研究者データベース

廣川 淳(ヒロカワ ジユン)
地球環境科学研究院 物質機能科学部門 分子材料化学分野
准教授

基本情報

所属

  • 地球環境科学研究院 物質機能科学部門 分子材料化学分野

職名

  • 准教授

学位

  • 博士(理学)(東京大学)

科研費研究者番号

  • 20262115

J-Global ID

所属学協会

  • 日本分光学会   日本化学会   日本エアロゾル学会   大気環境学会   大気化学研究会   Japan Association of Aerosol Science and Technology   

研究活動情報

論文

  • Kinetic study of OH uptake onto deliquesced NaCl particles by combining laser photolysis and laser-induced fluorescence
    Sakamoto Yosuke, Zhou Jun, Kohno Nanase, Nakagawa Maho, Hirokawa Jun, Kajii Yoshizumi
    Journal of Physical Chemistry Letters 9 4115 - 4119 2018年07月 [査読有り][通常論文]
  • Kinetic study of heterogeneous bromine release from the reaction between gaseous ozone and aqueous bromide solution
    Yosuke Sakamoto Yosuke, Goda Motoki, Jun Hirokawa Jun
    Journal of Physical Chemistry A 122 2723 - 2731 2018年02月 [査読有り][通常論文]
  • Satoshi Inomata, Kei Sato, Yosuke Sakamoto, Jun Hirokawa
    ATMOSPHERIC ENVIRONMENT 170 149 - 155 2017年12月 [査読有り][通常論文]
     
    Secondary organic aerosol formation during the ozonolysis of isoprene and ethene in the presence of ammonium nitrate seed particles (surface area concentrations = (0.8-3) x 10(7) nm(2) cm(-3)) was investigated using a 1 nm scanning mobility particle sizer. Based on the size distribution of formed particles, particles with a diameter smaller than the minimum diameter of the seed particles (less than similar to 6 nm) formed under dry conditions, but the formation of such particles was substantially suppressed during isoprene ozonolysis and was not observed during ethane ozonolysis under humid conditions. We propose that oligomeric hydroperoxides generated by stabilized Criegee intermediates (sCIs), including C-1-sCI (CH2OO), contribute to new particle formation while competing to be taken up onto preexisting particles. The OH reaction products of isoprene and ethene seem to not contribute to new particle formation; however, they are taken up onto preexisting particles and contribute to particle growth. (C) 2017 Elsevier Ltd. All rights reserved.
  • Ryoji Yajima, Yosuke Sakamoto, Satoshi Inomata, Jun Hirokawa
    JOURNAL OF PHYSICAL CHEMISTRY A 121 34 6440 - 6449 2017年08月 [査読有り][通常論文]
     
    We investigated the relative reactivity of stabilized CH2OO, produced by ethene ozonolysis, toward acetic acid and water vapor at a temperature of 298 +/- 2 K and atmospheric pressure. Hydroperoxymethyl acetate produced through the reaction between stabilized CH2OO and acetic acid was monitored using a chemical ionization mass spectrometer as a function of the acetic acid concentration at different relative humidities. The rate of the reaction between CH2OO and water vapor depended quadratically on the water vapor concentration, suggesting that CH2OO reacted with water dimers in preference to water monomers. We obtained the bimolecular rate constant for the reaction between CH2OO and water dirtier relative to the rate constant for the reaction between CH2OO and acetic acid, k(3)/k(1), of (6.3 +/- 0.4) X 10(-2). The k(3) value of (8.2 +/- 0.8) x 10(-12) cm(3) molecule(-1) s(-1) was derived by combining with a k(1) value of (1.3 +/- 0.1) x 10(-10) cm(3) molecule(-1) s(-1), which has been previously reported by direct kinetic studies. The k(3) value thus obtained is consistent with the absolute rate constants measured directly, suggesting that the reactivity of CH2OO is irrespective of the CH2OO generation method, namely, ethene ozonolysis or diiodomethane photolysis. We indirectly determined the yield of stabilized CH2OO from the ozonolysis of ethene of 0.59 +/- 0.17 and 0.55 +/- 0.16 under dry and humid (relative humidity 23-24%) conditions, respectively, suggesting that the yield is independent of the water vapor concentration. Our results suggest that hydroperoxymethyl acetate is the sole product of the reaction between stabilized CH2OO and acetic acid. The approach presented here can likely be extended to studies of the reactivities of more complicated and atmospherically relevant stabilized Criegee intermediates.
  • Satoshi Inomata, Jun Hirokawa
    CHEMISTRY LETTERS 46 1 38 - 41 2017年01月 [査読有り][通常論文]
     
