Kinetics and thermochemistry of electron attachment to SF6

Thermochemical analysis of the electron capture process of SF6 leads to a rate constant for the reverse process {article}{empty}{document}SF₆^ - → ² SF₆ + e^ -,k₂ = 1.5 × 1013 - 31.4/θ s^ - 1{document} , where θ = 2.303RT, in kcal/mol. The electron affinity of 32±3 kcal/mol is deduced from the observed bimolecularity of the capture process down to 0.1 torr Ar bath gas and estimated entropies of SF6 and SF . The capture process is discussed from the view point of the formation of a metastable SF electron (SF6·e ) Langevin complex which appears to have a lifetime of about 2 × 10−13 s. Curve crossing from the SF6·e complex to vibrationally excited (SF )* appears to have a normal rate and A factor. This is interpreted to indicate near‐resonant coupling between the orbiting electron and the vibronic motions of SF6, together with similarity in structure of SF6 and SF . It is shown that the apparent slowness of thermal electron ejection from SF is a result of an unfavorable equilibrium constant rather than a slow rate.