Anions in Space and in the Laboratory

Abstract

Abstract. The astronomical detection of molecular anions has prompted our study of their chemical reactions with atomic species that are abundant in the interstellar medium. We have recently explored the chemistry of a variety of Cx Ny − anions with hydrogen atoms and determined their reaction rate constants and products using the flowing afterglow-selected ion flow tube technique. Computational studies allow characterization of the structures of reactants and products, as well as the energetics along the reaction pathway. For anions containing one or two nitrogen atoms, reactions with hydrogen atoms are facile, and proceed primarily by associative detachment. In contrast, anions containing three nitrogen atoms are unreactive with hydrogen atoms due to reaction barriers and unfavorable thermodynamics.

Reaction of CN– with F, Cl, O, and S Atoms: Attachment or Associative Detachment?

“…These anions can react with neutral species and contribute in the building of larger negative species as inferred, for example, in the ion-neutral models developed by Vuitton et al for the upper atmosphere of Titan. The research in this ion-neutral chemistry has been developed experimentally , and also via quantum chemistry calculations. , The reactivity of anions in the interstellar media has been recently modeled by Senent et al, and the goals of the present contribution are to illustrate in detail some examples of the reactivity of the stable CN – anion with neutral atoms X (X = F, Cl, O, S) that can be found with diverse abundances in space and to discuss the stability of the products.…”

An investigation of the radiative electron attachment of C3N through dipole-bound states

“…The present results obtained at the rigid rotor level suggest that the effect of the formation of long-lived resonances via vibrationally excited bending vibrations should be considered in future studies. The alternative formation mechanism of large molecular anions via reactions of carbon anions with N atoms should also be considered for C 3 N − as suggested by Bierbaum [34] and Agúndez et al [35]. Five other negative ions observed in the ISM: CN -, C 5 N -, C 4 H -, C 6 H -, and C 8 H -, deserve separate studies of this kind, as their formation mechanisms are probably not the same.…”

Associative detachment in anion-atom reactions involving a dipole-bound electron

“…nions are ubiquitous in nature, from aqueous solution 1 and the earth's atmosphere 2 to astrochemical environments [3][4][5] . They are reactive species, very sensitive to their environment, and often essential intermediates in important chemical events 6 .…”