2002A&A...381..560M

In this paper we present measurements of the CH₂DCCH/CH₃CCH ratio along the TMC-1 ridge. The level of deuterium fractionation in this molecule is found to be larger than previously thought, but more significantly, the fractionation increases as one moves from the cyanopolyyne peak to the ammonia peak, as is the case with measurements of other molecules in TMC-1. This confirms the prediction of our recent chemical/dynamical model of TMC-1 and supports the hypothesis that the chemical evolution of TMC-1 has been affected by Alfven waves.