Effects of NOx on the molecular composition of secondary organic aerosol formed by the ozonolysis and photooxidation of α-pinene

Accepted Manuscript Effects of NOx on the molecular composition of secondary organic aerosol formed by the ozonolysis and photooxidation of α-pinene Jun-Hyun Park, Zaeem Bin Babar, Sun Jong Baek, Hyun Sik Kim, Ho-Jin Lim PII:

S1352-2310(17)30463-6

DOI:

10.1016/j.atmosenv.2017.07.022

Reference:

AEA 15436

To appear in:

Atmospheric Environment

Received Date: 18 November 2016 Revised Date:

10 July 2017

Accepted Date: 12 July 2017

Please cite this article as: Park, J.-H., Babar, Z.B., Baek, S.J., Kim, H.S., Lim, H.-J., Effects of NOx on the molecular composition of secondary organic aerosol formed by the ozonolysis and photooxidation of α-pinene, Atmospheric Environment (2017), doi: 10.1016/j.atmosenv.2017.07.022. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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Graphical abstract

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Effects of NOx on the molecular composition of secondary organic aerosols

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formed by the ozonolysis and photooxidation of α-pinene

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Jun-Hyun Parka,b, Zaeem Bin Babara, Sun Jong Baekc, Hyun Sik Kimb,**, and Ho-Jin

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Lima,*

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a

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Republic of Korea

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b

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Mass Spectrometry & Advanced Instrumentation Group, Korea Basic Science Institute,

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Cheongju 28119, Republic of Korea

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c

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*

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Corresponding author.

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ASTA Inc., Ltd., Suwon 443-270, Republic of Korea

Email address: [email protected] (Ho-Jin Lim). **

Cocorresponding author.

Email address: [email protected] (Hyun Sik Kim).

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Department of Environmental Engineering, Kyungpook National University, Daegu 41566,

Abstract

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The molecular composition of secondary organic aerosols (SOAs), obtained from the ozonolysis

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and photooxidation of α-pinene, was investigated using ultrahigh-resolution Fourier transform-

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ion cyclotron resonance mass spectrometry (FT-ICR MS) in negative ion mode electrospray

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ionization (ESI). SOA formation was performed in an indoor smog chamber. The molecular

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formulae of individual species were identified on the basis of the measured ionic mass using

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guidelines, such as number of atoms, elemental ratios, and the nitrogen rule. In each of the SOAs

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obtained, 815-3501 monomeric and oligomeric (mainly dimeric) species were identified below

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m/z 800. From ozonolysis, mainly 95% of the typical oxygenated species (CHO) were detected,

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whereas from photooxidation under high NOx conditions, 32% of nitrogen-containing species

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(CHON) were detected. Several common intense species (e.g., C9H14O6, C10H14O6, C10H16O5,

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C17H26O7, C19H28O9, C10H15NO8, and C10H15NO9) could be listed as candidate tracers for the

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conventional tracers for α-pinene SOA. The increased percentage of CHON as a primary effect

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of NOx on the SOA composition evidently affected other physicochemical parameters, such as

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elemental ratios (i.e., O/C, H/C, and N/C), the double-bond equivalent (DBE), the carbon

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oxidation state (OSC), and the organic-mass-to-carbon ratio (OM/OC). The O/C and OM/OC for

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CHON were greater than those observed for CHO, indicating that nitrogen preferentially exists

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in the oxidized form (e.g., -ONO2). The complexity of oligomerization was observed in DBE and

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OM/OC according to the number of carbon atoms.

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Key words: secondary organic aerosol, α-pinene, NOx effect, molecular composition, Fourier

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trasnsform ion cyclotron resonance mass spectrometry

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Organic aerosols accounts for a considerable fraction of atmospheric aerosols, which adversely

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affect human health, climate change, and visibility (Apte et al., 2015; Hallquist et al., 2009;

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Jimenez et al., 2009; Kanakidou et al., 2005). Organic aerosols comprises of primary organic

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aerosols (POAs), which are directly emitted as particles into the atmosphere, and secondary

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organic aerosols (SOAs), which are formed by chemical reactions of reactive organic gases

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(ROGs) in the atmosphere. The relative contribution of SOA changes with season and location

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(Carlton et al., 2010). Typically, SOAs are present in a high oxidation state with a high

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oxygen/carbon (O/C) ratio in a wide range relative to POA (Jimenez et al., 2009). Increased

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oxidation is directly related to enhanced polarity and hygroscopicity, making it favorable for

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cloud condensation nuclei to undergo microphysical cloud processes (Asa-Awuku et al., 2009;

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Engelhart et al., 2011; Lambe et al., 2011). These properties significantly depend on the SOA

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composition, which are considerably affected by formation pathways. ROGs are mainly emitted

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by natural processes of vegetation and human activities, e.g., fossil fuel combustion (Kanakidou

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et al., 2005). As the natural emissions of biogenic ROGs cannot be controlled, their contribution

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to the formation of SOA needs to be clearly understood for developing strategies to control

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particulate matter in the atmosphere (Carlton et al., 2010).

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Introduction

Biogenic ROGs, such as monoterpenes, contribute to a large fraction of global SOA

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(Hallquist et al., 2009; Kanakidou et al., 2005). α-Pinene (C10H16) is a representative biogenic

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ROG, which contributes to ~45% of the global SOA (Anderson-Skold and Simpson, 2001;

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Carlton et al., 2010). α-Pinene is widely used in several household products, such as cleaners and

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air fresheners (Wolkoff et al., 2000). It is very reactive to both OH radical and ozone as an

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unsaturated hydrocarbon with a single endocyclic double bond (Atkins and Arey, 2003). The formation of SOA is dependent on various parameters, such as mixing ratios of

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ROGs and oxidants, temperature, and humidity. NOx is the key species in the atmospheric

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chemical processes of SOA (Kroll et al., 2005; Kroll and Seinfeld, 2008; Lane et al., 2008; Li et

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al., 2007; Ziemann et al., 2012). The yield and composition of SOA are considerably affected by

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the reaction pathways of the RO2 radical, which is a crucial intermediate formed by the addition

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of O2, followed by the H abstraction of ROG by the OH radical. The RO2 radical reacts with HO2,

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RO2, NO2, and NO, affording peroxy alcohols, carbonyls and alcohols, alkyl peroxy nitrates, and

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alkyl nitrates, respectively (Kanakidou et al., 2005; Kroll and Seinfeld, 2008). The RO2 radical

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can also isomerize to multifunctional products via intramolecular ring formation (Crounse et al.,

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2011). In the peroxy radical reaction, NO competes with the HO2 radical to form less volatile

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products, leading to a high SOA yield. The RO2+NO reaction tends to decrease SOA yield for

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ROGs with 10 or fewer carbons (e.g., isoprene, monoterpenes, and simple aromatics) with the

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opposite tendancy for larger ROGs such as sesquiterpens (e.g., longifolene and aromadendrene)

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(Kroll and Seinfeld, 2008 and references therein). The reaction of RO2 with NO proceeds to form

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RO by the loss of an O atom to NO2 or to form an organonitrate. These organonitrates possibly

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partion into SOA, which could also be a common intermediate in the atmospheric oxidation of

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ROGs. Hence, it is crucial to detect the presence of organonitrates in the atmosphere as a tracer

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candidate for the SOAs from α-pinene to understand the oxidative aging of organic aerosols.

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Nitrogen-containing organics are commonly found in ambient and laboratory-generated

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aerosols (Bruns et al., 2010; O’Brien et al., 2013; Rincón et al., 2012; Wang et al., 2010).

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O’Brien et al. (2013) have analyzed samples collected from Bakersfield, CA, during the CalNex 4

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2010 campaign in the urban basin of Los Angeles and reported a large percentage of

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organonitrogen corresponding to isoprene and diesel SOA. Nah et al. (2015) have reported N-

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containing species (C8–C10) with extremely high N/C ratios in the nitrate-radical-initiated

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reaction of α-pinene and β-pinene, followed by further aging by OH radicals. The O/C and O/N

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(N/O) ratios of those species ranged from 0.4 to 0.6 and from 4 to 9 (0.11–0.25), respectively.

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Organonitrogen compounds from α-pinene were tentatively assigned as C10H15NO5, C10H15NO6,

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C10H16N2O7, C10H15NO9, and C9H13NO6 because of the limited resolution (~4,000) of the mass

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spectrometer used in the study.

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In this study, the effect of NOx on the SOAs obtained from α-pinene was investigated,

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with specific focus on SOA composition (especially nitrogen-containing species). SOAs from α-

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pinene were generated by ozonolysis and photooxidation under low and high NOx concentrations

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in an indoor smog chamber. An ultra-high-resolution 15 T FT-ICR MS system was employed for

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the detailed chemical speciation of SOA. In addition, the presence, abundance, and formation

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pathways of N-containing species were examined on the basis of chemical formulae, atomic

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ratios, and OM/OC ratios. Furthermore, typically observed products, dominant species, and

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oligomeric products were also discussed.

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2 Methods

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2.1 SOA sample preparation

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SOA was generated in a KNU smog chamber facility described in detail elsewhere (Babar et al.,

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2016). The facility included a 7 m3 Teflon reactor, a radiation source, an air purification system, and

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various analytical instruments (Supplementary Fig. S1). SOA experiments performed at room 5

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temperature (25oC) under dry conditions (<5% RH). Before each experiment, the Teflon bag was

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cleanded as follows: two initial flushings with purified air, an ozonolysis with ~200 ppb O3 for 1

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h, followed by a flushing, a photochemical cleaning with ~200 ppb H2O2 and ~200 ppb NO for 1

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h, and four final flushings with purified air. In each SOA experiment, a known amount of α-

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pinene (98%, Aldrich, MO, USA) was injected to achieve 1000 ppb through a septum into a U-

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shaped stainless steel tubing (known as evaporation tubing) wrapped with a heater, vaporized by

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gradual heating from room temperature to the desired temperature (i.e., 80°C) using a

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temperature controller (TZ4ST, Autonics, Korea), and passed into the reactor by N2 for 30 min at

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30 mL min-1. Ozone was generated by an ozone generator (Green Engineering, Korea) through the

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UV photolysis of ultra-high purity oxygen at 300 mL min-1. For an ozonolysis experiment, ozone

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was then introduced into the FEP reactor under the controlled O2 flow rate to provide the initial

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O3/α-pinene mixing ratio of 2. For the other ozonolysis (OH scavenged ozonolysis), n-hexane

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was added to 100 ppm to scavenge OH radicals between α-pinene introduction and O3 addition

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(Docherty and Ziemann, 2003; Ngyuen et al., 2010; Putman et al., 2012; Sato et al., 2013). The

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n-hexane level is estimated to scavenge 91% of OH radicals formed (Atkins and Arey, 2003;

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Paulson et al., 1998). For low NOx photooxidation, H2O2 vapor was introduced into the reactor

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by bubbling 50% H2O2 (516813, Aldrich, MO, USA) with a known amount of N2 to provide the

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initial H2O2/α-pinene mixing ratio of 1. H2O2 concentrations in the reactor were estimated using

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the saturation vapor pressure of H2O2 and the volume of H2O2 vapor fed into the reactor. For

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high NOx photooxidations (i.e., high NO and NO+NO2), then, NO and NO2 were introducted

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from the pressurized cylinders of NO (50 ppm, PS Chem, Korea) and NO2 (50 ppm, PS Chem)

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after the addition of H2O2. The reactants were well mixed with a mixing fan (A17238V2HBT-C,

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Active-White, Taiwan) switched on during the introduction of reactant and then switched off

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about 30 min before turning on UV lamps for the photooxidation and introducing O3 for the

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ozonolysis.

