Chemistry among the Stars: Reaction Kinetics at a New Frontier (RSC Liversidge Lecture)

Over the past decade, experiments in the Universities of Rennes and Birmingham have provided rate constants for over 40 reactions of molecular and atomic radicals with neutral molecules at temperatures down to 13 K using the CRESU (cinétique de réaction en écoulement supersonique uniforme) technique. The demonstration that reactions between electrically neutral species can be extremely rapid at these very low temperatures has excited interest both from theoreticians and from those seeking to understand the chemistry that gives rise to the 120 or so molecules that have been identified as being present in dense interstellar clouds. This laboratory work, and its astrochemical and theoretical contexts, are reviewed here. In addition, I deal briefly with the present limitations of the experiments and how they might be overcome in future work.