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DOI	10.5194/acp-23-3147-2023
	Comparison of isoprene chemical mechanisms under atmospheric night-time conditions in chamber experiments: evidence of hydroperoxy aldehydes and epoxy products from NO3 oxidation
	Carlsson, Philip T. M.; Vereecken, Luc; Novelli, Anna; Bernard, Francois; Brown, Steven S.; Brownwood, Bellamy; Cho, Changmin; Crowley, John N.; Dewald, Patrick; Edwards, Peter M.; Friedrich, Nils; Fry, Juliane L.; Hallquist, Mattias; Hantschke, Luisa; Hohaus, Thorsten; Kang, Sungah; Liebmann, Jonathan; Mayhew, Alfred W.; Mentel, Thomas; Reimer, David; Rohrer, Franz; Shenolikar, Justin; Tillmann, Ralf; Tsiligiannis, Epameinondas; Wu, Rongrong; Wahner, Andreas; Kiendler-Scharr, Astrid; Fuchs, Hendrik
发表日期	2023
ISSN	1680-7316
EISSN	1680-7324
起始页码	3147
结束页码	3180
卷号	23 期号:5 页码:34
英文摘要	The gas-phase reaction of isoprene with the nitrate radical (NO3) was investigated in experiments in the outdoor SAPHIR chamber under atmospherically relevant conditions specifically with respect to the chemical lifetime and fate of nitrato-organic peroxy radicals (RO2). Observations of organic products were compared to concentrations expected from different chemical mechanisms: (1) the Master Chemical Mechanism, which simplifies the NO3 isoprene chemistry by only considering one RO2 isomer; (2) the chemical mechanism derived from experiments in the Caltech chamber, which considers different RO2 isomers; and (3) the FZJ-NO3 isoprene mechanism derived from quantum chemical calculations, which in addition to the Caltech mechanism includes equilibrium reactions of RO(2 )isomers, unimolecular reactions of nitrate RO(2 )radicals and epoxidation reactions of nitrate alkoxy radicals. Measurements using mass spectrometer instruments give evidence that the new reactions pathways predicted by quantum chemical calculations play a role in the NO3 oxidation of isoprene. Hydroperoxy aldehyde (HPALD) species, which are specific to unimolecular reactions of nitrate RO2, were detected even in the presence of an OH scavenger, excluding the possibility that concurrent oxidation by hydroxyl radicals (OH) is responsible for their formation. In addition, ion signals at masses that can be attributed to epoxy compounds, which are specific to the epoxidation reaction of nitrate alkoxy radicals, were detected. Measurements of methyl vinyl ketone (MVK) and methacrolein (MACR) concentrations confirm that the decomposition of nitrate alkoxy radicals implemented in the Caltech mechanism cannot compete with the ring-closure reactions predicted by quantum chemical calculations. The validity of the FZJ-NO3 isoprene mechanism is further supported by a good agreement between measured and simulated hydroxyl radical (OH) reactivity. Nevertheless, the FZJ-NO3 isoprene mechanism needs further investigations with respect to the absolute importance of unimolecular reactions of nitrate RO2 and epoxidation reactions of nitrate alkoxy radicals. Absolute concentrations of specific organic nitrates such as nitrate hydroperoxides would be required to experimentally determine product yields and branching ratios of reactions but could not be measured in the chamber experiments due to the lack of calibration standards for these compounds. The temporal evolution of mass traces attributed to product species such as nitrate hydroperoxides, nitrate carbonyl and nitrate alcohols as well as hydroperoxy aldehydes observed by the mass spectrometer instruments demonstrates that further oxidation by the nitrate radical and ozone at atmospheric concentrations is small on the timescale of one night (12 h) for typical oxidant concentrations. However, oxidation by hydroxyl radicals present at night and potentially also produced from the decomposition of nitrate alkoxy radicals can contribute to their nocturnal chemical loss.
学科领域	Environmental Sciences; Meteorology & Atmospheric Sciences
语种	英语
WOS研究方向	Environmental Sciences & Ecology ; Meteorology & Atmospheric Sciences
WOS记录号	WOS:000946512800001
来源期刊	ATMOSPHERIC CHEMISTRY AND PHYSICS
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/273379
作者单位	Helmholtz Association; Research Center Julich; Centre National de la Recherche Scientifique (CNRS); National Oceanic Atmospheric Admin (NOAA) - USA; University of Colorado System; University of Colorado Boulder; Reed College - Oregon; Max Planck Society; University of York - UK; University of Gothenburg; University of Cologne; Gwangju Institute of Science & Technology (GIST); Wageningen University & Research
推荐引用方式 GB/T 7714	Carlsson, Philip T. M.,Vereecken, Luc,Novelli, Anna,et al. Comparison of isoprene chemical mechanisms under atmospheric night-time conditions in chamber experiments: evidence of hydroperoxy aldehydes and epoxy products from NO3 oxidation[J],2023,23(5):34.
APA	Carlsson, Philip T. M..,Vereecken, Luc.,Novelli, Anna.,Bernard, Francois.,Brown, Steven S..,...&Fuchs, Hendrik.(2023).Comparison of isoprene chemical mechanisms under atmospheric night-time conditions in chamber experiments: evidence of hydroperoxy aldehydes and epoxy products from NO3 oxidation.ATMOSPHERIC CHEMISTRY AND PHYSICS,23(5),34.
MLA	Carlsson, Philip T. M.,et al."Comparison of isoprene chemical mechanisms under atmospheric night-time conditions in chamber experiments: evidence of hydroperoxy aldehydes and epoxy products from NO3 oxidation".ATMOSPHERIC CHEMISTRY AND PHYSICS 23.5(2023):34.