Peroxyacetyl radical [CH3C(O)O2] is among the most abundant peroxy radicals in the atmosphere and is involved in OH-radical recycling along with peroxyacetyl nitrate formation. Herein, the ground (X̃) and first (Ã) excited state surfaces of cis and trans peroxyacetyl radical are characterized using high-level ab initio methods. Geometries, anharmonic vibrational frequencies, and adiabatic excitation energies extrapolated to the complete basis-set limit are reported from computations with coupled-cluster theory. Excitation of the trans conformer is found to induce a symmetry-breaking conformational change due to second-order Jahn-Teller interactions with higher-lying excited states. Additional benchmark computations are provided to aid future theoretical work on peroxy radicals.
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http://dx.doi.org/10.1063/1.4906490 | DOI Listing |
Sci Total Environ
December 2024
Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, China; Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, China. Electronic address:
As forest coverage and urban greening increase in China, the impact of biogenic volatile organic compounds (BVOCs) on urban atmospheric environment cannot be neglected. As one of the most abundant and reactive BVOCs globally, isoprene plays a crucial role in atmospheric radical chemistry. However, the reports on quantifying the impact of isoprene on atmospheric photochemistry remain scarce.
View Article and Find Full Text PDFEnviron Sci Technol
October 2024
Center for Computational Toxicology and Exposure, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, United States.
Photooxidation products resulting from volatile organic compounds (VOCs) reacting with sunlight are important contributors to gas-phase air pollution. We characterized the product-weighted mutagenic potencies (rev m mgC h) in TA100 of atmospheres resulting from the hydroxyl radical (OH)-initiated photochemical oxidation of 11 C or C alkenes or dienes in the presence of nitric oxide (NO) and from the ozonolysis of four VOCs without NO (isoprene; 1,3-pentadiene; 1,4-pentadiene; and 1,3-butadiene). Irradiated atmospheres from precursors with a single C═C bond (3-methyl-1-butene, 2-methyl-1-butene, -2-pentene, 2-methyl-2-butene, 1-butene, and 1-pentene) had low potencies (<5), whereas linear dienes with terminal C═C bonds had high potencies (50-65).
View Article and Find Full Text PDFGeosci Model Dev
February 2024
School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
We updated the chemical mechanism of the GEOS-Chem global 3-D model of atmospheric chemistry to include new recommendations from the NASA Jet Propulsion Laboratory (JPL) chemical kinetics Data Evaluation 19-5 and from the International Union of Pure and Applied Chemistry (IUPAC) and to balance carbon and nitrogen. We examined the impact of these updates on the GEOS-Chem version 14.0.
View Article and Find Full Text PDFSci Total Environ
March 2024
Joint International Research Laboratory of Atmospheric and Earth System Research, School of Atmospheric Sciences, Nanjing University, Nanjing, Jiangsu 210023, China; National Observation and Research Station for Atmospheric Processes and Environmental Change in Yangtze River Delta, Nanjing, Jiangsu Province, China.
Peroxyacetyl nitrate (PAN) is a significant indicator of atmospheric photochemical pollution, which can influence the regional distribution of ozone (O) and hydroxyl radical (OH) through long-range transport. However, investigations of PAN incorporating comprehensive measurement and explicit modeling analysis are limited, hindering complete understandings of its temporal behavior, sources, and impacts on photochemistry. Here we conducted a 1-year continuous observation of PAN and relative atmospheric species in Nanjing located in Yangtze River Delta (YRD).
View Article and Find Full Text PDFChemosphere
March 2024
State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing, 210023, China.
Indirect photodegradation is an important pathway for the reduction of steroid estrogens in sunlit surface waters. Nevertheless, the kinetics and mechanisms governing the interaction between coexisting carbonyl compounds and estrogens under visible light (Vis) remain unexplored. This study systematically investigates the Vis-induced photodegradation of 17β-estradiol (E2) in the presence of five specific carbonyl compounds-biacetyl (BD), acetone, glyoxal, pyruvic acid, and benzoquinone.
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