Association reactions of Fe+ with hydrocarbons: Implications for dense interstellar cloud chemistry

Reactions of Fe+ with several small hydrocarbons have been studied using the selected-ion flow tube (SIFT) technique at 0.35 torr and 294 K. These reactions, which occur solely by association, are expected to have a considerable influence upon the ratio of neutral to ionized Fe-bearing species within dense interstellar clouds. Furthermore, since Fe+ has generally been considered as one of the principal charge-carrying species within dense clouds, the reactions discussed here also have a very significant bearing on the overall degree of ionization within interstellar clouds. We discuss prospects for the formation of Fe-containing neutrals such as FeCO, FeC2Hn, and FeC4Hn (n = 1, 2) in dissociative recombination reactions of the adduct ions expected from the reaction of Fe+ with the abundant interstellar hydrocarbons C2H2 and C4H2.