Reactions of H, N, and O Atoms with Carbon Chain Anions of Interstellar Interest: An Experimental Study

The molecular ions HC and HC have recently been identified both in the laboratory and in astronomical environments. In addition, carbon chain anions have been proposed as potential carriers of the diffuse interstellar bands. Using a selected ion flow tube apparatus, we have determined the rate constants for the reactions of C and HC with H, N, and O atoms in order to characterize their interstellar chemistry. Reactions between the carbon chain anions and H and O occur readily, with rate constants ranging from mid to high 10 -10 cm 3 s -1 . H atom reactions proceed primarily by associative detachment, and O atom reactions proceed both by associative detachment and by extrusion of CO. Reactions between the carbon chains and N atoms are slower, but the reaction products that are observed could provide a negative ion pathway for the synthesis of observed interstellar species.