The production of HCN dimer and more complex oligomers in dense interstellar clouds

¹ School of Chemistry, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
² LETMEX, Université de Nice Sophia Antipolis, Parc Valois, U.F.R. Sciences, 06108 Nice Cedex 2, France
³ Departments of Physics and Astronomy, The Ohio State University, Columbus, OH 43210, USA

Corresponding author: E. Herbst, herbst@mps.ohio-state.edu

Received: 8 January 2001
Accepted: 16 January 2001

Abstract

Using quantum chemical and kinetic techniques, we show that the reaction between two HCN molecules under interstellar conditions cannot lead efficiently to a dimer of this species (H₂C₂N₂), whatever its structure. If the dimerization reaction does not occur efficiently, then it is impossible to synthesize detectable abundances of the pre-biotic HCN oligomer adenine (H₅C₅N₅) in the interstellar medium via successive neutral-neutral reactions between HCN and its dimer, trimer, and tetramer.