    We have developed a non-radioactive chemical ionization mass spectrometry method using acetic acid-acetate cluster as the reagent ion. By electron impact onto an acetic anhydride-Ar gas mixture, a strong and single ion peak of the acetic acidacetate cluster was observed. We demonstrated that the reagent ion can ionize carboxylic acids (RC(O)OH) and hydroperoxides (ROOH) produced in ethylene ozonolysis through the formation of adduct ions of these species and acetate. This technique could be used for the detection of various organic hydroperoxides as well as organic and inorganic acids in the atmosphere.
  • Yosuke Sakamoto, Ryoji Yajima, Satoshi Inomata, Jun Hirokawa
    PHYSICAL CHEMISTRY CHEMICAL PHYSICS 19 4 3165 - 3175 2017年01月 [査読有り][通常論文]
     
    Secondary organic aerosol (SOA) formation from isoprene ozonolysis was investigated using a Teflon bag reactor under dry and humid conditions. Both the number and volume concentrations of SOA were found to be decreased by the addition of water vapour. Gas-and particle-phase product analyses with a negative ion chemical ionization mass spectrometer show that oligomers composed of stabilized Criegee intermediates as the chain units contribute to the SOA formation and that water vapour inhibits stabilized Criegee intermediates from forming the oligomers, resulting in the suppression of SOA formation. Additionally, it is suggested that a portion of stabilized Criegee intermediates other than CH2OO have low reactivity toward H2O, and thus can be involved in the oligomer and SOA formation even under humid conditions. Volatility estimation predicts that the oligomers containing even one or two stabilized Criegee intermediates can be partitioned into the aerosol phase.
  • Phil A. Brown, Satoshi Inomata, Hiroshi Tanimoto, Kei Sato, Yosuke Sakamoto, Ryoji Yajima, Jun Hirokawa
    CHEMISTRY LETTERS 45 8 916 - 918 2016年08月 [査読有り][通常論文]
     
    A potential direct dissociation pathway is suggested through oxygen atom release from the energy-rich Criegee intermediate produced from ozonolysis of cycloalkenes. The yield of adipaldehyde from the ozonolysis of cyclohexene was independent of humidity; furthermore, the yield of pinonaldehdye from ozonolysis of a-pinene was independent of the presence of an OH scavenger. Excluding the production of dialdehydes as being mediated by either H2O or OH, a possible dissociation from the energy-rich Criegee intermediate involving the loss of an oxygen atom is suggested.
  • Momoko Nakayama, Chunmao Zhu, Jun Hirokawa, Tomohisa Irino, Hisayuki Yoshikawa-Inoue
    TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY 67 2015年 [査読有り][通常論文]
     
    To examine the behaviour of ozone (O-3) in the seasonal snowpack, measurements were taken of O-3 and CO2 in the interstitial air on Rishiri Island, which is located in northern Japan, during the 2010/11 winter season. Exhibiting variation on timescales ranging from several minutes to several days, the atmospheric O-3 in the surface air generally increased from December (38 ppb) to April (52 ppb). The ozone mixing ratio sharply decreased below the snow surface. Whereas the CO2 data in the interstitial air indicated that a rapid exchange between the snow and the atmosphere occurred intermittently, the O-3 mixing ratio remained low and constant (<5 ppb) in the snowpack interior. The vertical profile of the O-3 mixing ratio indicates that the e-folding lifetime of the O-3 loss reaction was 5.0+/-2.3 minutes during the day and 10.0+/-6.3 minutes at night, suggesting photochemical O-3 depletion occurred during the daytime. Kinetic experiments using ambient (maritime) air and snow indicate that the photochemical O-3 loss is proportional to the solar radiation and that the O-3 loss rate decreases as dawn approaches during the night. The result of the kinetic experiments using artificial O-3 in the pure air and snow suggests the important role of gaseous species in the ambient air towards O-3 depletion.
  • Satoshi Inomata, Kei Sato, Jun Hirokawa, Yosuke Sakamoto, Hiroshi Tanimoto, Motonori Okumura, Susumu Tohno, Takashi Imamura
    ATMOSPHERIC ENVIRONMENT 97 397 - 405 2014年11月 [査読有り][通常論文]
     
