TY - JOUR
T1 - Reaction of Criegee Intermediate with Nitric Acid at the Air-Water Interface
AU - Kumar, Manoj
AU - Zhong, Jie
AU - Zeng, Xiao Cheng
AU - Francisco, Joseph S.
N1 - Funding Information:
This work was supported by the National Science Foundation (CHE-1500217), funding from Beijing Advanced Innovation Center for Soft Matter Science & Engineering for summer visiting scholar, and the University of Nebraska Holland Computing Center.
Publisher Copyright:
© 2018 American Chemical Society.
PY - 2018/4/11
Y1 - 2018/4/11
N2 - The role of aqueous surfaces in promoting atmospheric chemistry is increasingly being recognized. However, the bimolecular chemistries of Criegee intermediates, which influence the tropospheric budget of OH radicals, organic acids, hydroperoxides, nitrates, sulfates, and particulate material, remain less explored on an aqueous surface. Herein we have employed Born-Oppenheimer molecular dynamics simulations and two-layer ONIOM (QM:MM) in an electronic embedding scheme to study the reaction and the spectroscopic signal of anti-CH3CHOO with nitric acid (HNO3) at the air-water interface, which is expected to be an important reaction in polluted urban environments. The results reveal that on the water surface, the HNO3-mediated hydration of anti-CH3CHOO is the most dominant pathway, whereas the traditionally believed direct reaction between anti-CH3CHOO and HNO3, which results in the formation of nitrooxyethyl hydroperoxide, is only the minor channel. Both reaction pathways follow a stepwise mechanism at the air-water interface and occur on the picosecond time scale. These new reactions are expected to be relevant in the hazy environments of globally polluted urban regions where nitrates and sulfates are abundantly present. During the hazy period, the high relative humidity and the presence of fog droplets may favor the HNO3-mediated Criegee hydration over the nitrooxyethyl hydroperoxide forming reaction. A similar reaction mechanism with Criegee intermediates could be expected on the water surface for organic acids, which possess HNO3-like functionalities, and may play a role in improving our knowledge of the organic acid budget in the terrestrial equatorial regions and high northern latitudes. The ONIOM calculations suggest that the N-O stretching bands around 1600-1200 cm-1 and NO2 bending band around 750 cm-1 in nitrooxyethyl hydroperoxide could be used as spectroscopic markers for distinguishing it from hydrooxyethyl hydroperoxide on the water surface.
AB - The role of aqueous surfaces in promoting atmospheric chemistry is increasingly being recognized. However, the bimolecular chemistries of Criegee intermediates, which influence the tropospheric budget of OH radicals, organic acids, hydroperoxides, nitrates, sulfates, and particulate material, remain less explored on an aqueous surface. Herein we have employed Born-Oppenheimer molecular dynamics simulations and two-layer ONIOM (QM:MM) in an electronic embedding scheme to study the reaction and the spectroscopic signal of anti-CH3CHOO with nitric acid (HNO3) at the air-water interface, which is expected to be an important reaction in polluted urban environments. The results reveal that on the water surface, the HNO3-mediated hydration of anti-CH3CHOO is the most dominant pathway, whereas the traditionally believed direct reaction between anti-CH3CHOO and HNO3, which results in the formation of nitrooxyethyl hydroperoxide, is only the minor channel. Both reaction pathways follow a stepwise mechanism at the air-water interface and occur on the picosecond time scale. These new reactions are expected to be relevant in the hazy environments of globally polluted urban regions where nitrates and sulfates are abundantly present. During the hazy period, the high relative humidity and the presence of fog droplets may favor the HNO3-mediated Criegee hydration over the nitrooxyethyl hydroperoxide forming reaction. A similar reaction mechanism with Criegee intermediates could be expected on the water surface for organic acids, which possess HNO3-like functionalities, and may play a role in improving our knowledge of the organic acid budget in the terrestrial equatorial regions and high northern latitudes. The ONIOM calculations suggest that the N-O stretching bands around 1600-1200 cm-1 and NO2 bending band around 750 cm-1 in nitrooxyethyl hydroperoxide could be used as spectroscopic markers for distinguishing it from hydrooxyethyl hydroperoxide on the water surface.
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U2 - 10.1021/jacs.8b01191
DO - 10.1021/jacs.8b01191
M3 - Article
C2 - 29564890
AN - SCOPUS:85045201296
SN - 0002-7863
VL - 140
SP - 4913
EP - 4921
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 14
ER -