Negative ion formation in compounds relevant to SF6 decomposition in electrical discharges

Dissociative and nondissociative electron attachment in the electron impact energy range 0–14 eV are reported for SOF2 SOF4, SO2F2, SF4, SO2, and SiF4 compounds which can be formed by electrical discharges in SF6. The electron energy dependences of the mass-identified negative ions were determined in a time-of-flight mass spectrometer. The ions studied include F− and SOF 2 −* from SOF2; SOF 3 − and F− from SOF4; SO2F 2 −* , SO2F−, F 2 − , and F− from SO2F2; SF 4 −* and F− from SF4; O−, SO−, and S− from SO2; and SiF 3 − and F− from SiF4. Thermochemical data have been determined from the threshold energies of some of the fragment negative ions. Lifetimes of the anions SOF 2 −* , SO2F 2 −* , and SF 4 −* are also reported.