A study of low energy electron attachment to trifluoromethyl sulphur pentafluoride, SF₅CF₃ using an electron-swarm mass spectrometric technique: atmospheric implications

An investigation of electron attachment to the potent greenhouse gas SF,CF, has been carried out in atmospheric pressure nitrogen and argon buffer gases at 300 K. The experiments were conducted under nonthermal electron-swarm conditions, using an instrument that combines a drift tube with a quadrupole mass spectrometer. Electron attachment rate constants, k(a), have been determined as a function of mean electron energy ()over bar> = 0.04-1.9 eV). k(a) decreases as )over bar> increases. The estimated thermal electron attachment rate constant is k(th)(SF5CF3) approximate to (7.7 +/- 0.6) x 10(-8) cm(3) molecule(-1) s(-1). The only observed anion product is SF;. Free electron attachment destroys SF,CF,. This places an upper limit on the atmospheric lifetime of SF,CF, of the order of 1000 years. (Int J Mass Spectrom 206 (2001) i-iv) (C) 2001 Elsevier Science B.V.