研究者総覧

原田 雅史 (ハラダ マサフミ)

  • 研究院生活環境科学系衣環境学領域 准教授
メールアドレス:
haradacc.nara-wu.ac.jp
Last Updated :2021/08/23

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学位

  • 博士(工学), 東京大学

研究キーワード

  • コロイド化学、界面化学、洗浄科学 

研究分野

  • ナノテク・材料, 無機・錯体化学

経歴

  • 1999年04月 奈良女子大学生活環境学部 助教授
  • 1996年05月 - 1998年09月 科学技術振興事業団 橋本相分離構造プロジェクト 研究員
  • 1995年08月 - 1996年03月 北海道大学触媒化学研究センター講師(中核的研究機関研究員)
  • 1993年04月 - 1995年03月 日本学術振興会特別研究員(東京大学工学部)

学歴

  • - 1993年 東京大学大学院 工学系研究科 工業化学
  • - 1988年 京都大学 工学部 高分子化学科

論文

  • Temperature dependence on the size control of palladium nanoparticles by chemical reduction in nonionic surfactant/ionic liquid hybrid systems

    Masafumi Harada; Miho Yamamoto; Maharu Sakata

    2020年08月, Journal of Molecular Liquids, 311, 113255 - 113255, doi

    研究論文(学術雑誌)

  • Cation Distribution in Monodispersed MFe2O4 (M = Mn, Fe, Co, Ni, and Zn) Nanoparticles Investigated by X-ray Absorption Fine Structure Spectroscopy: Implications for Magnetic Data Storage, Catalysts, Sensors, and Ferrofluids.

    Masafumi Harada; Masako Kuwa; Ryota Sato; Toshiharu Teranishi; Mari Takahashi; Shinya Maenosono

    2020年07月27日, ACS Applied Nano Materials, 3, 8389 - 8402, doi;url

    研究論文(学術雑誌)

  • Ligand-Stabilized CoO and NiO Nanoparticles for Spintronic Devices with Antiferromagnetic Insulators

    Masako Kuwa; Masafumi Harada; Ryota Sato; Toshiharu Teranishi

    2020年03月27日, ACS Applied Nano Materials, 3 (3), 2745 - 2755, doi;url

    研究論文(学術雑誌)

  • Indium oxide supported Pt-In alloy nanocluster catalysts with enhanced catalytic performance toward oxygen reduction reaction.

    Y. Cheng; X. Zhao; Y. Yu; L. Chen; T. Cheng; J. Huang; Y. Liu; M. Harada; A. Ishihara; Y. Wang

    2020年, J. Power Sources, 446, 227332

    研究論文(学術雑誌)

  • Insight into the Formation Mechanism of “Unprotected” Metal Nanoclusters.

    L. Chen; Y. Yu; M. Kuwa; T. Cheng; Y. Liu; H. Murakami; M. Harada; Y. Wang

    2020年, Acta Phys. –Chim. Sin., 36, 1907008

  • Reverse Monte Carlo Modeling for Local Structures of Noble Metal Nanoparticles Using High-energy XRD and EXAFS.

    M. Harada; R. Ikegami; L. S. R. Kumara; S. Kohara; O. Sakata

    2019年, RSC Advances, 9, 29511 - 29521

    研究論文(学術雑誌)

  • Tetra-, hexa- and octanuclear copper hydride complexes supported by tridentate phosphine ligands.

    M. Harada; T. Nakajima; K. Nakamae; R. Hatano; K. Imai; Y. Ura; T. Tanase

    2019年, Dalton Trans., 48, 12050 - 12059

    研究論文(学術雑誌)

  • Microwave-Assisted Polyol Synthesis of Pt/Pd and Pt/Rh Bimetallic Nanoparticles in Polymer Solutions Prepared by Batch and Continuous-Flow Processing

    Cong Cong; Sayaka Nakayama; Shinya Maenosono; Masafumi Harada

    Colloidal dispersions of Pt/Pd and Pt/Rh bimetallic nanoparticles have been synthesized by a microwave-assisted polyol method using ethylene glycol and glycerol as a solvent in the presence of poly(N-vinyl-2-pyrrolidone) (PVP). The structure of bimetallic nanoparticles has been investigated by means of high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS) elemental mapping, and extended X-ray absorption fine structure (EXAFS). The effectiveness of the batch and continuous-flow processing was demonstrated for the preparation of various bimetallic nanoparticles under multimode or single-mode microwave irradiation. In the single-mode microwave-assisted continuous-flow processing in contrast to the batch processing, the well-dispersed colloidal bimetallic nanoparticles were successfully produced at the boiling temperature of solvent. EXAFS analysis indicated that, in the case of Pt/Pd (1/1) and Pt/Rh (1/1) bimetallic nanoparticles prepared using both batch and continuous-flow processing, the distribution of different metallic species in a particle tended to be a "cluster-in-cluster" structure., 2018年01月10日, Industrial and Engineering Chemistry Research, 57 (1), 179 - 190, doi

    研究論文(学術雑誌)

  • Properties of Protic Ionic Liquids Comprised of N-Alkyldiethylenetriamine and Their Complexation of Copper(II) Ions

    Chisayo Nakayama; Masafumi Harada; Masayasu Iida

    Protic ionic liquids (PILs) comprised of alkylpolyaminium cations, such as monoprotonated N-hexyldiethylenetriaminium (HHexdien(+)) and N-(2-ethylhexyl)diethylenetriaminium (HEthexdien(+)), coupled with bis(trifluoromethylsulfonyl)amide (Tf2N-) and trifluoroacetate (TFA(-)) were prepared, and their properties and interactions with copper(II) ions were studied using differential scanning calorimetry (DSC), visible absorption spectra, and N-15 NMR and C-13 NMR spectroscopy. The alkyldiethylenetriaminium (triamine) PILs assume a liquid state at lower temperatures than the corresponding alkylethylenediaminium (diamine) PILs, and they exhibit a glass transition without crystallization for all of the systems studied. The protonation of the alkyltriamines predominantly occurs at the N(1) and N(3) amine moieties and depends on the counteranions (Tf2N- or TFA(-)) and the alkyl moiety (hexyl or ethylhexyl). The polarity parameters, such as E-T(30) (or E-T(N)), *, , and , were determined for the triamine PILs, as well as for the diamine PILs, to examine the amine effect. The coordination structure of the copper(II) ion in the present chelate-amine PILs was deduced based on the visible absorption spectra for the isolated copper(II)-alkyldiethylenetriamine complexes and for Cu(ClO4)(2) in molecular solvents. The lifetime of the copper(II)-triamine complex formed in the PIL was estimated to be ca. 10(-2) s at ambient temperature using the C-13 NMR spectroscopic paramagnetic relaxation times., 2017年08月, EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, (31), 3744 - 3754, doi;web_of_science

    研究論文(学術雑誌)

  • Formation of silver nanoparticles from ionic liquids comprising N-alkylethylenediamine: Effects of dissolution modes of the silver(I) ions in the ionic liquids

    Hua Er; Haruka Yasuda; Masafumi Harada; Eiji Taguchi; Masayasu Iida

    Silver nanoparticles (AgNPs) were prepared from ionic liquids (ILs) of silver(I) N-alkylethylenediamine (N-alkyl=N-2-ethylhexyl, N-octyl, and N-dodecyl) complexes (=AgILs) and from protic ionic liquids (PILs) of N-alkylethylenediamines containing dissolved silver(I) nitrate (=AgNO3-PILs) and the two methods were compared. The difference between the silver(l) ion-ligand interaction modes of the AgIL and AgNO3-PIL systems was distinctly reflected in the formation of the AgNPs. The effects of the molecular structures of the AgILs and PILs, such as the effects of the alkyl chains in the cationic unit and the counter anion, on the shape and size distribution of the AgNPs were also examined using transmission electron microscopy (TEM), visible (VIS) absorption spectra, and extended X-ray absorption fine structure (EXAFS). The effect of the ethyl-branch of the alkyl chains on the physicochemical properties of the AgILs is drastic. The AgILs generally provided a more favorable reaction field for AgNP production than the AgNO3-PIL. The preparation of AgNPs depends on the concentration of AgNO3 in the PILs; at approximately 0.01 mol kg(-1) of AgNO3 in the PILs, the PILs were capable of preventing the aggregation of silver(0) particles to allow the formation of AgNPs, while at higher AgNO3 concentrations (0.05 mol kg(-1)), even in the long-chained dodecyl-PIL system, larger continuous-shaped aggregates were detected. The bis(fluorosulfonyl)amide (FSA) anion is effective on decreasing the transition temperature for the formation of the liquid states, but not appropriate for the preparation of the AgNPs when combined with the N-2-ethylhexylethylenediamine-AglL cationic unit, compared to the NO3 and trifluoroacetate (TFA) salts. (C) 2017 Elsevier B.V. All rights reserved., 2017年06月, COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS, 522, 503 - 513, doi;web_of_science

    研究論文(学術雑誌)

  • In Situ Quick X-ray Absorption Fine Structure and Small-Angle X-ray Scattering Study of Metal Nanoparticle Growth in Water-in-Oil Microemulsions during Photoreduction

    Masafumi Harada; Risa Ikegami

    Formation of metal nanoparticles (silver (Ag) and palladium (Pd) nanoparticles) in water/alkane/sodium bis(2-ethylhexyl) sulfosuccinate (AOT) water-in-oil (w/o) microemulsions consisting of AOT, water, and organic solvent (n-heptane, n-octane, n-decane, and isooctane) by photo reduction was monitored by means of a combination of in situ quick X-ray absorption fine structure (QXAFS) and small angle X-ray scattering (SAXS) measurements. The stages of reduction nucleation and the association process (aggregative particle growth and Ostwald ripening) of metal atoms to produce metal nanoparticles were discriminated in the course of the photoreduction time. In situ QXAFS results indicated that the aggregative growth follows a sigmoidal profile described both by the solid-state kinetic model, specifically the Avrami-Erofe'ev model, and by the chemical-mechanism-based kinetic Finke-Watzky model. The SAXS results clearly showed that the formation of Ag and Pd nanoparticles preferentially follows a reduction nucleation and subsequent aggregative particle growth before the starting of Ostwald ripening-based growth. The rate of nucleation and aggregative growth in the formation of Pd nanoparticles tends to be higher than that in the formation of Ag nanoparticles, resulting in the larger particle size of Ag nanoparticles. Another interesting finding is that the growth rate and final particle size is inversely related where a decrease in growth rate corresponds to larger particle sizes., 2016年05月, CRYSTAL GROWTH & DESIGN, 16 (5), 2860 - 2873, doi;web_of_science

    研究論文(学術雑誌)

  • Microwave-Assisted Polyol Synthesis of Polymer-Protected Monometallic Nanoparticles Prepared in Batch and Continuous-Flow Processing

    Masafumi Harada; Cong Cong

    Microwave-assisted polyol synthesis of monometallic Pd, Rh, Ru, and Pt nanoparticles has been demonstrated by the use of ethylene glycol and glycerol as a reducing agent in the presence of poly(N-vinyl-2-pyrrolidone) (PVP). The size and morphology of the synthesized nanoparticles have been investigated by means of high-resolution transmission electron microscopy (HRTEM) and extended X-ray absorption fine structure (EXAFS). A comparison between batch scale-up and continuous-flow processing for the microwave-assisted polyol synthesis has been also indicated in terms of the size and morphology of various nanoparticles. In the single-mode MW-assisted continuous-flow processing (10 mL processing volume), the well-dispersed colloidal nanoparticles with a metal concentration equal to similar to 10 mM were successfully produced in a sealed glass reactor at boiling temperature of the solvent at a flow rate of 1 mL/min. Furthermore, in the multimode MW-assisted batch processing, the colloidal nanoparticles appeared to have a narrower size distribution in ethylene glycol than in glycerol. The availability of the size regulation (i.e., particle size, size distribution) is discussed., 2016年05月, INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, 55 (19), 5634 - 5643, doi;web_of_science

    研究論文(学術雑誌)

  • Formation Mechanism of Gold Nanoparticles Synthesized by Photoreduction in Aqueous Ethanol Solutions of Polymers Using In Situ Quick Scanning X-ray Absorption Fine Structure and Small-Angle X-ray Scattering

    Masafumi Harada; Syoko Kizaki

    The photoreduction process of [AuCl4](-) precursors in poly(N-vinyl-2-pyrrolidone) solution was investigated by utilizing a combination of in situ quick scanning X-ray absorption fine structure (QXAFS) and small-angle X-ray scattering (SAXS) measurements to elucidate the nucleation and subsequent aggregative particle growth of colloidal gold nanoparticles (Au NPs). The sequence of stages for the reduction-nucleation and association process (autocatalytic surface growth and aggregative particle growth) of Au atoms to generate Au NPs was observed during the photoreduction. QXAFS analysis revealed that the reduction of [AuCl2](-) species to Au-0 atoms is a slower step than that of [AuCl4](-) to [AuCl2](-), and the reduction of [AuCl2](-) to Au-0 atoms and the association of Au-0 atoms to produce Au nucleates concurrently proceeds during short-duration photoirradiation. A sigmoidal curve expressed by the solid-state kinetic model, specifically the Avrami-Erofe'ev model, was applicable to demonstrate the aggregative particle growth. Complementary in situ SAXS results showed that Ostwald ripening based growth of Au NPs is not observed after the termination of the aggregative growth stage in the long-duration photoirradiation., 2016年03月, CRYSTAL GROWTH & DESIGN, 16 (3), 1200 - 1212, doi;web_of_science

    研究論文(学術雑誌)

  • Interactions of nickel(II) ions in protic ionic liquids comprising N-hexyl( or N-2-ethtylhexyl)ethylenediamines

    Mayu Watanabe; Chisayo Nakayama; Haruka Yasuda; Masafumi Harada; Masayasu Iida

    The interactions of nickel(II) ions in a protic ionic liquid (PIL) comprising monoprotic N-alkyl (alkyl = hexyl or 2-ethylhexyl)-ethylenediaminium ions (HHexen(+) or HEthexen(+), respectively) combined with bis(trifluoromethanesulfonyl)amide (Tf2N-) or trifluoroacetate (TFA(-)) ions were investigated using visible (VIS) electronic and extended X-ray absorption fine structure (EXAFS) spectroscopy. These were compared to the analogous nickel(II) complexes in molecular solvents, and copper(II) ion in the same PIL systems. A complete extraction of nickel(II) and copper(II) ions from the aqueous phase was achieved by using the above mentioned PILs with the Tf2N- counter anion. Absorption spectra were used to explore the interaction mode of the nickel(II) ions with the chelating diamine PIL by the addition of nickel(II) salts to the PIL. This demonstrated a dominant formation of the tris(alkyl-en) complex at lower nickel(II) concentrations and changes of the complex to a cis-aniono bis(alkyl-en) complex with the addition of the nickel(II) salts. The ethyl-branch in the cationic unit of the PIL was observed to have a larger effect on the solubility of the copper(II) salts than that of the nickel(II) salts. The EXAFS spectra analysis of the nickel(II) ions in the PILs gives the significant information on the fine structure around the nickel(II) ion coordinated by hexylethylenediamine (Hexen) in the PILs. (C) 2015 Elsevier B.V. All rights reserved., 2016年02月, JOURNAL OF MOLECULAR LIQUIDS, 214, 77 - 85, doi;web_of_science