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VOCs were measured online at 15 min intervals using a Syntech-Spectra GC-PID

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GC955 series 600 system (Synspec, Netherlands). VOCs were preconcentrated on a Tenax GR

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adsorbent at normal temperature at a sample flow rate of 1.5 mL min–1, followed by thermal

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desorption and separation on a DB-1 column at a N2 flow rate of 1 mL min–1 and subsequent

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detection using a photoionization detector. NO and NO2 were continuously monitored using a

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NOx analyzer (CM2041, Casella, UK). The ozone concentration was measured using an ozone

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analyzer (400E, Teledyne, USA). Aerosol size distributions were measured using a sequential

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mobility particle sizer (SMPS+C, Grimm, Germany), comprising a differential mobility analyzer

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(DMA) and condensation particle counter (CPC). The relative humidity and temperature inside

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the reactor were monitored using a hygro-thermometer (HMT333, Vaisala, Finland).

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Table 1 summarizes the experimental conditions for the formation of SOAs from α-

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pinene and the results obtained. The reaction for the formation of each SOA was conducted for 5

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h. For chemical analysis, SOA samples were collected using a 47 mm Teflon filter (Whatman,

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Buckinghamshire, England), a 47 mm Teflon-coated glass fiber filter (Pall Corporation, Port

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Washington, NY), and a quartz fiber filter (Whatman, Buckinghamshire, England) for 1 h at a

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rate of 20 L/min at the end of the reaction. In addition, blank filter samples were collected for

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each SOA experiment. These Teflon filters were weighed before and after sampling to evaluate

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the mass of SOA using a micro balance (Sartorius, CP2P-F, Germany). For FT-ICR MS analysis,

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SOA retained on the Teflon-coated glass fiber filter was extracted in 4 mL of acetonitrile

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(Merck, Darmstadt, Germany) by ultrasonication for 1 h. For ESI FT-ICR MS, acetonitrile is

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preferred over water and methanol because of its enhanced ESI performance and low reactivity

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to SOA species (Heaton et al., 2009; Hall and Johnston, 2011; Bateman et al., 2012). Extracts

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were placed in a freezer below -20 °C until analysis.

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In addition, water-soluble organic carbon (WSOC) and water-soluble organic nitrogen

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(WSON) in the SOA samples were determined. The total organic carbon (TOC) and total

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nitrogen (TN) of the water extract of SOA samples were analyzed using a TOC–TN analyzer

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(TOC-L CPH, Shimadzu, Japan). NO2− and NO3− in the water extracts were analyzed using a

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Dionex ICS-3000 (IC; Dionex, USA). WSOC and WSON were determined as TOC and TN

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minus the sum of nitrogen from NO2− and NO3−, respectively. WSOC and WSON of SOAs were

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obtained after correction for filter blanks. Detailed analysis methods of TOC-TN and IC in the

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supplementary information (S1).

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2.2

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Samples were analyzed using a 15 T FT-ICR MS (Bruker Daltonics, Billerica, MA) with an ESI

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source at the Korean Basic Science Institute (KBSI, Ochang-eup, Korea) (Cho et al., 2013; Park

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et al., 2013; Yang et al., 2011). The direct infusion of SOA extracts was performed at 400 nL

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min-1 using a TriVersa NanoMate syringe pump (Advion, NY), followed by passage through a

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micro-electrospray ionization source (A-Chip, Advion) connected to the FT-ICR MS. Direct

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infusion (DI) in ESI with an ultra high resolution MS have been successfully used in the detailed

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speciation and evolution of SOA (Hall et al., 2013; Kundu et al., 2017; Ngyuen et al., 2010;

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Putman et al., 2012). DI-ESI provides the potential of concise analysis and nontargeted

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speciation, while it is unable to discriminate between isomeric compounds and inevitable from

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FT-ICR-MS data acquisition

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adduct formation (Lin et al., 2010). The potential of adduct formation might be substantially

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suppressed due to dilute solutions (TOC < 10-3 M) in this study (Kundu et al., 2017). Nitrogen at

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2.0 L min-1 and 450°C was used as the nebulizer gas, and nitrogen at 2.3 L min-1 and 210°C was

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used as the drying gas. The capillary voltage was 3,600 V, and the skimmer voltage was set to

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15.0 V to minimize in-source clustering and fragmentation (Sadezky et al., 2006). The

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continuous accumulation of selected ions was carried out in the broadband detection mode with a

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160–1000 m/z window for data acquisition. The collision cell radio frequency (rf) voltage and

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energy were 1,500 V and −3.0 eV, respectively. Spectra were recorded in the negative mode with

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4 M word data points and 2 s transient signals and summed over 200 time-domain transients to

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improve the signal-to-noise ratio (S/N). Daily mass calibration was performed with an external

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standard of L-arginine (11003, Fluka, Milwaukee, WI) and afforded a mass accuracy from -

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0.251 ppm to 0.349 ppm as the residual root-mean-square errors for its clustered ions of m/z

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173.104399, 347.216075, 521.327751, 695.439426, 869.551102, and 1043.662778. Further noise

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reduction was achieved by smoothing using the Gauss algorithm (width of 0.0002384 Dalton) by

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Bruker Data Analysis (Madison, WI). Fig. 1 shows the 15T FT-ICR MS spectra for the SOA

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samples obtained from α-pinene with a resolution of approximately 600,000 at m/z 400.

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2.3 FT-ICR-MS data analysis

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Ion peaks detected in the blank filter samples were eliminated from the mass analysis of SOA

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samples. Only SOA species with a mass of less than m/z 800 were used in the following data

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interpretation because of gradual increasing errors over the limit. 1578, 2759, 4492, 5817, and

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5041 peaks with S/N≥10 were observed in the ozonolysis, OH scavenged ozonolysis, low NOx 9

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photooxidation, high NO photooxidation, and high NO+NO2 photooxidation, respectively. The

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charge state of each ion was determined prior to the assignment of elemental composition. The

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presence of singly charged ions was confirmed by the presence of monoisotopic ions of 13C12Cn–1

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for 12Cn at an interval of greater than 1.0034 in mass. The presence of doubly and triply charged

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ions of

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(Stenson et al., 2002). The peak intensity of the monoisotopic ions was 1.11% relative to the

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nonisotopic peak intensity because of the isotopic abundance of carbon.

C12Cn–1 were confirmed an interval of greater than 0.5017 and 0.3347, respectively

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The chemical formulae of ions were determined using commercial Composer software

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(version 1.0.5, Sierra Analytics, Modesto, CA). Chemical formulae within an error of ± 0.5 ppm

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for the measured ions were listed by the Composer software. The molecular formula calculator

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was limited up to 100 carbon, 200 hydrogen, 50 oxygen, and 3 nitrogen atoms in the molecular

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formula. Molecular formulae for 1088, 1798, 2788, 4259, and 3747 monoisiotopic peaks were

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assigned in the ozonolysis, OH scavenged ozonolysis, low NOx photooxidation, high NO

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photooxidation, and high NO+NO2 photooxidation, respectively. The molecular formula

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assignment by the Composer software is based on the PREDATOR algorithm and Kendrick

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mass defect (KMD) analysis (Blakney et al., 2011; Hughey et al., 2001). The molecular formula

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for an SOA species was assigned using the CH2 homologous series. Herein, elemental

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compositions were assigned with the de novo cutoff at m/z 500 (Putman et al., 2012). The best

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formula was chosen according to rules reported in previous studies (Altieri et al., 2012; Koch et

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al., 2005; Kujawinski and Behn, 2006; Nizkorodov et al., 2011; Putman et al., 2012). The

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chemical formulae should satisfy the atomic ratios of O/C ≤ 1.2, 0.3 ≤ H/C ≤ 2.25, and N/C ≤ 0.5.

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The formula also should satisfy the nitrogen rule: molecules containing odd and even numbers of

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nitrogen atoms have odd and even molecular mass, respectively. Double-bond equivalent (DBE)

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related to the hydrogen deficiency corresponds to the number of double bonds and rings in a

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molecule. DBE for a molecule in CcHhNnOoSs is defined as DBE = c – h/2 + n/2 + 1.

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Only molecular formulae with a DBE of 0 or a positive integer were accepted. Considering the

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instrumental accuracy of 15 T FT-ICR MS, the chemical formula with the lowest error in m/z of

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less than ± 0.5 ppm was accepted as the identified formula. In case of multiple formulae with an

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error ≤0.5 ppm, the candidate with the lowest number of nitrogen atoms was assigned to have

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the chemical formula (Kujawinski et al., 2006). From ozonolysis, OH scavenged ozonolysis, low

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NOx photooxidation, high NO photooxidation, and high NO+NO2 photooxidation, 815, 1473,

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2141, 3501, and 3101 species were identified, respectively.

Internal recalibration (Bruker Data Analysis) was performed to further reduce the

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uncertainty of the measured ionic mass. The most intense 50% identified species (338-650) with

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no nitrogen atom in the mass range of 140-300, 300-500, and 500-800 m/z were used as

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reference ions for the internal recalibration, resulting in a low error of 0.27 ppm converging

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around 0 without any change in the molecular formula.

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3 Results and discussion

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As shown in Table 1, SOA mass concentrations by SMPS ranged from 579 to 3504 µg m-3 under

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the assumption of 1.25 g mL-1 for SOA (Saathoff et al., 2009). The SOA yields (defined as

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SOA/∆ROG, the mass of aerosol formed per mass of ROG reacted) obtained from ozonolysis

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with and without a OH radical scavenger increased up to 95% and 105%, respectively. The

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presence of OH radicals promotes the further oxidation of SOA during ozonolysis (Kleindienst et

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al., 2007). The lowest yield of 24% was observed for SOA formed from high NO photooxidation,

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possibly caused by the formation of volatile organonitrate compounds (Eddingsaas et al., 2012;

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Kroll and Seinfeld, 2008). Highly volatile SOA formed under high NOx conditions was verified

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by volatility measurement using a thermodenuder for SOA formed from α-pinene, β-pinene, and

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d-limonene (Lee et al., 2006). It is worthy to note the SOA yields could be biased low due to the

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wall loss of low volatility vapor products, especially until the particle formation, for experiments

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without aerosol seed particles (Ye et al., 2016; Yeh and Ziemann, 2014; Zhang et al., 2014,

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2015).

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The WSOC and WSON concentrations in SOA ranged from 131 to 700 µg C m-3 and

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from 1.9 to 18.6 µg N m-3, respectively. The corresponding N/C ratios ranged between 0.009 and

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0.04, indicative of the presence of a considerable percentage of nitrogen-containing SOA species.

