Gas-phase ion/molecule reactions in C2F4

Gas-phase ion/molecule reactions in tetrafluoroethylene (C2F4) were studied with a pulsed electron beam mass spectrometer. When a few Torr of major gas, N2, containing 1–10 mTorr C2F4 was ionized by 2 keV electrons, CF3+ and C2F4+ were formed as major ions. CF3+ reacted with C2F4 rapidly to form C3F7+. The cluster ion C3F7+(C2F4) started to appear below ∼280 K. In the clustering reactions of C3F7+ with C2F4, the equilibria could not be observed but the cluster ions C3F7+(C2F4)n were found to grow very slowly at the expense of the smaller cluster ions C3F7+(C2F4)n−1. The rate constant of reaction C2F4+ + C2F4 = C3F5+ + CF3 was measured to be (1.5 ± 0.5) × 10−11 cm3/molecule s and found to be temperature-independent in the range of 310–180 K. The thermochemical stabilities of X−(C2F4)n (X− = F−, Cl− and Br−) were measured. A peculiar behavior in reaction of F− with C2F4 was observed. Two isomers for F−(C2F4) were predicted.