[en] Absolute total dissociation cross sections, σ_t,diss, by electron-impact are reported for CHF₃ and C₃F₈ from 10 to 300 eV using the chemical gettering technique described by Winters and Inokuti (1982 Phys. Rev. A 25 1420). Data are concentrated in the near-threshold region (10-30 eV). The thresholds for dissociation of CHF₃ and C₃F₈ are determined to be 10.4 eV and 11.9 eV, respectively. Ionization thresholds occur at 16 eV for CHF₃ and 16.2 eV for C₃F₈. Neutral dissociation cross sections of both CHF₃ and C₃F₈ are obtained by subtracting the ionization cross sections, σ_t,ion, from the total dissociation cross sections, σ_t,diss

[en] Absolute total dissociation cross sections for electron impact, σ_t,diss, from 8 to 700 eV are reported for C₂F₆. 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