Attachment of electrons to nitrogen dioxide and sulphur hexafluoride

Microwave ionized gas afterglow studies of electron attachment to nitrogen dioxide and sulphur hexafluoride are reported. The two-body rate for attachment to nitrogen dioxide is found to be 1·1 ± 0·3 × 10 -12 cm 3 sec -1 at temperature 300°K. An apparent 300°K two-body attachment cross section to SF 6 of 3·0±0·5 × 10 -13 cm 2 is found, together with an attachment inhibition rate of 2·0±0·5 × 10 -15 cm 3 sec -1 by the diluent xenon gas. It is proposed that the diluent gas can collisionally detach vibrationally excited SF 6 - ions, setting up an equilibrium so that the electron removal rate is governed by dissociative attachment.