ssociation, forming C3F7+ which reacts in a secondary reaction with C2 F4 to regenerate CF3+. The neutral product of this secondary reaction is inferred to be C4F8; thus, dimerization Of C2F4 is catalyzed by CF3 +. For the reaction of C2F3+ With C2F4, WhiCh is fast, C3F5+ and a min or amount of C2F4+ are produced. The reaction of C2F4+ with C2F4 is sl ow, has a strong negative temperature dependence, and produces C3F5+ W hich is itself unreactive with C2F4. While CF3+ does not measurably re act With C-C4F8, CF3+ does react rapidly by F- transfer with both C3F6 and 2-C4F8.