Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Mass Spectrometry Society of Japan  

DOI： 10.5702/massspectrometry.a0127

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.5194/acp-23-7887-2023

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.5702/massspectrometry.A0124

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Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Cosmetic Chemists of Japan  

DOI： 10.5107/sccj.56.395

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Copernicus GmbH  

Abstract. Formaldehyde (HCHO) is one of the most abundant non-methane volatile organic compounds (VOCs) emitted by fires. HCHO also undergoes chemical
production and loss as a fire plume ages, and it can be an important oxidant precursor. In this study, we disentangle the processes controlling HCHO
by examining its evolution in wildfire plumes sampled by the NASA DC-8 during the Fire Influence on Regional to Global Environments and Air Quality experiment (FIREX-AQ) field campaign. In 9 of the 12 analyzed plumes,
dilution-normalized HCHO increases with physical age (range 1–6 h). The balance of HCHO loss (mainly via photolysis) and production (via
OH-initiated VOC oxidation) seems to control the sign and magnitude of this trend. Plume-average OH concentrations, calculated from VOC decays,
range from −0.5 (± 0.5) × 106 to 5.3 (± 0.7) × 106 cm−3. The production and loss rates of
dilution-normalized HCHO seem to decrease with plume age. Plume-to-plume variability in dilution-normalized secondary HCHO production correlates
with OH abundance rather than normalized OH reactivity, suggesting that OH is the main driver of fire-to-fire variability in HCHO secondary
production. Analysis suggests an effective HCHO yield of 0.33 (± 0.05) per VOC molecule oxidized for the 12 wildfire plumes. This finding can
help connect space-based HCHO observations to the oxidizing capacity of the atmosphere and to VOC emissions.

DOI： 10.5194/acp-21-18319-2021

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Association for the Advancement of Science (AAAS)  

While ozone increases rapidly in wildfire plumes, downwind its production rate slows dramatically as nitrogen oxide levels decline.

DOI： 10.1126/sciadv.abl3648

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acs.est.1c03803

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Copernicus GmbH  

Abstract. Wildfires are increasing in size across the western US, leading to
increases in human smoke exposure and associated negative health impacts.
The impact of biomass burning (BB) smoke, including wildfires, on regional
air quality depends on emissions, transport, and chemistry, including
oxidation of emitted BB volatile organic compounds (BBVOCs) by the hydroxyl
radical (OH), nitrate radical (NO3), and ozone (O3). During the
daytime, when light penetrates the plumes, BBVOCs are oxidized mainly by
O3 and OH. In contrast, at night or in optically dense plumes, BBVOCs
are oxidized mainly by O3 and NO3. This work focuses on the
transition between daytime and nighttime oxidation, which has significant
implications for the formation of secondary pollutants and loss of nitrogen
oxides (NOx=NO+NO2) and has been understudied. We present
wildfire plume observations made during FIREX-AQ (Fire Influence on Regional
to Global Environments and Air Quality), a field campaign involving multiple
aircraft, ground, satellite, and mobile platforms that took place in the
United States in the summer of 2019 to study both wildfire and agricultural
burning emissions and atmospheric chemistry. We use observations from two
research aircraft, the NASA DC-8 and the NOAA Twin Otter, with a detailed
chemical box model, including updated phenolic mechanisms, to analyze smoke
sampled during midday, sunset, and nighttime. Aircraft observations suggest
a range of NO3 production rates (0.1–1.5 ppbv h−1) in plumes
transported during both midday and after dark. Modeled initial instantaneous
reactivity toward BBVOCs for NO3, OH, and O3 is 80.1 %, 87.7 %, and 99.6 %, respectively. Initial NO3 reactivity is 10–104
times greater than typical values in forested or urban environments, and
reactions with BBVOCs account for >97 % of NO3 loss in
sunlit plumes (jNO2 up to 4×10-3s-1), while
conventional photochemical NO3 loss through reaction with NO and
photolysis are minor pathways. Alkenes and furans are mostly oxidized by OH
and O3 (11 %–43 %, 54 %–88 % for alkenes; 18 %–55 %, 39 %–76 %, for furans, respectively), but phenolic oxidation is split between
NO3, O3, and OH (26 %–52 %, 22 %–43 %, 16 %–33 %,
respectively). Nitrate radical oxidation accounts for 26 %–52 % of
phenolic chemical loss in sunset plumes and in an optically thick plume.
Nitrocatechol yields varied between 33 % and 45 %, and NO3
chemistry in BB plumes emitted late in the day is responsible for 72 %–92 % (84 % in an optically thick midday plume) of nitrocatechol
formation and controls nitrophenolic formation overall. As a result,
overnight nitrophenolic formation pathways account for 56 %±2 % of
NOx loss by sunrise the following day. In all but one overnight plume
we modeled, there was remaining NOx (13 %–57 %) and BBVOCs
(8 %–72 %) at sunrise.