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The minimum was observed for OH scavenged ozonolysis, while the maximum was observed for

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high NO and NO2 photooxidation. Assuming 10 carbon skeletons for the SOA species with one

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nitrogen atom on average, ~40% of N-containing compounds correspond to the maximum N/C

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ratio. As SOA was formed under different reactions, e.g., ozonolysis with and without OH

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scavengers and photooxidation with low and high NOx concentrations, a large variation in the

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SOA molecular composition was expected.

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3.1

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Chemical composition similarities were examined on the basis of the common fraction of the

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identified species between experiments. Table 2 summarizes the common fractions of the species

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identified from each experiment. SOA formed by ozonolysis contained 96% and 85% of SOA

Chemical composition similarity and high intensity species

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species as formed by OH scavenged ozonolysis and low NOx photooxidation. This can be

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attributed to the suppression of OH initiated and O3 initiated reactions in the later experiments,

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respectively. The slightly lower fraction of low NOx photooxidation was influenced by

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organonitrogens formed in the presence of trace NOx under low NOx photooxidation as

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addressed below. A lot of organonitrogen observed in high NO and high NO+NO2

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photooxidations contributed to common fractions of 0.18–0.35 for ozonolysis and OH scavenged

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ozonolysis. High NO and high NO+NO2 photooxidations contained common fractions of 0.84

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and 0.96 each other. These confirm that high similarity and consistency in species are observed

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for SOA formed through similar reaction pathways.

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Based on elemental composition, the SOA species were classified into CHO, CHON1,

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CHON2, and CHON3 classes representing oxygenated hydrocarbons with zero, one, two, and

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three nitrogen atoms in their molecular formulae, respectively. CHON collectively represents all

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nitrogen-containing species. Table S1 summarizes the intensity of 37 typical and major species

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in previously reported studies relative to the most intense peak in an experiment conducted

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herein. From ozonolysis, dimeric pinyl-diaterpenyl ester (C17H26O8, MW 358) was the most

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intense species as previously reported (Kristensen et al., 2014, 2016; Kourtchev et al., 2015).

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Other dimeric species, such as pinyl-diaterebyl ester (C16H24O8, MW 344), pinonyl-pinyl ester

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(C18H27O7, MW 356), and MW 388 species (C18H28O9), were also found to be quite intense. Low

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dimer intensities were observed from OH scavenged ozonolysis probably due to the decrease of

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carboxylic acid formation necessary to produce dimer esters (Kriestensen et al., 2016). Even

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though the OH scavenged ozonolysis was performed at high α-pinene concentration, dimer

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formations through RO2+RO2 reaction at low OH2/RO2 ratios unexpected under atmospheric

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conditions were likely minimal due to the slight branching ratio of the dimerization among

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competing pathways (Kwan et al., 2012). Dimer formations were considerably suppressed in

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photooxidations compared to ozonolysis. Low NOx photooxidation resulted in relatively intense

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monomeric species, such as norpinic acid, terebic acid, norpinonic acid, and diaterpenylic acid

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acetate. Although significant intensities of dimeric species, such as pinyl-diaterpenyl ester and

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the MW 370 dimer, were observed, the abundance of dimers was substantially reduced as

6

compared with that observed from ozonolysis (Kriestensen et al., 2016). Under high NOx

7

photooxidation, terebic acid, 3-methyl-1,2,3-butanetricarboxylic acid, and diaterpenylic acid

8

acetate were the most intense monomeric species. The MW 388 dimer was observed to be a

9

dominant non-N-containing dimer with relative intensities of 23% and 25% for high NO and

10

NO+NO2 photooxidations, respectively. Under high NO+NO2 photooxidation, dimeric pinyl-

11

diaterpenyl ester exhibited a relative intensity of 36%, whereas under high NO photooxidation, a

12

negligible intensity of 0.29% was observed. The MW 388 dimer were likely formed by the

13

reaction of products from OH initiated oxidation differently from dimeric pinyl-diaterpenyl ester

14

formed by the reaction of O3 initiated reaction products (Kriestensen et al., 2016). The decreased

15

dimer formations support the negative correlation betwen dimers and NOx at the Nordic boreal

16

forest of Hyytiälä (Kriestensen et al., 2016).

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In-source fragmentation tests with a skimmer voltage (fragmentation potential) up to 65

18

V showed insignificant change of oligomers in the mass spectra (Supplementary Fig. S2). A

19

decrease in the intensities of both monomeric and dimeric species was apparent with the increase

20

of fragmentation potential over 75 V. These confirm the identified dimers are covalent species

21

rather than adducts (Kourtchev et al., 2015). The MS/MS analysis for oxygenated dimers (MW

22

358 and MW 368) and and 3 N-containing dimers performed using an Orbitrap MS

23

(Supplementary S2) are shown in the supplementary Fig. S3 and Fig. S4. As seen in the MS/MS

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spectrum of MW 358 dimer, two prominent product ions (i.e., m/z 171.0654 - C8H11O4 and m/z

2

185.0812 - C9H11O4) of diaterpenylic acid and cis-pinic acid were consistent with previous

3

reports (Kristensen et al., 2016; Müller et al., 2009; Yasmeen et al., 2010). On the other hand, the

4

MS/MS spectra of N-containing dimers were very complex with apparent peaks formed by

5

neutral losses of CO2, HNO3, and CH2NO3. It suggests the presence of many possible isomers for

6

those products differently from oxygenated products. Further detailed fragmentations (i.e., MS3,

7

MS4) might be necessary to better interpret the structure of N-containing dimers. Oligomeric

8

products are formed by the reaction of SCIs, HPs, RO2 radicals, and stable products (Heaton et

9

al., 2007; Kanakidou et al., 2005; Kristensen et al., 2014; Zhang et al., 2015). The formation

10

mechanisms of monomeric and dimeric SOA species are summarized in the supplementary Fig.

11

S5 and Fig. S6, respectively (Capouet et al., 2008; Claeys et al., 2009; Kamens and Jaoui, 2001;

12

Kristensen et al., 2014; Toloka et al., 2004; Yasmeen et al., 2010). Various possible

13

combinations between reactive species for oligomerization might result in the identification of

14

thousands of species. Field measurements have confirmed the presence of dimeric species in the

15

atmospheric aerosol of forest and urban sites (Kourtchev et al., 2014a; Kristensen et al., 2013,

16

2016; Yasmeen et al., 2010). Moreover, dimeric SOA species remained stable during aging

17

under UV radiation in the presence of OH radicals and only UV radiation (Kourtchev et al.,

18

2015).

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According to the nitrogen rule, the substantial fraction of N-containing species are

20

evidently observed by even norminal ionic mass as shown in Fig. 1. The N-containing species

21

C10H15NO8 was the most dominant species obtained from high NO+NOx photooxidation. An

22

extremely high relative intensity of ~85% was also observed for C10H15NO9. Under high NO

23

photooxidation, high concentrations of C9H13NO7, C10H17NO7, and C10H17NO8 were also 15

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observed. These were found in α-pinene SOA formed from high NOx photooxidaiton and NO3

2

radical initiated reaction (Lee et al., 2016; Nah et al., 2015). Lee et al. (2016) reported 30

3

organonitrates of α-pinene SOA found during atmospheric and laboratory experiments. Five

4

most intense organonitrogen species were C10H15NO8, C10H15NO7, C10H17NO7, C10H17NO8, and

5

C9H13NO7, respectively, which were intense under high NOx photooxidation in this study.

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Table S2 summarizes the 50 most intense species obtained from each experiment. As

7

expected, all 30 species for ozonolysis, OH scavenged ozonolysis, and low NOx photooxidation

8

belonged to the CHO group. On the other hand, 12 and 15 CHON species from high NO and

9

high NO+NO2 photooxidations, respectively, were also included. The five most intense species

10

in each experiment included five monomeric CHO of C8H12O6 (MW 127.0736, norpinic acid and

11

isomers), C9H14O6 (MW 218.0790), C10H14O6 (MW 230.0790), C10H16O5 (MW 216.0998), and

12

C10H16O6 (MW 232.0947, diaterpenylic acid acetate), respectively; three dimeric CHO of CHO

13

of C17H26O8 (MW 358.1628, pinyl-diarterpenylic ester), C17H26O7 (MW 342.1679), and

14

C19H28O9 (MW 400.1733); respectively; and two CHON of C10H15NO8 (MW 277.0798) and

15

C10H15NO9 (MW 293.0747), respectively. Monomeric (≤C10) and dimeric species (C11–C20) were

16

determined on the basis of the number of carbon atoms. These common intense species

17

demonstrate potential to be tracers for the α-pinene SOA obtained after confirmation of their

18

atmospheric presence.

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3.2

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The elemental ratio is a useful parameter to investigate the chemical composition and

22

physicochemical properties of organic aerosols (Kroll et al., 2011; Kuwata et al., 2012; Lambe et

Atomic ratios of SOA species

16

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al., 2013). Table 3 shows the percentage and atomic ratio of each chemical group for SOA

2

experiments. Averaged data were obtained by normalization to the measured ion intensity. For

3

ozonolysis and low NOx photooxidation, 6.4% and 28.7% in number of N-containing species

4

were observed, respectively. Similar results were observed in previous studies. Ngyuen et al.

5

(2011) have reported 1% and 33% of N-containing species in SOAs formed by the low and high

6

NOx photooxidation of isoprene, respectively. In the studies, initial NOx mixing ratio was less

7

than 5 ppb. N-containing SOAs were not detected in the experiment performed under the strict

8

control of NOx concentrations to less than 25 ppt, indicating that even trace levels of NOx affect

9

the formation of N-containing SOA species by the reaction between peroxy radical and NO and

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the addition of NO3 radical (Krechmer et al., 2015).

The possible formation of N-containing SOAs can be determined by plotting O/N ratios

12

of all species. As shown in Fig. 2(a)-(c), N/O ratios of 0.05-0.2, 0.08-0.25, and 0.12-0.3 were

13

obtained for CHON1, CHON2, and CHON3 in high NO+NO2 photooxidation, respectively.

14

These values are less than the upper limit of 0.33, corresponding to all oxygen in SOA in the

15

form of nitrate (i.e., NO3). In addition, with increasing number of nitrogen atoms in a chemical

16

class, the O/C ratios apparently increased. As clearly shown in Fig. 2(d), O/C increased with N/C,

17

indicating that nitrogen is preferentially present in the oxidized form, i.e., NO, NO2, and NO3.

18

Nguyen et al. (2011) have reported different nitrate fragments (e.g., HNO3 and CH3NO3) from

19

the collision-induced dissociation of organonitrogen species. N-containing SOA species were

20

present in the oxidized forms of nitrogen oxides (e.g., -NO2 and -ONO2) or in the reduced form

21

of amino or amide groups (Chan et al., 2010; Chhabra et al., 2011; Lim and Ziemann, 2009;

22

Nguyen et al., 2011). Chhabra et al. (2011) have estimated up to 19% contribution of

23

organonitrates to oxygen in α-pinene SOA under high NOx photooxidation. SOA species with C-

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1

ONO2 and C-OH bonds replacing C–H bonds were identified using a realtime thermal desorptin

2

MS for high NOx photoxoidations of alkanes (Lim and Ziemann, 2009). In the absence of NOx, 93.0%, 86.9%, and 71.5% of CHO groups were observed for

4

ozonolysis, OH scavenged ozonolysis, and low NOx photooxidation, respectively. SOA formed

5

under high NOx contained an increased percentage of N-containing groups, in addition to

6

additional nitrogen atoms. Under high NO and NO+NO2 conditions, the percentage of CHO

7

groups considerably decreased to 30.1% and 37.1% (58.1% and 52.4% CHON), respectively,

8

with increasing percentage of N-containing species. The findings were fairly matched to the

9

result of WSOC and WSON described above. The intensity-weighted average of 7.0%–70% for

10

N-containing groups corresponded to N/C ratios between 0.06 and 0.20. Overall N/C ratios

11

observed for photooxidation under high NOx conditions were considerably greater than the

12

ambient N/C ratios of 0.01–0.03 (Aiken et al., 2008; Sun et al., 2011).

