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

Abstract

The molecular ions HC ##IMG## [http://ej.iop.org/images/0004-637X/667/2/1283/img1.gif] {img1.gif} and HC ##IMG## [http://ej.iop.org/images/0004-637X/667/2/1283/img2.gif] {img2.gif} 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 ##IMG## [http://ej.iop.org/images/0004-637X/667/2/1283/img3.gif] {img3.gif} and HC ##IMG## [http://ej.iop.org/images/0004-637X/667/2/1283/img3.gif] {img3.gif} 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.