scholarly journals Molecular composition and volatility of multi-generation products formed from isoprene oxidation by nitrate radical

2021 ◽  
Vol 21 (13) ◽  
pp. 10799-10824
Author(s):  
Rongrong Wu ◽  
Luc Vereecken ◽  
Epameinondas Tsiligiannis ◽  
Sungah Kang ◽  
Sascha R. Albrecht ◽  
...  
Keyword(s):  
Oxidation Products ◽  
Formation Mechanisms ◽  
Organic Nitrates ◽  
Ionization Mass ◽  
Nitrate Radical ◽  
Time Behavior ◽  
Vapor Pressures ◽  
Atmospheric Conditions ◽  
Isoprene Nitrates ◽  
Isoprene Oxidation

Abstract. Isoprene oxidation by nitrate radical (NO3) is a potentially important source of secondary organic aerosol (SOA). It is suggested that the second or later-generation products are the more substantial contributors to SOA. However, there are few studies investigating the multi-generation chemistry of isoprene-NO3 reaction, and information about the volatility of different isoprene nitrates, which is essential to evaluate their potential to form SOA and determine their atmospheric fate, is rare. In this work, we studied the reaction between isoprene and NO3 in the SAPHIR chamber (Jülich) under near-atmospheric conditions. Various oxidation products were measured by a high-resolution time-of-flight chemical ionization mass spectrometer using Br− as the reagent ion. Most of the products detected are organic nitrates, and they are grouped into monomers (C4 and C5 products) and dimers (C10 products) with 1–3 nitrate groups according to their chemical composition. Most of the observed products match expected termination products observed in previous studies, but some compounds such as monomers and dimers with three nitrogen atoms were rarely reported in the literature as gas-phase products from isoprene oxidation by NO3. Possible formation mechanisms for these compounds are proposed. The multi-generation chemistry of isoprene and NO3 is characterized by taking advantage of the time behavior of different products. In addition, the vapor pressures of diverse isoprene nitrates are calculated by different parametrization methods. An estimation of the vapor pressure is also derived from their condensation behavior. According to our results, isoprene monomers belong to intermediate-volatility or semi-volatile organic compounds and thus have little effect on SOA formation. In contrast, the dimers are expected to have low or extremely low volatility, indicating that they are potentially substantial contributors to SOA. However, the monomers constitute 80 % of the total explained signals on average, while the dimers contribute less than 2 %, suggesting that the contribution of isoprene NO3 oxidation to SOA by condensation should be low under atmospheric conditions. We expect a SOA mass yield of about 5 % from the wall-loss- and dilution-corrected mass concentrations, assuming that all of the isoprene dimers in the low- or extremely low-volatility organic compound (LVOC or ELVOC) range will condense completely.

scholarly journals Molecular composition and volatility of multi-generation products formed from isoprene oxidation by nitrate radical

2020 ◽  
Author(s):  
Rongrong Wu ◽  
Luc Vereecken ◽  
Epameinondas Tsiligiannis ◽  
Sungah Kang ◽  
Sascha R. Albrecht ◽  
...  
Keyword(s):  
Oxidation Products ◽  
Formation Mechanisms ◽  
Ionization Mass ◽  
Nitrate Radical ◽  
Time Behavior ◽  
Vapor Pressures ◽  
Atmospheric Conditions ◽  
Isoprene Nitrates ◽  
Wall Loss ◽  
Isoprene Oxidation