    研究論文(学術雑誌)

  • Solvation Structure of a Copper(II) Ion in Protic Ionic Liquids Comprising N-Hexylethylenediamine

    Shinobu Takemura; Sayaka Kawakami; Masafumi Harada; Masayasu Iida

    The fine and dynamic structure of the copper(II) ion solvated in a protic ionic liquid (PIL) comprising monoprotonated N-hexylethylenediaminium (HHexen(+)) and bis(trifluoromethanesulfonyl)amide (Tf2N-) [or trifluoroacetate (TFA(-))] was determined using NMR, visible electronic, and extended X-ray absorption fine structure (EXAFS) spectroscopy. The chelate-diamine group in the cationic unit facilitates advantageous dissolution of transition-metal salts in the present PIL. The interaction of the copper(II) ion with the chelate-diamine PIL was explored by the addition of copper(II) salts to the PIL, demonstrating competitive complexation between the ligand of the added copper(II) salt and the components of the ionic liquid to the copper(II) ion. The favorable mode of interaction of the present chelating PIL with the copper(II) ion was clarified based on a comparison of the interactions with analogous liquids, including the monoprotonated hexylaminium HHexam(Tf2N)-PIL, neat N-hexylethylenediamine (Hexen), and neat ethylenediamine (En). The coordination modes of the bis-Hexen and tris-Hexen copper(II) complexes in molecular liquids and in solids were also studied for comparison of the coordination structures around the copper(II) ion with those in the present PILs. The paramagnetic-induced relaxations derived from C-13 (Delta T-1p(-1)) and N-15 (Delta T-2p(-1)) NMR, the visible electronic spectra, and EXAFS analysis showed that the copper(II) ion tends to form a bis-Hexen complex in the HHexen-PIL despite the electrostatic repulsion and the fact that the counteranions are located at the axial sites, whereas in the HHexam(Tf2N)-PIL, the copper(II) ion exhibits affinity for the Tf2N anion over the protonated amines. The lifetime of the copper(II) complex formed in the PIL was determined to be approximate to 10(-4) s based on C-13 (Delta T-1p(-1)) and N-14 (Delta T-2p(-1)) NMR, which is appreciably longer than that in conventional molecular solvents., 2014年09月, INORGANIC CHEMISTRY, 53 (18), 9667 - 9678, doi;web_of_science

    研究論文(学術雑誌)

  • Syntheses, structures, and photochemical properties of (mu(3)-O) tris {bis(mu-carboxylato)} trimanganese complexes with naphthylacetate ligands with relevance to artificial solar energy-harvesting systems

    Misaki Nakai; Takuzo Funabiki; Chikara Ohtsuki; Masafumi Harada; Akio Ichimura; Rika Tanaka; Takanori Nishioka; Isamu Kinoshita; Masahiro Mikuriya; Jiamo Guo; Hiroaki Benten; Hideo Ohkita; Shinzaburo Ito; Makoto Obata; Yasuo Nakabayashi; Shigenobu Yano

    Two new trinuclear Mn complexes containing naphthalene moieties, [Mn-3(mu(3)-O)(mu-O2CCH2-1-naph)(6) (py)(3)] (1) and [Mn-3(mu(3)-O)(mu-O2CCH2-2-naph)(6)(py)(3)] (2) (naph-1-CH2CO2H = 1-naphthylacetic acid, naph-2-CH2CO2H = 2-naphthylacetic acid, py = pyridine), were synthesized. The X-ray crystallography of 1, the EXAFS analyses of 1 and 2, and the magnetic susceptibility data for these complexes showed that they are trinuclear complexes containing a [Mn-3(mu(3)-O)(mu-O2CR)(6)] core with mixed-valence Mn-3(II, III, III) centers. CVs exhibited an oxidation peak ascribed to Mn-3(III)/(MnMn2III)-Mn-II and a reduction peak ascribed to (MnMn2III)-Mn-II/(Mn2MnIII)-Mn-II in CH2Cl2. In the fluorescence spectra, the fluorescence intensities of 1 and 2 were smaller than those of the naphthylacetic acids and depended on the dielectric constant of solvent. These results suggested that there is electron transfer between the manganese centers and the naphthyl moieties. The fluorescence decays of 1 and 2 in CH3CN were also faster than the decays in the toluene solutions; this result parallels the lower intensity of the static fluorescence spectra in solvents with a higher dielectric constant. The fluorescence decay curves of 1 and 2 were fitted by two lifetimes, tau(1) and tau(2), suggesting that electron transfer occurs from the monomer (tau(1)) and the excimer (tau(2)) of the naphthyl moieties to the manganese center. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved., 2013年09月, INORGANICA CHIMICA ACTA, 406, 130 - 137, doi;web_of_science

    研究論文(学術雑誌)

  • Sites of protonation and copper(II)-complexation in protic ionic liquids comprised of N-hexylethylenediaminium cation

    Mayu Watanabe; Shinobu Takemura; Sayaka Kawakami; Emi Syouno; Hiromichi Kurosu; Masafumi Harada; Masayasu Iida

    Protonation sites of a chelating mono-protic ionic liquid (PIL) comprising N-hexylethylenediaminium (= HHexen(+)) depending on the counter anion were studied by N-15 and C-13 NMR spectroscopy and DFT calculation. In the case of the bis(trifluoromethanesulfonyl) amide (=TFSA(-)) PIL, the protonation occurred almost at the secondary amine, whereas the protonation occurred preferentially at the primary amine in the trifluoroacetate (= TFA(-)) PIL The formation of a chelating copper(II) complex with the cationic unit of the PIL despite the electrostatic repulsion was revealed using the paramagnetic broadenings of the C-13 NMR spectra of the PILs. (C) 2013 Elsevier B.V. All rights reserved., 2013年07月, JOURNAL OF MOLECULAR LIQUIDS, 183, 50 - 58, doi;web_of_science

    研究論文(学術雑誌)

  • Influence of the organization of water-in-ionic liquid microemulsions on the size of silver particles during photoreduction

    Masafumi HARADA; Masako Yamada; Yoshifumi Kimura; Kenji Saijo

    2013年, J. Colloid Interface Sci., 406, 94-104

  • Nanometer-scale water droplet free from the constraint of reverse micelles at low temperatures

    H. Murakami; T. Sada; M. Yamada; M. Harada

    Temperature dependence of the configurational fluctuation of water confined in a reverse micellar solution has been studied by absorption spectroscopy of a probe molecule. We have found that the configurational fluctuation is liquidlike below the homogeneous nucleation temperature. This is proposed to be due to a large reduction in the confinement of water, and is explained in terms of water shedding from the reverse micelle. Further, the configurational fluctuation is frozen at ∼210 K. A reverse micellar solution is considered to be a promising candidate for studies of supercooled water. © 2013 American Physical Society., 2013年11月07日, Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, 88 (5), 052304, doi

    研究論文(学術雑誌)

  • Nucleation and Aggregative Growth Process of Platinum Nanoparticles Studied by in Situ Quick XAFS Spectroscopy

    Masafumi Harada; Yoshiko Kamigaito

    The early stage in the nucleation and subsequent aggregative particle growth of the colloidal platinum (Pt) dispersions produced by photoreduction in an aqueous ethanol solution of poly(N-vinyl-2-pyrrolidone) (PVP) was quantitatively investigated by means of in situ quick XAFS (QXAFS) measurements. The stages of the reduction-nucleation and the association process (aggregative particle growth and Ostwald ripening) of Pt atoms to produce Pt nanoparticles was successfully discriminated in course of the photoreduction time. The present QXAFS analysis indicated that Pt nuclei (i.e., (Pt-0)(m) nucleates approximately m = 4) were continuously produced in the reduction-nucleation process at the early time, followed by the aggregative particle growth with the autocatalytic reduction of Pt ionic species on the surface of Pt nuclei to produce Pt nanoparticles. Subsequently the particle growth proceeded via Ostwald ripening, resulting in the production of larger Pt nanoparticles at a later time. It was also found that the aggregative particle growth follows a sigmoidal profile well described either by the solid-state kinetic model or by the chemical-mechanism-based kinetic model, specifically the Avrami-Erofe'ev or Finke-Watzky models. The difference in terms of the formation mechanism was observed between the reduction of (PtCl62-)-Cl-IV and (PtCl42-)-Cl-II as a source material. Also presented is that the addition of the photoactivator such as benzoin, benzophenone, and acetophenone in the system is very effective to enhance the rate for the formation of Pt nanoparticles., 2012年02月, LANGMUIR, 28 (5), 2415 - 2428, doi;web_of_science

    研究論文(学術雑誌)

  • Biosorption of Trivalent Chromium from Aqueous Solution by Red Seaweed Polysiphonia nigrescens

    P. Blanes; L. Sala; S. Garcia; J. Gonzalez; M. Frascaroli; M. Harada; C. Cong; Y. Niwa; C. Matulewicz; H. Prado; A. Cortadi; M. Gattuso

    2011年11月, J. Water Resource and Protection, 3, 832 - 843

  • Nucleation and Growth of Metal Nanoparticles during Photoreduction Using In Situ Time-Resolved SAXS Analysis

    Masafumi Harada; Noriko Tamura; Mikihito Takenaka

    Formation of metal nanoparticles (rhodium (Rh) and palladium (Pd) nanoparticles) in an aqueous ethanol solution of poly(N-vinyl-2-pyrrolidone) (PVP) by photoreduction was monitored by means of in situ and time-resolved small-angle X-ray scattering (SAXS) measurements. The kinetics of association process (nucleation, growth, and particle coalescence) of metal atoms to produce metal nanoparticles was successfully evaluated by the quantitative SAXS analysis for the number-average of radius (R-0), number of particles (n(p)), standard deviation in radius (sigma(R)/R-0), and total volume (V-p) of metal nanoparticles produced by the photoreduction. The time evolution of particle size, number of particles, and particle size distribution indicated that the formation of Rh nanoparticles predominantly follows an autocatalytic reduction-nucleation process before the onset of Ostwald ripening-based growth. On the other hand, in the formation of Pd nanoparticles, the reduction-nucleation process occurred significantly faster at the early stage of the reaction, and the dominant growth of Pd nanoparticles subsequently proceeded via an Ostwald ripening-based growth mechanism. It was also found that the rate of nucleation and growth during the metal particle formation is strongly affected by the initial metal concentration and the addition of NaCl., 2011年07月, JOURNAL OF PHYSICAL CHEMISTRY C, 115 (29), 14081 - 14092, doi;web_of_science

    研究論文(学術雑誌)

  • Transport Properties and Solvation Structure of Mixtures of Carbon Dioxide and Room-Temperature Ionic Liquids

    Masashi Demizu; Masafumi Harada; Kenji Saijo; Masahide Terazima; Yoshifumi Kimura

    Translational diffusion coefficients of diphenylcyclopropenone (DPCP), diphenylacetylene (DPA), and carbon monoxide (CO) in carbon dioxide (CO2) mixtures of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([BMIm][NTf2]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]), respectively, were determined by transient grating (TG) spectroscopy under various pressures of CO2. With increasing CO2 pressure up to 15 MPa, the diffusion coefficients of DPCP and DPA increased by an order of magnitude, while the increase of the diffusion coefficient of CO was relatively small. Sound velocities of the mixtures were also determined by TO spectroscopy, which decreased by ca. 20% with increasing pressure up to 10 MPa, and then turned to increase with pressure. The solvation structure around DPCP was also investigated by Raman spectroscopy. It was found that the vibrational spectra of solute and solvent molecules did not show remarkable changes. Small-angle X-ray scattering (SAXS) profiles for CO2 mixture of 1-octyl-3-methylimidazolium tetrafluoroborate ([OMIm][BF4]) were measured under various pressures of CO2. The peak observed for the SAXS profile at 3 nm(-1) for [OMIm][BF4] did not show meaningful shift with increasing CO2 pressure, while the peak width showed a small increase., 2011年01月, BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN, 84 (1), 70 - 78, doi;web_of_science

    研究論文(学術雑誌)

  • Mechanism of Silver Particle Formation during Photoreduction Using In Situ Time-Resolved SAXS Analysis

    Masafumi Harada; Etsuko Katagiri

    Formation mechanisms of silver (Ag) particles in an aqueous ethanol solution of poly(N-vinyl-2-pyrrolidone) (PVP) by the photoreduction of AgClO4 were investigated by means of in situ small-angle X-ray scattering (SAXS) measurements. The kinetics of association process (nucleation, growth, and coalescence) of Ag-o atoms to produce Ag particles was successfully revealed by the quantitative SAXS analysis for the number-average of radius (R-0), number of particles (n(Ag)), reduced standard deviation (sigma(R)/R-0), and volume fraction (phi(Ag)) of Ag. particles produced by the photoreduction. The rate of nucleation and growth process during Ag particle formation strongly depend on the initial metal concentration. The time evolution of radius and number of Ag particles indicates that a mechanism of Ag particle formation is composed of different three processes, that is, reduction-nucleation, Ostwald ripening, and particle coalescence. In a rapid reduction-nucleation process, small nuclei or particles (average radius similar to 2.5 nm) are produced by an autocatalytic reduction. After the formation of small nuclei or particles proceeds, Ostwald ripening and particle coalescence, predicted by the Lifshitz-Slyozov-Wagner theory (LSW theory), subsequently occur, resulting in the particle growth (average radius similar to 11.5 nm)., 2010年12月, LANGMUIR, 26 (23), 17896 - 17905, doi;web_of_science

    研究論文(学術雑誌)

  • Characterization of water/AOT/benzene microemulsions during photoreduction to produce silver particles

    Masafumi Harada; Kenji Saijo; Naoki Sakamoto; Kazuki Ito

    Colloidal dispersions of silver (Ag) particles were prepared by the photoreduction of silver perchlorate (AgClO(4)) in water/AOT/benzene water-in-oil (w/o) microemulsions consisting of sodium bis(2-ethylhexyl) sulfosuccinate (AOT), water and benzene. Formation mechanisms of Ag particles prepared in the presence of benzoin by photoreduction from Ag(+)-containing w/o microemulsions were investigated by UV-vis, transmission electron microscopy (TEM), extended X-ray absorption fine structure (EXAFS) and small-angle X-ray scattering (SAXS) measurements. By a combination of TEM and EXAFS results, Ag particles show a metallic nature after the photoreduction and the diameter of Ag particles ranges between 5 and 30 nm. In situ time-resolved SAXS measurements show that the integrated rate equation can be applied in the reduction process of Ag(+) ons to Ag(0)atoms, and the autocatalytic Ag particle growth proceeds in the association process of Ag(0) atoms during the photoreduction of Ag(+)-containing w/o microemulsions. The nanometer-sized water droplets microemulsified by AOT in benzene continuous-phase regulated the size of Ag particles, and the size and shape of water droplets were retained during the Ag particle formation. (C) 2009 Elsevier Inc. All rights reserved., 2010年03月, JOURNAL OF COLLOID AND INTERFACE SCIENCE, 343 (2), 423 - 432, doi;web_of_science

