Cross sections for electron collisions with tetrafluoroethane (C2H2F4)

Summary form only given. Recent, growing interest in electron collision and transport data for tetrafluoroethane (C₂H₂F₄) stems from the ever growing application of this gas and its mixtures in cooling systems and also in radiation particle detectors, resistive plate chambers in particular. Having that in mind and some new data we have decided to revise and extend our previous studies of electron interactions with that molecule. Our aim was to develop a more detailed set of cross sections and to improve its uniqueness as compared to the previously constructed set. Additional attention was focused on low electron energy region. A method that we used in our study was a standard swarm procedure. Our starting set consisted of elastic momentum transfer and 14 inelastic processes. Energy dependencies of eleven vibration excitations were assumed both in their magnitude and shape, while the threshold energies were taken from the literature. Electron attachment, dissociative excitation and ionization cross sections were calculated by using the Quantemol code. That set was normalized by using a Boltzmann equation solver and a Monte Carlo code, so as to obtain the electron swarm parameters - drift velocity, W, and effective ionization coefficient, (α-n)/N consistent with experimental data. Calculations were made for pure gas and mixtures with Ar of various compositions. Calculated data cover a wide interval of electron mean energies. After a number of iterative trials, during which the cross sections were modified in order to overcome some obvious inconsistencies, it was shown that two more cross sections had to be introduced to the set: the effective excitation with a broad peak around 15 eV, and the low energy attachment.