DOI： 10.5194/acp-21-16293-2021

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Proceedings of the National Academy of Sciences  

Oceans emit large quantities of dimethyl sulfide (DMS) to the marine atmosphere. The oxidation of DMS leads to the formation and growth of cloud condensation nuclei (CCN) with consequent effects on Earth’s radiation balance and climate. The quantitative assessment of the impact of DMS emissions on CCN concentrations necessitates a detailed description of the oxidation of DMS in the presence of existing aerosol particles and clouds. In the unpolluted marine atmosphere, DMS is efficiently oxidized to hydroperoxymethyl thioformate (HPMTF), a stable intermediate in the chemical trajectory toward sulfur dioxide (SO₂) and ultimately sulfate aerosol. Using direct airborne flux measurements, we demonstrate that the irreversible loss of HPMTF to clouds in the marine boundary layer determines the HPMTF lifetime (<italic>τ</italic>_{<italic>HPMTF</italic>} &lt; 2 h) and terminates DMS oxidation to SO₂. When accounting for HPMTF cloud loss in a global chemical transport model, we show that SO₂ production from DMS is reduced by 35% globally and near-surface (0 to 3 km) SO₂ concentrations over the ocean are lowered by 24%. This large, previously unconsidered loss process for volatile sulfur accelerates the timescale for the conversion of DMS to sulfate while limiting new particle formation in the marine atmosphere and changing the dynamics of aerosol growth. This loss process potentially reduces the spatial scale over which DMS emissions contribute to aerosol production and growth and weakens the link between DMS emission and marine CCN production with subsequent implications for cloud formation, radiative forcing, and climate.

DOI： 10.1073/pnas.2110472118

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Other Link： https://syndication.highwire.org/content/doi/10.1073/pnas.2110472118

Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acs.est.1c01963

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Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acs.est.0c01345

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Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1002/jms.4619

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Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1002/jms.4508

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Publisher：Copernicus GmbH  

Abstract. Particles in smoke emitted from biomass combustion have a large impact on global climate and urban air quality. There is limited understanding of how particle optical properties – especially the contributions of black carbon (BC) and brown carbon (BrC) – evolve with photochemical aging of smoke. We analyze the evolution of the optical properties and chemical composition of particles produced from combustion of a wide variety of biomass fuels, largely from the Western U.S.. The smoke is photochemically aged in a reaction chamber over atmospheric-equivalent timescales ranging from 0.25–8 days. Various aerosol optical properties (e.g., the single scatter albedo, the wavelength dependence of absorption, and the BC mass absorption coefficient (MACBC)) evolved with photochemical aging, with the specific evolution dependent on the initial particle properties and conditions. The impact of coatings on BC absorption (the so-called lensing effect) was small, even after photochemical aging. The initial evolution of the BrC absorptivity (MACBrC) varied between individual burns, but decreased consistently at longer aging times; the wavelength-dependence of the BrC absorption generally increased with aging. The observed changes to BrC properties result from a combination of SOA production and heterogeneous oxidation of primary and secondary OA mass, with SOA production being the major driver of the changes. The SOA properties varied with time, reflecting both formation from precursors having a range of lifetimes with respect to OH and the evolving photochemical environment within the chamber. Although the absorptivity of BrC generally decreases with aging, the dilution-corrected absorption may actually increase from the production of SOA. These experimental results provide context for the interpretation of ambient observations of the evolution of particle optical properties in biomass combustion-derived smoke plumes.

DOI： 10.5194/acp-2020-137

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Publisher：Copernicus GmbH  

Abstract. Total reactive nitrogen (Nr, defined as all nitrogen-containing compounds except for N2 and N2O) was measured by catalytic conversion to NO and detection by NO-O3 chemiluminescence together with individual Nr species during a series of laboratory fires of fuels characteristic of Western U.S. wildfires, conducted as part of the FIREX FireLab 2016 study. Data from 75 stack fires were analyzed to examine the systematics of nitrogen emissions. The Nr/total-carbon ratios measured in the emissions were compared with fuel and ash N/C ratios and mass to estimate that a mean (± std. dev.) of 0.68 (± 0.14) of fuel nitrogen was emitted as N2 and N2O. The remaining fraction of Nr was emitted as individual compounds: nitric oxide (NO), nitrogen dioxide (NO2), nitrous acid (HONO), isocyanic acid (HNCO), hydrogen cyanide (HCN), ammonia (NH3), and 44 nitrogen-containing volatile organic compounds (NVOCs). The relative difference between the total reactive nitrogen measurement, Nr, and the sum of measured individual Nr compounds had a mean (± std. dev) of 0.152 (± 0.098). Much of this unaccounted Nr is expected to be particle-bound species, not included in this analysis. A number of key species, e.g. HNCO, HCN and HONO, were confirmed not to correlate only with flaming or only with smoldering combustion when using modified combustion efficiency (MCE = CO2/(CO + CO2)) as a rough indicator. However, the systematic variations of the abundance of these species relative to other nitrogen-containing species were successfully modeled using positive matrix factorization (PMF). Three distinct factors were found for the emissions from combined coniferous fuels, aligning with our understanding of combustion chemistry in different temperature ranges: a combustion factor (Comb-N) (800–1200 °C) with emissions of the inorganic compounds NO, NO2 and HONO, and a minor contribution from organic nitro compounds (R-NO2); a high-temperature pyrolysis factor (HT-N) (500–800 °C) with emissions of HNCO, HCN and nitriles; and a low-temperature pyrolysis factor (LT-N) (

DOI： 10.5194/acp-2020-66

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Mass Spectrometry Society of Japan  