Abstract. Isoprene oxidation by nitrate radical (NO3) is a potentially important source of secondary organic aerosol (SOA). It is suggested that the second or later-generation products are the more substantial contributors to SOA. However, there are few studies investigating the multi-generation chemistry of isoprene-NO3 reaction, and information about the volatility of different isoprene nitrates, which is essential to evaluate their potential to form SOA and determine their atmospheric fate, is rare. In this work, we studied the reaction between isoprene and NO3 in the SAPHIR chamber (Jülich) under near atmospheric conditions. Various oxidation products were measured by a high-resolution time-of-flight chemical ionization mass spectrometer using Br− as the reagent ion. They are grouped into monomers (C4- and C5-products), and dimers (C10-products) with 1–3 nitrate groups according to their chemical composition. Most of the observed products match expected termination products observed in previous studies, but some compounds such as monomers and dimers with three nitrogen atoms were rarely reported in the literature as gas-phase products from isoprene oxidation by NO3. Possible formation mechanisms for these compounds are proposed. The multi-generation chemistry of isoprene and NO3 is characterized by taking advantages of the time behavior of different products. In addition, the vapor pressures of diverse isoprene nitrates are calculated by different parametrization methods. An estimation of the vapor pressure is also derived from their condensation behavior. According to our results, isoprene monomers belong to intermediate volatility or semi-volatile organic compounds and thus have little effect on SOA formation. In contrast, the dimers are expected to have low or extremely low volatility, indicating that they are potentially substantial contributors to SOA. However, the monomers constitute 80 % of the total explained signals on average, while the dimers contribute less than 2 %, suggesting that the contribution of isoprene NO3 oxidation to SOA by condensation should be low under atmospheric conditions. We expect a SOA mass yield of about 5 % from the wall loss and dilution corrected mass concentrations, assuming that all of the isoprene dimers in the low- or extremely low-volatility organic compound (LVOC or ELVOC) range will condense completely.

scholarly journals Modeling secondary organic aerosol formation from isoprene oxidation under dry and humid conditions

2011 ◽  
Vol 11 (2) ◽  
pp. 893-909 ◽  
Author(s):  
F. Couvidat ◽  
C. Seigneur
Keyword(s):  
Experimental Data ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Organic Nitrates ◽  
Atmospheric Conditions ◽  
Aerosol Formation ◽  
Yield Increase ◽  
Isoprene Oxidation ◽  
Smog Chambers

Abstract. A new model for the formation of secondary organic aerosol (SOA) from isoprene was developed. This model uses surrogate molecular species (hydroxy-hydroperoxides, tetrols, methylglyceric acid, organic nitrates) to represent SOA formation. The development of this model used available experimental data on yields and molecular composition of SOA from isoprene and methacrolein oxidation. This model reproduces the amount of particles measured in smog chambers under both low-NOx and high-NOx conditions. Under low-NOx conditions, the model reproduces the transitional formation of hydroxy-hydroperoxides particles, which are photolyzed and lead to SOA mass decrease after reaching a maximum. Under high-NOx conditions, particles are assumed to be formed mostly from the photo-oxidation of a PAN-type molecule derived from methacrolein (MPAN). This model successfully reproduces the complex NOx-dependence of isoprene oxidation and suggests a possible yield increase under some high-NOx conditions. Experimental data correspond to dry conditions (RH < 10%). However, particles formed from isoprene are expected to be highly hydrophilic, and isoprene oxidation products would likely partition between an aqueous phase and the gas phase at high humidity in the atmosphere. The model was extended to take into account the hydrophilic properties of SOA, which are relevant under atmospheric conditions, and investigate the effect of particulate liquid water on SOA formation. An important increase in SOA mass was estimated for humid conditions due to the hydrophilic properties. Experiments under high relative humidity conditions should be conducted to confirm the results of this study, which have implications for SOA modeling.

scholarly journals Characterization of organic nitrate constituents of secondary organic aerosol (SOA) from nitrate-radical-initiated oxidation of limonene using high-resolution chemical ionization mass spectrometry

2018 ◽  
Vol 18 (8) ◽  
pp. 5467-5481 ◽  
Author(s):  
Cameron Faxon ◽  
Julia Hammes ◽  
Michael Le Breton ◽  
Ravi Kant Pathak ◽  
Mattias Hallquist
Keyword(s):  
High Resolution ◽  
Chemical Ionization ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Formation Mechanisms ◽  
Organic Nitrate ◽  
Organic Nitrates ◽  
Ionization Mass ◽  
Nitrate Radical ◽  
Particle Phase

