2020ApJ...905...90C

We probe a new pathway for the formation of smaller anions from the temporary negative ion states (anion resonances) of C_nN^– (n = 1-3, 5-7) in the circumstellar envelope of IRC+10216. C_nN^– (n = 1-3, 5-7) anions were collisionally excited to their resonance states and were observed to decay into a variety of smaller anions. The measured kinetic-energy-release distributions for the anionic fragments arising from each of the parent anions indicate a concerted manner of occurrence of these fragments, implying rich dissociation dynamics. C₂^– and C₂N^– were found to be dominant fragments of these anions, suggesting their presence in the external layers of IRC+10216 where UV photons penetrate. C_nN^– (n = 1-3) were also observed to undergo dissociative and nondissociative double-electron detachments, with the former being dominant. The significance of this new pathway in determining the stability and abundance of anions in IRC+10216 is discussed.