Highly Oxygenated Molecules from Atmospheric Autoxidation of Hydrocarbons: A Prominent Challenge for Chemical Kinetics Studies

Ehn, Mikael; Berndt, Torsten; Wildt, Jürgen; Mentel, Thomas F.

doi:10.1002/kin.21130

Cited by 55 publications

(46 citation statements)

References 55 publications

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“…Due to their high O/C ratios (close to unity), they have sufficiently low volatilities to contribute to aerosol nucleation and growth. Several studies have quantified HOM yields from monoterpenes (Ehn et al, ; Ehn et al, ; Jokinen et al, ), isoprene (Jokinen et al, ), and AVOCs (e.g., alkyl benzenes; Molteni et al, ; Praske et al, ; S. Wang et al, ). The exact formation pathways and properties of HOMs are still under investigation (Berndt et al, ; Bianchi et al, ; Ehn et al, ).…”

Section: Nucleation and Growth Mechanisms: New Results From Laboratormentioning

confidence: 99%

“…Several studies have quantified HOM yields from monoterpenes Ehn et al, 2017;Jokinen et al, 2015), isoprene , and AVOCs (e.g., alkyl benzenes; Molteni et al, 2018;Praske et al, 2018;. The exact formation pathways and properties of HOMs are still under investigation (Berndt et al, 2016;Bianchi et al, 2019;Ehn et al, 2017). Schobesberger et al (2013) have shown that HOMs (e.g., C 10 H 12-16 O 2-10 ) formed from OH oxidation reactions of pinanediol (C 10 H 18 O 2 , a first generation oxidation product of monoterpenes) interact with sulfuric acid to form monomers to tetramers ( Figure 4), and these HOMs can enhance J for sulfuric acid.…”

Section: Homs Formed From Vocs Oxidation Reactionsmentioning

confidence: 99%

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New Particle Formation in the Atmosphere: From Molecular Clusters to Global Climate

et al. 2019

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New particle formation (NPF) represents the first step in the complex processes leading to formation of cloud condensation nuclei. Newly formed nanoparticles affect human health, air quality, weather, and climate. This review provides a brief history, synthesizes recent significant progresses, and outlines the challenges and future directions for research relevant to NPF. New developments include the emergence of state‐of‐the‐art instruments that measure prenucleation clusters and newly nucleated nanoparticles down to about 1 nm; systematic laboratory studies of multicomponent nucleation systems, including collaborative experiments conducted in the Cosmics Leaving Outdoor Droplets chamber at CERN; observations of NPF in different types of forests, extremely polluted urban locations, coastal sites, polar regions, and high‐elevation sites; and improved nucleation theories and parameterizations to account for NPF in atmospheric models. The challenges include the lack of understanding of the fundamental chemical mechanisms responsible for aerosol nucleation and growth under diverse environments, the effects of SO2 and NOx on NPF, and the contribution of anthropogenic organic compounds to NPF. It is also critical to develop instruments that can detect chemical composition of particles from 3 to 20 nm and improve parameterizations to represent NPF over a wide range of atmospheric conditions of chemical precursor, temperature, and humidity.

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Section: Nucleation and Growth Mechanisms: New Results From Laboratormentioning

confidence: 99%

Section: Homs Formed From Vocs Oxidation Reactionsmentioning

confidence: 99%

New Particle Formation in the Atmosphere: From Molecular Clusters to Global Climate

et al. 2019

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“…Evidence for the operation of peroxy radical isomerization reactions has been reported in numerous theoretical and laboratory studies (e.g. Vereecken and Peeters, 2004;Peeters et al, 2009;Crounse et al, 2013;Ehn et al, 2014;2017;Jokinen et al, 2014;Rissanen et al, 2015;Jørgensen et al, 2016), and new information is constantly emerging on this important aspect of peroxy radical chemistry. The present 10 section provides a summary of selected classes of isomerization reaction that are currently being considered and represented in ongoing mechanism development work.…”

Section: Unimolecular Reactions Of Ro 2 Radicalsmentioning

confidence: 98%

“…These reactions therefore potentially play an important role in HO x radical recycling under NO xlimited conditions, and in rapid chain oxidation mechanisms generating highly oxidised multifunctional molecules, HOMs (e.g. Peeters et al, 2009;Crounse et al, 2013;Ehn et al, 2014;2017;Jokinen et al, 2014;Rissanen et al, 2015). The relative contributions of the various reactions available for RO 2 thus influence the distribution and functional group content 30 of the oxidized products formed, and their physicochemical properties (e.g.…”

mentioning

confidence: 99%

Estimation of rate coefficients and branching ratios for reactions of organic peroxy radicals for use in automated mechanism construction