DOI： 10.5702/massspectrometry.a0075

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Copernicus GmbH  

Abstract. Biomass burning is an important source of aerosol and
trace gases to the atmosphere, but how these emissions change chemically
during their lifetimes is not fully understood. As part of the Fire
Influence on Regional and Global Environments Experiment (FIREX 2016), we
investigated the effect of photochemical aging on biomass burning organic
aerosol (BBOA) with a focus on fuels from the western United States.
Emissions were sampled into a small (150 L) environmental chamber and
photochemically aged via the addition of ozone and irradiation by 254 nm
light. While some fraction of species undergoes photolysis, the vast
majority of aging occurs via reaction with OH radicals, with total OH
exposures corresponding to the equivalent of up to 10 d of atmospheric
oxidation. For all fuels burned, large and rapid changes are seen in the
ensemble chemical composition of BBOA, as measured by an aerosol mass
spectrometer (AMS). Secondary organic aerosol (SOA) formation is seen for
all aging experiments and continues to grow with increasing OH exposure, but
the magnitude of the SOA formation is highly variable between experiments.
This variability can be explained well by a combination of differences in OH
exposure and the total concentration of non-methane organic gases (NMOGs) in
the chamber before oxidation, as measured by PTR-ToF-MS (r2 values from
0.64 to 0.83). From this relationship, we calculate the fraction of carbon
from biomass burning NMOGs that is converted to SOA as a function of
equivalent atmospheric aging time, with carbon yields ranging from 24±4 % after 6 h to 56±9 % after 4 d.

DOI： 10.5194/acp-19-12797-2019

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Language：English   Publishing type：Research paper (scientific journal)  

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Copernicus GmbH  

Volatile and intermediate-volatility non-methane organic gases (NMOGs) released from biomass burning were measured during laboratory-simulated wildfires by proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF). We identified NMOG contributors to more than 150 PTR ion masses using gas chromatography (GC) pre-separation with electron ionization, H3O+ chemical ionization, and NO+ chemical ionization, an extensive literature review, and time series correlation, providing higher certainty for ion identifications than has been previously available. Our interpretation of the PTR-ToF mass spectrum accounts for nearly 90ĝ€-% of NMOG mass detected by PTR-ToF across all fuel types. The relative contributions of different NMOGs to individual exact ion masses are mostly similar across many fires and fuel types. The PTR-ToF measurements are compared to corresponding measurements from open-path Fourier transform infrared spectroscopy (OP-FTIR), broadband cavity-enhanced spectroscopy (ACES), and iodide ion chemical ionization mass spectrometry (Iĝ' CIMS) where possible. The majority of comparisons have slopes near 1 and values of the linear correlation coefficient, R2, ofĝ€ &amp
ĝ€-0.8, including compounds that are not frequently reported by PTR-MS such as ammonia, hydrogen cyanide (HCN), nitrous acid (HONO), and propene. The exceptions include methylglyoxal and compounds that are known to be difficult to measure with one or more of the deployed instruments. The fire-integrated emission ratios to CO and emission factors of NMOGs from 18 fuel types are provided. Finally, we provide an overview of the chemical characteristics of detected species. Non-aromatic oxygenated compounds are the most abundant. Furans and aromatics, while less abundant, comprise a large portion of the OH reactivity. The OH reactivity, its major contributors, and the volatility distribution of emissions can change considerably over the course of a fire.

DOI： 10.5194/acp-18-3299-2018

Scopus

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Language：English   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Proton-transfer-reaction mass spectrometry (PTR-MS) has been widely used to study the emissions, distributions, and chemical evolution of volatile organic compounds (VOCs) in the atmosphere. The applications of PTR-MS have greatly promoted understanding of VOC sources and their roles in air-quality issues. In the past two decades, many new mass spectrometric techniques have been applied in PTR-MS instruments, and the performance of PTR-MS has improved significantly. This Review summarizes these developments and recent applications of PTR-MS in the atmospheric sciences. We discuss the latest instrument development and characterization work on PTR-MS instruments, including the use of time-of-flight mass analyzers and new types of ion guiding interfaces. Here we review what has been learned about the specificity of different product ion signals for important atmospheric VOCs. We present some of the recent highlights of VOC research using PTR-MS including new observations in urban air, biomass-burning plumes, forested regions, oil and natural gas production regions, agricultural facilities, the marine environment, laboratory studies, and indoor air. Finally, we will summarize some further instrument developments that are aimed at improving the sensitivity and specificity of PTR-MS and extending its use to other applications in atmospheric sciences, e.g., aerosol measurements and OH reactivity measurements.