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For the five experiments, the H/C, O/C, and N/C ratios were in the ranges of 1.48–1.50,

14

0.53–0.75, and 0–0.07, respectively. The CHON3 groups obtained from ozonolysis and low NOx

15

photooxidation exhibited extraordinarily low H/C and O/C ratios probably because of the

16

inappropriate formula identification and unknown chemical reactions, and currently uncertain.

17

Overall, the H/C and O/C ratios were similar to those reported previously for biogenic SOAs

18

formed by ozonolysis (Kundu et al., 2012; Putman et al., 2012). For the CHO group, H/C ratios

19

ranged from 1.45 to 1.49 under low NOx condition and ozonolysis, slightly greater than that

20

observed under high NOx conditions (1.39). On the other hand, O/C ratios under low NOx

21

condition and ozonolysis were 0.53, which was less than that observed for high NOx

22

concentrations (0.59). This observation is related to extensive oxidation under high NOx

23

concentrations with high OH concentrations (Bateman et al., 2009; Hall et al., 2013; Nguyen et

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al., 2011), in addition to the contribution of NO3 radical (Chhabra et al., 2011). The average H/O

2

and O/C ratios obtained herein are comparable to those reported previously, as summarized in

3

Table 4. Elemental ratios could be insignificantly affected by the ionization efficiency and

4

dynamic mass range of analysis methods (Bateman et al., 2012; Nguyen et al., 2011). The mean

5

H/C ratio (1.50) and O/C ratio (0.54) observed for ozonolysis were in good agreement with the

6

ranges of those reported in previous studies, 1.46–1.54 and 0.38–0.79 (Hall et al., 2013; Kim et

7

al., 2014; Kourtchev et al., 2014; Putman et al., 2012). These values are fairly comparable to the

8

ratios of 1.48 and 0.52 for organic aerosols obtained at the Hyytiälä forest (Kourtchev et al.,

9

2013). The fairable results were also observed for SOA obtained from photooxidation under high

10

NOx conditions, with average O/C and H/C ratios of 1.49 and 0.74, respectively. The O/C ratio is

11

in the range of oxygenated organic aerosols classified by AMS for urban atmosphere (Aiken et

12

al., 2008). As shown in Table 4, O/C and H/C ratios of d-limonene (structural isomer of α-

13

pinene) were similar to those of α-pinene. Isoprene afforded slightly higher H/C and O/C ratios

14

possibly because of the substantial contribution from highly oxidized tetrols and associated

15

oligomers. It is noteworthy to consider differences in the reaction conditions and chemical

16

analysis methods.

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Fig. 3 shows the H/C and O/C ratios of SOA species obtained from α-pinene in the van

18

Krevelen diagram, which has been widely used to investigate the evolution of complex mixtures

19

such as SOA (Chen et al., 2015; Chhabra et al., 2011; Heald et al., 2010; Kim et al., 2003;

20

Lambe et al., 2012; Nguyen et al., 2010; Visser et al., 1983). In this study, the elemental ratios

21

were more clearly differentiated by the chemical group. The SOA species of N-containing

22

groups were positioned at substantially higher O/C ratios relative to the CHO group, while the

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H/C ratios were slightly greater for CHON. Clearly, the magnitude increased with the number of

2

nitrogen atoms for SOA under high NOx conditions. Interstingly, highly oxidized species with

3

high H/C ratios were observed in CHON group. Chen et al. (2015) have argued that the SOA

4

data obtained from laboratory experiments nearly extended to high oxidation states with a slope

5

of 0.6 in the van Krevelen diagram characterized by a large dataset of ambient measurements.

6

Organic aerosols with both high O/C and H/C ratios werewas referred to explain the discrepancy

7

in species, such as aqueous-phase SOAs. Meanwhile, it was reported that organonitrates were

8

considerably hydrolyzed to form alcohol and nitric acid in ambient condition (Liu et al., 2012).

9

The conversion rate in laboratory generated SOA was considerably fast in the range of 2-7 day-1

10

with a positive effect of humidity and inorganic salt (Bean and Ruiz, 2016; Liu et al., 2012). The

11

converstion of organonitrate to alcohol could explain the formation of highly oxidized species

12

with high H/C ratios described above, sinec it resulted in decreased O/C ratio and increased H/C

13

ratio. For example, when one nitrate is hydrolyzed in a species with 10 carbons, O/C 0.8, H/C

14

1.6, and 2 nitrates, O/C and H/C ratios will be changed to 0.6 and 1.7 (a slope of -0.5 in the van

15

Krevelen diagram), respectively. A van Krevelen diagram of typical α-pinene SOA species listed

16

above is shown in the supplementary (Fig. S7).

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3.3 DBE, OM/OC, and carbon oxidation state (OSC)

19

Fig. 4 shows the distribution of DBE for CHO and CHON for ozonolysis and high NOx

20

photooxidaitons. For species containing a high number of nitrogen atoms, DBE clearly

21

increased, indicating that nitrogen predominantly occurs as nitrate. Prominent DBEs were

22

observed between 3 and 4 for monomer and 5 and 6 for dimer groups, respectively. Previous

23

studies have proposed different oligomerization pathways according to change in the dominant 20

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DBE (Bateman et al., 2009; Kundu et al., 2012; Walser et al., 2008). The increase of 2 DBE was

2

explained as Criegee radical, hemiacetal, and HP reaction channels (Supplementary Fig. S6). By

3

contrast, the increase of 3 DBE was explained by the additiveness of monomeric DBEs via

4

condensation (i.e., aldol and esterification). Therefore, the oligomerization observed herein is

5

possibly contributed by the Criegee radical, hemi-acetal, and HP reaction channels. The detailed

6

estimation for the contribution of each channel is not within the scope of this study.

9 10

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The organic mass (OM) to organic carbon (OC) ratio of individual compounds and the mean OM/OC ratio were calculated as follows:

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OM/OCi = xi(1 + 16/12O/C + 1/12H/C + 14/12N/C) OM/OC = ΣOM/OCi/Σxi

Here, xi corresponds to the observed ion peak abundance. The OM/OC ratios ranged from 1.85

12

to 2.21 with high values obtained for high NOx conditions as compared to those obtained for

13

ozonolysis, which may be directly related to the variation in the O/C ratios, accompanied by

14

organonitrates as in the previous discussion. The OM/OC ratio was comparable to those obtained

15

for the atmospheric oxygenated organic aerosols as determined in the AMS data (Aiken et al.,

16

2008; Timonene et al., 2012). In addition, the OM/OC ratios decreased with increasing carbon

17

numbers in a molecule, possibly associated with the loss of water by oligomerization via

18

condensation (Kundu et al., 2012; Mazzoleni et al., 2012). The difference between OM/OC ratios

19

for a monomer and a dimer formed by self condensation can be mathematically determined.

20

Mass of the dimer can be expressed in terms of monomeric and dimeric OM/OC ratio. The

21

difference in OM/OC (∆OM/OC) is calculated as follows.

22

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OMdi,condensation = OMmono/OC x MWC x 2NC,mono – MWH2O 21

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OMdi,condensation = OMdi/OC x MWC x 2NC,mono

2

OMmono/OC x MWC x 2NC,mono – MWH2O = OMdi/OC x MWC x 2NC,mono

3

∆OM/OC = OMdi/OC – OMmono/OC = – MWH2O/(2MWC x NC,mono)

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where OMdi,condensation is mass of dimer formed by condensation, OMmono/OC monomeric OM/OC,

5

OMdi/OC dimeric OM/OC, MWC molecular weight of carbon, MWH2O molecular weight of H2O,

6

and NC,mono number of carbon in monomer. For C10 monomeric species, calculated ∆OM/OC of

7

−0.075 seems much less than the difference between intense monomeric and dimeric species

8

shown in Fig. 5(c). This might be an indication of the complexity in oligomerizaion such as self

9

and cross condenations between monomers with rich diversity in molecular composition and

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abundance, along with SCI and HP channels.

The average oxidation of carbon for a complex organic mixture, such as SOA, is also

12

useful to understand the aging of organic matter, which is associated with SOA characteristics of

13

volatility and density (Chhabra et al.; 2015; Hao et al., 2011). Kroll et al. (2011) have extensively

14

discussed the usefulness and importance of the average carbon oxidation state (OSC) in the

15

formation and aging of SOA. OSC gradually increased with photooxidation aging during SOA

16

formation (Aljawhary et al., 2013; Bateman et al., 2009; Chhabra et al., 2015; Hall et al., 2013).

17

The degree of COS was calculated by COS = 2(O/C) − H/C − 5(N/C), following that proposed

18

by Kroll et al. (2011). It was assumed that all nitrogen atoms in SOA species were in the form of

19

nitrate (-ONO2) with the nitrogen oxidation state of +5. Intensity-weighted average OSC was

20

obtained for each experiment after calculating OSCi for individual molecular formula using the

21

following equations:

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OSCi = 2(O/C)i – (H/C)i – 5(N/C)i 22

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OSC = Σ(ΙiOSCi)/ΣΙi where OSCi, (O/C)i, (H/C)i, (N/C)i, and Ιi is OSC, O/C, H/C, N/C, and intensity of species i,

3

respectively. Nitrogen in CHON was found predominantly in the form of nitrate (i.e., -ONO2)

4

(Farmer et al., 2010; Kroll et al., 2011; Ruggeri et al., 2016). Oxygen, hydrogen, and nitrate

5

nitrogen have nominal oxidation numbers of –2, +1, and +5, respectively. Alternatively, average

6

OSC can also be simply calculated using the following equation of intensity-weighted mean O/C,

7

H/C, and N/C: OSC = 2O/C – H/C – 5 N/C. In this study, increased OSC was observed from high

8

NOx photooxidations relative to ozonolysis and low NOx photooxidation, probably caused by

9

enhanced oxidation by OH radicals and nitrogen oxides. CHO groups exhibited OSC values of

10

−0.44 and −0.28 for low and high NOx photooxidations, respectively (see Fig. 5). OSC was

11

considerably affected by the percentage of N-containing compounds and number of nitrogen

12

atoms. Under high NO photooxidation, OSC values were −0.28, −0.39, −0.49, and −0.60 for

13

CHO, CHON1, CHON2, and CHON3, respectively. SOA formed in this study was probably

14

aged up to the representative OSC of semivolatile oxygenated organic aerosols in the atmosphere.