Abstract. The gas-phase nitrate radical (NO3⚫) initiated oxidation of limonene can produce organic nitrate species with varying physical properties. Low-volatility products can contribute to secondary organic aerosol (SOA) formation and organic nitrates may serve as a NOx reservoir, which could be especially important in regions with high biogenic emissions. This work presents the measurement results from flow reactor studies on the reaction of NO3⚫ with limonene using a High-Resolution Time-of-Flight Chemical Ionization Mass Spectrometer (HR-ToF-CIMS) combined with a Filter Inlet for Gases and AEROsols (FIGAERO). Major condensed-phase species were compared to those in the Master Chemical Mechanism (MCM) limonene mechanism, and many non-listed species were identified. The volatility properties of the most prevalent organic nitrates in the produced SOA were determined. Analysis of multiple experiments resulted in the identification of several dominant species (including C10H15NO6, C10H17NO6, C8H11NO6, C10H17NO7, and C9H13NO7) that occurred in the SOA under all conditions considered. Additionally, the formation of dimers was consistently observed and these species resided almost completely in the particle phase. The identities of these species are discussed, and formation mechanisms are proposed. Cluster analysis of the desorption temperatures corresponding to the analyzed particle-phase species yielded at least five distinct groupings based on a combination of molecular weight and desorption profile. Overall, the results indicate that the oxidation of limonene by NO3⚫ produces a complex mixture of highly oxygenated monomer and dimer products that contribute to SOA formation.

scholarly journals Modeling secondary organic aerosol formation from isoprene oxidation under dry and humid conditions

2010 ◽  
Vol 10 (8) ◽  
pp. 20559-20605
Author(s):  
F. Couvidat ◽  
C. Seigneur
Keyword(s):  
Experimental Data ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Organic Nitrates ◽  
Atmospheric Conditions ◽  
Aerosol Formation ◽  
Yield Increase ◽  
Isoprene Oxidation ◽  
Smog Chambers

Abstract. A new model for the formation of secondary organic aerosol (SOA) from isoprene was developed. This model uses surrogate molecular species (hydroxy-hydroperoxides, tetrols, methylglyceric acid, organic nitrates) to represent SOA formation. The development of this model used available experimental data on yields and molecular composition of SOA from isoprene and methacrolein oxidation. This model reproduces the amount of particles measured in smog chambers under both low-NOx and high-NOx conditions. Under low-NOx conditions, the model reproduces the transitional formation of hydroxy-hydroperoxides particles, which are photolyzed and lead to SOA mass decrease after reaching a maximum. Under high-NOx conditions, particles are assumed to be formed mostly from the photo-oxidation of a PAN-type molecule derived from methacrolein (MPAN). This model successfully reproduces the complex NOx-dependence of isoprene oxidation and suggests a possible yield increase under some high-NOx conditions. Experimental data correspond to dry conditions (RH<10%). However, particles formed from isoprene are expected to be highly hydrophilic, and isoprene oxidation products would likely partition between an aqueous phase and the gas phase at high humidity in the atmosphere. The model was extended to take into account the hydrophilic properties of SOA, which are relevant under atmospheric conditions, and investigate the effect of particulate liquid water on SOA formation. An important increase in SOA mass was estimated for atmospheric conditions due to the hydrophilic properties. Experiments should be conducted to confirm the results of this study, which have implications for SOA modeling.

scholarly journals Characterization of organic nitrate constituents of secondary organic aerosol (SOA) from nitrate-radical-initiated oxidation of limonene using High-Resolution Chemical Ionization Mass Spectrometry

