Electron attachment to SF$_{6}$ at high temperatures

We have recently reported flowing-afterglow Langmuir-probe experiments on electron attachment to SF$_{6}$, thermal electron detachment from SF$_{6}^{-}$, and the pressure dependence of the processes involved, in the temperature range 300-670 K, including theoretical analysis of the possible outcomes of the electron-SF$_{6}$ interaction, with modeling of the data. One significant result of that work was the finding that the electron affinity of SF$_{6}$ is 1.20 $\pm $ 0.05 eV.\footnote{A. A. Viggiano et al., J. Chem. Phys. 127, 244303, (2007).} We have now extended the temperature range up to 1300 K. The electron attachment rate constant at 700 K is 1.7 x 10$^{-7}$ cm$^{3}$ s$^{-1}$ (yielding SF$_{5}^{-}$ and SF$_{6}^{-}$ product), and the thermal detachment rate constant for SF$_{6}^{-}$ is 580 s$^{-1}$. F$^{-}$ becomes a major ion product at 1000 K and above. We suspect that in this temperature range the SF$_{6}$ molecules are decomposing, because the SF$_{5}^{-}$ ion product disappears above 1100 K, and only the F$^{-}$ ion product remains. Further work must be carried out to determine the origin of the F$^{-}$, whether from decomposition or a surface-ionization effect.