The gas-phase destruction of interstellar carbon dioxide: Calculations on the reactions between CO and H and between CO and H

¹ LETMEX, Université de Nice Sophia Antipolis, Parc Valrose, U.F.R. Sciences, 06108 Nice Cedex 2, France
² Departments of Physics and Astronomy, The Ohio State University, Columbus, OH 43210, USA

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

Received: 27 December 2001
Accepted: 28 February 2002

Abstract

Carbon dioxide is an abundant component of cold interstellar grains, but its gas-phase abundance is not high. To partially explain this low abundance, it has been suggested that gas-phase CO₂ is destroyed by reaction with both atomic and molecular hydrogen. Although there are experimental studies concerning the rate of the reaction between CO₂ and H, there are no modern experimental studies for the analogous reaction with H₂. In this paper, we report quantum chemical and dynamical research on the reactive systems CO₂ + H and CO₂ + H₂. Our results for the former are in excellent agreement with experiment and previous theory, while our results for the latter show this reaction to possess an extremely large potential energy barrier, far in excess of the reaction endothermicity.