2017 ◽  
Author(s):  
Cameron Faxon ◽  
Julia Hammes ◽  
Ravi Kant Pathak ◽  
Mattias Hallquist
Keyword(s):  
High Resolution ◽  
Chemical Ionization ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Formation Mechanisms ◽  
Organic Nitrate ◽  
Organic Nitrates ◽  
Ionization Mass ◽  
Nitrate Radical ◽  
Particle Phase

Abstract. The gas phase nitrate radical (NO3•) initiated oxidation of limonene can produce organic nitrate species with varying physical properties. Low-volatility products can contribute to secondary organic aerosol (SOA) formation and organic nitrates may serve as a NOx reservoir, which could be especially important in regions with high biogenic emissions. This work presents the measurement results from flow reactor studies on the reaction of NO3• and limonene using a High-Resolution Time-of-Flight Chemical Ionization Mass Spectrometer (HR-ToF-CIMS) combined with a Filter Inlet for Gases and AEROsols (FIGAERO). Major condensed-phase species were identified, and the identity and volatility properties of the most prevalent organic nitrates in the produced SOA were determined. Analysis of multiple experiments resulted in the identification of several dominant species (including C10H15NO6, C10H17NO6, C8H11NO6, C10H17NO7, and C9H13NO7) that occurred in the SOA under all conditions considered. The observed and expected (listed) products (associated with the Master Chemical Mechanism (MCM) limonene mechanism) were compared, and many non-listed species were identified. Additionally, the formation of dimers was consistently observed and these species resided almost completely in the particle phase. The identities of these species are discussed, and formation mechanisms are proposed. Cluster analysis of the desorption temperatures corresponding to the analyzed particle-phase species yielded at least five distinct groupings based on a combination of molecular weight and desorption profile. Overall, the results indicate that the oxidation of limonene by NO3• produces a complex mixture of highly oxygenated monomer and dimer products that contribute to SOA formation.

Photooxidation and ozonolysis of Δ3-carene and its oxidation product caronaldehyde in the atmospheric simulation chamber SAPHIR

2021 ◽  
Author(s):  
Luisa Hantschke ◽  
Anna Novelli ◽  
Birger Bohn ◽  
Changmin Cho ◽  
David Reimer ◽  
...  
Keyword(s):  
Oxidation Product ◽  
Boreal Forests ◽  
Oxidation Products ◽  
Organic Nitrate ◽  
Organic Nitrates ◽  
Peroxy Radicals ◽  
Atmospheric Conditions ◽  
Oxidation Reactions ◽  
Reaction Rate Constants ◽  
Simulation Chamber

&lt;p&gt;Of the total global annual monoterpene emissions, &amp;#916;&lt;sup&gt;3&lt;/sup&gt;-carene contributes 4.5 %, making it the 7&lt;sup&gt;th&lt;/sup&gt; most abundant monoterpene worldwide. As it is primarily emitted by pine trees, &amp;#916;&lt;sup&gt;3&lt;/sup&gt;-carene can regionally gain in importance, for example in boreal forests and Mediterranean regions.&amp;#160; Oxidation products of monoterpenes such as organic nitrates and aldehydes are known to impact the formation of secondary pollutants such as ozone and particles, so understanding their atmospheric formation and fate is crucial.&lt;/p&gt;&lt;p&gt;The photooxidation and ozonolysis of &amp;#916;&lt;sup&gt;3&lt;/sup&gt;-carene and the photooxidation and photolysis of its main daytime photooxidation product caronaldehyde were investigated in the atmospheric simulation chamber SAPHIR. Oxidation reactions were studied under atmospheric conditions with high (&gt; 8 ppbv) and low (&lt; 2 ppbv) NOx concentrations. Reaction rate constants of the reaction of &amp;#916;&lt;sup&gt;3&lt;/sup&gt;-carene with OH and O&lt;sub&gt;3&lt;/sub&gt;, and of the reaction of caronaldehyde with OH as well as photolysis frequencies of caronaldehyde were determined. Production and destruction rates of the sum of hydroxyl and peroxy radicals (ROx = OH+HO2+RO2) were analysed to determine if there were unaccounted production and loss processes of radicals in the oxidation of &amp;#916;&lt;sup&gt;3&lt;/sup&gt;-carene. The yield of &amp;#916;&lt;sup&gt;3&lt;/sup&gt;-carene&amp;#8217;s oxidation product caronaldehyde was determined from measured timeseries from OH photooxidation and ozonolysis experiments. Additionally, the OH yield from ozonolysis of &amp;#916;&lt;sup&gt;3&lt;/sup&gt;-carene was determined.&lt;/p&gt;&lt;p&gt;Organic nitrate (RONO&lt;sub&gt;2&lt;/sub&gt;) yields of the reaction of RO&lt;sub&gt;2&lt;/sub&gt; + NO, from RO&lt;sub&gt;2&lt;/sub&gt; produced from the reactions of &amp;#916;&lt;sup&gt;3&lt;/sup&gt;-carene and caronaldehyde with OH were determined by analyzing the reactive nitrogen species (NOy) in the chamber.&lt;/p&gt;

