A theoretical study on the reactions of Hg with halogens: Atmospheric implications

Electronic structure calculations were performed using DFT and high-level ab initio methods to understand the role of atomic halogens in the transformation of gaseous mercury in the Arctic atmosphere. The latter methods were found to be superior in reproducing the reaction enthalpies as well as the geometrical parameters and vibrational frequencies, and therefore they were employed to calculate the energy potentials for the capture-deactivation approach to study the kinetics of halogen-mercury atomic recombination. Using the calculated rate constants and inferred concentrations of halogen atoms in the Arctic troposphere, we found that atomic bromine might be responsible for the mercury depletion episodes.