15

It could be further aged up to high OSC by continuous oxidation (Kroll et al., 2011). The mean

16

OSC values ranged from −0.47 for ozonolysis in the presence of OH radical to −0.37 for high

17

NOx concentrations (Table 3). The lower OSC observed for ozonolysis was comparable to those

18

reported previously for SOA formed from the ozonolysis of α-pinene. For example, Putman et al.

19

(2012) have determined OSC between −0.42 and −0.68 with lower OSC for high order oligomers.

20

SOAs formed from α-pinene under high O3/ROG resulted in elevated OSC between −0.02 and

21

0.23 (Chhabra et al., 2015). Mean OSC for high NOx photooxidations was less than the OSC

22

values of 0.41–0.71 for SOAs under exposure to extremely high OH radical concentrations,

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1

corresponding to 2.8–7.5 days of atmospheric aging (Chhabra et al., 2015).

2 3

4

4

The SOA species obtained from α-pinene by ozonolysis and photooxidation were identified

5

using an ultrahigh-resolution 15 T FT-ICR MS system. Among several thousands of identified

6

peaks, not only typical oxygenated species (e.g., 3-methyl-1,2,3-butanetricarboxylic acid,

7

pinonic acid, and norpinoic acid) but also nitrogen-containing species were observed. Increased

8

percentage of nitrogen-containing species was formed under photooxidation in the presence of

9

NOx. N-containing compounds were also observed from ozonolysis and photooxidation in the

10

absence of NOx, possibly formed by residual NOx in the reaction mixture. This observation

11

indicated the impact of NOx on the atmospheric chemistry and composition of SOA. Some

12

typical tracers for α-pinene, such as 3-methyl-1,2,3-butanetricarboxylic acid, were obtained in

13

29%, while most of the other tracers, pinic acid, pinonic acid, and 3-acetyl hexanedioic acid,

14

were obtained at concentrations of less than 1%. As previously reported, C10H15NO8 (MW

15

277.0798) and C10H15NO9 (MW 293.0747) were dominant organonitrates. Commonly observed

16

species of high intensity in the FT-ICR MS, such as C9H14O6 (MW 218.0790), C10H14O6 (MW

17

230.0790), C10H16O5 (MW 216.0000), C17H26O7 (MW 216.0998), and C19H28O9 (MW 400.1733)

18

would be considered as additional tracers.

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Concludions

Oligomeric species accounted for a large percentage of SOA species. Molecular DBE

20

and OM/OC as a function of the number of carbon atoms imply various pathways of

21

oligomerization via the formation of Criegee radicals and hydroperoxides and condensation. A

22

difference of 2 DBE between monomers and dimers was reportedly associated with a pathway 24

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1

via Criegee radicals and hydroperoxides. The typical decrease of the OM/OC with carbon atoms

2

of a component was clearly observed possibly because of H2O lost during condensation. The elemental ratios of H/C and O/C ranged from 1.38 to 1.49 and from 0.52 to 0.59 for

4

the CHO group with slight changes associated with the different reaction conditions utilized for

5

the five experiments. The N/C ratio increased to 0.06 and 0.07 under photooxidation in the

6

presence of NO and NO+NO2, respectively. These elemental ratios were comparable to those

7

observed previously for the SOAs of α-pinene considering the various formation conditions and

8

chemical analysis methods of SOAs. The H/C and OC ratios were similar to those observed for

9

d-limonene, which is a structural isomer and a representative biogenic monoterpene along with

10

α-pinene. α-Pinene exhibited slightly lower H/C and OC ratios as compared with those observed

11

for isoprene, a predominant biogenic ROG.

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In the van Krevelen diagram, SOA species of high intensity in the FT-ICR MS were

13

positioned between the slopes of −0.5 and 2 for the CHO group. N-containing species were

14

positioned to the right of the CHO group because of the contribution of the nitrate group to the

15

increased O/C. With increasing number of nitrogen atoms, the O/C clearly shifted toward the

16

right. The effect of nitrogen as a nitrate group also resulted in increased OM/OC for N-

17

containing species.

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Acknowledgements

20

This work was supported by the National Research Foundation of Korea (NRF) grant funded by

21

the Korea government (MEST) (No. 2011-01350000) and KBSI grant G37120. Also, this work

22

was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) 25

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1

granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (No.

2

20142010201810).

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References

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Aiken, A.C., Decarlo, P.F., Kroll, J.H., Worsnop, D.R., Huffman, J.A., Docherty, K.S., Ulbrich, I.M., Mohr, C., Kimmel, J.R., Sueper, D., Sun, Y., Zhang, Q., Trimborn, A., Northway, M., Ziemann, P.J., Canagaratna, M.R., Onasch, T.B., Alfarra, M.R., Prevot, A.S., Dommen, J., Duplissy, J., Metzger, A., Baltensperger, U., Jimenez, J.L., 2008. O/C and OM/OC ratios of primary, secondary, and ambient organic aerosols with high-resolution time-of-flight aerosol mass spectrometry. Environ. Sci. Technol. 42, 4478-4485. Aljawhary, D., Lee, A.K.Y., Abbatt, J.P.D., 2013. High-resolution chemical ionization mass spectrometry (ToF-CIMS): Application to study SOA composition and processing. Atmos. Meas. Tech. 6, 3211-3224. Altieri, K.E., Hastings, M.G., Peters, A.J., Sigman, D.M., 2012. Molecular characterization of water soluble organic nitrogen in marine rainwater by ultra-high resolution electrospray ionization mass spectrometry. Atmos. Chem. Phys. 12, 3557-3571. Andersson-Skold, Y., Simpson, D., 2001. Secondary organic aerosol formation in northern Europe: A model study. J. Geophys. Res. - Atmos. 106, 7357-7374. Apte, J.S., Marshall, J.D., Cohen, A.J., Brauer, M., 2015. Addressing global mortality from ambient PM2.5. Environ. Sci. Technol. 49, 8057-8066. Asa-Awuku, A., Engelhart, G.J., Lee, B.H., Pandis, S.N., Nenes, A., 2009. Relating CCN activity, volatility, and droplet growth kinetics of β-caryophyllene secondary organic aerosol. Atmos. Chem. Phys. 9, 795-812. Atkinson, R. Arey, J., 2003. Atmospheric degradation of volatile organic compounds. Chem. Rev. 103, 4605-4638. Babar, Z.B., Park, J.-H., Kang, J., Lim, H.-J., 2016. Characterization of a smog chamber for studying formation and physicochemical properties of secondary organic aerosol. Aerosol Air Qual. Res. 16, 3102–3113 Bateman, A.P., Laskin, J., Laskin, A., Nizkorodov, S.A., 2012. Applications of high-resolution electrospray ionization mass spectrometry to measurements of average oxygen to carbon ratios in secondary organic aerosols. Environ. Sci. Technol. 46, 8315-8324. Bateman, A.P., Nizkorodov, S.A., Laskin, J., Laskin, A., 2009. Time-resolved molecular characterization of limonene/ozone aerosol using high-resolution electrospray ionization mass spectrometry. Physical chemistry chemical physics : Phys. Chem. Chem. Phys. 11, 7931-7942. Bean, J.K., Ruiz, L.H., 2016. Gas–particle partitioning and hydrolysis of organic nitrates formed from the oxidation of α-pinene in environmental chamber experiments. Atmos. Chem. Phys., 16, 2175–2184. Bruns, E.A., Perraud, V., Zelenyuk, A., Ezell, M.J., Johnson, S.N., Yu, Y., Imre, D., FinlaysonPitts, B.J., Alexander, M.L., 2010. Comparison of FTIR and particle mass spectrometry for the measurement of particulate organic nitrates. Environ. Sci. Technol. 44, 1056-1061. Capouet, M., Müller, J.-F., Ceulemans, K., Compernolle, S. Vereecken, L., Peeters, J., 2008. Modeling aerosol formation in α-pinene photo-oxidation experiments. J. Geophys. Res. 113, D02308, doi:10.1029/2007JD008995. Carlton, A.G., Pinder, R.W., Bhave, P.V., Pouliot, G.A., 2010. To what extent can biogenic SOA be controlled? Environ. Sci. Technol. 44, 3376-3380.

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27

ACCEPTED MANUSCRIPT

EP

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Chan, A.W.H., Chan, M.N., Surratt, J.D., Chhabra, P.S., Loza, C.L., Crounse, J.D., Yee, L.D., Flagan, R.C., Wennberg, P.O., Seinfeld, J.H., 2010. Role of aldehyde chemistry and NOx concentrations in secondary organic aerosol formation. Atmos. Chem. Phys. 10, 7169-7188. Chen, Q., Heald, C.L., Jimenez, J.L., Canagaratna, M.R., Zhang, Q., He, L.-Y., Huang, X.-F., Campuzano-Jost, P., Palm, B.B., Poulain, L., Kuwata, M., Martin, S.T., Abbatt, J.P.D., Lee, A.K.Y., Liggio, J., 2015. Elemental composition of organic aerosol: The gap between ambient and laboratory measurements. Geophys. Res. Lett. 42, 4182-4189. Chhabra, P.S., Lambe, A.T., Canagaratna, M.R., Stark, H., Jayne, J.T., Onasch, T.B., Davidovits, P., Kimmel, J.R., Worsnop, D.R., 2015. Application of high-resolution time-of-flight chemical ionization mass spectrometry measurements to estimate volatility distributions of α-pinene and naphthalene oxidation products. Atmos. Meas. Tech. 8, 1-18. Chhabra, P.S., Ng, N.L., Canagaratna, M.R., Corrigan, A.L., Russell, L.M., Worsnop, D.R., Flagan, R.C., Seinfeld, J.H., 2011. Elemental composition and oxidation of chamber organic aerosol. Atmos. Chem. Phys. 11, 8827-8845. Cho, Y., Jin, J.M., Witt, M., Birdwell, J.E., Na, J.G., Roh, N.S., Kim, S., 2013. Comparing laser desorption ionization and atmospheric pressure photoionization coupled to fourier transform ion cyclotron resonance mass spectrometry to characterize shale oils at the molecular level. Energy & Fuels 27, 1830-1837. Claeys, M., L A E Y S , Iinuma, Y. Szmigielski, R., Surratt, J.D., Blockhuys, F., Alsenoy, C.V., Böge, O., Sierau, B., González, Y.G., Vermeylen, R., Veken, P.V.D., Shahgholi, M., Chan, A.W.H., Herrmann, H. Seinfeld, J.H. Maenhaut, W., 2009. Terpenylic acid and related compounds from the oxidation of α-pinene: Implications for new particle formation and growth above forests. Environ. Sci. Technol. 43, 6976–6982. Crounse, J.D., Paulot, F., Kjaergaard, H.G., Wennberg, P.O., 2011. Peroxy radical isomerization in the oxidation of isoprene. Phys. Chem. Chem. Phys., 13, 13607–13613. Docherty, K.S., Ziemann, P.J., 2003. Effects of stabilized Criegee intermediate and OH radical scavengers on aerosol formation from reactions of β-pinene with O3. Aerosol Sci. Technol. 37, 877-891. Eddingsaas, N.C., Loza, C.L., Yee, L.D., Chan, M., Schilling, K.A., Chhabra, P.S., Seinfeld, J.H., Wennberg, P.O., 2012. α-pinene photooxidation under controlled chemical conditions - part 2: SOA yield and composition in low- and high-NOx environments. Atmos. Chem. Phys. 12, 7413-7427. Engelhart, G.J., Moore, R.H., Nenes, A., Pandis, S.N., 2011. Cloud condensation nuclei activity of isoprene secondary organic aerosol. J. Geophys. Res. 116. D02207, doi:10.1029/2010JD014706. Farmer, D. K., Matsunaga, A., Docherty, K.S., Surratt, J.D., Seinfeld, J.H., Ziemann, P.J., Jimenez, J.L., 2010. Response of an aerosol mass spectrometer to organonitrates and organosulfates and implications for at atmospheric chemistry, Proc. Natl. Acad. Sci. U. S. A., 107(15), 6670–6675. Hall, W.A., Johnston, M.V., 2011. Oligomer content of α-pinene secondary organic aerosol. Aerosol Sci. Tech. 45, 37-45. Hall, W.A.t., Pennington, M.R., Johnston, M.V., 2013. Molecular transformations accompanying the aging of laboratory secondary organic aerosol. Environ. Sci. Technol. 47, 2230-2237. Hallquist, M., Wenger, J.C., Baltensperger, U., Rudich, Y., Simpson, D., Claeys, M., Dommen, J., Donahue, N.M., George, C., Goldstein, A.H., Hamilton, J.F., Herrmann, H., Hoffmann, T.,

