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Licensed Unlicensed Requires Authentication Published by De Gruyter (O) August 14, 2015

Theoretical Kinetics Study of the Reactions Forming the ClCO Radical Cycle in the Middle Atmosphere of Venus

Carlos J. Cobos and Adela E. Croce

Abstract

A quantum-chemistry and kinetics study of key chemical reactions involved in the ClCO radical cycle of the Venus atmosphere: Cl + CO + M → ClCO + M (1); ClCO + O2 + M → ClC(O)OO + M (2) and ClC(O)OO + Cl → CO2 + ClO + Cl (3) (M = CO2), has been performed at 150–300 K. Unimolecular reaction rate theories on potential energy features derived at the G4//B3LYP/6-311+G(3df) ab initio composite level were employed. Limiting low pressure rate coefficients calculated for Reaction (1) are in good agreement with recommended experimental values. The present results validate rate coefficient values measured for Reaction (2) over relevant strato-mesosphere Venusian conditions. Rate coefficients calculated by the SACM/CT for Reaction (3) are given by k3 = 2.5 × 10−11 (T/300)0.5 cm3 molecule1 s1. In the absence of experimental data, these values provide the first reliable prediction for k3.

Acknowledgement

This research project was supported by the Universidad Nacional de La Plata, the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and the Agencia Nacional de Promoción Científica y Tecnológica. We thank to Professor Jürgen Troe for continuing support and hospitality.

Received: 2015-3-31
Accepted: 2015-7-28
Published Online: 2015-8-14
Published in Print: 2015-10-28

©2015 Walter de Gruyter Berlin/Boston