Electron Attachment to Pentafluorobenzene, to Oxygen in a Mixture of 90% Argon and 10% Methane, and to Oxygen in Various Polar/nitrogen Mixtures.

By means of electron swarm experiments, electron attachment to pentafluorobenzene (C(,6)HF(,5)) in nitrogen (N(,2)) and to oxygen (O(,2)) in various gas mixtures has been studied. The variation of the electron attachment rate for C(,6)HF(,5) in N(,2) with the gas pressure and with the mean electron energy was determined. The lifetime of the species C(,6)HF(,5)('-*) against autoionization was deduced and the electron attachment cross section for C(,6)HF(,5) was calculated. The influence of the permanent electric dipole of C(,6)HF(,5) upon the electron attachment process is discussed. Electron attachment to O(,2) in P-10 (90% argon + 10% methane) and in mixtures of various polar molecules with N(,2) was investigated. As a preliminary to these studies electron drift velocities in P-10 and in the various mixtures of polar species with N(,2) were determined. These drift velocities are reported and discussed. The variation of the electron attachment rate for O(,2) in P-10 with the P-10 pressure and the mean electron energy was determined. The attachment rate as a function of mean electron energy was found to possess distinct structure. Models which account for this structure and for the variation of the attachment rate with the P-10 pressure are advanced and the corresponding reaction rate constants are presented. The electron attachment rates for O(,2) in mixtures of N(,2) with 1-butene, dimethyl amine, ammonia, trifluoromethane, and acetaldehyde were measured. Models of the variation of the attachment rate with the concentration of the polar species are advanced and the corresponding reaction rate constants are presented.