scholarly journals Phase partitioning and volatility of secondary organic aerosol components formed from α-pinene ozonolysis and OH oxidation: the importance of accretion products and other low volatility compounds

2015 ◽  
Vol 15 (14) ◽  
pp. 7765-7776 ◽  
Author(s):  
F. D. Lopez-Hilfiker ◽  
C. Mohr ◽  
M. Ehn ◽  
F. Rubach ◽  
E. Kleist ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Mass Spectrometer ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Negative Ion ◽  
Ionization Mass ◽  
Particle Phase ◽  
Vapor Pressures ◽  
Aerosol Mass

Abstract. We measured a large suite of gas- and particle-phase multi-functional organic compounds with a Filter Inlet for Gases and AEROsols (FIGAERO) coupled to a high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) developed at the University of Washington. The instrument was deployed on environmental simulation chambers to study monoterpene oxidation as a secondary organic aerosol (SOA) source. We focus here on results from experiments utilizing an ionization method most selective towards acids (acetate negative ion proton transfer), but our conclusions are based on more general physical and chemical properties of the SOA. Hundreds of compounds were observed in both gas and particle phases, the latter being detected by temperature-programmed thermal desorption of collected particles. Particulate organic compounds detected by the FIGAERO–HR-ToF-CIMS are highly correlated with, and explain at least 25–50 % of, the organic aerosol mass measured by an Aerodyne aerosol mass spectrometer (AMS). Reproducible multi-modal structures in the thermograms for individual compounds of a given elemental composition reveal a significant SOA mass contribution from high molecular weight organics and/or oligomers (i.e., multi-phase accretion reaction products). Approximately 50 % of the HR-ToF-CIMS particle-phase mass is associated with compounds having effective vapor pressures 4 or more orders of magnitude lower than commonly measured monoterpene oxidation products. The relative importance of these accretion-type and other extremely low volatility products appears to vary with photochemical conditions. We present a desorption-temperature-based framework for apportionment of thermogram signals into volatility bins. The volatility-based apportionment greatly improves agreement between measured and modeled gas-particle partitioning for select major and minor components of the SOA, consistent with thermal decomposition during desorption causing the conversion of lower volatility components into the detected higher volatility compounds.

scholarly journals Molecular understanding of new-particle formation from alpha-pinene between −50 °C and 25 °C

2020 ◽  
Author(s):  
Mario Simon ◽  
Lubna Dada ◽  
Martin Heinritzi ◽  
Wiebke Scholz ◽  
Dominik Stolzenburg ◽  
...  
Keyword(s):  
Oxidation State ◽  
Atmospheric Aerosols ◽  
Particle Formation ◽  
Oxidation Products ◽  
Basis Set ◽  
Ionization Mass ◽  
Vapor Pressures ◽  
New Particle Formation ◽  
Wide Range ◽  
Earth’S Climate