    研究論文(学術雑誌)

  • Photochemical synthesis of silver particles using water-in-ionic liquid microemulsions in high-pressure CO2

    Masafumi Harada; Chika Kawasaki; Kenji Saijo; Masashi Demizu; Yoshifumi Kimura

    Silver particles (Ag particles) were synthesized by the photoreduction of silver perchlorate (AgClO4) in water-in-ionic liquid (IL) microemulsions consisting of nonionic surfactant Tween 20, water, and ionic liquids, [1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]) or 1-octyl-3-methylimidazolium tetrafluoroborate ([OMIm][BF4])], mixed with a high-pressure (25 MPa) CO2. The time evolution of the Ag particle formation by photoreduction was investigated by UV-Vis, cryo-TEM, extended X-ray absorption fine structure (EXAFS), and small-angle X-ray scattering (SAXS) measurements. In the particle formation process, aggregation and precipitation of Ag particles were suppressed under high-pressure CO2. The average diameters of the metallic Ag particles prepared in water-in-[BMIm][BF4] and water-in-[OMIm][BF4] microemulsions were estimated from TEM to be 3.2 and 3.7 nm, respectively. SAXS analysis shows that the average diameters of the water droplets, which consisted of ionic precursors of AgClO4 and Ag particles (or Ag aggregates), were estimated to be about 30-40 nm. In the process of Ag particle formation, the water droplet size under high-pressure CO2 is more effectively regulated than that under ambient air, thereby preventing Ag particles from aggregating and precipitating. (C) 2009 Elsevier Inc. All rights reserved., 2010年03月, JOURNAL OF COLLOID AND INTERFACE SCIENCE, 343 (2), 537 - 545, doi;web_of_science

    研究論文(学術雑誌)

  • Oxygen-Sensing Properties of 5,10,15,20-Tetraphenylporphinato Platinum(II) and Palladium(II) Covalently Bound on Poly(isobutyl-co-2,2,2-trifluoroethyl methacrylate)

    Makoto Obata; Noriko Matsuura; Kazunori Mitsuo; Hiroki Nagai; Keisuke Asai; Masafumi Harada; Shiho Hirohara; Masao Tanihara; Shigenobu Yano

    A novel methacrylate monomer bearing 5,10,15,20-tetraphenyl porphyrinato palladium(II) (PdTPP) (monomer 1a) was synthesized and copolymerized with isobutyl methacrylate (IBM) and 2,2,2-trifluoroethyl methacrylate (TFEM) to give poly (IBM-co-TFEM) bearing PdTPP (copolymer 2a) as a dye-conjugated oxygen-permeable polymer for pressure-sensitive paint applications. The introduction of PdTPP into copolymer 2a was confirmed by UV-vis spectroscopy and extended X-ray absorption fine structure analysis. The Stern-Volmer plots of the copolymer 2a and a mixture of PdTPP and poly(IBM-co-TFEM) both showed downward curvature, unlike that of the platinum complex analogue (copolymer 2b) previously reported. The plots were successfully fitted with a two-site model to give two distinct Stern-Volmer constants (K(SV1) and K(SV2)) and the partition ratio f(1). Interestingly, the f(1) values for the copolymer 2a were almost constant at about 0.98, whereas those of the mixture of PdTPP and poly(IBM-co-TFEM) increased from 0.889 to 0.967 as the temperature was increased. This finding suggests that there are two distinct microheterogeneities, one temperature-dependent and the other temperature-independent, in the mixture of PdTPP and poly(IBM-co-TFEM). The dye-conjugation approach effectively eliminates the temperature-dependent, but not the temperature-independent microheterogeneity. The luminescence decays of copolymers 2a and 2b and the corresponding mixtures in the absence of oxygen indicated that the temperature-dependent microheterogeneity involves an oxygen diffusion process, whereas the temperature-independent one appears to be inherent nature in PdTPP. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 663-670, 2010, 2010年02月, JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY, 48 (3), 663 - 670, doi;web_of_science

    研究論文(学術雑誌)

  • Thermodynamic and Dynamic of Chromium Biosorption by Pectic and Lignocellulocic Biowastes.

    S.E. Bellu; L.F. Sala; J.C. Gonzalez; S.I. Garcia; M.I. Frascaroli; P. Blanes; J. Garcia; J.S. Peregrin; A.M. Atria; J. Ferron; M. Harada; C. Cong; Y. Niwa

    2010年, J. Water Resource and Protection, 2, 888 - 897

  • Photochemical synthesis of silver particles in Tween 20/water/ionic liquid microemulsions

    Masafumi Harada; Yoshifumi Kimura; Kenji Saijo; Tetsuya Ogawa; Seiji Isoda

    Metal particles of silver (Ag) were synthesized by the photoreduction of silver perchlorate (AgClO4) in water-in-ionic liquid (ILs) microemulsions consisting of Tween 20, water and ionic liquids. The ILs were tetrafluoroborate anions associated with the cations 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]) and 1-octyl-3-methylimidazolium tetrafluoroborate ([OMIm][BF4]). The time evolution of Ag particle formation by photoreduction using UV-irradiation was investigated by UV-Vis, cryo-TEM, extended X-ray absorption fine structure (EXAFS) and small angle X-ray scattering (SAXS) measurements. The average diameter of the metallic Ag particles prepared in the water-in-[BMIm][BF4] and water-in-[OMIm][BF4] microemulsions was estimated from TEM to be 8.9 and 4.9 nm, respectively, which was consistent with that obtained from the SAXS analysis. Using Guinier plots in a low q-range (<0.16 nm(-1)), we demonstrate that the average diameter of the water droplets that consisted of aggregates of ionic precursors of AgClO4 before reduction and Ag particles after reduction, in the microemulsions, was estimated to be about 20-40 nm. The diameter of the water droplets increased as a function of photoreduction time because of the formation of Ag particles and their aggregates. EXAFS analysis indicated that Ag+ ions were completely reduced to Ago atoms during the photoreduction, followed by the formation of larger Ag particles. (C) 2009 Elsevier Inc. All rights reserved., 2009年11月, JOURNAL OF COLLOID AND INTERFACE SCIENCE, 339 (2), 373 - 381, doi;web_of_science

    研究論文(学術雑誌)

  • Characterization of metal nanoparticles prepared by photoreduction in aqueous solutions of various surfactants using UV-vis, EXAFS and SAXS

    Masafumi Harada; Kenji Saijo; Naoki Sakamoto

    Photoreduction formation mechanisms of metal particles (gold (Au) and platinum (Pt) particles) in aqueous surfactant solutions of dodecyltrimethylammonium chloride (DTAC) and polyethylene glycol lauryl ether (PEG) have been studied by transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), and extended X-ray absorption. ne structure (EXAFS) measurements. EXAFS results confirmed the metallic nature of the nanoparticles, and showed that the average particle size significantly depends neither on the metal species nor on the charged properties (cationic, anionic, or nonionic) of surfactants. The SAXS analysis indicated that the structure of DTAC and PEG micelles could be fitted with the hard-sphere model having the interaction radius R(HS) and the spherically shaped core-shell structure. At the beginning of the photoirradiation, the increase of the SAXS intensity at q < 1.0 nm(-1) was not due to the change of the size and shape of the produced metal particles, but due to the increase in number of produced metal particles in the growth process. Once the radius of metal particles produced during the photoirradiation exceeded a radius (R(shell)) of the individual micelles, the metal particle growth was noticeably accelerated and the larger aggregates were formed, which were not stabilized by adsorbed surfactant molecules on their metal surface. (C) 2009 Elsevier B. V. All rights reserved., 2009年10月, COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS, 349 (1-3), 176 - 188, doi;web_of_science

    研究論文(学術雑誌)

  • Extended X-Ray Absorption Fine Structure Study on Reaction of Anti-tumor Platinum Complexes with Reduced Glutathione

    Makoto Obata; Masafumi Harada; Hiromi Ohi; Shiho Hirohara; Michael Gottchaldt; Shigenobu Yano

    Reactions of cis-diamminedichloroplatinum(II) (cisplatin) and 1,1-cyclobutanedicarboxylatodiammineplatinum(II) (carboplatin) with reduced glutathione, a tripeptide that is abundant in cells, were studied by means of X-ray absorption spectroscopy. Back-scattering amplitudes F-i(k) and phase shifts Phi(i)(k) were theoretically derived, and validated by applying them to calculate extended X-ray absorption fine structure (EXAFS) oscillations of cisplatin and K-2[Pt(SCN)(4)] in the solid state. EXAFS oscillations of reaction mixtures of cisplatin or carboplatin with reduced glutathione were fitted to the standard EXAFS equation using the F-i(k) and Phi(i)(k) functions to give the coordination numbers of N or O atoms (N-N/O) and of Cl or S atoms (N-Cl/S). For both cisplatin and carboplatin, the N-N/O value decreased and the N-Cl/S values increased monotonically as the reaction proceeded. However, the reaction rate for carboplatin was significantly slower than that for cisplatin., 2009年10月, CHEMICAL & PHARMACEUTICAL BULLETIN, 57 (10), 1107 - 1109, doi;web_of_science

    研究論文(学術雑誌)

  • In situ time-resolved XAFS analysis of silver particle formation by photoreduction in polymer solutions

    Masafumi Harada; Yasuhiro Inada; Masaharu Nomura

    Formation mechanisms of silver (Ag) particles in an aqueous ethanol solution of poly(N-vinyl-2-pyrrolidone) (PVP) by the photoreduction of AgClO4 were investigated by using UV-Vis, transmission electron microscopy (TEM), extended X-ray absorption fine structure (XAFS), and in situ energy-dispersive X-ray absorption fine structure (in situ DXAFS) measurements. The average diameter of the Ag particles prepared in the presence and absence of benzoin as a photo-activator was estimated from TEM to be 7.4 and 5.1 nm, respectively, and their particle size distributions ranged from 2 to 15 nm. XAFS analysis indicated that metallic Ag particles were synthesized, and the reduction rate of Ag+ to Ag-0, the creation of Ag-0-Ag-0 bonds and their particle growth by the association of Ag-0-Ag-0 was regulated by the metal concentration and the inclusion of benzoin. In situ DXAFS measurements were performed in real time to investigate the kinetics of Ag+ reduction and Ag particle formation. During the induction period the reduction of Ag+ to Ag-0 occurred, and subsequent nucleation and growth process concurrently proceeded after the induction period. The intermediate small Ag particles (C.N. smaller than about 4) were generated in the nucleation process, and grown up to larger particles (C.N.s equal to 4.5 +/- 1.5) in the longer-duration photoreduction. (C) 2009 Elsevier Inc. All rights reserved., 2009年09月, JOURNAL OF COLLOID AND INTERFACE SCIENCE, 337 (2), 427 - 438, doi;web_of_science

    研究論文(学術雑誌)

  • Small-angle X-ray scattering study of metal nanoparticles prepared by photoreduction in aqueous solutions of sodium dodecyl sulfate

    Masafumi Harada; Kenji Saijo; Naoki Sakamoto; Hisahiro Einaga

    Photoreduction formation mechanisms of metal particles (gold (Au) and platinum (Pt) particles) in aqueous solution of sodium dodecyl sulfate (SDS) have been investigated using transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), and extended X-ray absorption fine structure (EXAFS) measurements. The anionic surfactant SDS was used as a stabilized reagent to disperse metal particles in aqueous solutions. The average particle diameter of Au and Pt particles was estimated from TEM as 4.5 and 2.7 nm, respectively. The SAXS analysis showed that in high concentration of SDS the size of Au and Pt particles is consistent with those obtained from TEM and EXAFS measurements, and the micelles of SDS retain a core-shell structure in aqueous solutions after the formation of metal particles. In the particle formation process, metal particles were photochemically produced in the core of micelles and they did not significantly affect the morphology of micelles, although these metal ions were almost randomly distributed in solution before the photoreduction. The particle growth rate of Au and Pt could be evaluated on the basis of the weight fraction of these metal particles, and it was found that Au particle growth occurs more rapidly than Pt particle growth in the aqueous SDS solutions. (C) 2009 Elsevier B.V. All rights reserved., 2009年08月, COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS, 345 (1-3), 41 - 50, doi;web_of_science

    研究論文(学術雑誌)

  • In Situ Time-Resolved XAFS Studies of Metal Particle Formation by Photoreduction in Polymer Solutions

    Masafumi Harada; Yasuhiro Inada

    Formation mechanisms of metal particles (rhodium (Rh) and palladium (Pd) particles) in an aqueous ethanol solution of poly(N-vinyl-2-pyrrolidone) (PVP) by photoreduction were investigated by UV-vis, transmission electron microscopy (TEM), and in situ X-ray absorption fine structure (in situ XAFS). The average diameter of the Rh and Pd particles prepared by the photoreduction was estimated from TEM to be 2.2 and 2.0 nm, respectively. In situ energy-dispersive XAFS (in situ DXAFS) measurements were performed to investigate the reduction process of Rh(III) and Pd (II) aqua chlorocomplexes as well as their particle formation process. The reduction rate of these aqua chlorocomplexes could be quantitatively evaluated from the change of X-ray absorbance assigned to the contribution of metal-chloride bonds in these complexes. The reduction rate of Rh(III) aqua chlorocomplexes was found to be slower than that of Pd (II). It was also demonstrated that the reduction process of Rh(III) complexes possessed an induction period before the onset of Rh particle formation, although the Pd(II) complexes displayed no induction period, since the reduction of Pd (II) occurred immediately after mixing of an ethanol solution of Pd(II) complexes with aqueous PVP solutions., 2009年06月, LANGMUIR, 25 (11), 6049 - 6061, doi;web_of_science

    研究論文(学術雑誌)

  • Relationship Between the Structure of Manganese Oxides on Alumina and Catalytic Activities for Benzene Oxidation with Ozone

    Hisahiro Einaga; Masafumi Harada; Atsushi Ogata

    Catalytic oxidation of benzene with ozone was carried out over alumina-supported manganese oxides. Manganese oxides was highly dispersed on alumina at low loading levels (Mn < 2.5 wt%) and aggregated Mn(3)O(4) crystallites were formed at the high loading levels (> 7.5 wt%). Both the Mn oxide species were active for benzene oxidation with ozone, and the former showed slightly higher activities. TPO studies of used catalysts revealed that the oxidation behavior of benzene was not so much influenced by the Mn loadings., 2009年05月, CATALYSIS LETTERS, 129 (3-4), 422 - 427, doi;web_of_science

    研究論文(学術雑誌)

  • Diffusion of gold ions and gold particles during photoreduction processes probed by the transient grating method

