What Is Required for Highly Oxidized Molecules To Form Clusters with Sulfuric Acid?

Elm, Jonas; Myllys, Nanna; Kurtén, Theo

doi:10.1021/acs.jpca.7b03759

Cited by 64 publications

(78 citation statements)

References 91 publications

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“…In these systems, autoxidation reactions proceed through successive isomerizations and O 2 additions, resulting in the formation of molecules with high O/C ratios and, often, multiple hydroperoxide groups (31). Such compounds have recently been observed to undergo gas-particle transfer (32) and have been shown to be important in particle nucleation (33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50).…”

mentioning

confidence: 99%

Atmospheric autoxidation is increasingly important in urban and suburban North America

Praske

Otkjær

Crounse

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

178

310

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Gas-phase autoxidation-regenerative peroxy radical formation following intramolecular hydrogen shifts-is known to be important in the combustion of organic materials. The relevance of this chemistry in the oxidation of organics in the atmosphere has received less attention due, in part, to the lack of kinetic data at relevant temperatures. Here, we combine computational and experimental approaches to investigate the rate of autoxidation for organic peroxy radicals (RO 2 ) produced in the oxidation of a prototypical atmospheric pollutant, n-hexane. We find that the reaction rate depends critically on the molecular configuration of the RO 2 radical undergoing hydrogen transfer (H-shift). RO 2 H-shift rate coefficients via transition states involving six-and seven-membered rings (1,5 and 1,6 H-shifts, respectively) of α-OH hydrogens (HOC-H) formed in this system are of order 0.1 s −1 at 296 K, while the 1,4 H-shift is calculated to be orders of magnitude slower. Consistent with H-shift reactions over a substantial energetic barrier, we find that the rate coefficients of these reactions increase rapidly with temperature and exhibit a large, primary, kinetic isotope effect. The observed H-shift rate coefficients are sufficiently fast that, as a result of ongoing NO x emission reductions, autoxidation is now competing with bimolecular chemistry even in the most polluted North American cities, particularly during summer afternoons when NO levels are low and temperatures are elevated.atmospheric chemistry | air pollution | autoxidation

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confidence: 99%

Atmospheric autoxidation is increasingly important in urban and suburban North America

Praske

Otkjær

Crounse

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

178

310

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“…It displays that a transformation from original SA to the coexistence of original SA molecules and acid molecular clusters. As proposed in previous report, carboxylic acid could be connected tightly with inorganic acid molecules through intermolecular H‐bonding interactions, which induces a local anisotropic environment in the system. Namely, the produced acid molecular cluster consists of the SA and HNO 3 molecule via H‐bonds.…”

Section: Resultsmentioning

confidence: 99%

“…It leads to that those residual HNO 3 , which are not involved in clustering reaction, would present in the form of free ions (H + and NO 3− ) rather than in the form of stable hydrates in acid‐treated composites . In light of the electronegativity of C=O group, carboxylic acid could act as the role of proton receptor to provide electrostatic forces for H + . It induces a weak interaction (C=O⋅⋅⋅H + ) between SA and H + and thus change the related electric charge density, related to the fresh band at 1383 cm −1 in FTIR spectrum of SA/Kaol‐0.5 (Figure b&6) …”

Section: Resultsmentioning

confidence: 99%

“…[49] In light of the electronegativity of C=O group, carboxylic acid could act as the role of proton receptor to provide electrostatic forces for H + . [46] It induces a weak interaction (C=O⋅⋅⋅H + ) between SA and H + and thus change the related electric charge density, related to the fresh band at 1383 cm À 1 in FTIR spectrum of SA/Kaol-0.5 (Figure 5b&6). [50] Consequently, the residuary H + is easily to infiltrate into the interspaces among SA molecules.…”

Section: Supercooling Behavior Of Compositesmentioning

confidence: 99%

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Thermal Performance and Interfacial Aspects of Kaolinite‐Based Stearic Acid Composite in the Presence of Nitric Acid

Yang

Zuo

et al. 2019

ChemistrySelect

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The effect of nitric acid on the thermal performance of stearic acid/kaolinite (SA/Kaol) composite phase change materials (PCMs) was studied. SA/Kaol was subjected to HNO3 manipulations at different acidity conditions. The results indicated that inferior thermal properties were detected at the acid‐treated composites with pH < 2. The latent heat value of SA/Kaol‐0.5 demonstrated an obvious reduction of about 30% compared with that of SA/Kaol, and its supercooling extent could reach as many as 11.2 °C while that of SA/Kaol was only 1.4 °C. Based on interfacial reaction analysis, the reduced crystallinity of SA should be attributed to the confinement effect originated from acid molecular clusters, while the supercooling behavior was caused by external ions. These ions could hinder SA molecules from adsorbing to the surface of crystal nucleus and thus delay the solidification process. As a result of segregation effect, the latent heat value of acid‐treated samples was deteriorated but the supercooling extent was relieved during thermal cycles. This work was the first that reported the effect of nitrogen oxides on PCMs. We believe that the results could play an enlightening role in the stability study of thermal property during PCMs practical applications.

