Atmospheric chemistry of CF3O2: A theoretical study on mechanisms and pathways of the CF3O2 + I reaction

Mechanisms and reaction channels of the CF3O2 with atomic iodine reaction were studied using quantum chemistry methods. The result indicates that the title reaction can take place on either the singlet or triplet potential energy surfaces (PES). On the singlet PES, addition and substitution mechanisms were located, and the former one is dominant. The most favorable channel involves the association of CF3O2 and I to form CF3OOI via a barrierless process. CF2O + FOI or CF3O + IO and other products could be formed as well, but they can be neglected because of highly energy barriers and unstable products. On the triplet PES, the most feasible product should be CF3O + IO via a modest barrier in the atmospheric condition, especially at higher temperature and lower pressure condition. However it is unfavorable thermodynamically to the overall reaction. Time-dependent DFT (TD-DFT) calculations indicate that CF3OOI takes photolysis easily in the sunlight at the wavelength of 548 and 427 nm. (C) 2012 Elsevier Ltd. All rights reserved.