Computational investigations on the HO2 + CHBr2O2 reaction: mechanisms, products, and atmospheric implications
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Using quantum chemistry methods, mechanisms and products of the CHBr2O2 + HO2 reaction in the atmosphere were investigated theoretically. Computational result indicates that the dominant product is CHBr2OOH + O2 formed on the triplet potential energy surface (PES). While CBr2O + OH + HO2 produced on the singlet PES is subdominant to the overall reaction under the typical atmospheric condition below 300 K. Due to higher energy barriers surmounted, other products including CBr2O2 + H2O2, CBr2O + HO3H, CH2O + HO3Br, CHBrO + HO3 + Br, and CHBr2OH + O3 make minor contributions to the overall reaction. In the presence of OH radical, CHBr2OOH generates CHBr2O2 and CBr2O2 + H2O subsequently, which enters into new Br-cycle in the atmosphere. The substitution effect of alkyl group and halogens plays negligible roles to the dominant products in the RO2 + HO2 (X = H, CH3, CH2OH, CH2F, CH2Cl, CH2Br, CH2Cl, and CH2Br) reactions in the atmosphere.
KeywordsCHBr2O2 HO2 Mechanisms Halogen effect Atmospheric reaction
This work has been supported by the National Natural Science Foundation of China (No. 41775119, 21507027), Focus on Research and Development Plan in Shandong Province (2018GSF117017).
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