Interstellar reactions of kinetically excited radicals with molecular hydrogen

Dissociative recombination reactions are very efficient and highly exothermic. The exothermicity of these processes could allow reactions between some recombination products and interstellar H2 to occur with reasonable efficiency, even though such reactions are inhibited by an activation energy barrier. The implications of this proposal, for models of cold cloud chemistry, are considered for such radical-H2 reactions, specifically the reaction of OH radicals with H2. For example, OH· produced by the dissociative recombination of HOCO+ should possess adequate translational energy to react with interstellar H2: this reaction should, therefore, be considered a source of interstellar H2O.