DOI： 10.1021/acs.chemrev.7b00325

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Proton-transfer-reaction mass spectrometry (PTR-MS) allows the detection of a large number of trace gases in air through proton-transfer reaction with H3O+ reagent ions and detection by a mass spectrometer. Measurement sensitivities can be experimentally determined using calibration gases or calculated using the rate constant for the proton-transfer reaction, but rate constants have only been measured for a subset of compounds. Numerous theoretical approaches that describe the ion-molecule collision processes have shown how to accurately calculate capture collision rate constants between an ion and neutral molecules using the polarizability and permanent dipole moment of the molecule. Here we show that polarizability, dipole moment, and resulting capture rate constants for proton-transfer reactions of H3O+ with various different volatile organic compounds (VOCs) can be obtained using the molecular mass, elemental composition, and functionality of VOCs. The polarizabilities of a class of VOCs possessing a specific number of electronegative atoms were linearly correlated with their molecular mass. The dipole moments in a series of VOCs, in which VOCs contain a specific functional group and arbitrary residual hydrocarbon parts, can be approximated as a constant value. The capture rate constants calculated using polarizability and dipole moment, as estimated from molecular mass, elemental composition, and functional group, agreed within 10% with measured values for most VOCs. Those capture rate constants were applied to the calculation of the sensitivities of VOCs detected by our PTR-MS, taking into account the ion transmission efficiency and the degree of fragmentation of protonated VOCs observed in that instrument as well as chemical properties of the VOCs. The resulting calculated sensitivities agreed within 20-50% of those measured by PTR-MS, but several notable exceptions exist. This result shows that the neutral concentration of a VOC detected as a protonated molecule in PTR-MS can be approximated using only molecular mass, elemental composition, and functionality of the VOC. The present study is useful for all PTR-MS instruments regardless of the type of mass analyzer; however, the identification of elemental composition by high mass resolution instrumentation is important. (C) 2017 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ijms.2017.04.006

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Language：Japanese   Publisher：The Surface Science Society of Japan  

DOI： 10.1380/jsssj.38.581

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.5702/massspec.S17-21

CiNii Books

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Mass Spectrometry Society of Japan  

<p>Hydrogen fluoride (HF) was produced by a homemade HF generator in order to investigate the properties of strong hydrogen-bonded clusters such as (HF)<i>_n</i>. The HF molecules were ionized in the form of complex ions associated with the negative core ions Y⁻ produced by atmospheric pressure corona discharge ionization (APCDI). The use of APCDI in combination with the homemade HF generator led to the formation of negative-ion HF clusters Y⁻(HF)<i>_n</i> (Y=F, O₂), where larger clusters with <i>n</i>≥4 were not detected. The mechanisms for the formation of the HF, F⁻(HF)<i>_n</i>, and O₂⁻(HF)<i>_n</i> species were discussed from the standpoints of the HF generator and APCDI MS. By performing energy-resolved collision-induced dissociation (CID) experiments on the cluster ions F⁻(HF)<i>_n</i> (<i>n</i>=1–3), the energies for the loss of HF from F⁻(HF)₃, F⁻(HF)₂, and F⁻(HF) were evaluated to be 1 eV or lower, 1 eV or higher, and 2 eV, respectively, on the basis of their center-of-mass energy (<i>E</i>_CM). These <i>E</i>_CM values were consistent with the values of 0.995, 1.308, and 2.048 eV, respectively, obtained by <i>ab initio</i> calculations. The stability of [O₂(HF)<i>_n</i>]⁻ (<i>n</i>=1–4) was discussed on the basis of the bond lengths of O₂H–F⁻(HF)<i>_n</i> and O₂⁻H–F(HF)<i>_n</i> obtained by <i>ab initio</i> calculations. The calculations indicated that [O₂(HF)₄]⁻ separated into O₂H and F⁻(HF)₃.</p>

DOI： 10.5702/massspectrometry.A0063

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.5702/massspec.S16-57

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Herein it is shown that a combination of direct analysis in real time (DART) with a corona discharge system consisting of only a needle electrode easily improves DART ionization efficiency. Positive and negative DC corona discharges led to a formation of abundant excited helium atoms as well as the reactant ions H3O+(H2O)(n) and O-2(center dot-) in the DART analyte ionization area. These phenomena resulted in an increase in the absolute intensities of (de) protonated analytes by a factor of 2-20 over conventional DART. The other analyte ions detected in this corona-DART system (i.e., molecular ions, fragment ions, oxygenated (de) protonated analytes, dehydrogenated deprotonated analytes, and negative ion adducts) were quite similar to those obtained from DART alone. This indicates a lack of side reactions due to the corona discharge. The change in the relative intensities of individual analyte-related ions due to the combination of a corona discharge system with DART suggests that there is no effect of the abundant excited helium in the analyte ionization area on the fragmentation processes or enhancement of oxidation due to hydroxyl radicals HO center dot. Furthermore, it was found that the corona-DART combination can be applied to the highly sensitive analysis of n-alkanes, in which the alkanes are ionized as positive ions via hydride abstraction and oxidation, independent of the type of alkane or the mass spectrometer used.

DOI： 10.1039/c6an00779a

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Language：English   Publishing type：Research paper (scientific journal)  

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Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

DOI： 10.1088/0022-3727/48/30/305401

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Other Link： http://stacks.iop.org/0022-3727/48/i=30/a=305401?key=crossref.409b0c12fd19960931e605b459936fa8

Language：English   Publishing type：Research paper (scientific journal)  

© 2015 by Begell House, Inc. For biological and medical applications of low-temperature atmospheric-pressure plasmas (APPs), gas- and liquid-phase chemical reactions caused by the plasmas determine the effectiveness of the APP-based treatments of biological systems. In this study, ions generated by helium-based low-frequency APP jets were identified by mass spectrometry. It is shown that, among all positive ions generated by plasma jets in ambient air, hydronium ions (H3O+) are the dominant ions that form water clusters. The stability of a hydronium ion with water molecules suggests that all positive ions generated by plasma jets would transfer their charges to hydronium ions if water molecules were abundant, such as in humid air or water. Similarly, it is shown that, among all negative ions generated by the plasma jets in ambient air, relatively few, such as OH-, HO2-, NO2-, NO3-, HCO3-, and HCO4-, form water clusters stably. The densities of positive and negative ions generated in ambient air by the APP jet system, as well as the concentrations of H2O2 and NO2- generated in pure water exposed to the same plasma, have been also measured.