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“…Although the chemical composition of α-pinene SOA has been extensively studied, uncertainty still remains regarding the chemical structure and functional groups of the compounds responsible for nucleation. Recent quantum chemical results indicate that multi carboxylic acids with three 70 or more acid moieties are some of the most likely compounds to participate in new particle formation (Elm et al, 2017;Elm et al, 2019).…”

Section: Introduction 40mentioning

confidence: 99%

The Aarhus Chamber Campaign on Highly Oxidized Multifunctional Organic Molecules and Aerosols (ACCHA): Particle Formation and Detailed Chemical Composition at Different Temperatures

Kristensen

Jensen

Quéléver

et al. 2020

Preprint

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Abstract. Little is known about the effects of low temperatures on the formation of SOA from α-pinene. In the current work, ozone-initiated oxidation of α-pinene at initial concentrations of 10 and 50 ppb, respectively, is performed at temperatures of 20, 0 and −15 °C in the Aarhus University Research on Aerosol (AURA) smog chamber during the Aarhus Chamber Campaign on highly oxidized multifunctional organic molecules and Aerosol (ACCHA). Here, we show how temperature influences the formation and chemical composition of α-pinene-derived SOA with a specific focus on the formation of organic acids and dimer esters. With respect to particle formation, results show significant increase in both particle formation rates, particle number concentrations and particle mass concentrations at lower temperatures. In particular, the number concentrations of sub-10 nm particles were significantly enhanced at the lower 0 and -15 °C temperatures. Temperatures also affect chemical composition of the formed SOA. Here, detailed off-line chemical analyses show organic acids contributing from 15 to 30 % by mass, with highest contributions observed at the lower temperatures indicative of enhanced condensation of these semi-volatile species. In comparison, 30 identified dimer esters contribute between 4–11 % to SOA mass. No significant differences in the chemical composition (i.e. organic acids and dimer esters) of the α-pinene-derived SOA particles are observed between experiments performed at 10 and 50 ppb initial α-pinene concentrations, thus suggesting a higher influence of reaction temperature compared to that of α-pinene loading on the SOA chemical composition. Interestingly, the effect of temperature on the formation of dimer esters differs between the individual species. The formation of less oxidized (oxygen-to-carbon ratio (O:C) < 0.4) dimer esters is shown to increase at lower temperatures while the formation of the more oxidized (O:C > 0.4) species is suppressed, consequently resulting in temperature-modulated composition of the α-pinene derived SOA. Temperature ramping experiments exposing α-pinene-derived SOA to changing temperatures (heating and cooling) reveal that the chemical composition of the SOA with respect to dimer esters is governed almost solely by the temperature during the initial oxidization and insusceptible to subsequent changes in temperature. Similarly, the resulting SOA mass concentrations were found to be more influenced by the initial α-pinene oxidation temperatures, thus suggesting that the formation conditions to a large extent govern the type of SOA formed, rather than the conditions to which the SOA is later exposed. For the first time, we discuss the relation between the identified dimer ester and the highly oxidized multifunctional organic molecules (HOMs) measured by Chemical Ionization Atmospheric Pressure interface Time-of-Flight mass spectrometer (CI-APi-TOF) during ACCHA experiments. We propose that, although very different in chemical structures and O:C-ratios, dimer esters and HOMs may be linked through the mechanism of RO2 autoxidation, and that dimer esters and HOMs merely represent two different fates of the RO2 radicals.

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What Is Required for Highly Oxidized Molecules To Form Clusters with Sulfuric Acid?

Cited by 64 publications

References 91 publications

Atmospheric autoxidation is increasingly important in urban and suburban North America

Atmospheric autoxidation is increasingly important in urban and suburban North America

Thermal Performance and Interfacial Aspects of Kaolinite‐Based Stearic Acid Composite in the Presence of Nitric Acid

The Aarhus Chamber Campaign on Highly Oxidized Multifunctional Organic Molecules and Aerosols (ACCHA): Particle Formation and Detailed Chemical Composition at Different Temperatures

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