    Masafumi Harada; Koichi Okamoto; Masahide Terazima

    The translational diffusion of Au (gold) ions and Au particles during the photoreduction process from AuCl(4)(-) to metallic Au particles in aqueous ethanol solutions containing poly(N-vinyl-2-pyrrolidone) was investigated by using UV-vis absorption and the laser-induced transient grating (TG) methods. The TG signal of AuCl(4)(-) solution before photoirradiation was composed of three contributions; the thermal grating, the species grating due to the creation of AuCl(2)(-), and that due to the depletion of AuCl(4)(-). Upon photoirradiation, the species grating signal due to AuCl(4)(-) diminished rapidly and the TG signal due to Au particles appeared within a few Minutes and became stronger at a very short time. The Subsequent reduction of AuCl(2)(-) was concomitant with the formation of ALL metal particles. The rapid growth of Au(0) atoms into Au particles took place in the short-duration photoirradiation. With the increase of the photoirradiation time, the TG signal was composed of two kinds of Au particle fragments possessing different diffusion coefficients. This is probably due to the pulse-laser induced fragmentation of the larger Au particles. Effects of the polymer on the particle formation were investigated by the concentration dependence of the polymer in the solution. The formation of Au particles by the photoreduction was also compared with that of Pt particles. (c) 2009 Elsevier Inc. All rights reserved., 2009年04月, JOURNAL OF COLLOID AND INTERFACE SCIENCE, 332 (2), 373 - 381, doi;web_of_science

    研究論文(学術雑誌)

  • Aggregation in methanol and formation of molecular glasses for europium(III) N-acylaminocarboxylates: effects of alkyl chain length and head group

    Gerile Naren; Ami Yasuda; Masayasu Iida; Masafumi Harada; Toshiharu Suzuki; Masako Kato

    Europium(III) complexes of N-acyl-DL-alaninates (acyl = acetyl, butanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl and tetradecanoyl), N-octanoyl-DL-phenylalaninate, and N-octanoyl-L-serinate were prepared to understand the effects of alkyl chain length and the type of head group on the formation of glassy states and on the aggregation behaviour in solutions. The acylalaninate complexes had a tendency to form a transparent glass, whereas Eu(ala)(3) (ala = DL-alaninate) was easily crystallized. Of the C2(acetyl)-C14(tetradecanoyl) chains in the ligands, the C4-C8 chains were the most favourable to assume a stable glassy state by solvent vaporization. The europium(III) complexes having an acyl chain of C6 (hexanoyl) or longer exhibited a peak below 2q = 5. due to the presence of a bilayer structure in the glassy state. The octanoylserinate complex easily formed an anisotropic glass by a solvent-cast method, while the octanoylphenylalaninate complex transformed from a transparent glass to an anisotropic glass by an annealing treatment. The trend of glass formation was related with the aggregation behaviour of the complexes in methanol detected by self-diffusion and luminescence properties., 2009年, DALTON TRANSACTIONS, (28), 5512 - 5522, doi;web_of_science

    研究論文(学術雑誌)

  • Synthesis of ruthenium particles by photoreduction in polymer solutions

    Masafumi Harada; Saki Takahashi

    Colloidal dispersions of poly(N-vinyl-2-pyrrolidone)-protected ruthenium (Ru) particles have been synthesized by the photoreduction of Ru(III) ionic solutions in the presence of photo-activator such as benzophenone and benzoin. The size and the structure of the synthesized particles have been extensively investigated by UV-vis, transmission electron micrograph (TEM) and extended X-ray absorption fine structure (EXAFS). Metallic Ru particles with an average diameter of 1.3 nm were successfully synthesized in the presence of benzophenone, although mixtures of partly oxidized Ru particles and metallic Ru particles were synthesized in the presence of benzoin. Photoreduction of Ru(III) ionic precursors to Ru atoms was promoted by ketyl radicals, which is more efficiently generated by the photoirradiation of benzophenone than by that of benzoin. The photoirradiation of benzophenone in the Ru(III) ionic solutions is an efficient and convenient method to produce metallic Ru particles in polymer solutions rather than the refluxing and the hydrothermal method of ionic solutions of Ru. (C) 2008 Elsevier Inc. All rights reserved., 2008年09月, JOURNAL OF COLLOID AND INTERFACE SCIENCE, 325 (1), 1 - 6, doi;web_of_science

    研究論文(学術雑誌)

  • In situ observation of formation of silver particles in water-in-scCO(2) emulsions

    Masafumi Harada; Kana Kuramitsu; Yoshifumi Kimura; Kenji Saijo

    Metal particles of silver (Ag) have been synthesized in the presence of Aerosol-OT (AOT) and a small amount of 2,2,3,3,4,4,5,5-octafluoro-1-pentanol (F-pentanol) and ethanol as co-solvents in water-in-scCO(2) microemulsions by the reduction of AgClO4. The time evolution of the formation of Ag particles both by the photoreduction using UV-irradiation and using hydrazine as a reducing reagent has been studied by in situ UV-vis, small angle X-ray scattering (SAXS), extended X-ray absorption fine structure (EXAFS), and transmission electron micrograph (TEM) observations. The average diameter of the Ag particle in the dilute colloidal dispersions prepared by the photoreduction and by the hydrazine reduction was estimated from TEM to be 6.4 and 2.9 nm, respectively, which was consistent with that obtained from SAXS analysis using the Schultz-Zimm distribution for the q-range from 0.3 to 1.6 nm(-1). By using Guinier plot in a small q-range (<0.3 nm(-1)), it was demonstrated that the average diameter of water droplet, which consists of aggregates of ionic precursors of AgClO4 before reduction and Ag particles after reduction in the microemulsions, was estimated to be about 20 nm. The change of water droplet size at the dilute concentration of Ag+ ions is negligible in contrast to the case of the higher concentration where the diameter of water droplet rapidly increases from 15.8 to 17.8 nm due to the formation of Ag particles in the AOT-rich phase at the beginning of hydrazine reduction. EXAFS analysis also indicates that Ag+ ions were completely reduced to Ag-0 atoms in the AOT-rich phase by the hydrazine reduction, followed by the formation of larger Ag particles, while Ag+ ions were partly reduced in the photoreduction by UV-irradiation. Once the Ag particles produced under high-pressure condition were released to the ambient condition, these particles were partly oxidized in which Ag-Ag metallic bonds disappeared and the formation of Ag-O bonds occurred. (C) 2008 Elsevier B.V. All rights reserved., 2008年09月, COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS, 327 (1-3), 21 - 33, doi;web_of_science

    研究論文(学術雑誌)

  • Synthesis of Pt/Ru bimetallic nanoparticles in high-temperature and high-pressure fluids

    Masaki Ueji; Masafumi Harada; Yoshifumi Kimura

    A high-temperature and high-pressure flow-reactor system was applied to the synthesis of monometallic ruthenium (Ru) nanoparticles and platinum/ruthenium (Pt/Ru) bimetallic nanoparticles using the thermal reduction of ruthenium ion (Ru(III)) and the mixture of platinum (Pt(IV)) and ruthenium ions in water and ethanol mixture in the presence of poly(N-vinyl-2-pyrrolidone). Monometallic Ru nanoparticles with an average diameter of ca. 2 nm were synthesized above 200 degrees C at 30 MPa. The monometallic Ru nanoparticles tended to make large aggregates in colloidal dispersions. By the reduction of the mixture solution of Pt(IV) and Ru(III) in water and ethanol above 200 degrees C at 30 Wa, Pt/Ru bimetallic nanoparticles with an average diameter of ca. 2.5 nm were synthesized with relatively small size distribution. The EXAFS spectra for the Pt/Ru bimetallic particles indicated that the particle possesses metallic bonds between Pt and Ru atoms in contrast to the case of the nanoparticles produced by thermal reduction under ambient pressure at 100 degrees C [M. Harada, N. Toshima, K. Yoshida, S. Isoda, J. Colloid Interface Sci. 283 (2005) 64], and that the Pt/Ru bimetallic particle has a Pt-core/Ru-shell structure. (c) 2008 Elsevier Inc. All rights reserved., 2008年06月, JOURNAL OF COLLOID AND INTERFACE SCIENCE, 322 (1), 358 - 363, doi;web_of_science

    研究論文(学術雑誌)

  • Formation of molecular glasses and the aggregation in solutions for lanthanum(III), calcium(II), and yttrium(III) complexes of octanoyl-DL-alaninate

    Gerile Naren; Rie Masuda; Masayasu Iida; Masafumi Harada; Hiromichi Kurosu; Toshiharu Suzuki; Takayoshi Kimura

    Octanoylalaninato-metal (metal = calcium(II), yttrium(III), lanthanum(III), and zinc(II)) complexes were prepared and the first three metal complexes were found to readily form transparent and stable molecular glasses from methanol and chloroform solutions. The process of glass formation from solution was studied in detail. The effect of the central metal ions on the formation of glassy states was remarkable: the lanthanum and calcium complexes assumed glassy or crystalline states depending on the isolation method and the yttrium complex had a large tendency to assume an amorphous state, whereas the zinc complex did not assume a pure and stable glassy-state. The glass transition temperatures were 50 degrees C for the yttrium complex and 70-75 degrees C for the lanthanum and calcium complexes when these complexes are monohydrates prepared by a solvent-cast method, whereas they increase by 10-30 degrees for the hemihydrates which were obtained by an annealing treatment at 110 degrees C. The coordinated water was eliminated from the solid above the glass transition temperature. The glassy state was regarded as a result of the self-aggregation of the metal complex in solution by an entanglement of the methylene chains with one another. SAXS showed the presence of two disordered bilayer structures with 2.2 nm and 4.5 nm periods in the glassy states. The structures of the molecular assemblies in the solid states and solutions were compared by SAXS and NMR studies. EXAFS studies confirmed the coordination numbers of oxygen atoms around the yttrium and lanthanum atoms in the glassy states for the yttrium and lanthanum complexes to be about 7., 2008年04月, DALTON TRANSACTIONS, (13), 1698 - 1709, doi;web_of_science

    研究論文(学術雑誌)

  • Synthesis of colloidal particles of poly(2-vinylpyridine)-coated palladium and platinum in organic solutions under the high temperatures and high pressures

    Masafumi Harada; Masaki Ueji; Yoshifumi Kimura

    Colloidal dispersions of poly(2-vinylpyridine)-coated palladium (Pd) and platinum (Pt) particles in the toluene/1-propanol solution have been synthesized by the decomposition and reduction of palladium acetylacetonate (Pd(acac)2) and platinum acetylacetonate (Pt(acac)(2)) under the high-temperatures and high-pressures conditions. The size and the structure of the synthesized particles have been examined by transmission electron micrograph (TEM) and extended X-ray absorption fine structure (EXAFS). At 473 K and 25 MPa, colloidal dispersions ([Pd] = 7.5 mm) of Pd particles of 1.9 nm as an average diameter, which had narrow particle size distributions, were synthesized within a few seconds. Pt particles were also synthesized with an average diameter of 2.1 nm. On the other hand, bimetallic Pd/Pt particles were not synthesized at 473-623 K and 25 MPa, probably due to the difference of decomposition rate of each starting compound. (c) 2007 Elsevier B.V. All rights reserved., 2008年02月, COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS, 315 (1-3), 304 - 310, doi;web_of_science

    研究論文(学術雑誌)

  • Syntheses, structural characterization and photophysical properties of 4-(2-pyridyl)-1,2,3-triazole rhenium(I) complexes

    Makoto Obata; Asuka Kitamura; Akemi Mori; Chiaki Kameyama; Justyna A. Czaplewska; Rika Tanaka; Isamu Kinoshita; Toshiyuki Kusumoto; Hideki Hashimoto; Masafumi Harada; Yuji Mikata; Takuzo Funabiki; Shigenobu Yano

    Novel chelators, i. e., 4-(2-pyridyl)- 1,2,3- triazole derivatives, were synthesized by means of Cu( I)- catalyzed 1,3- dipolar cycloaddition and used to prepare luminescent Re( I) complexes [ReCl(CO)(3)( Bn- pyta)], [ ReCl(CO)(3)(AcGlc- pyta)] and [ ReCl(CO)(3)(Glc- pyta)] (Bn- pyta = 1- benzyl- 4-( 2- pyridyl)- 1,2,3- triazole, AcGlc- pyta = 2-( 4-( 2- pyridyl)- 1,2,3- triazol- 1- yl) ethyl 2,3,4,6- tetra- O- acetyl- beta-D- glucopyranoside, Glc- pyta = 2-( 4-( 2- pyridyl)- 1,2,3- triazol- 1- yl) ethyl beta-D- glucopyranoside). X- Ray crystallography of Bn- pyta and Glc- pyta indicated an azocompound-like structure while the 1,2,4- triazole isomer has an azine character. [ ReCl( CO) 3( Bn- pyta)] crystallized in the monoclinic system with space group P2(1)/n. Bn- pyta ligand coordinates with the nitrogen atoms of the 2- pyridyl group and the 3- position of 1,2,3- triazole ring, which is a very similar coordinating fashion to that of the 2,2' - bipyridine derivative. The glucoconjugated Re( I) complexes [ ReCl( CO)(3)( AcGlc- pyta)] and [ ReCl( CO)(3)( Glc- pyta)] hardly crystallized, and were analyzed by applying extended X- ray absorption fine structure ( EXAFS) analysis. The EXAFS analyses suggested that the glucoconjugation at the 1- position of the 1,2,3- triazole makes no influence to the coordinating fashion of 4-( 2- pyridyl)- 1,2,3- triazole. [ ReCl( CO) 3( Bn- pyta)] showed a blue-shifted maximum absorption (333 nm, 3.97 x 10(3) M-1 cm(-1)) compared with [ReCl(CO)(3)(bpy)] ( 371 nm, 3.35 x 10(3) M-1 cm(-1)). These absorptions were clearly assigned to be the mixed metal- ligand-to-ligand charge transfer (MLLCT) on the basis of time-dependent density functional theory calculation. The luminescence spectrum of [ReCl(CO)(3)( Bn- pyta)] also showed this blue- shifted feature when compared with that of [ ReCl( CO) 3( bpy)]. The luminescence lifetime of [ ReCl( CO)(3)( Bn- pyta)] was determined to be 8.90 mu s in 2-methyltetrahydrofuran at 77 K, which is longer than that of [ReCl(CO)(3)( bpy)] ( 3.17 mu s). The blue- shifted electronic absorption and elongated luminescence lifetime of [ ReCl( CO)(3)( Bn- pyta)] suggested that 4-( 2- pyridyl)- 1,2,3- triazole functions as an electron-rich bidentate chelator., 2008年, DALTON TRANSACTIONS, (25), 3292 - 3300, doi;web_of_science

    研究論文(学術雑誌)

  • In situ XAFS studies of au particle formation by photoreduction in polymer solutions