DOI： 10.1615/PlasmaMed.2016016443

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Field measurements of seven nitro-organic compounds including nitromethane and ten related volatile organic compounds were carried out using proton-transfer-reaction mass spectrometry at a busy intersection of an urban city, Kawasaki, Japan from 26th February to 6th March, 2011. Among the nitro-organic compounds, nitromethane was usually observed along with air pollutants emitted from automobiles. The mixing ratios of nitromethane varied substantially and sometimes clearly varied at an approximately constant interval. The interval corresponded to the cycle of the traffic signals at the intersection and the regular peaks of nitromethane concentrations were caused by emissions from diesel trucks running with high speed. In addition to the regular peaks, sharp increases of nitromethane concentrations were often observed irregularly from diesel trucks accelerating in front of the measurement site. For other nitro-organic compounds such as nitrophenol, nitrocresol, dihydroxynitrobenzene, nitrobenzene, nitrotoluene, and nitronaphthalene, most of the data fluctuated within the detection limits. (C) 2014 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.atmosenv.2014.07.058

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Language：Japanese   Publisher：The Japan Society of Applied Physics  

DOI： 10.11470/jsapmeeting.2014.1.0_1713

CiNii Research

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Mass Spectrometry Society of Japan  

The fragmentation behavior of deprotonated L-phenylalanine (Phe) and its homologues including L-homophenylalanine (HPA) and L-phenylglycine (PG) was investigated using collision-induced dissociation mass spectrometry coupled with a negative ion atmospheric pressure corona discharge ionization (APCDI) technique. The deprotonated molecules [M−H]⁻ fragmented to lose unique neutral species, <i>e.g.</i>, the loss of NH₃, CO₂, toluene and iminoglycine for [Phe−H]⁻; styrene and ethenamine/CO₂ for [HPA−H]⁻; and CO₂ for [PG−H]⁻. All of the fragmentations observed are attributable to the formation of intermediates and/or product ions which include benzyl carbanions having resonance-stabilized structures. The carbanions are formed <i>via</i> proton rearrangement through a transition state or <i>via</i> a simple dissociation reaction. These results suggest that the principal factor governing the fragmentation behavior of deprotonated Phe homologues is the stability of the intermediate and/or product ion structures.

DOI： 10.5702/massspectrometry.A0027

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

The positive and negative ionization characteristics of 20 different alpha-amino acids were investigated using Direct Analysis in Real Time (DART) mass spectrometry. Almost all of the amino acids M were ionized to generate the (de) protonated analytes [M +/- H](+/-) via proton transfer reactions with the typical background ions H3O+(H2O)(n) and O-2(center dot)- and resonant electron capture by M. The application of DART to amino acids also resulted in molecular ion formation, fragmentation, oxidations involving oxygen attachment and hydrogen loss, and formation of adducts [M + R](-) with negative background ions R-(O-2(center dot-), HCO2-, NO2- and COO-(COOH)), depending on the physicochemical and/or structural properties of individual amino acids. The relationship between each amino acid and the ionization reactions observed suggested that fragmentation can be attributed to pyrolysis during analyte desorption as well as excess energy obtained via (de)protonation. Oxidation and [M + R](-) adduct formation, in contrast, most likely originate from reactions with active oxygen such as hydroxyl radicals HO center dot, indicating that the typical background neutral species involved in analyte ionization in DART mass spectrometry contain HO center dot.

DOI： 10.1039/c3an02193a

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Association of Aerosol Science and Technology  

Secondary organic aerosols (SOAs) are produced through chemical reactions initiated by the oxidation of volatile organic compounds (VOCs). Understanding of SOA formation mechanisms is still insufficient because multi-step reactions from a variety of VOCs are involved. In order to clarify the chemical mechanisms for SOA formation, we are investigating gas- and aerosol-phase species produced from VOC oxidation by using mass spectrometry and laser spectroscopy techniques. Here, we describe the application of mass spectrometry to SOA component analyses and recent results, including those from our group. Chemical kinetics studies of the VOC oxidation reactions in relation to SOA formation are also mentioned.