AC C

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45

28

ACCEPTED MANUSCRIPT

EP

TE D

M AN U

SC

RI PT

Iinuma, Y., Jang, M., Jenkin, M.E., Jimenez, J.L., Kiendler-Scharr, A., Maenhaut, W., McFiggans, G., Mentel, T.F., Monod, A., Prevot, A.S.H., Seinfeld, J.H., Surratt, J.D., Szmigielski, R., Wildt, J., 2009. The formation, properties and impact of secondary organic aerosol: current and emerging issues. Atmos. Chem. Phys. 9, 5155-5236. Hao, L.Q., Romakkaniemi, S., Yli-Pirilä, P., Joutsensaari, J., Kortelainen, A., Kroll, J.H., Miettinen, P., Vaattovaara, P., Tiitta, P., Jaatinen, A., Kajos, M.K., Holopainen, J.K., Heijari, J., Rinne, J., Kulmala, M., Worsnop, D.R., Smith, J.N., Laaksonen, A., 2011. Mass yields of secondary organic aerosols from the oxidation of α-pinene and real plant emissions. Atmos. Chem. Phys. 11, 1367-1378. Heald, C.L., Kroll, J.H., Jimenez, J.L., Docherty, K.S., DeCarlo, P.F., Aiken, A.C., Chen, Q., Martin, S.T., Farmer, D.K., Artaxo, P., 2010. A simplified description of the evolution of organic aerosol composition in the atmosphere. Geophys. Res. Lett. 37, L08803, doi:10.1029/2010GL042737. Heaton, K.J., Dreyfus, M.A., Wang, S., Johnston, M.V., 2007. Oligomers in the early stage of biogenic secondary organic aerosol formation and growth. Environ. Sci. Technol. 41, 61296136. Heaton, K.J., Sleighter, R.L., Hatcher, P.G., Hall, W.A., Johnston, M.V., 2009. Composition domains in monoterpene secondary organic aerosol. Environ. Sci. Technol. 43, 7797-7802. Hughey, C.A., Hendrickson, C.L., Rodgers, R.P., Marshall, A.G., Qian, K.N., 2001. Kendrick mass defect spectrum: A compact visual analysis for ultrahigh-resolution broadband mass spectra. Anal. Chem. 73, 4676-4681. Jimenez, J.L., Canagaratna, M.R., Donahue, N.M., Prevot, A.S.H., Zhang, Q., Kroll, J.H., DeCarlo, P.F., Allan, J.D., Coe, H., Ng, N.L., Aiken, A.C., Docherty, K.S., Ulbrich, I.M., Grieshop, A.P., Robinson, A.L., Duplissy, J., Smith, J.D., Wilson, K.R., Lanz, V.A., Hueglin, C., Sun, Y.L., Tian, J., Laaksonen, A., Raatikainen, T., Rautiainen, J., Vaattovaara, P., Ehn, M., Kulmala, M., Tomlinson, J.M., Collins, D.R., Cubison, M.J., Dunlea, E.J., Huffman, J.A., Onasch, T.B., Alfarra, M.R., Williams, P.I., Bower, K., Kondo, Y., Schneider, J., Drewnick, F., Borrmann, S., Weimer, S., Demerjian, K., Salcedo, D., Cottrell, L., Griffin, R., Takami, A., Miyoshi, T., Hatakeyama, S., Shimono, A., Sun, J.Y., Zhang, Y.M., Dzepina, K., Kimmel, J.R., Sueper, D., Jayne, J.T., Herndon, S.C., Trimborn, A.M., Williams, L.R., Wood, E.C., Middlebrook, A.M., Kolb, C.E., Baltensperger, U., Worsnop, D.R., 2009. Evolution of organic aerosols in the atmosphere. Science 326, 1525-1529. Kamens, R.M., Jaoui, M., 2001. Modeling aerosol formation from alpha-pinene plus NOx in the presence of natural sunlight using gas-phase kinetics and gas-particle partitioning theory. Environ. Sci. Technol. 35, 1394-1405. Kanakidou, M., Seinfeld, J.H., Pandis, S.N., Barnes, I., Dentener, F.J., Facchini, M.C., Van Dingenen, R., Ervens, B., Nenes, A., Nielsen, C.J., Swietlicki, E., Putaud, J.P., Balkanski, Y., Fuzzi, S., Horth, J., Moortgat, G.K., Winterhalter, R., Myhre, C.E.L., Tsigaridis, K., Vignati, E., Stephanou, E.G., Wilson, J., 2005. Organic aerosol and global climate modelling: a review. Atmos. Chem. Phys. 5, 1053-1123. Kim, H., Liu, S., Russell, L.M., Paulson, S.E., 2014. Dependence of real refractive indices on O:C, H:C and mass fragments of secondary organic aerosol generated from ozonolysis and photooxidation of limonene and α-pinene. Aerosol. Sci. Tech. 48, 498-507. Kim, S., Kramer, R.W., Hatcher, P.G., 2003. Graphical method for analysis of ultrahighresolution broadband mass spectra of natural organic matter, the van Krevelen diagram.

AC C

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45

29

ACCEPTED MANUSCRIPT

EP

TE D

M AN U

SC

RI PT

Anal. Chem. 75, 5336-5344. Kleindienst, T.E., Lewandowski, M., Offenberg, J.H., Jaoui, M., Edney, E.O., 2007. Ozoneisoprene reaction: Re-examination of the formation of secondary organic aerosol. Geophys. Res. Lett. 34. L01805, doi:10.1029/2006GL027485. Koch, B.P., Witt, M., Engbrodt, R., Dittmar, T., Kattner, G., 2005. Molecular formulae of marine and terrigenous dissolved organic matter detected by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. Geochim. Cosmochim. Acta 69, 3299-3308. Kourtchev, I., Doussin, J.-F, Giorio, C., Mahon, B., Wilson, E.M., Maurin, N., Pangui, E., Venables, D.S., Wenger, J.C., Kalberer. M., 2015. Molecular composition of fresh and aged secondary organic aerosol from a mixture of biogenic volatile compounds: a highresolution mass spectrometry study. Atmos. Chem. Phys. 15, 5683–5695. Kourtchev, I., Doussin, J.F., Giorio, C., Mahon, B., Wilson, E.M., Maurin, N., Pangui, E., Venables, D.S., Wenger, J.C., Kalberer, M., 2015. Molecular composition of fresh and aged secondary organic aerosol from a mixture of biogenic volatile compounds: a high-resolution mass spectrometry study. Atmos. Chem. Phys. 15, 5683-5695. Kourtchev, I., Fuller, S., Aalto, J., Ruuskanen, T.M., McLeod, M.W., Maenhaut, W., Jones, R., Kulmala, M., Kalberer, M., 2013. Molecular composition of boreal forest aerosol from Hyytiala, Finland, using ultrahigh resolution mass spectrometry. Environ. Sci. Technol. 47, 4069-4079. Kourtchev, I., Fuller, S.J., Giorio, C., Healy, R.M., Wilson, E., O'Connor, I., Wenger, J.C., McLeod, M., Aalto, J., Ruuskanen, T.M., Maenhaut, W., Jones, R., Venables, D.S., Sodeau, J.R., Kulmala, M., Kalberer, M., 2014a. Molecular composition of biogenic secondary organic aerosols using ultrahigh-resolution mass spectrometry: comparing laboratory and field studies. Atmos. Chem. Phys. 14, 2155-2167. Kourtchev, I., O'Connor, I.P., Giorio, C., Fuller, S.J., Kristensen, K., Maenhaut, W., Wenger, J.C., Sodeau, J.R., Glasius, M., Kalberer, M., 2014b. Effects of anthropogenic emissions on the molecular composition of urban organic aerosols: An ultrahigh resolution mass spectrometry study. Atmos. Environ. 89, 525-532. Krechmer, J.E., Coggon, M.M., Massoli, P., Nguyen, T.B., Crounse, J.D., Hu, W., Day, D.A., Tyndall, G.S., Henze, D.K., Rivera-Rios, J.C., Nowak, J.B., Kimmel, J.R., Mauldin, R.L., 3rd, Stark, H., Jayne, J.T., Sipila, M., Junninen, H., Clair, J.M., Zhang, X., Feiner, P.A., Zhang, L., Miller, D.O., Brune, W.H., Keutsch, F.N., Wennberg, P.O., Seinfeld, J.H., Worsnop, D.R., Jimenez, J.L., Canagaratna, M.R., 2015. Formation of low volatility organic compounds and secondary organic aerosol from isoprene hydroxyhydroperoxide low-NO oxidation. Environ. Sci. Technol. 49, 10330-10339. Kristensen, K., Cui, T., Zhang, H., Gold, A., Glasius, M., Surratt, J.D., 2014. Dimers in α-pinene secondary organic aerosol: Effect of hydroxyl radical, ozone, relative humidity and aerosol acidity. Atmos. Chem. Phys. 14, 4201-4218. Kristensen, K., Watne, Å.K., Hammes, J., Lutz, A., Petäjä, T. Hallquist, M., Bilde, M., Glasius, M., 2016. High-molecular weight dimer esters are major products in aerosols from α‑ pinene ozonolysis and the boreal forest. Environ. Sci. Technol. Lett. 3, 280−285. Kroll, J.H., Donahue, N.M., Jimenez, J.L., Kessler, S.H., Canagaratna, M.R., Wilson, K.R., Altieri, K.E., Mazzoleni, L.R., Wozniak, A.S., Bluhm, H., Mysak, E.R., Smith, J.D., Kolb, C.E., Worsnop, D.R., 2011. Carbon oxidation state as a metric for describing the chemistry

