Kinetics and thermochemistry of electron attachment to SF6

✍ Scribed by Shawn P. Heneghan; Sidney W. Benson

• Publisher: John Wiley and Sons
• Year: 1983
• Tongue: English
• Weight: 442 KB
• Volume: 15
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550150202

✦ Synopsis

Thermochemical analysis of the electron capture process of SFs leads to a rate constant for the reverse process SF; 2 SF6 + e-, k 2 = 1.5 X 1013-31'.4/H s-l, where 0 = 2.303RT, in kcal/mol. The electron affinity of 32 f 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 SFeelectron (SFCeL) Langevin complex which appears to have a lifetime of about 2 X s.

Curve crossing from the SFceL 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 SFG 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. (1975).