Computational Investigations On The Ho2 + Chbr2o2 Reaction: Mechanisms, Products, And Atmospheric Implications

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+O-2 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 300K. Due to higher energy barriers surmounted, other products including CBr2O2+H2O2, CBr2O+HO3H, CH2O+HO3Br, CHBrO+HO3+Br, and CHBr2OH+O-3 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.