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Theoretical Investigation of the Photoexcited NO 2 +H 2 O reaction at the Air–Water Interface and Its Atmospheric Implications
Author(s) -
MartinsCosta Marilia T. C.,
Anglada Josep M.,
Francisco Joseph S.,
RuizLópez Manuel F.
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201902769
Subject(s) - radical , atmospheric chemistry , dissociation (chemistry) , ozone , troposphere , chemistry , reaction rate constant , kinetic energy , gas phase , adsorption , excited state , photochemistry , analytical chemistry (journal) , kinetics , environmental chemistry , atmospheric sciences , atomic physics , physics , organic chemistry , quantum mechanics
Abstract The atmospheric role of photochemical processes involving NO 2 beyond its dissociation limit (398 nm) is controversial. Recent experiments have confirmed that excited NO 2 * beyond 420 nm reacts with water according to NO 2 * +H 2 O→HONO+OH. However, the estimated kinetic constant for this process in the gas phase is quite small ( k ≈10 −15 –3.4×10 −14 cm 3 molecule −1 s −1 ) suggesting minor atmospheric implications of the formed radicals. In this work, ab initio molecular dynamics simulations of NO 2 adsorbed at the air–water interface reveal that the OH production rate increases by about 2 orders of magnitude with respect to gas phase, attaining ozone reference values for NO 2 concentrations corresponding to slightly polluted rural areas. This finding substantiates the argument that chemistry on clouds can be an additional source of OH radicals in the troposphere and suggests directions for future laboratory experimental studies.