DOI： 10.11203/jar.29.s18

CiNii Books

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Other Link： https://jlc.jst.go.jp/DN/JALC/10032824543?from=CiNii

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

We carried out time-resolved experiments using a proton-transfer-reaction mass spectrometer and a chassis dynamometer to characterize nitromethane emission from automotive exhaust. We performed experiments under both cold-start and hot-start conditions, and determined the dependence of nitromethane emission on vehicle velocity and acceleration/deceleration as well as the effect of various types of exhaust-gas treatment system. We found that nitromethane emission was much lower from a gasoline car than from diesel trucks, probably due to the reduction function of the three-way catalyst of the gasoline car. Diesel trucks without a NO reduction catalyst using hydrocarbons produced high emissions of nitromethane, with emission factors generally increasing with increasing acceleration at low vehicle velocities. (C) 2013 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.atmosenv.2013.09.031

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Nitro-organic compounds, some of which cause adverse health effects in humans, are emitted in diesel engine exhaust. Speciation and quantification of these nitro-organic compounds in diesel engine exhaust particles have been extensively conducted; however, investigations into the emissions of gaseous nitro-organic compounds in diesel engine exhaust have not. In the present study, the properties of gaseous nitro-organic compounds in diesel engine exhaust were investigated through time-resolved measurement with a proton-transfer-reaction mass spectrometer and a chassis dynamometer. Three diesel trucks were tested, each with a different type of exhaust-gas treatment system (i.e., aftertreatment). Among the nitro-organic compounds detected, the emission of nitromethane was commonly observed and found to be related to the emissions of carbon monoxide, benzene, and acetone. The emission of other nitro-organic compounds, such as nitrophenol, depended on the vehicle, possibly due to the type of aftertreatment installed. (C) 2013 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.atmosenv.2013.03.035

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Collision-induced dissociation (CID) experiments were performed on atmospheric ion adducts [M + R](-) formed between various types of organic compounds M and atmospheric negative ions R- [such as O-2 (-), HCO3 (-), COO-(COOH), NO2 (-), NO3 (-), and NO3 (-)(HNO3)] in negative-ion mode atmospheric pressure corona discharge ionization (APCDI) mass spectrometry. All of the [M + R](-) adducts were fragmented to form deprotonated analytes [M - H](-) and/or atmospheric ions R-, whose intensities in the CID spectra were dependent on the proton affinities of the [M - H](-) and R- fragments. Precursor ions [M + R](-) for which R- have higher proton affinities than [M - H](-) formed [M - H](-) as the dominant product. Furthermore, the CID of the adducts with HCO3 (-) and NO3 (-)(HNO3) led to other product ions such as [M + HO](-) and NO3 (-), respectively. The fragmentation behavior of [M + R](-) for each R- observed was independent of analyte type (e.g., whether the analyte was aliphatic or aromatic, or possessed certain functional groups).

DOI： 10.1007/s13361-013-0576-2

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.5702/massspectrometry.A0020

CiNii Books

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Language：Japanese   Publishing type：Research paper (scientific journal)  

Hydrate clusters with atmospheric ions have been of long-standing interest in the field of atmospheric sciences, because of their central role in the formation of tropospheric aerosols. A large number of thermochemical studies of the typical positive-ion hydrate clusters, H&lt
inf&gt
3&lt
/inf&gt
O&lt
sup&gt
+&lt
/sup&gt
(H&lt
inf&gt
2&lt
/inf&gt
O)&lt
inf&gt
n&lt
/inf&gt
, using mass spectrometry have been reported, while there is little thermochemical information concerning negative-ion hydrate clusters. The absence of information is due to lack of ionization methods for the reproducible formation of specific negative atmospheric ions and their hydrates, and resulting difficulties in obtaining reliable mass spectrometry data from negative-ion hydrate clusters. We have recently established an atmospheric pressure DC corona discharge device that includes a specific needle electrode that leads to the regular formation of various atmospheric negative ions Y&lt
sup&gt
-&lt
/sup&gt
. Furthermore, the use of this discharge system coupled to mass spectrometers resulted in the stable formation of large hydrate clusters, Y&lt
sup&gt
-&lt
/sup&gt
(H&lt
inf&gt
2&lt
/inf&gt
O)&lt
inf&gt
n&lt
/inf&gt
, due to adiabatic expansion caused by pressure difference between the ambient discharge area (760 torr) and the vacuum region in the mass spectrometers (≈ 1 torr). Here, we show the resulting mass spectra of large hydrate clusters, Y&lt
sup&gt
-&lt
/sup&gt
(H&lt
inf&gt
2&lt
/inf&gt
O)&lt
inf&gt
n&lt
/inf&gt
, with the negative atmospheric ions, Y&lt
sup&gt
-&lt
/sup&gt
, such as HO&lt
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-&lt
/sup&gt
, O&lt
inf&gt
2&lt
/inf&gt
&lt
sup&gt
-&lt
/sup&gt
, HO&lt
inf&gt
2&lt
/inf&gt
&lt
sup&gt
-&lt
/sup&gt
, CO&lt
inf&gt
3&lt
/inf&gt
&lt
sup&gt
-&lt
/sup&gt
, NO&lt
inf&gt
3&lt
/inf&gt
&lt
sup&gt
-&lt
/sup&gt
and NO&lt
inf&gt
3&lt
/inf&gt
-(HNO&lt
inf&gt
3&lt
/inf&gt
)&lt
inf&gt
2&lt
/inf&gt
, which play a central role in atmospheric chemistry. Those reliable mass spectrometry data have provided information about specific cluster sizes having particular thermochemical stability in individual cluster ion series, Y&lt
sup&gt
-&lt
/sup&gt
(H&lt
inf&gt
2&lt
/inf&gt
O)&lt
inf&gt
n&lt
/inf&gt
, which may correspond to first hydrated shell and magic number for Y&lt
sup&gt
-&lt
/sup&gt
(H&lt
inf&gt
2&lt
/inf&gt
O)&lt
inf&gt
n&lt
/inf&gt
. Here, we also describe the detailed mechanism of the formation of negative atmospheric ions, Y&lt
sup&gt
-&lt
/sup&gt
, and their hydrates, Y&lt
sup&gt
-&lt
/sup&gt
(H&lt
inf&gt
2&lt
/inf&gt
O)&lt
inf&gt
n&lt
/inf&gt
, in an atmospheric pressure corona discharge ionization mass spectrometry. © 2013 The Japan Society for Analytical Chemistry.

