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

ADELA E. CROCE; CARLOS J. COBOS

Zeitschrift für Physikalische Chemie

OLDENBOURG VERLAG

Lugar: Munich; Año: 2015 vol. 229 p. 1541 - 1559

0942-9352

A quantum-chemistry and kinetics study of key chemical reactionsinvolved in the ClCO radical cycle of the Venus atmosphere: Cl + CO + 𝑀 ¡ú ClCO +𝑀 (1); ClCO + O2 + 𝑀 ¡ú ClC(O)OO +𝑀 (2) and ClC(O)OO + Cl ¡ú CO2+ClO+Cl (3) (𝑀=CO2), has been performed at 150¨C300 K. Unimolecular reaction rate theories on potential energy featuresderived at the G4//B3LYP/6-311+G(3df) ab initio composite level were employed. Limiting low pressurerate coefficients calculated for Reaction (1) are in good agreement withrecommended experimental values. The present results validate rate coefficientvalues measured for Reaction (2) over relevant strato-mesosphere Venusianconditions. Rate coefficients calculated by the SACM/CT for Reaction (3) are given by 𝑘3= 2.5 ¡Á 10−11 (𝑇/300)0.5 cm3 molecule−1 s−1. In the absence ofexperimental data, these values provide the first reliable prediction for 𝑘3.