    Masafumi Harada; Hisahiro Einaga

    Formation mechanisms of metal particles (gold (Au) particles) in an aqueous ethanol solution of HAuCl4 with poly(N-vinyl-2-pyrrolidone) (PVP) by the photoreduction method were investigated by UV-vis, transmission electron microscopy (TEM), and in situ and ex situ X-ray absorption fine structure (XAFS) analysis. The average diameters of the dilute and concentrated Au particles in PVP solution are estimated from TEM to be 106 angstrom and 925 angstrom, respectively. XAFS analysis was carried out to elucidate the reduction process of AuCl4- ionic species to metallic Au particles for the Au-L-3 edge of the colloidal dispersions of the concentrated Au solutions. In the photoreduction process, the reduction of AuCl2- species to Au-0 atoms is a slower process than that of AuCl4- to AuCl2-, and the reduction of AuCl2- to Au-0 atoms and the association of Au-0 atoms to form seed Au particles (particle diameter between 5.5 and 30 angstrom) concurrently proceeds in the short-duration photoirradiation. In addition, in the long-duration photoirradiation, the slow progression of Au particle growth occurs with the association of Au-0-Au-0 metallic bonds, resulting in the formation of larger Au particles (particle diameter larger than 500 angstrom)., 2007年06月, LANGMUIR, 23 (12), 6536 - 6543, doi;web_of_science

    研究論文(学術雑誌)

  • Preparation of Pt/Rh bimetallic colloidal particles in polymer solutions using borohydride-reduction

    Masafumi Harada; Hisahiro Einaga

    Colloidal dispersions of Pt/Rh bimetallic particles have been synthesized by the reduction of Pt(IV)/Rh(III) ionic solutions by using borohydride-reduction in the presence of poly (N-vinyl-2-pyrrolidone). The size and the structure of the synthesized particles have been examined by transmission electron micrograph (TEM) and extended X-ray absorption fine structure (EXAFS). We have succeeded in producing the bimetallic Pt/Rh particles with an average diameter of 2.8 nm in polymer solutions by the stepwise addition of sodium borohydride aqueous solution. The distribution of different metallic species in a particle tended to be "cluster-in-cluster" structure, in contrast to the bimetallic particle with an average diameter of 1.4 nm synthesized by alcohol-reduction which have a core-shell structure. (c) 2007 Elsevier Inc. All rights reserved., 2007年04月, JOURNAL OF COLLOID AND INTERFACE SCIENCE, 308 (2), 568 - 572, doi;web_of_science

    研究論文(学術雑誌)

  • Diffusion of platinum ions and platinum nanoparticles during photoreduction processes using the transient grating method

    Masafumi Harada; Koichi Okamoto; Masahide Terazima

    The photoreduction process of PtCl62- to Pt nanoparticles in poly(N-vinyl-2-pyrrolidone) solutions upon UV light irradiation was investigated by monitoring the change in the diffusion coefficient (D). The D values of chemical species during UV irradiation was measured by the laser-induced transient grating (TG) method. The TG signal of the PtCl62-solution before UV irradiation was composed of three kinds of contributions, the thermal grating, the species grating due to the creation of PtCl42-, and the species grating due to the depletions of PtCl62-. Upon UV irradiation of the solution, the species grating signal due to PtCl62- diminished and then the TG signal of Pt nanoparticles gradually appeared. This result indicates that the gradual clustering of Pt-0 atoms into Pt nanoparticles occurs after all PtCl62- ions are photochemically reduced to PtCl42- and subsequently transformed to Pt-0 atoms with a short delay. With increasing time of the UV irradiation, the TG signal intensity increased, while D of the Pt nanoparticles did not change. This suggests that the number of Pt nanoparticles increases, but the size of the Pt nanoparticles with the polymer layer is unchanged, in the course of the UV irradiation., 2006年10月, LANGMUIR, 22 (22), 9142 - 9149, doi;web_of_science

    研究論文(学術雑誌)

  • Novel oxygen chirality induced by asymmetric coordination of an ether oxygen atom to a metal center in a series of sugar-pendant dipicolylamine copper(II) complexes

    Y Mikata; Y Sugai; M Obata; M Harada; S Yano

    Six sugar-pendant 2,2'-dipicolylamine (DPA) ligands (L1-3 and L'1-3) have been prepared. OH-protected and unprotected D-glucose, D-mannose, and D-xylose were attached to a DPA moiety via an O-glycoside linkage. X-ray crystallography of the copper(II) complexes (1-5) with these ligands revealed that the anomeric oxygen atom is coordinated to the metal center in the solid state, generating a chiral center at the oxygen atom. The CD spectra of these copper complexes in methanol or aqueous solution exhibit Cotton effects in the d-d transition region, which indicates that the ether oxygen atoms remain coordinated to the metal center and the oxygen-atom chirality is preserved even in solution. For complexes 1 and 2, the inverted oxygen-atom chirality and chelate-ring conformation in the solid state are well correlated with the mirror-image CD spectra in methanol solution. The concomitant inversion of the asymmetric configuration around the copper center was also observed in a methanol solution of complex 3 and a pyridine solution of complex 2. The square-pyramidal/octahedral copper(II) centers also exhibited characteristic absorption and CD spectra., 2006年02月, INORGANIC CHEMISTRY, 45 (4), 1543 - 1551, doi;web_of_science

    研究論文(学術雑誌)

  • In situ and time-resolved SAXS studies of Pd nanoparticle formation in a template of block copolymer microdomain structures

    N Sakamoto; M Harada; T Hashimoto

    Time-resolved small-angle X-ray scattering (SAXS) measurements were performed to study in-situ formation of palladium (Pd) nanoparticles in block copolymer microdomains. The nanoparticles were reduced in a reaction medium containing a fixed composition of polyisoprene-block-poly(2-vinylpyridine) (PI-b-P2VP), palladium acetylacetonate, Pd(acac)2, and benzyl alcohol as a solvent and a reducing agent. The polymer concentration is high enough so that it forms swollen ordered lamellae before reduction. The reduction was induced by a rapid temperature jump, and the polymer concentration was kept constant in a sealed sample cell. It was clearly elucidated that the formation of Pd nanoparticles occurred in the templates of the swollen lamellar microdomains. By fitting the theoretical scattered intensity for spherical particles to the observed SAXS profiles, we analyzed time evolution of mean radius, standard deviation of radius, and total volume of Pd nanoparticles in concentrated PI-b-P2VP solutions after T-jump. These results and the information obtained in our previous communication indicate that Pd(II) ions before reduction distribute equally well in both the PI and P2VP lamellae; after T-jump Pd nanoparticles form and grow only in the P2VP lamellae after an induction period, and the growth stops when the size reaches a steady value; the final size and total volume of Pd nanoparticles created depend on the reduction temperature. The formation of I'd nanoparticles in a P2VP homopolymer solution was also investigated by the same method as that employed for the block copolymer solution in order to compare the two results with and without the template and hence to explore roles of the template on the nanoparticle formation., 2006年02月, MACROMOLECULES, 39 (3), 1116 - 1124, doi;web_of_science

    研究論文(学術雑誌)

  • SAXS and XAFS analysis in forming of metal nanoparticles in water-in-scCO2 microemulsions

    Masafumi Harada; Yoshifumi Kimura

    Metal particles of silver (Ag) and copper (Cu) have been synthesized in the presence of Aerosol-OT (AOT) or fluorinated surfactants in water-in-scCO2 microemulsions by the chemical reduction of AgClO4 and Cu(ClO4)2. The formation of Ag particles by the photo-reduction using UV-light have been confirmed by in-situ UV-Vis, X-ray absorption fine structure (XAFS), and small angle X-ray scattering (SAXS) measurements. Cu particles have also been prepared by the addition of a reducing reagent sodium borohydride, and the electronic structure of Cu ionic species has been investigated after reduction in the water-in-scCO2 microemulsions. The average size of aggregates of Ag particles in the microemulsions by means of in-situ SAXS measurements also has been estimated., 2006年, Solid State Phenomena, 114, 321 - 328, doi

    研究論文(学術雑誌)

  • Formation Mechanism of Pt Particles by Photo-reduction of Pt Ions in Polymer Solutions.

    Masafumi Harada; Hisahiro Einaga

    2006年, Langmuir, 22, 2371 - 2377

  • SAXS and XAFS analysis in forming of metal nanoparticles in water-in-scCO(2) microemulsions

    Masafumi Harada; Yoshifumi Kimura

    Metal particles of silver (Ag) and copper (Cu) have been synthesized in the presence of Aerosol-OT (AOT) or fluorinated surfactants in water-in-scCO(2) microemulsions by the chemical reduction of AgClO4 and Cu(ClO4)(2). The formation of Ag particles by the photo-reduction using UV-light have been confirmed by in-situ UV-Vis, X-ray absorption fine structure (XAFS), and small angle X-ray scattering (SAXS) measurements. Cu particles have also been prepared by the addition of a reducing reagent sodium borohydride, and the electronic structure of Cu. ionic species has been investigated after reduction in the water-in-sCO(2) microemulsions. The average size of aggregates of Ag particles in the microemulsions by means of in-situ SAXS measurements also has been estimated., 2006年, HIGH PRESSURE TECHNOLOGY OF NANOMATERIALS, 114, 321 - 328, doi;web_of_science

    研究論文(学術雑誌)

  • Synthesis of colloidal dispersions of rhodium nanoparticles under high temperatures and high pressures

    M Harada; D Abe; Y Kimura

    Colloidal dispersions of rhodium (Rh) nanoparticles have been synthesized by the reduction of Rh ions (III) in high-temperature and high-pressure water, ethanol, or water-ethanol mixture under the existence of the protective polymer of poly(N-vinyl-2-pyrrolidone). The possibility of the regulation of the particle size and size distribution has been tested under several solvents at various temperatures and pressures. At 473 K and 25 MPa, particularly, concentrated colloidal dispersions of Rh particles of 2.5 +/- 0.5 nm were synthesized from the ionic solution of ethanol ([Rh] = 15 mM) within a few seconds. Dilute colloidal dispersions of Rh particles were also synthesized from the, dilute ionic solution ([Rh] = 1.5 mM) with a diameter of 2.0 +/- 0.4 nm. From the water solution, Rh particles tended to form aggregates, especially for the lower concentration solution. In the case of solutions in water and ethanol mixture, the average diameter of Rh particles tended to be larger than in ethanol solution, and their distribution became broad. (c) 2005 Elsevier Inc. All rights reserved., 2005年12月, JOURNAL OF COLLOID AND INTERFACE SCIENCE, 292 (1), 113 - 121, doi;web_of_science

    研究論文(学術雑誌)

  • Synthesis of poly(isobutyl-co-2,2,2-trifluoroethyl methacrylate) with 5,10,,15,20-tetraphenylporphinato platinum(II) moiety as an oxygen-sensing dye for pressure-sensitive paint

    M Obata; Y Tanaka; N Araki; S Hirohara; S Yano; K Mitsuo; K Asai; M Harada; T Kakuchi; C Ohtsuki

    Pressure-sensitive paint (PSP), which consists of luminescent molecules embedded in an oxygen-permeable polymer, has been developed for use in wind-tunnel experiments. To improve the PSP technique, a novel luminescent methacrylate monomer, 5-[4-(2-methacryloyloxyethoxycarbonyl)phenyl]-10,15,20-triphenylporphinato platinum(II), was synthesized and copolymerized with isobutyl methacrylate and 2,2,2-trifluoroethyl methacrylate to produce a dye-pendant copolymer (2). The introduction of 5,10,15,20-tetraphenylporphinato platinum(II) (PtTPP) dye into 2 was confirmed by ultraviolet-visible spectroscopy and extended X-ray absorption fine structure measurements. The extent of PtTPP dye incorporation in 2 was proportional to the molar fraction of the PtTPP-pendant methacrylate monomer in the feed. The oxygen-sensing property of 2 was compared with that of a PSP consisting of PtTPP dye embedded in poly(isobutyl-co-2,2,2-trifluoroethyl methacrylate). Although the simple mixture of PtTPP and poly(isobutyl-co-2,2,2-tyifluoroethyl methacrylate) showed a marked deviation from a single Stern-Volmer relation, novel copolymer 2 gave a highly linear Stern-Volmer plot. This was unequivocal evidence of dye conjugation on the oxygen-sensing polymer film. (c) 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2997-3006, 2005., 2005年07月, JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY, 43 (14), 2997 - 3006, doi;web_of_science

    研究論文(学術雑誌)

  • Aggregated structure analysis of polymer-protected platinum/ruthenium colloidal dispersions using EXAFS, HRTEM, and electron diffraction measurements

    M Harada; N Toshima; K Yoshida; S Isoda

    Polymer-protected platinum/ruthenium colloidal dispersions were prepared by refluxing mixed solutions of hexachloroplatinic(IV) acid and ruthenium(III) chloride in a mixture of ethanol/water (l/l v/v) in the presence of poly(N-vinyl-2-pyrrolidone). The electronic spectra and transmission electron micrographs suggested that the colloidal dispersions are almost composed of the mixture of the small monometallic Pt and Ru clusters over all the ratio of Pt/Ru compositions. Extended X-ray absorption fine structure analyses and high resolution electron microprobe analyses indicated that no Pt/Ru alloy clusters exist in the dispersions, and the aggregation occurs between small monometallic Pt clusters (diameter ca. 15 Angstrom) and partially oxidized Ru microclusters (diameter less than 10 Angstrom). Electron diffraction measurements also suggested that the diffraction pattern of aggregated Pt/Ru cluster particles prepared by the simultaneous reduction of Pt and Ru ions is the same as that of the physical mixture of the small monometallic Pt and Ru clusters separately prepared. Therefore, it can be concluded that the aggregated Pt/Ru cluster particles, with 10 to 60 Angstrom in diameter, are built up by small monometallic Pt clusters and partially oxidized Ru microclusters, and that Pt/Ru alloy clusters are not formed. (C) 2004 Elsevier Inc. All rights reserved., 2005年03月, JOURNAL OF COLLOID AND INTERFACE SCIENCE, 283 (1), 64 - 78, web_of_science

    研究論文(学術雑誌)

  • Au/Rh nanoparticles synthesized under high temperatures and high pressures

    M Ueji; M Harada; Y Kimura

    Small size gold (Au) and rhodium (Rh) nanoparticles have been produced by flowing the solution containing Au(III) and Rh(III) ions with poly(N-vinyl-2-pyrrolidone) through a high-temperature and high-pressure reactor. Au, mostly monometallic, particles (7.5 nm) are produced together with the smaller Rh nanoparticles (2.5 nm) within a few seconds, of which the structure and sizes are identified by the transmission electron micrograph (TEM) images and the extended X-ray absorption fine structure (EXAFS)., 2005年02月, CHEMISTRY LETTERS, 34 (2), 200 - 201, doi;web_of_science

    研究論文(学術雑誌)

  • 液体二酸化炭素を用いた洗浄システムと各種人工汚染布に対する洗浄性

    原田雅史

    2005年, 日本家政学会誌, 56 (4), 241-253

  • Photochemical Preparation of Poly(N-vinyl-2-pyrrolidone)-Stabilized Platinum Colloids and Their Deposition on Titanium Dioxide.

    Hisahiro Einaga; Masafumi Harada

    2005年, Langmuir, 21, 2578 - 2584

  • Synthesis of Pt/Rh and Pt/Pd bimetallic particles under high-temperatures and high-pressures and the analysis of the structure.

