Oligomer Content of α-Pinene Secondary Organic Aerosol

Hall, Wiley A.; Johnston, Murray V.

doi:10.1080/02786826.2010.517580

Cited by 99 publications

(132 citation statements)

References 24 publications

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“…4b. The total oligomer signal intensity was comparable to our previous study of α-pinene SOA formed under similar reaction conditions, where the oligomer content was experimentally determined to be about 50 % of the total SOA mass (Hall IV and Johnston, 2011). For the Tu study, we estimate the NVOC mixing ratio to be approximately 2 ppbv based on the yield estimate of Ehn et al (2014) for β-pinene ozonolysis.…”

Section: Comparison To Recent Experimental Measurements and Atmosphersupporting

confidence: 57%

“…Reactions such as these increase the aerosol yield by forming additional SOA beyond what would be expected from partitioning alone, if they form non-volatile products from semi-volatile reactants in the particle phase (Lopez-Hilfiker et al, 2016;Shiraiwa et al, 2014). Experimental measurements have shown that oligomers can constitute up to about 50 % of the mass of SOA produced from biogenic precursors in laboratory reactors, though it is not clear how much of the oligomeric matter is produced from semi-volatile vs. non-volatile precursors (Hall IV and Johnston, 2011). …”

Section: Introductionmentioning

confidence: 99%

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Nanoparticle growth by particle-phase chemistry

Apsokardu¹,

Johnston²

2018

Atmos. Chem. Phys.

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Abstract. The ability of particle-phase chemistry to alter the molecular composition and enhance the growth rate of nanoparticles in the 2-100 nm diameter range is investigated through the use of a kinetic growth model. The molecular components included are sulfuric acid, ammonia, water, a non-volatile organic compound, and a semi-volatile organic compound. Molecular composition and growth rate are compared for particles that grow by partitioning alone vs. those that grow by a combination of partitioning and an accretion reaction in the particle phase between two organic molecules. Particle-phase chemistry causes a change in molecular composition that is particle diameter dependent, and when the reaction involves semi-volatile molecules, the particles grow faster than by partitioning alone. These effects are most pronounced for particles larger than about 20 nm in diameter. The modeling results provide a fundamental basis for understanding recent experimental measurements of the molecular composition of secondary organic aerosol showing that accretion reaction product formation increases linearly with increasing aerosol volume-to-surface-area. They also allow initial estimates of the reaction rate constants for these systems. For secondary aerosol produced by either OH oxidation of the cyclic dimethylsiloxane (D 5 ) or ozonolysis of β-pinene, oligomerization rate constants on the order of 10 −3 to 10 −1 M −1 s −1 are needed to explain the experimental results. These values are consistent with previously measured rate constants for reactions of hydroperoxides and/or peroxyacids in the condensed phase.

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Section: Comparison To Recent Experimental Measurements and Atmosphersupporting

confidence: 57%

Section: Introductionmentioning

confidence: 99%

Nanoparticle growth by particle-phase chemistry

Apsokardu¹,

Johnston²

2018

Atmos. Chem. Phys.

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“…According to several studies SOA particles may contain oligomers, polymers and other high molecular weight molecules (Tolocka et al, 2004;Gao et al, 2004;Kalberer et al, 2004;Hallquist et al, 2009;Hall IV and Johnston, 2011;Kundu et al, 2012). Such oligomers and polymers are likely to affect the phase state of SOA particles.…”

Section: Discussionmentioning

confidence: 99%

Humidity-dependent phase state of SOA particles from biogenic and anthropogenic precursors

et al. 2012

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Abstract. The physical phase state (solid, semi-solid, or liquid) of secondary organic aerosol (SOA) particles has important implications for a number of atmospheric processes. We report the phase state of SOA particles spanning a wide range of oxygen to carbon ratios (O / C), used here as a surrogate for SOA oxidation level, produced in a flow tube reactor by photo-oxidation of various atmospherically relevant surrogate anthropogenic and biogenic volatile organic compounds (VOCs). The phase state of laboratory-generated SOA was determined by the particle bounce behavior after inertial impaction on a polished steel substrate. The measured bounce fraction was evaluated as a function of relative humidity and SOA oxidation level (O / C) measured by an Aerodyne high resolution time of flight aerosol mass spectrometer (HR-ToF AMS).The main findings of the study are: (1) biogenic and anthropogenic SOA particles are found to be amorphous solid or semi-solid based on the measured bounced fraction (BF), which was typically higher than 0.6 on a 0 to 1 scale. A decrease in the BF is observed for most systems after the SOA is exposed to relative humidity of at least 80 % RH, corresponding to a RH at impaction of 55 %. (2) Long-chain alkanes have a low BF (indicating a "liquid-like", less viscous phase) particles at low oxidation levels (BF < 0.2 ± 0.05 for O / C = 0.1). However, BF increases substantially upon increasing oxidation. (3) Increasing the concentration of sulphuric acid (H 2 SO 4 ) in solid SOA particles (here tested for longifolene SOA) causes a decrease in BF levels. (4) In the majority of cases the bounce behavior of the various SOA systems did not show correlation with the particle O / C. Rather, the molar mass of the gas-phase VOC precursor showed a positive correlation with the resistance to the RH-induced phase change of the formed SOA particles.

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“…SVOC can react further to produce nonvolatile organic compounds (NVOC) that reside fully in the particle phase [3,4]. Recent measurements of laboratory generated SOA show that oligomers formed by the reaction of SVOC monomers to produce mostly dimer and trimer species constitute more than half of the NVOC [5,6]. Because of the large number of monomer building blocks and reactions that may couple them together, these oligomers exhibit great molecular complexity.…”

Section: Introductionmentioning

confidence: 99%

Oligomer Formation Pathways in Secondary Organic Aerosol from MS and MS/MS Measurements with High Mass Accuracy and Resolving Power

Hall

Johnston

2012

J. Am. Soc. Mass Spectrom.

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Secondary organic aerosol (SOA) is formed when organic molecules react with oxidants in the gas phase to form particulate matter. Recent measurements have shown that more than half of the mass of laboratory-generated SOA consists of high molecular weight oligomeric compounds. In this work, the formation mechanisms of oligomers produced in the laboratory by ozonolysis of α-pinene, an important SOA precursor in ambient air, are studied by MS and MS/MS measurements with high accuracy and resolving power to characterize monomer building blocks and the reactions that couple them together. The distribution of oligomers in an SOA sample is complex, typically yielding over 1000 elemental formulas that can be assigned from an electrospray ionization mass spectrum. Despite this complexity, MS/MS spectra can be found that give strong evidence for specific oligomer formation pathways that have been postulated but not confirmed. These include aldol and gem-diol reactions of carbonyls as well as peroxyhemiacetal formation from hydroperoxides. The strongest evidence for carbonyl reactions is in the formation of hydrated products. Less compelling evidence is found for dehydrated products and secondary ozonide formation. The number of times that a monomer building block is observed as a fragmentation product in the MS/MS spectra is shown to be independent of the monomer vapor pressure, suggesting that oligomer formation is not driven by equilibrium partitioning of a monomer between the gas and particle phases, but rather by reactive uptake where a monomer collides with the particle surface and rapidly forms an oligomer.

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Oligomer Content of α-Pinene Secondary Organic Aerosol

Cited by 99 publications

References 24 publications

Nanoparticle growth by particle-phase chemistry

Nanoparticle growth by particle-phase chemistry

Humidity-dependent phase state of SOA particles from biogenic and anthropogenic precursors

Oligomer Formation Pathways in Secondary Organic Aerosol from MS and MS/MS Measurements with High Mass Accuracy and Resolving Power

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