    To understand the mechanism of formation of the secondary organic aerosols (SOAs) produced by the ozonolysis of isoprene, proton transfer reaction mass spectrometry (PTR-MS) was used to identify the semi-volatile organic compounds (SVOCs) produced in both the gaseous and the aerosol phases and to estimate the gas aerosol partitioning of each SVOC in chamber experiments. To aid in the identification of the SVOCs, the products were also studied with negative ion-chemical ionization mass spectrometry (NI-CIMS), which can selectively detect carboxylic acids and hydroperoxides. The gaseous products were observed by on-line PTR-MS and NI-CIMS, whereas the SVOCs in SOAs collected on a filter were vaporized by heating the filter and were then analysed by off-line PTR-MS and NI-CIMS. The formation of oligomeric hydroperoxides involving a Criegee intermediate as a chain unit was observed in both the gaseous and the aerosol phases by NI-CIMS. PTR-MS also detected oligomeric hydroperoxides as protonated molecules from which a H2O molecule was eliminated, [M-OH](+). In the aerosol phase, oligomers involving formaldehyde and methacrolein as chain units were observed by PTR-MS in addition to oligomeric hydroperoxides. The gas-aerosol partitioning of each component was calculated from the ion signals in the gaseous and aerosol phases measured by PTR-MS. From the gas-aerosol partitioning, the saturated vapour pressures of the oligomeric hydroperoxides were estimated. Measurements by a fastmobility-particle-sizer spectrometer revealed that the increase of the number density of the particles was complete within a few hundred seconds from the start of the reaction. (C) 2014 Elsevier Ltd. All rights reserved.
  • Yosuke Sakamoto, Satoshi Inomata, Jun Hirokawa
    JOURNAL OF PHYSICAL CHEMISTRY A 117 48 12912 - 12921 2013年12月 [査読有り][通常論文]
     
    Ethylene ozonolysis was investigated in laboratory experiments using a Teflon bag reactor. A negative ion chemical ionization mass spectrometer (NI-CIMS) using SO2Cl- and Cl- as reagent ions was used for product analysis. In addition to the expected gas-phase products, such as formic acid and hydroperoxymethyl formate, oligomeric hydroperoxides composed of the Criegee intermediate (CH2OO) as a chain unit were observed. Furthermore, we observed secondary organic aerosol (SOA) formation from the ethylene ozonolysis, and the particle-phase products were also analyzed by NI-CIMS. The CH2OO oligomers were also observed as particle-phase components, suggesting that the oligomeric hydroperoxides formed in the gas phase partition into the particle phase. By adding methanol as a stabilized Criegee intermediate scavenger, both the gas-phase oligomer formation and SOA formation were strongly suppressed. This indicates that CH2OO plays a critical role in the formation of oligomeric hydroperoxides followed by SOA formation in ethylene ozonolysis. A new formation mechanism for the oligomeric hydroperoxides, which includes sequential addition of CH2OO to hydroperoxides, is proposed.
  • Kei Sato, Satoshi Inomata, Jia-Hua Xing, Takashi Imamura, Risa Uchida, Sayaka Fukuda, Kazumichi Nakagawa, Jun Hirokawa, Motonori Okumura, Susumu Tohno
    ATMOSPHERIC ENVIRONMENT 79 147 - 154 2013年11月 [査読有り][通常論文]
     
