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Astron. Astrophys. 338, 1080-1083 (1998)


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The rate of the reaction between H and DCN

Eric Herbst 1, 2 and D. Talbi 3

1 Department of Physics, The Ohio State University, Columbus, OH 43210, USA
2 Department of Astronomy, The Ohio State University, Columbus, OH 43210, USA
3 Laboratoire d'Etude Theorique des Milieux Extrêmes, Ecole Normale Supérieure, 24 rue Lhomond, F-75005 Paris, France

Received 7 April 1998 / Accepted 3 August 1998

Abstract

It has been suggested that the slightly endothermic reaction between H and DCN to produce HCN and D serves to deplete DCN in hot core regions of giant molecular clouds. We have calculated the rate of this reaction for a range of temperatures up to 500 K with a combination of ab initio quantum chemical and dynamical techniques. We find that the reaction has two potential barriers lying between the reactants and products. These barriers permit only a very slow reaction except at high temperatures. We calculate that the rate coefficient k of the reaction follows the formula k (cm3 s-1) = 2 10[FORMULA], where [FORMULA] is a tunneling correction. The estimated rate coefficient at 300 K is 5 10-18 cm3 s-1; this rate coefficient is far too small to be important in the destruction of DCN.

Key words: ISM: clouds – ISM: abundances – ISM: molecules – molecular processes

Send offprint requests to: Eric Herbst

© European Southern Observatory (ESO) 1998

Online publication: September 17, 1998

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