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Photodissociation Mechanisms of Major Mercury(II) Species in the Atmospheric Chemical Cycle of Mercury
Author(s) -
FrancésMonerris Antonio,
CarmonaGarcía Javier,
Acuña A. Ulises,
Dávalos Juan Z.,
Cuevas Carlos A.,
Kinnison Douglas E.,
Francisco Joseph S.,
SaizLopez Alfonso,
RocaSanjuán Daniel
Publication year - 2020
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201915656
Subject(s) - mercury (programming language) , photodissociation , chemistry , atmospheric chemistry , elemental mercury , metal , environmental chemistry , photochemistry , inorganic chemistry , ozone , organic chemistry , adsorption , computer science , programming language
Mercury is a contaminant of global concern that is transported throughout the atmosphere as elemental mercury Hg 0 and its oxidized forms Hg I and Hg II . The efficient gas‐phase photolysis of Hg II and Hg I has recently been reported. However, whether the photolysis of Hg II leads to other stable Hg II species, to Hg I , or to Hg 0 and its competition with thermal reactivity remain unknown. Herein, we show that all oxidized forms of mercury rapidly revert directly and indirectly to Hg 0 by photolysis. Results are based on non‐adiabatic dynamics simulations, in which the photoproduct ratios were determined with maximum errors of 3%. We construct for the first time a complete quantitative mechanism of the photochemical and thermal conversion between atmospheric Hg II , Hg I , and Hg 0 compounds. These results reveal new fundamental chemistry that has broad implications for the global atmospheric Hg cycle. Thus, photoreduction clearly competes with thermal oxidation, with Hg 0 being the main photoproduct of Hg II photolysis in the atmosphere, which significantly increases the lifetime of this metal in the environment.