    In order to understand the effect of OH radical scavengers on secondary organic aerosol formation, aerosol yields from the isoprene ozonolysis were measured in the presence of sufficient amounts of OH radical scavengers. Cyclohexane, CO, n-hexane, and diethyl ether were used as the OH radical scavengers. The aerosol yield was determined to be 0.002-0.023 for experiments without OH radical scavengers in the aerosol mass range 2-120 mu g M-3. Similar aerosol yields were observed in experiments using cyclohexane. The aerosol yield observed with n-hexane was close to that observed without scavengers at 120 mu g m(-3), but this aerosol yield was slightly lower than those observed in reactions without scavengers in the range 3-83 mu g m(-3). The offline aerosol samples obtained in experiments with cyclohexane or n-hexane contained oxygenated hydrocarbons with six or more carbon atoms. Aerosol formation in experiments that used cyclohexane or n-hexane as the scavenger was enhanced. This was caused by the oxidation products of the OH radical scavengers, although the increase in the yield could not be quantified. The aerosol yields were 0.002-0.014 for experiments with CO and diethyl ether in the aerosol mass range 4-120 mu g 111(-3). The reaction of CO with OH radicals forms HO2 radicals, whereas the reactions of cyclohexane, n-hexane, and diethyl ether, respectively, with OH radicals form organic peroxy (RO2) radicals. Present results show that the aerosol yield is independent of the HO2/RO2 ratio or that it decreases with increasing HO2/RO2 ratio. Since the H02 concentration is much higher than the RO2 concentration in the atmosphere, the results obtained using CO in this study will be a good approximation of the aerosol yield from the ozonolysis of isoprene in the atmosphere. 2013 Elsevier Ltd. All rights reserved.
  • Gary A. Morris, Walter D. Komhyr, Jun Hirokawa, James Flynn, Barry Lefer, Nicholay Krotkov, Fong Ngan
    JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY 27 8 1318 - 1330 2010年08月 [査読有り][通常論文]
     
    This paper reports on the development of a new technique for inexpensive measurements of SO2 profiles using a modified dual-ozonesonde instrument payload. The presence of SO2 interferes with the standard electrochemical cell (ECC) ozonesonde measurement, resulting in -1 molecule of O-3 reported for each molecule of SO2 present (provided [O-3] > [SO2]). In laboratory tests, an SO2 filter made with CrO3 placed on the inlet side of the sonde removes nearly 100% of the SO2 present for concentrations up to 60 ppbv and remained effective after exposure to 2.8 x 10(16) molecules of SO2 [equivalent to a column similar to 150 DU (1 DU = 2.69 x 10(20) molecules m(-2))]. Flying two ECC instruments on the same payload with one filtered and the other unfiltered yields SO2 profiles, inferred by subtraction. Laboratory tests and field experience suggest an SO2 detection limit of similar to 3 pbb with profiles valid from the surface to the ozonopause [i. e., similar to(8-10 km)]. Two example profiles demonstrate the success of this technique for both volcanic and industrial plumes.
  • Jun Hirokawa, Takehiro Kato, Fumitaka Mafune
    ANALYTICAL CHEMISTRY 81 20 8380 - 8386 2009年10月 [査読有り][通常論文]
     
    Recently, chemical ionization mass spectrometry (CIMS) has been widely applied to the in situ measurements of atmospheric trace species. In this article, we propose a new chemical ionization scheme using a chloride ion transfer reaction from SO2Cl- as the reagent ion and discuss the applicability of this technique to the detection of nitrous acid (HONO) in the atmosphere. From laboratory investigations, the detection sensitivity was found to depend on the flow rate of SO2 introduced into the ion source region and the pressure inside the chemical ionization region, which suggests that the chemical ionization reaction is reversible. The detection sensitivity was well described in terms of the forward and backward rates. The present limit of detection is estimated to be 60 parts per trillion by volume (pptv) for an integration time of 1 min. Improvement of the CIMS instrument would enable the measurements of the daytime level of HONO, which might be less than 50 pptv. In addition, the possibility of the interference is discussed from thermodynamic considerations based on A initio calculations, and the effects of the sampling artifacts are experimentally quantified.
  • Jun Hirokawa, Takehiro Kato, Fumitaka Mafune
    JOURNAL OF PHYSICAL CHEMISTRY A 112 47 12143 - 12150 2008年11月 [査読有り][通常論文]
     