    Y. Kimura; D. Abe; E. Maru; M. Ueji; M. Harada

    2005年, Proc. of the 14th International Conference on the Properties of Water and Stream, 345 - 349

  • Development and Application of the Multipurpose Optical Flow Cell under Supercritical Condition of Water.

    T. Fujisawa; E. Maru; F. Amita; M. Harada; T. Uruga; Y. Kimura

    2005年, Proc. of the 14th International Conference on the Properties of Water and Stream, 445 - 450

  • Structural Changes in alumina-supported manganese oxides during ozone decomposition.

    H. Einaga; M. Harada; S. Futamura

    2005年, Chemical Physics Letters, 408, 377 - 380

  • Electro- and photochemical properties of a (μ-alkoxo)bis(μ-carboxylato)diruthenium complex having two tetraphenylporphinato zinc(II) moieties.

    M Obata; N Tanihara; M Nakai; M Harada; S Akimoto; Yamazaki, I; A Ichimura; Kinoshita, I; M Mikuriya; M Hoshino; S Yano

    The novel (mu-alkoxo) bis(mu-carboxylato) diruthenium complex K[Ru-2(dhpta)(mu-O2C-p-ZnTPP)(2)] 3 was prepared by simple ligand substitution reaction. Strong antiferromagnetic interaction between two Ru-III ions of 3 was observed with a coupling constant of - 425 similar to - 404 cm(-1). The cyclic voltammogram of 3 can be explained in terms of superposition of those of ZnTPP-p-CO2H and K[Ru-2(dhpta)(mu-O2CPh)(2)] 2, indicating no significant electrochemical interaction. The large conproportionation constant estimated from the reduction potentials for (RuRuIII)-Ru-III and (RuRuIII)-Ru-II indicates great stability of the mixed- valence state. The mixed- valence species [(RuRuIII)-Ru-II(dhpta)(mu-O2C-p-ZnTPP) (2)](2-) 4 was prepared by controlled potential electrolysis. The electronic absorption spectrum of 4 was quite similar to that of [(RuRuIII)-Ru-II(dhpta)(mu-O2CCH3)(2)](2-) which is a typical Class II complex. The fluorescence from the S-2 state of the ZnTPP unit of 3 was significantly (78%) quenched. The electron transfer from the ZnTPP unit to RuIII ions in 3 is a plausible mechanism, even though energy transfer could not be ruled out completely. The free energy change for electron transfer, DeltaG(CS), was estimated to be ca. - 1.1 eV, which is similar to typical values for the reorganization energy lambda in polar solvents. Hence, the electron transfer scheme is situated almost at the top of the Marcus parabola, enabling ultrafast electron transfer., 2004年, Dalton Trans., (20), 3283 - 3287, doi;web_of_science

    研究論文(学術雑誌)

  • Photochemical deposition of platinum on TiO2 by using poly(vinyl alcohol) as an electron donor and a protecting polymer

    M. HARADA; H. Einaga

    2004年, Catalysis Communications, 5, 63 - 67

  • Synthesis of platinum nano-particles in high-temperatures and high-pressures fluids

    Y Kimura; D Abe; T Ohmori; M Mizutani; M Harada

    Colloidal dispersions of platinum nano-particles have been synthesized by the reduction of platinum ion(IV) in the high-temperature and high-pressure water, ethanol, and water-ethanol mixtures in the presence of the protective polymer of poly(Nvinyl-2-pyrrolidone) (PVP). The syntheses have been tested at various temperatures (from 100 to 300degreesC) and pressures (from 5 to 25 MPa). The diameter and the composition have been examined by UV-Vis, extended X-ray absorption fine structure (EXAFS), and transmission electron micrograph (TEM), respectively. At 200degreesC and 25 MPa, colloidal dispersions of platinum particles of small size (2.6 +/- 0.5 nm) were synthesized from 1: 1 mixture of water and ethanol within a few seconds. From the analysis of the EXAFS. it is suggested that the elementary particle size obtained under the present condition is larger than that obtained under the ambient condition. We have also succeeded in producing the colloidal dispersions in aqueous solution, although the size and its distribution were relatively larger than the case of water-ethanol mixture. In ethanol solution we could not synthesize a well-dispersed colloidal solution at high temperatures. The possibility of the regulation of the particle size and distribution is discussed. (C) 2003 Elsevier B.V. All rights reserved., 2003年12月, COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS, 231 (1-3), 131 - 141, doi;web_of_science

    研究論文(学術雑誌)

  • Generation of active sites for CO photooxidation on TiO2 by platinum deposition

    H Einaga; M Harada; S Futamura; T Ibusuki

    Photocatalytic oxidation of CO to CO2 was carried out with TiO2 and Pt/TiO2 catalysts at room temperature to investigate the effect of Pt deposition. The rate for CO photooxidation by Pt/TiO2 was higher than that by TiO2. The reaction rate increased with incident light intensity to the power of 0.7 for Pt/TiO2 and 0.5 for TiO2. The dependency of reaction rate on the concentration of CO and water vapor was explained in terms of Langmuir-Hinshelwood mechanism, where CO was more efficiently adsorbed on Pt sites compared with TiO2. On the basis of diffuse reflectance FTIR spectroscopic studies and CO photodesorption measurements, Pt on TiO2 acted as the active sites on which CO was chemically adsorbed and oxidized to CO2 on photoirradiation in the presence of O-2., 2003年09月, JOURNAL OF PHYSICAL CHEMISTRY B, 107 (35), 9290 - 9297, doi;web_of_science

    研究論文(学術雑誌)

  • Synthesis of (mu-alkoxo)bis(mu-carboxylato)diruthenium complex having porphyrin moieties as a potential photo-harvesting functionality

    N Tanihara; M Obata; M Harada; Y Mikata; A Hamazawa; Kinoshita, I; K Isobe; A Ichimura; M Hoshino; M Mikuriya; S Yano

    The ligand substitution reaction of K[Ru-2(dhpta)(mu-O2CCH3)(2)] (H(5)dhpta=1,3-diamino-2-hydroxypropanetetraacetic acid) with zinc 5-(4-carboxylphenyl)-10,15,20-triphenylporphyrin (ZnTPP-p-COOH) afforded a diruthenium complex having porphyrin moieties, K[Ru-2(dhpta)(mu-O2C-p-ZnTPP)(2)]. This product was characterized by UV-Vis and H-1 NMR spectroscopy, and EXAFS analysis. (C) 2003 Elsevier Science B.V. All rights reserved., 2003年05月, INORGANIC CHEMISTRY COMMUNICATIONS, 6 (5), 447 - 450, doi;web_of_science

    研究論文(学術雑誌)

  • Templating fabrication and catalysis of platinum nanowires in mesoporous channels of FSM-16

    Atsushi Fukuoka; Naonori Higashimoto; Makoto Sasaki; Masafumi Harada; Shinji Inagaki; Yoshiaki Fukushima; Masaru Ichikawa

    2000年, Studies in Surface Science and Catalysis, 130, 3041 - 3046, doi

    論文集(書籍)内論文

  • Incorporation of metal nanoparticles into block copolymer nanodomains via in-situ reduction of metal ions in microdomain space

    T Hashimoto; M Harada; N Sakamoto

    1999年10月, MACROMOLECULES, 32 (20), 6867 - 6870, web_of_science

    研究論文(学術雑誌)

  • Small-angle x-ray scattering analysis of polymer-protected platinum, rhodium, and platinum/rhodium colloidal dispersions

    T Hashimoto; K Saijo; M Harada; N Toshima

    Formations of poly(N-vinyl-2-pyrrolidone) (PVP)-metal ion (Pt, Ph or Pt/Rh(1/1)) complexes in H2O/C2H5OH ("polymer-metal ion complexes") before alcohol-reduction and PVP-Pt, Rh, or Pt/Rh(1/1) metal cluster ("polymer-metal cluster") after alcohol-reduction were studied by small-angle x-ray scattering (SAXS). SAXS intensity of the solution containing polymer-metal ion complexes is higher than that of the reference polymer solution without metal ions, suggesting that concentration fluctuations of polymer segments are enhanced due to the formation of polymer-metal ion complexes. Spatial distributions of metal clusters in colloidal dispersions are different from each other among the cases of Pt, Ph, and Pt/Rh(1/1) colloidal dispersions. The superstructure (greater than 10.0 nm in diameter), whose average sizes highly depend on the metal element employed, are formed. These superstructures are composed of several fundamental clusters with a diameter of similar to 2.0-4.0 nm. Colloidal dispersions of Ph form a percolation network of clusters with an average period of similar to 6.0 nm inside the higher-order organization of its superstructure. Experimental results concerning the physical aging show the high stability of colloidal dispersions of metal clusters protected by water-soluble PVP. (C) 1998 American Institute of Physics. [S0021-9606(98)51437-7], 1998年10月, JOURNAL OF CHEMICAL PHYSICS, 109 (13), 5627 - 5638, web_of_science

    研究論文(学術雑誌)

  • XAFS characterization of platinum clusters synthesized in the channel of a mesoporous zeolite

    T Shido; T Yamamoto; M Harada; M Ichikawa

    [Pt-15(CO)(30)](2-) was synthesized by reductive carbonylation of H2PtCl6 in the channels of FSM-16 modified with NEt4Cl. The platinum clusters in the channels whose diameter was 28 Angstrom were characterized by Pt L-III edge EXAFS as well as FT-IR, UV-vis spectroscopy, and TEM measurements. After exposure of H2PtCl6/NEt4Cl/FSM-16 to CO + H2O at 323 K. Pt carbonyl clusters were selectively produced. The Pt Lm edge EXAFS spectrum of this sample was exactly the same as that of [NEt4](2)[Pt-15(CO)(30)]. and gave Pt-Pt distances typical of these types of platinum clusters at 2.68 and 3.08 Angstrom. Uniform platinum ''particles'' (15 Angstrom diameter) were observed in the channels of FSM-16 by a TEM measurement; this suggests that [Pt-15(CO)(30)](2-). was synthesized in the channel of FSM-16. The platinum clusters in the channel were converted to platinum metal particles by evacuation above 363 K. Pt L-III EXAFS spectra of these samples revealed that the bridge CO of the clusters were desorbed by the evacuation at 343 K while retaining their cluster framework; the clusters were converted to Pt50-60 panicles by evacuation above 363 K., 1997年04月, JOURNAL DE PHYSIQUE IV, 7 (C2), 855 - 857, web_of_science

    研究論文(学術雑誌)

  • On the EXAFS determination of the site for the chemisorption of selenophene on sulfided Ni-Mo/Al2O3

    L Medici; M Harada; R Prins

    Simulation of the Mo and Ni K-edge EXAFS spectra of sulfided Ni-Mo/Al2O3 catalysts shows that the Mo EXAFS spectrum is rather insensitive to the chemisorption of selenophene; this means that, in contradiction to a former claim the site for selenophene chemisorption cannot be determined from a comparison of the influences of selenophene chemisorption on the Mo and Ni EXAFS spectra. Experimental EXAFS spectra of a carefully sulfided Ni-Mo/Al2O3 catalyst showed no difference between Mo and Ni K-edge spectra taken before and after adsorption of selenophene., 1996年05月, MENDELEEV COMMUNICATIONS, 6 (3), 121 - 122, web_of_science

    研究論文(学術雑誌)

  • Electronic structure of transition metal clusters from density functional theory: Transition monometallic dimers

    M Harada; H Dexpert

    The electronic structure of transition metal clusters is of great interest for a wide range of investigations including the properties of catalytic systems. In order to determine the electronic structure of transition metal dimers, the calculations of total energies and geometry optimizations have been carried out on Pd-2, Rh-2, Ru-2, Au-2, and Pt-2 dimers using a method based on the density functional theory with local and non-local levels. This method is expected to be very useful to predict the electronic structure of small mono- and/or bi-metallic cluster systems., 1996年02月, COMPTES RENDUS DE L ACADEMIE DES SCIENCES SERIE II FASCICULE B-MECANIQUE PHYSIQUE ASTRONOMIE, 322 (3), 239 - 246, web_of_science

    研究論文(学術雑誌)

  • Electronic structure of transition metal clusters from density functional theory .1. Transition metal dimers

    M Harada; H Dexpert

    The electronic structure of transition metal clusters is of great interest for a wide range of investigations including the properties of catalytic systems. In order to determine the electronic structure of transition metal dimers, calculations of total energies and geometry optimizations have been carried out on Pd-2, Rh-2, Ru-2, Au-2, and Pt-2 dimers as well as PdPt, RhPt, RuPt, and PdAu dimers using a method based on density functional theory (DFT) with nonlocal (NLDFT) correction. The typical applications of DFT for the determination of the general features of electronic structure of Pd-4, Rh-4, Au-4, and Pt-4 clusters have also been performed at the level of NLDFT using the norm-conserving pseudopotential method (NCPP). The results of these calculations are in good qualitative agreement with those of the previous DFT calculations. The Mulliken charge analysis has indicated that a charge transfer occurs between the atoms of Pd and Pt, as well as between Rh and Pt atoms, Ru and Pt atoms, and Pd and Au atoms in the corresponding bimetallic dimers. Finally, this DFT method is expected to be very helpful to predict the electronic structure of small metal cluster systems., 1996年01月, JOURNAL OF PHYSICAL CHEMISTRY, 100 (2), 565 - 572, web_of_science

    研究論文(学術雑誌)

  • Electronic structure of transition metal clusters from density functional theory .1. Transition metal dimers

    M Harada; H Dexpert

    The electronic structure of transition metal clusters is of great interest for a wide range of investigations including the properties of catalytic systems. In order to determine the electronic structure of transition metal dimers, calculations of total energies and geometry optimizations have been carried out on Pd-2, Rh-2, Ru-2, Au-2, and Pt-2 dimers as well as PdPt, RhPt, RuPt, and PdAu dimers using a method based on density functional theory (DFT) with nonlocal (NLDFT) correction. The typical applications of DFT for the determination of the general features of electronic structure of Pd-4, Rh-4, Au-4, and Pt-4 clusters have also been performed at the level of NLDFT using the norm-conserving pseudopotential method (NCPP). The results of these calculations are in good qualitative agreement with those of the previous DFT calculations. The Mulliken charge analysis has indicated that a charge transfer occurs between the atoms of Pd and Pt, as well as between Rh and Pt atoms, Ru and Pt atoms, and Pd and Au atoms in the corresponding bimetallic dimers. Finally, this DFT method is expected to be very helpful to predict the electronic structure of small metal cluster systems., 1996年01月, JOURNAL OF PHYSICAL CHEMISTRY, 100 (2), 565 - 572, web_of_science

    研究論文(学術雑誌)