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30

ACCEPTED MANUSCRIPT

EP

TE D

M AN U

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RI PT

of atmospheric organic aerosol. Nature Chem. 3, 133-139. Kroll, J.H., Ng, N.L., Murphy, S.M., Varutbangkul, V., Flagan, R.C., Seinfeld, J.H., 2005. Chamber studies of secondary organic aerosol growth by reactive uptake of simple carbonyl compounds. J. Geophys. Res. 110, L18808, doi:10.1029/2005GL023637. Krolla, J.H., Seinfeld, J.H., 2008. Chemistry of secondary organic aerosol: Formation and evolution of low-volatility organics in the atmosphere. Atmos. Environ. 42, 3593–3624. Kujawinski, E.B., Behn, M.D., 2006. Automated analysis of electrospray ionization Fourier transform ion cyclotron resonance mass spectra of natural organic matter. Anal. Chem. 78, 4363-4373. Kundu, S., Fisseha, R., Putman, A.L., Rahn, T.A., Mazzoleni, L.R., 2012. High molecular weight SOA formation during limonene ozonolysis: insights from ultrahigh-resolution FT-ICR mass spectrometry characterization. Atmos. Chem. Phys. 12, 5523-5536. Kundu, S., Fisseha, R., Putman, A.L., Rahn, T.A., Mazzoleni, L.R., 2017. Molecular formula composition of b-caryophyllene ozonolysis SOA formed in humid and dry conditions. Atmos. Environ. 154, 70-81. Kuwata, M., Martin, S.T., 2012. Phase of atmospheric secondary organic material affects its reactivity. P. Natl. Acad. Sci. USA 109, 17354-17359. Kwan, A.J., Chan, A.W.H., Ng, N.L. Kjaergaard, H.G., Seinfeld, J.H., Wennberg, P.O., 2012. Peroxy radical chemistry and OH radical production during the NO3-initiated oxidation of isoprene. Atmos. Chem. Phys., 12, 7499–7515. Lambe, A.T., Cappa, C.D., Massoli, P., Onasch, T.B., Forestieri, S.D., Martin, A.T., Cummings, M.J., Croasdale, D.R., Brune, W.H., Worsnop, D.R., Davidovits, P., 2013. Relationship between oxidation level and optical properties of secondary organic aerosol. Environ. Sci. Technol. 47, 6349-6357. Lambe, A.T., Onasch, T.B., Croasdale, D.R., Wright, J.P., Martin, A.T., Franklin, J.P., Massoli, P., Kroll, J.H., Canagaratna, M.R., Brune, W.H., Worsnop, D.R., Davidovits, P., 2012. Transitions from functionalization to fragmentation reactions of laboratory secondary organic aerosol (SOA) generated from the OH oxidation of alkane precursors. Environ. Sci. Technol. 46, 5430-5437. Lambe, A.T., Onasch, T.B., Massoli, P., Croasdale, D.R., Wright, J.P., Ahern, A.T., Williams, L.R., Worsnop, D.R., Brune, W.H., Davidovits, P., 2011. Laboratory studies of the chemical composition and cloud condensation nuclei (CCN) activity of secondary organic aerosol (SOA) and oxidized primary organic aerosol (OPOA). Atmos. Chem. Phys. 11, 8913-8928. Lane, T.E., Donahue, N.M., Pandis, S.N., 2008. Simulating secondary organic aerosol formation using the volatility basis-set approach in a chemical transport model. Atmos. Environ. 42, 7439-7451. Lee, A., Goldstein, A.H., Kroll, J.H., Ng, N.L., Varutbangkul, V., Flagan, R.C., Seinfeld, J.H., 2006. Gas-phase products and secondary aerosol yields from the photooxidation of 16 different terpenes. J. Geophys. Res. 111, D17305, doi:10.1029/2006JD007050. Lee, B.H., Mohr, C., Lopez-Hilfiker, F.D., Lutz, A., Hallquist, M., Lee, L., Romer, P., Cohen, R.C., Iyer, S., Kurten, T., Hu, W.W., Day, D.A., Campuzano-Jost, P., Jimenez, J.L., Xu, L., Ng, N.L., Guo, H.Y., Weber, R.J., Wild, R.J., Brown, S.S., Koss, A., de Gouw, J., Olson, K., Goldstein, A.H., Seco, R., Kim, S., McAvey, K., Shepson, P.B., Starn, T., Baumann, K., Edgerton, E.S., Liu, J.M., Shilling, J.E., Miller, D.O., Brune, W., Schobesberger, S., D'Ambro, E.L., Thornton, J.A., 2016b. Highly functionalized organic nitrates in the

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31

ACCEPTED MANUSCRIPT

EP

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M AN U

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southeast United States: Contribution to secondary organic aerosol and reactive nitrogen budgets. P. Natl. Acad. Sci. USA. 113, 1516-1521. Li, J.L., Henni, A., Tontiwachwuthikul, P., 2007. Reaction kinetics of CO2 in aqueous ethylenediamine, ethyl ethanolamine, and diethyl monoethanolamine solutions in the temperature range of 298-313 K, using the stopped-flow technique. Ind. Eng. Chem. Res. 46, 4426-4434. Lim, Y.B., Ziemann, P.J., 2009. Chemistry of secondary organic aerosol formation from OH radical-initiated reactions of linear, branched, and cyclic alkanes in the presence of NOx. Aerosol. Sci. Tech. 43, 604-619. Lin, L., Yu, Q., Yan, X., Hang, W., Zheng, J., Xing, J., Huanga, B., 2010. Direct infusion mass spectrometry or liquid chromatography mass spectrometry for human metabonomics? A serum metabonomic study of kidney cancer. Analyst 135, 2970–2978. Liu, S., Shilling, J.E., Song, C., Hiranuma, N., Zaveri, R.A., Russell, L.M., 2012. Hydrolysis of organonitrate functional groups in aerosol particles, Aerosol Sci. Technol. 46, 13591369. Mazzoleni, L.R., Saranjampour, P., Dalbec, M.M., Samburova, V., Hallar, A.G., Zielinska, B., Lowenthal, D.H., Kohl, S., 2012. Identification of water-soluble organic carbon in nonurban aerosols using ultrahigh-resolution FT-ICR mass spectrometry: organic anions. Environ. Chem. 9, 285. Müller, L., Reinnig, M.-C., Hayen, H., Hoffmann, T., 2009. Characterization of oligomeric compounds in secondary organic aerosol using liquid chromatography coupled to electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. Rapid Commun. Mass Spectrom. 23, 971–979. Nah, T. Sanchez, J. Boyd, C.M., Ng, N.L., 2016. Photochemical aging of α‑ pinene and β‑ pinene secondary organic aerosol formed from nitrate radical oxidation. Environ. Sci. Technol., 50, 222−231. Nah, T., Sanchez, J., Boyd, C.M., Ng, N.L., 2015. Photochemical Aging of α-pinene and βpinene secondary organic aerosol formed from nitrate radical oxidation. Environ. Sci. Technol. 50, 222-231. Nguyen, T.B., Bateman, A.P., Bones, D.L., Nizkorodov, S.A., Laskin, J., Laskin, A., 2010. Highresolution mass spectrometry analysis of secondary organic aerosol generated by ozonolysis of isoprene. Atmos. Environ. 44, 1032-1042. Nguyen, T.B., Laskin, J., Laskin, A., Nizkorodov, S.A., 2011. Nitrogen-containing organic compounds and oligomers in secondary organic aerosol formed by photooxidation of isoprene. Environ. Sci. Technol. 45, 6908-6918. Nizkorodov, S.A., Laskin, J., Laskin, A., 2011. Molecular chemistry of organic aerosols through the application of high resolution mass spectrometry. Phys. Chem. Chem. Phys. 13, 36123629. O’Brien, R.E., Laskin, A., Laskin, J., Liu, S., Weber, R., Russell, L.M., Goldstein, A.H., 2013. Molecular characterization of organic aerosol using nanospray desorption/electrospray ionization mass spectrometry: CalNex 2010 field study. Atmos. Environ. 68, 265-272. Park, K.H., Kim, M.S., Baek, S.J., Bae, I.H., Seo, S.W., Kim, J., Shin, Y.K., Lee, Y.M., Kim, H.S., 2013. Simultaneous molecular formula determinations of natural compounds in a plant extract using 15 T Fourier transform ion cyclotron resonance mass spectrometry. Plant Methods 9:15, 1-12.

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Paulson, S.E., Chung, M., Sen, A.D., Orzechowska, G., 1998. Measurement of OH radical formation from the reaction of ozone with several biogenic alkenes. J. Geophys. Res., 103, D19, 25,533-25,539. Putman, A.L., Offenberg, J.H., Fisseha, R., Kundu, S., Rahn, T.A., Mazzoleni, L.R., 2012. Ultrahigh-resolution FT-ICR mass spectrometry characterization of α-pinene ozonolysis SOA. Atmos. Environ. 46, 164-172. Rincón, A.G., Calvo, A.I., Dietzel, M., Kalberer, M., 2012. Seasonal differences of urban organic aerosol composition - an ultra-high resolution mass spectrometry study. Environ. Chem. 9, 298. Ruggeri, G., Bernhard, F.A., Henderson, B.H., and Takahama, S.: Model-measurement comparison of functional group abundance in α-pinene and 1,3,5-trimethylbenzene secondary organic aerosol formation, 2016. Atmospheric Chemistry and Physics, 16, 8729–8747, doi:10.5194/acp-16-8729-2016. Saathoff, H., Naumann, K.H., Mohler, O., Jonsson, A.M., Hallquist, M., Kiendler-Scharr, A., Mentel, T.F., Tillmann, R., Schurath, U., 2009. Temperature dependence of yields of secondary organic aerosols from the ozonolysis of alpha-pinene and limonene. Atmos. Chem. Phys. 9, 1551-1577. Sadezky, A., Mellouki, C.A., Römpp, A., Winterhalter, R., Bras, G.L., Moortgat, G.K., 2006. Formation of secondary organic aerosol and oligomers from the ozonolysis of enol ethers. Atmos. Chem. Phys. 6, 5009–5024. Sato, K., Inomata, S., Xing, J.H., Imamura, T., Uchida, R., Fukuda, S., Nakagawa, K., Hirokawa, J., Okumura, M., Tohno, S., 2013. Effect of OH radical scavengers on secondary organic aerosol formation from reactions of isoprene with ozone. Atmos. Environ. 79, 147-154. Stenson, A.C., Landing, W.M., Marshall, A.G., Cooper, W.T., 2002. Ionization and fragmentation of humic substances in electrospray ionization Fourier transform-ion cyclotron resonance mass spectrometry. Anal. Chem. 74, 4397-4409. Sun, Y.L., Zhang, Q., Schwab, J.J., Demerjian, K.L., Chen, W.N., Bae, M.S., Hung, H.M., Hogrefe, O., Frank, B., Rattigan, O.V., Lin, Y.C., 2011. Characterization of the sources and processes of organic and inorganic aerosols in New York city with a high-resolution timeof-flight aerosol mass apectrometer. Atmos. Chem. Phys. 11, 1581-1602. Timonen, H., Carbone, S., Aurela, M., Saarnio, K., Saarikoski, S., Ng, N.L., Canagaratna, M.R., Kulmala, M., Kerminen, V.M., Worsnop, D.R., Hillamo, R., 2013. Characteristics, sources and water-solubility of ambient submicron organic aerosol in springtime in Helsinki, Finland. J. Aerosol Sci. 56, 61–77. Visser, S.A., 1983. Application of Van Krevelen's graphical-statistical method for the study of aquatic humic material. Environ. Sci. Technol. 17, 412-417. Walser, M.L., Desyaterik, Y., Laskin, J., Laskin, A., Nizkorodov, S.A., 2008. High-resolution mass spectrometric analysis of secondary organic aerosol produced by ozonation of limonene. Physical chemistry chemical physics : Phys. Chem. Chem. Phys. 10, 1009-1022. Wang, X.F., Gao, S., Yang, X., Chen, H., Chen, J.M., Zhuang, G.S., Surratt, J.D., Chan, M.N., Seinfeld, J.H., 2010. Evidence for high molecular weight nitrogen-containing organic salts in urban aerosols. Environ. Sci. Technol. 44, 4441-4446. Wolkoff, P., Clausen, P.A., Wilkins, C.K., Nielsen, G.D., 2000. Formation of strong airway irritants in terpene/ozone mixtures. Indoor Air 10, 82-91.