    Uptake kinetics of gas phase nitrous acid (HONO) by a pH-controlled aqueous solution was investigated by using a wetted wall flow tube. The gas phase concentration of HONO after exposure to the aqueous solution was measured selectively by the chemical ionization mass spectrometer in a high sensitive manner. The uptake rate of the gaseous HONO was found to depend on the pH of the solution. For the uptake by neutral and alkaline solutions, the gas phase concentration was observed to decay exponentially, suggesting that the uptake was fully limited by the gas phase diffusion. On the other hand, the uptake by the acidic solution was found to be determined by both the gas phase diffusion and the liquid phase processes such as physical absorption and reversible acid dissociation reaction. The decay was analyzed by the rate equations using the time dependent uptake coefficient involving the saturation of the liquid surface. While the uptake processes by the solution at pH = 2-3 were well described by those calculated using the physical and chemical parameters reported for the bulk, the uptake rates by the solution at 4 < pH < 7 deviate from the calculated ones. The present result can suggest that the pH at the liquid surface is lower than that in the bulk liquid, which is responsible for the additional resistance of mass transfer from the gas to the liquid phase.
  • Hiroshi Tanimoto, Nobuyuki Aoki, Satoshi Inomata, Jun Hirokawa, Yasuhiro Sadanaga
    INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 263 1 1 - 11 2007年05月 [査読無し][通常論文]
     
    A proton transfer reaction-time-of-flight mass spectrometer (PTR-TOFMS) has been developed for real-time measurements of volatile organic compounds in air. The instrument is designed to be operated with a hollow cathode discharge ion source and an ion drift tube at relatively high pressures. Each component of the system, an ion source, a drift tube, an ion transfer region, and a time-of-flight mass spectrometer, are in detail characterized by a number of laboratory experiments. The optimized instrumental configuration enables us to gain high intensities of hydronium (H3O+) ions, typically similar to 7 x 10(5) counts for 1-min integration at a drift tube pressure of similar to 5 Torr. It also suppresses background signals, and interferences from sample air (NO+ and O-2(+)), which undergo fast reactions with volatile organic compounds, to similar to 0.5% of those of H3O+ ions. We find that the use of the custom-built discharge source show higher overall sensitivities than of a commercially available radioactive source. Potentials to detect oxygenated VOCs (aldehydes, ketones, and alcohols), halocarbons, and amines are also suggested. The detection limits for acetaldehyde, acetone, isoprene, benzene, toluene, and p-xylene were determined to be at the sub-ppbv levels for a 1-min integration time. A good linear response at trace levels is certified, but slight sensitivity dependency on water vapor contents is revealed. We finally demonstrate that the instrument can be used for on-line monitoring to detect large variations from emission sources in real-time. (c) 2007 Elsevier B.V. All rights reserved.
  • Kazuyuki Kita, Yu Morino, Yutaka Kondo, Yuichi Komazaki, Nobuyuki Takegawa, Yuzo Miyazaki, Jun Hirokawa, Shigeru Tanaka, Thomas L. Thompson, Ru-Shan Gao, David W. Fahey
    JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY 23 8 1104 - 1113 2006年08月 [査読無し][通常論文]
     
    A chemical ionization mass spectrometer (CIMS) instrument has been developed for high-precision measurements of gaseous nitric acid (HNO3) specifically under high- and variable-humidity conditions in the boundary layer. The instrument's background signals (i.e., signals detected when HNO3-free air is measured), which depend on the humidity and HNO3 concentration of the sample air, are the most important factor affecting the limit of detection (LOD). A new system to provide HNO3-free air without changing both the humidity and the pressure of the sampled air was developed to measure the background level accurately. The detection limit was about 23 parts per trillion by volume (pptv) for 50-s averages. Field tests, including an intercomparison with the diffusion scrubber technique, were carried out at a surface site in Tokyo, Japan, in October 2003 and June 2004. A comparison between the measured concentrations of HNO3 and particulate nitrate indicated that the interference from particulate nitrate was not detectable (i.e., less than about 1%). The intercomparison indicated that the two independent measurements of HNO3 agreed to within the combined uncertainties of these measurements. This result demonstrates that the CIMS instrument developed in this study is capable of measuring HNO3 mixing ratios with the precision, accuracy, and time resolution required for atmospheric science.
  • S Inomata, H Tanimoto, N Aoki, J Hirokawa, Y Sadanaga
    RAPID COMMUNICATIONS IN MASS SPECTROMETRY 20 6 1025 - 1029 2006年 [査読無し][通常論文]
     