DOI： 10.2116/bunsekikagaku.62.955

Scopus

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The surface deposits of the traces stained with discharges on the brass plate electrode in atmospheric pressure DC negative corona have been analyzed. The surface analysis showed that the major deposits on the traces originate from nitrogen oxide ions NOx- and neutrals NOx, or carbon clusters C-n. The relationship between the plane positions and resulting deposits obtained with the point-to-plane electrodes with arbitrary needle angle to the plane provided the information about the general behavior of negative ions NOx- and neutral species NOx occurring in stationary inhomogeneous electric fields. (c) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.elstat.2012.05.004

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

The interaction between negative atmospheric ions and various types of organic compounds were investigated using atmospheric pressure corona discharge ionization (APCDI) mass spectrometry. Atmospheric negative ions such as O (2) (-) , HCO (3) (-) , COO-(COOH), NO (2) (-) , NO (3) (-) , and NO (3) (-) (HNO3) having different proton affinities served as the reactant ions for analyte ionization in APCDI in negative-ion mode. The individual atmospheric ions specifically ionized aliphatic and aromatic compounds with various functional groups as atmospheric ion adducts and deprotonated analytes. The formation of the atmospheric ion adducts under certain discharge conditions is most likely attributable to the affinity between the analyte and atmospheric ion and the concentration of the atmospheric ion produced under these conditions. The deprotonated analytes, in contrast, were generated from the adducts of the atmospheric ions with higher proton affinity attributable to efficient proton abstraction from the analyte by the atmospheric ion.

DOI： 10.1007/s13361-012-0363-5

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The relationship between orifice temperature and the size distribution in water clusters Y-(H2O)(n) with various negative atmospheric core ions Y- such as O-2(-), HO-, HO2-, NO2-, NO3-, NO3- (HNO3)(2), CO3- and HCO4- has been investigated using atmospheric pressure negative corona discharge mass spectrometry. Although the cluster distributions shifted in the lower-mass region with increasing orifice temperature due to insufficient cooling during adiabatic expansion, the anomalous discontinuities in ion peak intensity at certain size clusters Y-(H2O)(m) in the Y-(H2O)(n) cluster series reproducibly observed at the lowest orifice temperature did not vary with change in temperature. The results obtained suggest that the clusters Y-(H2O)(m) have particular thermochemical stability compared to other size clusters Y-(H2O) under arbitrary temperature conditions, and that the Y-(H2O)(m) would correspond to the magic number or first hydrated shell in the cluster series Y-(H2O)(n). The specific stability of Y-(H2O)(m) was also confirmed by using the ratio of Y-(H2O),, to Y-(H2O)(n+1) peak intensity, which is a reliable method to identify the magic numbers in arbitrary cluster distributions obtained by varying the temperature and solvent partial pressure in a reaction chamber. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ijms.2011.06.007

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Volatile organic compound (VOC) emission rates during the growth and simulated harvest phases were determined for switchgrass (Panicum virgatum) using laboratory chamber measurements. Switchgrass is a candidate for use in second-generation (cellulosic) biofuel production and the acreage dedicated to its growth in the USA has already increased during the past decade. We estimate that the yearly emissions from switchgrass plantations, including both the growth and harvest phases will be on the order of 3 kg C ha(-1) methanol, 1 kg C ha(-1) acetaldehyde, 1 kg C ha(-1) acetone, 0.9 kg C ha(-1) monoterpenes, 0.5 kg C ha(-1) isoprene + another compound, most likely 1-penten-3-ol, 0.2 kg C ha(-1) hexenals, and 0.1 kg C ha(-1) hexenols. These emission rates are much lower than those expected from Eucalyptus or poplar plantations, which are other potential biofuel crops and have significantly higher VOC emissions, suggesting that the choice of species in the production of biofuels could have serious implications for regional air quality. (C) 2011 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.atmosenv.2011.03.042

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Reliable mass spectrometry data from large water clusters Y-(H2O)(n) with various negative core ions Y- such as O-2(-), HO-, HO2-, NO2-, NO3-, NO3-(HNO3)(2), CO3- and HCO4- have been obtained using atmospheric pressure negative corona discharge mass spectrometry. All the core Y- ions observed were ionic species that play a central role in tropospheric ion chemistry. These mass spectra exhibited discontinuities in ion peak intensity at certain size clusters Y-(H2O)(m) indicating specific thermochemical stability. Thus, Y-(H2O)(m) may correspond to the magic number or first hydrated shell in the cluster series Y-(H2O)(n). The high intensity discontinuity at HO-(H2O)(3) observed was the first mass spectrometric evidence for the specific stability of HO-(H2O)(3) as the first hydrated shell which Eigen postulated in 1964. The negative ion water clusters Y-(H2O)(n) observed in the mass spectra are most likely to be formed via core ion formation in the ambient discharge area (760 torr) and the growth of water clusters by adiabatic expansion in the vacuum region of the mass spectrometers (approximate to 1 torr). The detailed mechanism of the formation of the different core water cluster ions Y-(H2O)(n) is described. Copyright (C) 2010 John Wiley & Sons, Ltd.