  • STRUCTURAL-ANALYSIS OF CHELATE RESIN-IRON COMPLEX BY USING EXTENDED X-RAY-ABSORPTION FINE-STRUCTURE SPECTROSCOPY

    T TERANISHI; M HARADA; K ASAKURA; H ASANUMA; Y SAITO; N TOSHIMA

    Polystyrene-based chelate resin, functionalized by tridentate iminodiacetic acid moieties, has the special ability to increase the specific surface area by complexing with multivalent cations and drying after being washed with the organic solvent miscible with water. The extended X-ray absorption fine structure (EXAFS) technique was applied to analyze the structure of the chelate resin-Fe(II) and -Fe(III) complexes. The EXAFS data for the chelate resin-Fe(III) complex, which has the largest surface area among the various chelate resin-metal complexes investigated, indicate that the Fe(III) ion has the coordination number of 6 with one iminodiacetic acid moiety and three water molecules, which are retained in a dry state. The surplus positive charge, due to the 1:1 complexation of Fe(III) ion with IDA moiety (-2), repulses other surplus positive charges or Fe(III) ions, resulting in preventing the pores from shrinking and in making the surface area quite large. In contrast, in the case of the chelate resin-Fe(II) complex, the coordination number of the Fe(II) ion is 4, suggesting the coordination of Fe(II) to four or five oxygen and/or nitrogen atoms including one or two iminodiacetic acid moieties and one water molecule which cannot be removed by drying after being washed with the solvent. It has also been confirmed that the chelate resin-Fe(II) complex can adsorb an NO gas by coordination of NO to the vacant orbital of Fe(II) ions, resulting in the 5-coordinate structure., 1994年08月, JOURNAL OF PHYSICAL CHEMISTRY, 98 (33), 7967 - 7975, web_of_science

    研究論文(学術雑誌)

  • SMALL-ANGLE SCATTERING FROM HEXAGONALLY PACKED CYLINDRICAL PARTICLES WITH PARACRYSTALLINE DISTORTION

    T HASHIMOTO; T KAWAMURA; M HARADA; H TANAKA

    Elastic small-angle scattering of X-rays, neutrons, and light from an assembly of hexagonally packed cylindrical particles with a paracrystalline distortion was investigated. The scattering formula is presented, and the effects of the paracrystalline distortion factor g and volume fraction of the particles on the scattering profiles are discussed. This scattering theory is applied to small-angle X-ray scattering (SAXS) from a binary mixture of a sphere-forming block copolymer and a lamellar-forming block copolymer. The SAXS study confirmed that the two copolymers are mixed at the molecular level, forming the hexagonally packed cylindrical morphology, and the various characteristic parameters describing the morphology were extracted from the best fit between the experimental and theoretical scattering profiles. The SAXS results were confirmed by transmission electron microscopy., 1994年05月, MACROMOLECULES, 27 (11), 3063 - 3072, web_of_science

    研究論文(学術雑誌)

  • STRUCTURAL-ANALYSIS OF POLYMER-PROTECTED PLATINUM/RHODIUM BIMETALLIC CLUSTERS USING EXTENDED X-RAY-ABSORPTION FINE-STRUCTURE SPECTROSCOPY - IMPORTANCE OF MICROCLUSTERS FOR THE FORMATION OF BIMETALLIC CLUSTERS

    M HARADA; K ASAKURA; N TOSHIMA

    The colloidal dispersions of polymer-protected platinum/rhodium bimetallic cluster particles are easily prepared by refluxing solutions of hexachloroplatinic(IV) acid and rhodium(III) chloride in ethanol/water (1/1 v/v) in the presence of poly(N-vinyl-2-pyrrolidone). These colloidal dispersions of the Pt/Rh bimetallic cluster particles are very stable and have a size distribution from 2 to 7 nm in diameter. The electronic spectra and the transmission electron micrographs suggest that the colloidal dispersions are not a mixture of monometallic Rh and monometallic Pt particles but are mostly composed of Pt/Rh alloy particles. Electron microprobe analysis indicates that the metal composition of each alloy particle with nearly average diameter is kept as the charged mole ratio of Pt/Rh. Extended X-ray absorption fine structure analyses, high-resolution electron microprobe analysis, and scanning tunneling microscopy indicate that colloidal alloy particles consist of an assembly of Pt/Rh bimetallic microclusters, each of which has a Pt core and a modified Pt core structure of colloidal dispersions of Pt/Rh(1/4) and Pt/Rh(1/1 or 4/1) bimetallic clusters, respectively. The importance of the microcluster is discussed in detail for the formation of Pt/Rh bimetallic cluster particles., 1994年03月, JOURNAL OF PHYSICAL CHEMISTRY, 98 (10), 2653 - 2662, web_of_science

    研究論文(学術雑誌)

  • STRUCTURAL-ANALYSIS OF POLYMER-PROTECTED PALLADIUM RHODIUM BIMETALLIC CLUSTERS USING EXAFS SPECTROSCOPY

    M HARADA; K ASAKURA; Y UEKI; N TOSHIMA

    The structures of the colloidal dispersions of the Pd/Rh bimetallic clusters, prepared by refluxing the solution of their salts in water/ethanol in the presence of Poly(N-vinyl-2-pyrrolidone), were investigated by means of an extended X-ray absorption fine structure (EXAFS) technique. On the basis of the EXAFS measurements of the Pd/Rh(1/1) alloy foil, the Pd-Rh bond distance in this alloy foil is about 2.70 angstrom, different neither from the Pd-Pd bond distance in the Pd foil nor the Rh-Rh bond distance in the Rh foil. Comparison of the difference of the peak height between the Pd foil and the Pd/Rh(1/1) alloy foil with that between the Rh foil and the same alloy foil has also shown that the disorder in the Pd foil or in the Rh foil is nearly the same as that in the Pd/Rh(1/1) alloy foil, even at room temperature. Under the condition that each contribution has the corresponding bond distance with the same disorder, the contributions of Pd-Pd, Pd-Rh, Rh-Rh, and Rh-Pd bonds can be completely distinguished from each other in the Pd/Rh bimetallic cluster. From the electron microprobe analysis and the obtained coordination numbers of the colloidal dispersions of the Pd/Rh(1/1 and 1/2) bimetallic clusters, it can be concluded that the small particles (less than 20 angstrom in diameter) mainly consist of Rh clusters and the large particles (more than 35 angstrom in diameter) of Pd clusters. The bimetallic alloy clusters have diameters in the range 25-35 angstrom. The small sum of coordination numbers around the Rh atom of the dispersions suggests that the Rh microcluster particles coexist in the colloidal dispersions and that the Rh atoms of the bimetallic alloy clusters are highly dispersed on the surface., 1993年10月, JOURNAL OF PHYSICAL CHEMISTRY, 97 (41), 10742 - 10749, web_of_science

    研究論文(学術雑誌)

  • CATALYTIC ACTIVITY AND STRUCTURAL-ANALYSIS OF POLYMER-PROTECTED AU/PD BIMETALLIC CLUSTERS PREPARED BY THE SUCCESSIVE REDUCTION OF HAUCL4 AND PDCL2

    M HARADA; K ASAKURA; N TOSHIMA

    Colloidal dispersions of the poly(N-vinyl-2-pyrrolidone)-protected gold/palladium bimetallic clusters were prepared by successive reduction in order to compare the catalytic activity and the structure of the clusters. The catalytic activity of the colloidal dispersions of the Au/Pd(1/4) clusters for the selective partial hydrogenation depends on the reduction order in the preparation of the clusters. The clusters prepared by successive reduction starting from the reduction of gold ions (Au --> Pd) have higher activity than those prepared by the reverse order (Pd --> Au). The EXAFS measurements indicate that the Au/Pd(1/4 and 1/1) bimetallic clusters prepared by the successive (Pd --> Au) reduction have the cluster-in-cluster structure. In the case of the successive (Au --> Pd) reduction, however, the dispersions contain both large monometallic Au clusters and monometallic Pd clusters, not Au/Pd bimetallic clusters. Mixing the dispersions of the Au and Pd monometallic clusters changes their structures at room temperature in solution, resulting in bimetallic alloy structures in the course of time, which is suggested by both the TEM observation and the electronic spectra., 1993年05月, JOURNAL OF PHYSICAL CHEMISTRY, 97 (19), 5103 - 5114, web_of_science

    研究論文(学術雑誌)

  • A CLUSTER-IN-CLUSTER STRUCTURE OF THE SIO2-SUPPORTED PTPD CLUSTERS

    K ASAKURA; Y YAMAZAKI; H KURODA; M HARADA; N TOSHIMA

    The structures of SiO2-supported PtPd alloy clusters with the size of about 20 angstrom which were prepared from the PtPd colloid solutions were investigated by means of EXAFS. The phase shift and amplitude functions were derived from PtPd foils with the atomic ratio of 1:9, 1:1 and 9:1. The curve fitting analyses showed that the PtPd clusters were present in a ''cluster-in-cluster'' structure in which the homogeneous clusters were composed of several smaller clusters composed of the atoms of each metal., 1993年, JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 32, 448 - 450, web_of_science

    研究論文(学術雑誌)

  • STRUCTURAL-ANALYSIS OF POLYMER-PROTECTED PD/RH BIMETALLIC CLUSTERS BY USING EXAFS SPECTROSCOPY

    M HARADA; K ASAKURA; N TOSHIMA

    The colloidal dispersions of the palladium-rhodium bimetallic clusters, prepared by refluxing the solution of their salts in water/ethanol in the presence of poly(N-vinyl-2-pyrrolidone) under nitrogen, are analyzed by EXAFS spectroscopy, showing that the bond distance between the Pd atom and Rh atom in the cluster is about 2.70 angstrom on the basis of the EXAFS measurements of the Pd/Rh alloy foils. The coordination numbers of the Pd/Rh dispersions indicate that the small particles in size mainly consist of Pd/Rh bimetallic clusters and the large particles, of palladium clusters., 1993年, JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 32, 451 - 453, web_of_science

    研究論文(学術雑誌)

  • STRUCTURE OF POLYMER-PROTECTED PALLADIUM PLATINUM BIMETALLIC CLUSTERS AT THE OXIDIZED STATE - EXTENDED X-RAY ABSORPTION FINE-STRUCTURE ANALYSIS

    M HARADA; K ASAKURA; Y UEKI; N TOSHIMA

    The mild oxidation and reduction processes of the Pd/Pt bimetallic clusters protected by poly(N-vinyl-2-pyrrolidone) were investigated with an extended X-ray absorption fine structure (EXAFS) technique. From the intensity of the EXAFS spectrum due to the Pd-O bond, each Pd atom on the surface of the Pd/Pt(4/1) cluster is estimated to be surrounded by the 0.21-2.3 atoms of oxygen, depending on the extent of the oxidation. Depending on the contact time with molecular oxygen, the Pd-O bond of the bimetallic clusters has a different coordination distance from 1.96 to 2.17 angstrom, about 0.15 angstrom longer than the first coordination distance of palladium oxide (2.03 angstrom). The longest distance in the oxidized cluster may suggest a weaker interaction between palladium and oxygen atoms than that of palladium oxide. The structure change by treatment with hydrogen is more remarkable in the Pd/Pt(4/1) bimetallic clusters prepared by refluxing in ethanol/water under air than that prepared under nitrogen. For example, the coordination number of Pd atoms around the Pt atom of the clusters prepared under air changes from 3.9 +/- 0.3 to 4.3 +/- 0.5 and then 5.8 +/- 0.8 due to the extent of the hydrogenation, while that of the clusters prepared under nitrogen changes from 3.8 +/- 0.4 to 3.9 +/- 0.6 and then to 4.3 +/- 0.4. The similar phenomenon has also been observed for the Pd/Pt(1/1) bimetallic clusters. From these data, the easy oxidation of the Pd atoms on the surface of the cluster and the high stability of the Pt atoms in the core may be concluded to result in the increasing reactivity of the bimetallic clusters by contact with oxygen., 1992年11月, JOURNAL OF PHYSICAL CHEMISTRY, 96 (24), 9730 - 9738, web_of_science

    研究論文(学術雑誌)

  • CATALYTIC ACTIVITY AND STRUCTURAL-ANALYSIS OF POLYMER-PROTECTED AU-PD BIMETALLIC CLUSTERS PREPARED BY THE SIMULTANEOUS REDUCTION OF HAUCL4 AND PDCL2

    N TOSHIMA; M HARADA; Y YAMAZAKI; K ASAKURA

    The colloidal dispersions of the poly(N-vinyl-2-pyrrolidone)-protected gold/palladium bimetallic clusters were prepared by simultaneous reduction of HAuC14 and PdCl2 in the presence of poly(N-vinyl-2-pyrrolidone). The bimetallic clusters were relatively uniform in size (e.g., 1.6 nm in average diameter) and were used as a catalyst for the selective partial hydrogenation of 1,3-cyclooctadiene at 30-degrees-C under 1 atm of hydrogen. The initial rate of the hydrogenation depended on the metal composition of the cluster catalyst, and the maximum catalytic activities were achieved at Au/Pd - 1/4. The catalytic activities of the mixtures of the monometallic Au and Pd clusters were higher than those expected for the two kinds of the monometallic clusters without reciprocal actions. The structures of the bimetallic clusters were studied using extended X-ray absorption fine structure (EXAFS). The structural parameters were determined by fitting the experimental data for the two absorption edges simultaneously using improved computer program. As a consequence of this improvement, the coordination numbers of Au atoms around the Pd atom and of Pd atoms around the Au atom could be determined with greater confidence. The EXAFS data of the Au/Pd(1/4 and 1/1) bimetallic clusters prepared by simultaneous reduction indicate that the surface of the particle entirely consists of palladium atoms and the core of gold atoms (an Au core structure)., 1992年11月, JOURNAL OF PHYSICAL CHEMISTRY, 96 (24), 9927 - 9933, web_of_science

    研究論文(学術雑誌)

  • STRUCTURAL-ANALYSIS OF POLYMER-PROTECTED PD/PT BIMETALLIC CLUSTERS AS DISPERSED CATALYSTS BY USING EXTENDED X-RAY ABSORPTION FINE-STRUCTURE SPECTROSCOPY

    N TOSHIMA; M HARADA; T YONEZAWA; K KUSHIHASHI; K ASAKURA

    Extended X-ray absorption fine structure (EXAFS) was applied to the determination of the structure of colloidal dispersions of the poly(N-vinyl-2-pyrrolidone)-protected palladium/platinum bimetallic clusters, which work as the catalysts for selective partial hydrogenation of 1,3-cyclooctadiene to cyclooctene. The catalytic activity was found to depend on the structure of the bimetallic clusters. The EXAFS data on the Pd/Pt (4/1) bimetallic clusters, which are the most active catalysts, indicate a Pt core structure, in which the 42 Pd atoms are on the surface of the cluster particle and 13 Pt atoms are at the center of the particle, forming a core. In contrast, the Pd/Pt (1/1) bimetallic clusters are suggested to have a modified Pt core structure, in which 28 Pt atoms connect directly with each other, being located both in the core and on the surface, and 27 Pd atoms form three islands on the surface of the cluster particle., 1991年09月, JOURNAL OF PHYSICAL CHEMISTRY, 95 (19), 7448 - 7453, web_of_science

    研究論文(学術雑誌)

  • THE POLYMER-PROTECTED PD-PT BIMETALLIC CLUSTERS HAVING CATALYTIC ACTIVITY FOR SELECTIVE HYDROGENATION OF DIENE - PREPARATION AND EXAFS INVESTIGATION ON THE STRUCTURE