    A novel ion source based on direct current (d.c.) discharge has been developed for proton transfer reaction ionization operated at relatively high ion drift tube pressure. The shape and geometry of the ion source are designed to maximize overall ion intensity and to minimize interference from sample air. The initial performance of the technique, including speciation and intensity of reagent ions, their stability, and the impact of artifact signals, is evaluated by means of a proton transfer reaction time-of-flight mass spectrometer (PTR-TOFMS) newly built in our laboratory. Intensities of the hydronium (H3O+) ions are typically (5-7) X 10(5) counts for a 1-min integration time with a duty cycle of similar to 1%. The fluctuations of the ion signals over a period of hours are within 4%. Although the formation of artifact ions from sample air (NO+ and O-2(+)), which react with volatile organic compounds (VOCs) and subsequently cause fragmentation, is observed as background signals in addition to hydronium and mono- and di-hydrate H3O+ ions, intensities of both NO+ and O-2(+) ions are only similar to 0.5% of those of 2 H3O+ ions. Using our PTR-TOFMS system at a drift tube pressure of similar to 5 Torr, the detection sensitivities are significantly improved and the detection limits for propene, acetaldehyde, acetone, isoprene, benzene, toluene, and p-xylene are estimated to be at the sub-ppbv level for 1-min integration. Copyright (c) 2006 John Wiley & Sons, Ltd.
  • S Kato, Y Kajii, R Itokazu, J Hirokawa, S Koda, Y Kinjo
    ATMOSPHERIC ENVIRONMENT 38 19 2975 - 2981 2004年06月 [査読無し][通常論文]
     
    CO, O-3, and hydrocarbon measurements were conducted at Okinawa island, a southern Japanese island, during winter in 2000. The observed air was affected by the pollution transported from Chinese coastal area. Hydrocarbon concentration decreased as carbon number increased. This indicated that the measurement site was not affected by local anthropogenic sources. But negative correlation between 03 and sporadically high CO was observed. This indicated the fast transportation of polluted air from source region. Backward trajectory analyses showed that the air mass came from Chinese coastal area contained higher concentration of hydrocarbons than other trajectory categories. Transport time from source area to the observatory and observed hydrocarbon concentrations had negative correlations. The observed data at Okinawa were compared with the result obtained at Ogasawara island, a more remote island in the Western Pacific, in 1999. Their distance from the continent were different, however, the way of hydrocarbon decrease was same manner at these two sites. The standard deviation of the log natural of the mixing ratio for many hydrocarbons had more deviation at Okinawa than at Ogasawara. This indicated that Okinawa was more affected by polluted air which transported from the source region than Ogasawara. (C) 2004 Elsevier Ltd. All rights reserved.

書籍

  • 反応速度論
    真船 文隆, 廣川 淳 (担当:共著)
    裳華房 2017年09月
  • 基礎の化学
    田中 俊逸, 神谷 裕一, 廣川 淳, 中村 博 (担当:共著)
    三共出版 2015年03月
  • オゾン層破壊の科学
    北海道大学出版会 2007年

その他活動・業績

共同研究・競争的資金等の研究課題

  • 対流圏大気における化学反応過程の解明

教育活動情報

主要な担当授業

  • ナノ環境材料化学特論Ⅰ
    開講年度 : 2018年
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 触媒化学、環境修復、グリーンケミストリー、大気化学、オゾン層、オゾンホール、光化学オキシダント、反応速度論 Catalytic chemistry, Environmental remediation, Green sustainable chemistry, Atmospheric chemistry, Ozone layer, Ozone hole, Photochemical oxidant, Chemical kinetics
  • 環境計量学特論
    開講年度 : 2018年
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 環境計測、水質汚濁、大気汚染、計量法、環境法、統計学、環境分析法、放射線計測、計量管理 environmental measurement, water pollution, air pollution, dosimetry, metrology, environment law, statistics, environmental analytical methods, measuring control
  • 化学Ⅰ
    開講年度 : 2018年
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 原子の構造、原子軌道、化学結合、混成軌道、物質の三態、電解質溶液


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