Some interstellar reactions involving electrons and neutral species: Attachment and isomerization

While the role of neutral-neutral reactions in the chemistry of interstellar clouds is now recognized to be an important one, the role of negative ions is still regarded as minimal. In this paper, we present two possible exceptions to this view. First, we show that the radiative attachment reaction between electrons and the radical C3N to form the negative ion C3N- is sufficiently rapid to produce an abundance of the negative ion that is possibly large enough to be detected in the interstellar medium. Second, we show that electron-catalyzed isomerization of a metastable isomer M to its stable form S (M + e --> M- --> transition state --> S---> S + e) is facile for conversion of the metastable isomer l-C3H into its stable counterpart c-C3H.