Jenkin¹,

Valorso²,

Aumont³

et al. 2019

Preprint

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Abstract. Organic peroxy radicals (RO2), formed from the degradation of hydrocarbons and other volatile organic compounds (VOCs), play a key role in tropospheric oxidation mechanisms. Several competing reactions may be available for a given RO2 radical, the relative rates of which depend on both the structure of RO2 and the ambient conditions. Published kinetics and branching ratio data are reviewed for the bimolecular reactions of RO2 with NO, NO2, NO3, OH and HO2; and for their self-reactions and cross-reactions with other RO2 radicals. This information is used to define generic rate coefficients and structure-activity relationship (SAR) methods that can be applied to the bimolecular reactions of a series of important classes of hydrocarbon and oxygenated RO2 radical. Information for selected unimolecular isomerization reactions (i.e. H-atom shift and ring-closure reactions) is also summarised and discussed. The methods presented here are intended to guide the representation of RO2 radical chemistry in the next generation of explicit detailed chemical mechanisms.

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“…These "non-HOM" RO2 radicals may then also be key molecules for determining the final branching leading to the different observed HOM with 7 or more O atoms. This may shed light on one of the main open challenges (Ehn et al, 2017) in understanding HOM formation, namely how RO2 radicals with e.g. 6, 8 and 10 O atoms can form within a second, yet the relative distribution of these three does not change if the reaction time is allowed to increase (Berndt et al, 2015).…”

Section: Yield Estimation and Temperature Influence For Molecule-specmentioning

confidence: 99%

Effect of temperature on the formation of Highly-oxygenated Organic Molecules (HOM) from alpha-pinene ozonolysis

Quéléver¹,

Kristensen²,

Jensen³

et al. 2018

Preprint

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Abstract. Highly-oxygenated Organic Molecules (HOM) are important contributors to Secondary Organic Aerosol (SOA) and New-Particle Formation (NPF) in the boreal atmosphere. This newly discovered class of molecules is efficiently formed from atmospheric oxidation of biogenic volatile organic compounds (VOC), such as monoterpenes, through a process called autoxidation. This process, in which peroxy-radical intermediates isomerize to allow addition of molecular oxygen, is expected to be highly temperature-dependent. Here, we studied the dynamics of HOM formation during alpha-pinene ozonolysis experiments performed at three different temperatures, 20&#8201;&#176;C, 0&#8201;&#176;C and &#8722;15&#8201;&#176;C, in the Aarhus University Research on Aerosol (AURA) chamber. We found that the HOM formation, under our experimental conditions (50&#8201;ppb alpha-pinene, 100&#8201;ppb ozone), decreased considerably as temperature decreased, with molar yields dropping by around a factor of 50 when experiments were performed at 0&#8201;&#176;C, compared to 20&#8201;&#176;C. At &#8722;15&#8201;&#176;C, the HOM signals were already close to the detection limit of the nitrate-based Chemical Ionization Atmospheric Pressure interface Time Of Flight (CI-APi-TOF) mass spectrometer used for measuring gas-phase HOM. Surprisingly, very little difference was seen in the mass spectral distribution of the HOM molecules of interest at 0&#8201;&#176;C and 20&#8201;&#176;C, with e.g. the ratios between the typical HOM products C10H14O7, C10H14O9, and C10H14O11 remaining fairly constant. The more oxidized species have undergone more isomerization steps, yet, at lower temperature, they did not decrease more than the less oxidized species. One possible explanation is be that the rate-limiting step forming these HOM occurs before the products become oxygenated enough to be detected by our CI-APi-TOF (i.e. typically seven or more oxygen atoms). The strong temperature dependence of HOM formation was observed under temperatures highly relevant for the boreal forest, but the exact magnitude of this effect in the atmosphere will be much more complex: the fate of peroxy-radicals is a competition between autoxidation (influenced by temperature and VOC type) and bimolecular termination pathways (influenced mainly by concentration of reaction partners). While the temperature influence is likely smaller in the boreal atmosphere than in our chamber, the magnitude and complexity of this effect clearly deserves more consideration in future studies in order to estimate the ultimate role of HOM on SOA and NPF under different atmospheric conditions.

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Highly Oxygenated Molecules from Atmospheric Autoxidation of Hydrocarbons: A Prominent Challenge for Chemical Kinetics Studies

Cited by 55 publications

References 55 publications

New Particle Formation in the Atmosphere: From Molecular Clusters to Global Climate

New Particle Formation in the Atmosphere: From Molecular Clusters to Global Climate

Estimation of rate coefficients and branching ratios for reactions of organic peroxy radicals for use in automated mechanism construction

Effect of temperature on the formation of Highly-oxygenated Organic Molecules (HOM) from alpha-pinene ozonolysis

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