First experimental kinetic study of the atmospherically important reaction of BrHg + NO2

Atomic bromine is known to dominate the oxidation of Hg(0) to Hg(II) via a two-step process in the atmosphere-formation of BrHg and subsequent reactions of BrHg with atmospheric radicals, particularly NO2. We report the first experimental determination of the rate constants for this reaction, which we measured versus temperature (313-373 K) and pressure (80-700 Torr) using laser photolysis-laser induced fluorescence (LP-LIF). Rate constants for addition are 3-11 times lower than those predicted by a previous computational study. We also confirm the existence of competing channel, which we assign to the predicted mercury reduction reaction.