DOI： 10.1002/jms.1870

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Association of Aerosol Science and Technology  

Ambient corona discharge has been used as an ionizer in a wide range of research and industrial fields such as environmental, analytical and aerosol sciences, and possibly even commercial electric appliances. Terminal ions produced via ion evolutions through successive ion-molecule reactions in corona discharge can readily and efficiently supply the charge for ionization in ambient air. Despite substantial progress in the application of corona discharge, the elementary processes involved in terminal ion formation and evolution are not yet well understood. It has been reported that negative ion evolution is rather complex compared to that of positive ions, and that it is difficult to regulate the reproducible formation of specific negative ion species. We have recently established an atmospheric pressure corona discharge system containing a specific corona needle that successfully leads to regular and reproducible generation of various positive and negative ions originating from ambient air. The system coupled with mass spectrometers made it possible to study the relationship between terminal ion formation and discharge conditions. In this paper, the formation and evolution mechanism of terminal ions such as H₃O⁺, HO^-, NO<i>_x</i>^- and CO<i>_x</i>^- depending on the electric field strength on the needle tip and the resulting kinetic energy of electrons accelerated at the tip will be described.<br>

DOI： 10.11203/jar.26.203

CiNii Books

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

The change in the distribution pattern of negative ions HO(-), NO observed on arbitrary point-to-plane electrode configuration has been investigated by varying the angle of needle to the plane electrode, under atmospheric pressure corona discharge conditions. The stationary inhomogeneous electric field distributions between the point-to-plane electrodes with arbitrary needle angle were calculated. The experimental and theoretical results obtained suggested that the negative ion evolutions progress along field lines established between the electrodes with arbitrary configurations and the resulting terminal ion formation on a given field line is attributable to the electric field strength on the needle tip surface where the field line arose. The NO ions were dominantly produced on the field lines arising from the needle tip apex region with the highest electric field strength, while the field lines emanating from the tip peripheral regions with lower field strength resulted in the formation of the HO(-) ion.

DOI： 10.1140/epjd/e2010-10449-7

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Language：English   Publishing type：Research paper (scientific journal)  

CiNii Books

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

The dependence of negative ion formation on the inhomogeneous electric field strength in atmospheric pressure negative corona discharge with point-to-plane electrodes has been described. The distribution of negative ions HO(-), NO(x)(-) and CO(x)(-) and their abundances on the plane electrode was obtained with a mass spectrometer. The ion distribution on the plane was divided into two regions, the center region on the needle axis and peripheral region occurring the dominant NO(x)(-) and CO(x)(-) ions and HO- ion, respectively. The calculated electricfield strength in inhomogeneous electric field established on the needle tip surface suggested that the abundant formation of NO(x)(-) and CO(x)(-) ions and HO(-) ion is attributed to the high field strength at the tip apex region over 10(8) Vm(-1) and the low field strength at the tip peripheral region of the order of 10(7) Vm(-1), respectively. The formation of HO(-), NO(x)(-) and CO(x)(-) has been discussed from the standpoint of negative ion evolution based on the thermochemical reaction and the kinetic energy of electron emitted from the needle tip.

DOI： 10.1140/epjd/e2008-00238-4

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The dependence of the formation of negative core ions Y- and their hydrated cluster ions Y-(H2O)(n) on needle voltage has been examined by using atmospheric pressure corona discharge ionization mass spectrometry. An insect pin (200 mu m in diameter, 20 mm in length, and ca. 1 mu m in the tip radius) was used as the corona needle. At the lowest effective needle voltage (- 1.9 kV), water cluster ions OH-(H2O)(n) with a core ion OH- were observed. Furthermore there was a discontinuity between the abundances of OH-(H2O)(3) at m/z 71 and OH-(H2O)(4) at m/z 89, suggesting that the cluster OH-(H2O)(3) is more stable than OH-(H2O)(4). The ion OH-(H2O)(3) which may be referred to as "the first hydrated shell" is formed via hydration of the core ion OH- in air. Various different core ions Y- appeared as the hydrated cluster ions Y-(H2O)(n) with increasing needle voltage. At relatively low voltage (-2.3 kV), the dominant hydrated clusters observed were OH-(H2O)(n) and O2H-(H2O)(n). At the highest corona voltage (-3.5 kV), the well-known long-lived core ion NO3- and its hydrated clusters NO3-(H2O)(n) were mainly observed. The resulting negative core ions OH-, NO2-, NO3-, HNO3-, CO3-, and CO4-, which are atmospherically important ions or stable terminal ion species in tropospheric atmosphere, are discussed from the standpoint of ion evolution in air. (C) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ijms.2006.07.027

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Country：Japan

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Country：Japan

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Country：Japan

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Type：Lecture

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