Abstract. Highly-oxygenated organic molecules (HOMs) contribute substantially to the formation and growth of atmospheric aerosol particles, which affect air quality, human health and Earth's climate. HOMs are formed by rapid, gas-phase autoxidation of volatile organic compounds (VOCs) such as α-pinene, the most abundant monoterpene in the atmosphere. Due to their abundance and low volatility, HOMs can play an important role for new-particle formation (NPF) and the early growth of atmospheric aerosols, even without any further assistance of other low-volatility compounds such as sulfuric acid. Both the autoxidation reaction forming HOMs and their new-particle formation rates are expected to be strongly dependent on temperature. However, experimental data on both effects are limited. Dedicated experiments were performed at the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber at CERN to address this question. In this study, we show that a decrease in temperature (from +25 to −50 °C) results in a reduced HOM yield and reduced oxidation state of the products, whereas the new-particle formation rates (J1.7 nm) increase substantially. Measurements with two different chemical ionization mass spectrometers (using nitrate and protonated water as reagent ion, respectively) provide the molecular composition of the gaseous oxidation products and a 2-dimensional volatility basis set model (2D-VBS) provides their volatility distribution. The HOM yield decreases with temperature from 6.2 % at 25 °C to 0.7 % at −50 °C. However, there is a strong reduction of the saturation vapor pressure of each oxidation state as the temperature is reduced. Overall, the reduction in volatility with temperature leads to an increase in the nucleation rates by up to three orders of magnitude at −50 °C compared with 25 °C. In addition, the enhancement of the nucleation rates by ions decreases with decreasing temperature, since the neutral molecular clusters have increased stability against evaporation. The resulting data quantify how the interplay between the temperature-dependent oxidation pathways and the associated vapor pressures affect biogenic new-particle formation at the molecular level. Our measurements therefore improve our understanding of pure biogenic new-particle formation for a wide range of tropospheric temperatures and precursor concentrations.

scholarly journals A product study of the isoprene+NO<sub>3</sub> reaction

2009 ◽  
Vol 9 (14) ◽  
pp. 4945-4956 ◽  
Author(s):  
A. E. Perring ◽  
A. Wisthaler ◽  
M. Graus ◽  
P. J. Wooldridge ◽  
A. L. Lockwood ◽  
...  
Keyword(s):  
Thermal Dissociation ◽  
Organic Aerosol ◽  
Proton Transfer Reaction ◽  
Product Formation ◽  
Oxidation Products ◽  
Organic Nitrate ◽  
Organic Nitrates ◽  
Isoprene Nitrates ◽  
Additional Constraints ◽  
Product Study

Abstract. Oxidation of isoprene through reaction with NO3 radicals is a significant sink for isoprene that persists after dark. The main products of the reaction are multifunctional nitrates. These nitrates constitute a significant NOx sink in the nocturnal boundary layer and they likely play an important role in formation of secondary organic aerosol. Products of the isoprene+NO3 reaction will, in many locations, be abundant enough to affect nighttime radical chemistry and to persist into daytime where they may represent a source of NOx. Product formation in the isoprene + NO3 reaction was studied in a smog chamber at Purdue University. Isoprene nitrates and other hydrocarbon products were observed using Proton Transfer Reaction-Mass Spectrometry (PTR-MS) and reactive nitrogen products were observed using Thermal Dissociation–Laser Induced Fluorescence (TD-LIF). The organic nitrate yield is found to be 65±12% of which the majority was nitrooxy carbonyls and the combined yield of methacrolein and methyl vinyl ketone (MACR+MVK) is found to be ∼10%. PTR-MS measurements of nitrooxy carbonyls and TD-LIF measurements of total organic nitrates agreed well. The PTR-MS also observed a series of minor oxidation products which were tentatively identified and their yields quantified These other oxidation products are used as additional constraints on the reaction mechanism.

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