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Yang, H.J., Park, K.H., Lim, D.W., Kim, H.S., Kim, J., 2012. Analysis of cancer cell lipids using matrix-assisted laser desorption/ionization 15-T Fourier transform ion cyclotron resonance mass spectrometry. Rapid Commun. Mass. Sp. 26, 621-630. Yasmeen, F., Vermeylen, R., Szmigielski, R., Iinuma, Y., Böge, O., Herrmann, H., Maenhaut, W., Claeys, M., 2010. Terpenylic acid and related compounds: precursors for dimers in secondary organic aerosol from the ozonolysis of α- and β-pinene. Atmos. Chem. Phys. 10, 9383-9392. Ye, P., Ding, X., Hakala, J., Hofbauer, V., Robinson, E.S., Donahue, N.M., 2016, Vapor wall loss of semi-volatile organic compounds in a Teflon chamber, Aerosol Sci. Technol. 50, 822-834. Yeh, G.K., Ziemann, P.J., 2014. Alkyl nitrate formation from the reactions of C8−C14 n‑ alkanes with OH radicals in the presence of NOx: Measured yields with essential corrections for gas−wall partitioning. J. Phys. Chem. A 118, 8147−8157. Zhang, X., McVay, R.C., Huang, D.D., Dalleska, N.F., Aumont, B., Flagana, R.C., Seinfeld, J.H., 2015. Formation and evolution of molecular products in α-pinene secondary organic aerosol. Proc. Natl. Acad. Sci. 112. 68–14173. Zhanga, X., Cappa, C.D., Jathar, S.H., McVay, R.C., Ensberg, J.J., Kleeman, M.J., Seinfeld, J.H., 2014. Influence ce of vapor wall loss in laboratory chambers on yields of secondary organic aerosol. Proc. Natl. Acad. Sci. 111, 5802-5807. Ziemann, P.J., Atkinson, R., 2012. Kinetics, products, and mechanisms of secondary organic aerosol formation. Chem. Soc. Rev. 41, 6582-6605.

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ACCEPTED MANUSCRIPT Table 1 Experimental conditions and results of SOA formation. Experimental ID of O3, O3+Hx, OH, OH, OH+NO, and OH+NOx represent SOA formation experiments under ozonolysis, OH

photooxidation, respectively.

O3 O3+Hx OH OH+NO OH+NOx

ppb 1033.9 1017.6 1028.6 1126.4 1022.4

ppb ppb 1033.9 0 1015.4 0 330.2 1000 1126.0 1000 1021.6 1000

NOini NO2ini

O3ini Hexanea SOASMPSb SOAGAc WSOC WSON

ppb 0 0 0 1064 1008

ppb 1175 1242 0 0 0

ppb 2 3 2 37 1072

a

ppm 100 -

µg/m3 3504 3133 1248 579 2129

µg/m3 1831 1305 772 491 1200

µg/m3 695 700 179 131 441

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ID

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scavenged ozonolysis, low NOx photooxidation, high NO photooxidation, and high NO+NO2

µg/m3 6.09 5.49 1.87 8.40 18.57

WSON/ WSOC 0.05 0.04 0.05 0.31 0.22

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ACCEPTED MANUSCRIPT Table 2 The fraction of species commonly found between experiments. Numbers in the parentheses represent the number of peaks identified by negative ion ESI FT-ICR MS analyses.

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Experimental ID of O3, O3+Hx, OH, OH, OH+NO, and OH+NOx represent SOA formation experiments under ozonolysis, OH scavenged ozonolysis, low NOx photooxidation, high NO photooxidation, and high NO+NO2 photooxidation, respectively. O3+Hx

OH

OH+NO

OH+NOx

1

0.955

0.849

0.745

0.747

O3+Hx (1473)

0.524

1

0.847

0.704

0.696

OH (2141)

0.338

0.615

1

0.676

0.650

OH+NO (3501)

0.179

0.309

0.409

1

0.839

OH+NOx (3101)

0.205

0.348

0.447

0.956

1

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O3 (815)

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ACCEPTED MANUSCRIPT Table 3 Intensity-weighted averages of atomic ratios, double bond equivalent (DBE), and oxidation state of carbon (OSC) of chemical groups of SOA. Numbers in the parentheses represent

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number of identified ions. Experimental ID of O3, O3+Hx, OH, OH, OH+NO, and OH+NOx represent SOA formation experiments under ozonolysis, OH scavenged ozonolysis, low NOx photooxidation, high NO photooxidation, and high NO+NO2 photooxidation, respectively.

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O/C 0.54 0.60 0.87 0.22 0.54 0.52 0.58 0.84 0.66 0.54 0.51 0.60 0.86 0.52 0.54 0.57 0.72 0.90 1.06 0.71 0.56 0.72 0.90 1.06 0.69

N/C OM/OC OSC 0 1.84 −0.41 0.059 1.99 −0.66 0.092 2.44 −0.67 0.081 1.48 −1.08 0.0039 1.85 −0.43 0 1.82 −0.45 0.058 1.97 −0.66 0.090 2.39 −0.70 0.133 2.18 −1.06 0.0074 1.85 −0.47 0 1.81 −0.44 0.058 2.00 −0.64 0.094 2.42 −0.68 0.161 1.97 −0.89 0.013 1.86 −0.49 0 1.88 −0.28 0.070 2.17 −0.39 0.133 2.49 −0.49 0.203 2.79 −0.60 0.061 2.15 −0.38 0 1.87 −0.29 0.072 2.17 −0.39 0.134 2.49 −0.50 0.206 2.80 −0.62 0.055 2.11 −0.37

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H/C 1.49 1.55 1.96 1.11 1.50 1.49 1.54 1.94 1.72 1.51 1.47 1.55 1.94 1.12 1.50 1.42 1.48 1.62 1.70 1.50 1.42 1.48 1.62 1.71 1.49

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Fraction 94.54 (676) 4.05 (104) 1.58 (34) 0.03 (1) 100 (815) 88.46 (960) 9.33 (408) 2.16 (101) 0.06 (4) 100 (1473) 79.64(1300) 16.07 (644) 4.16 ( 189) 0.13 (8) 100 (2141) 41.88 (1158) 32.33 (1053) 19.45 (870) 6.34 (420) 100 (3501) 47.57 (1094) 30.95 (955) 16.61 (740) 4.87 (312) 100 (3101)

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Class CHO CHON1 CHON2 CHON3 Total O3+Hx CHO CHON1 CHON2 CHON3 Total OH CHO CHON1 CHON2 CHON3 Total OH+NO CHO CHON1 CHON2 CHON3 Total OH+NOx CHO CHON1 CHON2 CHON3 Total

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DBE 5.14 5.75 2.79 19.0 5.13 5.19 5.91 2.71 5.78 5.20 5.80 5.81 2.61 10.77 5.68 5.72 5.82 5.26 5.00 5.62 5.61 5.75 5.23 4.84 5.55

ACCEPTED MANUSCRIPT Table 4 Elemental ratios of SOA for representative biogenic ROGs of isoprene, α-pinene, and dlimonene. H/C 1.50 1.54 1.44 1.45 1.46 1.46 1.47 1.50 1.49 1.23 1.08 1.33 1.45 1.60 d-Limonene 1.58 1.58

O/C N/C Reactions Analysis 0.53 0 O3 ESI(-) FT-ICR MS 0.46 NAb O3 ESI(-) FT-ICR MS 0.32 NA O3 AMS 0.43 NA O3 ESI(+, -) FT-ICR MS 0.38 NA O3 AMS 0.55 NA O3 ESI(-) Orbitrap MS 0.79 NA O3 (-)CIMS 0.56 0.02 Low NOx ESI(-) FT-ICR MS 0.74 0.07 High NOx ESI(-) FT-ICR MS 0.60 NA Low NOx ESI(+, -) FT-ICR MS AMS 0.94 NA Low NOx 1.01 NA Low NOx (-)CIMS 0.42 NA High NOx AMS 0.8 0.06 NO3 AMS 0.46 NA O3 ESI(-) Orbitrap MS 0.45 NA O3 ESI(+, -) Orbitrap MS 0.43 NA O3 ESI(+) Orbitrap MS 0.5 NA O3 ESI(-) Orbitrap MS a a 1.5 0.6 NA O3 ESI(-) FT-ICR MS AMS 1.45 0.37 NA High NOx Isoprene 1.53 0.63 NA O3 ESI(+, -) Orbitrap MS 1.61 0.54 <0.002 Low NOx ESI(-) Orbitrap MS 1.83 0.71 NA Low NOx AMS 1.75 0.90 NA Low NOx AMS 2.1 1.1 NA Low NOx (-)CIMS 1.55 0.83 0.019 High NOx ESI(-) Orbitrap MS a represents data in a group woith m/z between 140-300.

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Refs This study Putman et al. (2012) Kuwata et al. (2012) Hall et al. (2013) Kim et al. (2014) Kourtchev et al. (2014) Chhabra et al. (2015) This study This study Hall et al. (2013) Lambe et al. (2013) Chhabra et al. (2015) Kim et al. (2014) Nah et al. (2015) Bateman et al. (2009) Nguyen et al. (2010) Walser et al. (2009) Walser et al. (2009) Kundu et al. (20120 Kim et al. (2014) Nguyen et al. (2010) Nguyen et al. (2011) Kuwata et al. (2012) Krechmer et al. (2015) Krechmer et al. (2015) Nguyen et al. (2011)

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ROGs α-Pinene

NA represents not available.

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Fig. 1. Mass spectra of 15T FT-ICR MS in negative ESI mode for α-pinene SOA samples.

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Experimental ID of O3, O3+Hx, OH, OH+NO, and OH+NOx represent SOA formation

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experiments under ozonolysis, OH scavenged ozonolysis, low NOx photooxidation, high NO

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Fig. 2. Atomic ratios of (a) N/O ratios for (a) CHON1, (b) CHON2, and (c) CHON3 groups

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Fig. 3. van Krevelen diagram for CHO, CHON1, CHON2, and CHON3. Color represents

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Highlights The detailed molecular composition of SOA was identified by ultra-high resolution mass spectrometry. N-containing species were largely found in SOA formed under high NOx

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photooxidation.

N-containing species were present in high O/C ratios with elevated carbon oxidation states.

Several common abundant species demonstrate potential to be tracers for α-

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pinene SOA.