Electron impact dissociation cross sections for C₂F₆

Absolute total dissociation cross sections for electron impact, σ_t,diss, from 8 to 700 eV are reported for C₂F ₆. A dense set of data was obtained in the technologically important 8-30 eV energy range relevant to modelling the type of plasmas used in both fundamental and applied scientific investigations. The threshold for dissociation was found to be 12.0 0.2 eV and appears to be associated with a Rydberg state. Estimated values for the total neutral dissociation cross section, σ_neut,diss, were obtained by subtracting the ionization cross sections (all ionizing events cause dissociation) from the total dissociation cross section. It is shown that a calibration error in a paper by one of us (HFW) caused a distortion of several previous investigations. When the data from the present work are used to recalibrate data from swarm experiments, agreement becomes quite reasonable. There is now a consistent set of data obtained from several investigators which describe the dissociation of C₂F₆. Neutral dissociation cross sections are obtained from electron-impact excitation calculations and found to be in reasonable agreement with measurements over most of the energy range.