    N TOSHIMA; T YONEZAWA; M HARADA; K ASAKURA; Y IWASAWA

    1990年05月, CHEMISTRY LETTERS, (5), 815 - 818, web_of_science

    研究論文(学術雑誌)

  • Structure and Photochemical Properties of (μ-Alkoxo)bis(μ-carboxylato)diruthenium Complexes with Naphthylacetate Ligands

    Misaki Nakai; Takuzo Funabiki; Chikara Ohtsuki; Masafumi Harada; Akio Ichimura; Rika Tanaka; Isamu Kinoshita; Masahiro Mikuriya; Hiroaki Benten; Hideo Ohkita; Shinzaburo Ito; Makoto Obata; Shigenobu Yano

    2006年04月, Inorganic Chemistry, 45 (7), 3048 - 3056, doi;url

    研究論文(学術雑誌)

MISC

  • 小角X線散乱法による金属ナノ粒子の形成ダイナミクス

    原田雅史

    2016年, C & I Commun, 41 (2), 18 - 20

  • 超臨界流体を用いた貴金属超微粒子の合成

    木村佳文; 原田雅史

    Colloidal dispersions of noble metal nano-particles have been synthesized by the reduction of metallic ions in sub- and supercritical fluids of water, ethanol, 1-propanol, toluene and their mixtures. By using flow type reactor withstanding high-pressure and high-temperature, the reduction of metallic ions has been accomplished with-in a few seconds under the presence of protective polymer. Several kinds of metallic ions such as gold, platinum, rhodium, palladium, ruthenium, and their mixtures have been used to synthesize mono-metallic or bimetallic nano-particles successfully. The particle size and structure of particles have been controlled by the solvent species and temperature of the reaction., 2010年, 高圧力の科学と技術, 20 (1), 11 - 18, doi

  • 金属ナノ粒子の形成プロセスの解明

    原田雅史

    2009年08月, C & I Commun, 34 (3), 19 - 21

    記事・総説・解説・論説等(学術雑誌)

  • 金属ナノ粒子形成過程の追跡

    原田雅史

    2011年06月, 触媒, 53 (4), 241 - 247

    記事・総説・解説・論説等(学術雑誌)

  • In-Situ XAFS Studies of Au Particle Formation by Photoreduction in Polymer Solutions.

    原田雅史; 永長久寛

    2009年02月, PF Activity Report 2007 #25 Part A, Highlight, 38 - 39

    機関テクニカルレポート,技術報告書,プレプリント等

書籍等出版物

  • ナノ材料解析の実際

    原田雅史 (, 範囲: 分担)

    講談社サイエンティフィク, 2016年, 279-283

  • アパレル科学概論

    原田雅史; 松生勝他 (, 範囲: 分担)

    朝倉書店, 2002年09月, 169-180

講演・口頭発表等

  • イオン液体/非イオン性界面活性剤混合系での紫外線照射を用いた銀ナノ粒子の合成とサイズ制御

    巫宛霖、奥西満里奈、原田雅史

    日本化学会第101春季年会

    ポスター発表

  • 銀ナノ粒子を含有したAOT/水/有機溶媒混合エマルション系のSAXS/SANSによる構造解析

    原田雅史、山本実穂

    日本化学会第101春季年会

    口頭発表(一般)

  • スピネル型MCo2O4(M=Mn,Fe,Co,Ni,Zn)電極触媒の酸素生成反応活性とin situ XASによる構造評価

    小手川福笑、桑雅子、原田雅史

    日本化学会第101春季年会

    口頭発表(一般)

  • 銀ナノ粒子を含有したAOT/水/有機溶媒混合エマルション系のSAXS/SANSによる構造解析

    原田雅史、山本実穂

    2020年度量子ビームサイエンスフェスタ(第38回PFシンポジウム)

    ポスター発表

  • スピネル型MCo2O4(M=Mn,Fe,Co,Ni,Zn)電極触媒の酸素生成反応活性とin situ XASによる構造評価

    小手川福笑、原田雅史

    2020年度量子ビームサイエンスフェスタ(第38回PFシンポジウム)

    ポスター発表

  • スピネル型電極触媒の酸素生成反応活性とin situ XASによる構造評価

    小手川福笑; 桑 雅子; 原田雅史

    電気化学会第87回大会, 2020年03月

    ポスター発表

  • イオン液体/非イオン性界面活性剤混合系での化学還元を用いた金属ナノ粒子の合成とサイズ制御

    坂田万青; 山本実穂; 原田雅史

    第10回イオン液体討論会, 2019年11月

    ポスター発表

  • 銀ナノ粒子を含有したAOT/水/有機溶媒混合エマルション系のSAXS/SANSによる構造解析

    山本実穂; 原田雅史

    日本化学会第99春季年会, 2019年03月, 甲南大学岡本キャンパス, false

  • スピネル型電極触媒の酸素生成反応活性とin situ XASによる構造評価

    原田雅史; 桑 雅子

    日本化学会第99春季年会, 2019年03月, 甲南大学岡本キャンパス, false

  • スピネル型電極触媒の酸素発生反応活性とin situ XASによる構造評価

    桑 雅子; 原田雅史

    第28回MRS-J年次大会, 2018年12月, 北九州国際会議場, false

  • マイクロ波で合成したスピネルフェライトナノ粒子の磁気特性

    原田雅史; 桑 雅子; 佐藤良太; 寺西利治

    第28回MRS-J年次大会, 2018年12月, 北九州国際会議場, false

  • イオン液体中における非イオン性界面活性剤の会合体形成と金属ナノ粒子合成への応用

    山本実穂; 原田雅史

    第69回コロイドおよび界面化学討論会, 2018年09月, 筑波大学つくばキャンパス, false

  • 高エネルギーX線回折を用いた貴金属ナノ粒子の三次元構造解析

    原田雅史; 池上梨沙; ロシャンタクマーラ; 小原真司; 坂田修身

    第68回コロイドおよび界面化学討論会, 2017年09月, 神戸大学鶴甲キャンパス, false

  • イオン液体中における非イオン性界面活性剤の会合体形成と金属ナノ粒子合成への応用

    山本実穂; 原田雅史

    第68回コロイドおよび界面化学討論会, 2017年09月, 神戸大学鶴甲キャンパス, false

  • 複合フェライトナノ粒子のEXAFS構造解析と磁気特性

    桑雅子; 原田雅史; 佐藤良太; 寺西利治

    第20回XAFS討論会, 2017年08月, 姫路・西はりま地場産業センター, false

  • 複合酸化物ナノ粒子の構造と磁気特性

    原田雅史; 桑 雅子; 中川あすみ; 佐藤良太; 寺西利治

    2016年度量子ビームサイエンスフェスタ(第34回PFシンポジウム), 2017年03月, false

  • イオン液体中における非イオン性界面活性剤の会合体形成と金属ナノ粒子合成への応用

    山本実穂; 浅野ちひろ; 原田雅史

    第7回イオン液体討論会, 2016年10月, false

  • マイクロ波加熱を用いた酸化物ナノ粒子の迅速合成と構造解析

    桑 雅子; 原田雅史; 佐藤良太; 寺西利治

    日本油化学会第55回年会, 2016年09月, false

  • イオン液体中における非イオン性界面活性剤の会合体形成と金属ナノ粒子合成への応用

    山本実穂; 浅野ちひろ; 原田雅史

    日本油化学会第55回年会, 2016年09月, false

  • Microwave-Assisted Synthesis of Transition-metal Oxide Nanoparticles.

    原田雅史

    2nd International Conference of Polyol Mediated Synthesis, 2016年07月, true

  • XAFS Studies of Metal Nanoparticles Prepared by Using Microwave Heating.

    原田雅史

    2nd International Conference of Polyol Mediated Synthesis, 2016年07月, true

  • マイクロ波加熱を用いた貴金属ナノ粒子の合成と構造解析

    原田雅史; 中山彩也香; 池上梨沙

    2015年度量子ビームサイエンスフェスタ(第33回PFシンポジウム), 2016年03月, false

  • イオン液体中における非イオン性界面活性剤の会合体形成と金属ナノ粒子合成への応用

    山本実穂; 浅野ちひろ; 原田雅史

    日本化学会第96春季年会, 2016年03月, false

  • マイクロ波急速加熱による二元金属ナノ粒子の合成と構造解析

    中山彩也香; 池上梨沙; 原田雅史

    日本化学会第96春季年会, 2016年03月, false

  • マイクロ波加熱を用いた酸化物ナノ粒子の迅速合成と構造解析

    桑 雅子; 原田雅史; 佐藤良太; 寺西利治

    日本化学会第96春季年会, 2016年03月, false

  • マイクロ波加熱を用いた酸化物ナノ粒子の合成と構造解析

    原田雅史; 中川あすみ; 小貝真由; 佐藤良太; 寺西利治

    第3回物構研サイエンスフェスタ(第32回PFシンポジウム), 2015年03月, false

  • 二元金属Pt/RhおよびPt/Pdナノ粒子の形成過程の時間分解in-situ Quick XAFS解析

    池上梨沙; 原田雅史

    日本化学会第95春季年会, 2015年03月, false

  • イオン液体中における非イオン性界面活性剤の会合体形成と金属ナノ粒子合成への応用

    原田雅史; 浅野ちひろ; 堀口詩織; 西条賢次

    日本化学会第95春季年会, 2015年03月, false

  • アルキルエチレンジアミン系プロトン性イオン液体における銅(II)およびニッケル(II)イオンの錯形成

    渡辺麻友; 竹村 忍; 原田雅史; 飯田雅康

    第37回溶液化学シンポジウム, 2014年11月, false

  • マイクロ波加熱を用いた酸化物(CoO, NiO, Fe3O4)ナノ粒子の迅速合成

    原田雅史; 小貝真由; 佐藤良太; 寺西利治

    第8回日本電磁波エネルギー応用学会シンポジウム, 2014年11月, false

  • 時間分解in-situ XAFS/SAXS測定による金属ナノ粒子形成過程の解明

    池上梨沙; 国清紘子; 原田雅史

    第17回XAFS討論会, 2014年09月, false

  • イオン液体中における非イオン性界面活性剤の会合体形成と金属ナノ粒子合成への応用

    原田雅史

    物構研サイエンスフェスタ2013(第31回PFシンポジウム), 2014年03月, false

  • イオン液体中における非イオン性界面活性剤の会合体形成と金属ナノ粒子合成への応用

    原田雅史; 堀口詩織; 西条賢次

    日本化学会第94春季年会, 2014年03月, false

  • マイクロ波加熱を用いたCoOおよびNiO酸化物ナノ粒子の迅速合成

    小貝真由; 原田雅史; 佐藤良太; 寺西利治

    日本化学会第94春季年会, 2014年03月, false

  • キレートアミン型プロトン性イオン液体と銅(II)塩との相互作用に及ぼす対イオンの効果

    竹村 忍; 飯田雅康; 原田雅史

    第4回イオン液体討論会, 2013年11月, false

  • アルキルエチレンジアミン型プロトン性イオン液体のプロトン付加位置およびニッケル(II)との相互作用

    渡辺麻友; 飯田雅康; 原田雅史

    第4回イオン液体討論会, 2013年11月, false

  • 逆ミセル溶液中の水のダイナミクスの温度変化

    村上 洋; 佐田智子; 山田真紗子; 原田雅史

    第64回コロイドおよび界面化学討論会, 2013年09月, 名古屋工業大学, false

  • マイクロ波加熱を用いたCoOおよびNiO酸化物ナノ粒子の合成

    原田雅史; 佐田智子; 高橋優里

    第64回コロイドおよび界面化学討論会, 2013年09月, 名古屋工業大学, false

  • 時間分解in situ XAFS/SAXS測定による金ナノ粒子形成機構の解明

    原田雅史

    第1回物構研サイエンスフェスタ(第30回PFシンポジウム), 2013年03月

  • ヘキシルアミン系プロトン性イオン液体における銅(II)イオンの錯形成

    竹村 忍; 飯田雅康; 原田雅史

    第3回イオン液体討論会, 2012年12月, false

  • ヘキシルアミン系プロトン性イオン液体における銅(II)イオンの錯形成

    竹村 忍; 飯田雅康; 原田雅史

    第35回溶液化学シンポジウム, 2012年11月, 早稲田大学, false

  • 時間分解in-situ XAFS/SAXS測定による金属ナノ粒子形成過程の解明

    原田雅史

    第29回PFシンポジウム, 2012年03月

  • 時間分解in-situ XAFS/SAXS測定による金属ナノ粒子形成過程の解明

    国清紘子; 原田雅史; 竹中幹人

    日本化学会第92春季年会, 2012年03月

  • ナノ拘束空間中水の揺らぎの温度変化

    村上 洋; 山田真沙子; 佐田智子; 原田雅史

    第49回日本生物物理学会年会, 2011年09月

  • ナノメートル空間拘束下にある水の揺らぎの温度変化

    村上 洋; 山田真沙子; 佐田智子; 原田雅史

    日本物理学会2011年秋季大会, 2011年09月

  • イオン液体/非イオン性界面活性剤混合系での紫外線照射を用いた銀ナノ粒子の合成とサイズ制御

    巫 宛霖; 奥西満里奈; 原田雅史

    日本化学会第101春季年会(オンライン開催), 2021年03月21日

  • 銀ナノ粒子を含有したAOT/水/有機溶媒混合エマルション系のSAXS/SANSによる構造解析

    原田雅史; 山本実穂

    日本化学会第101春季年会(オンライン開催), 2021年03月21日

  • スピネル型MCo2O4(M=Mn,Fe,Co,Ni,Zn)電極触媒の酸素生成反応活性とin situ XASによる構造評価

    小手川福笑; 桑 雅子; 原田雅史

    日本化学会第101春季年会(オンライン開催), 2021年03月20日

  • 銀ナノ粒子を含有したAOT/水/有機溶媒混合エマルション系のSAXS/SANSによる構造解析

    原田雅史; 山本実穂

    2020年度量子ビームサイエンスフェスタ(第38回PFシンポジウム), 2021年03月10日

  • スピネル型MCo2O4(M=Mn,Fe,Co,Ni,Zn)電極触媒の酸素生成反応活性とin situ XASによる構造評価

    小手川福笑; 原田雅史

    2020年度量子ビームサイエンスフェスタ(第38回PFシンポジウム), 2021年03月10日

  • スピネル型MCo2O4(M=Mn,Fe,Co,Ni,Zn)電極触媒の酸素生成反応活性とin situ XASによる構造評価

    小手川福笑; 桑 雅子; 原田雅史

    ナノ学会第19回大会(オンライン開催), 2021年05月21日, 2021年05月20日, 2021年05月20日

担当経験のある科目(授業)

  • 衣環境科学演習 (奈良女子大学)

  • 衣環境科学論 (奈良女子大学)

  • 衣環境管理論演習 (奈良女子大学)

  • 衣環境管理論 (奈良女子大学)

  • 衣環境学実験Ⅱ(化学) (奈良女子大学)

  • 衣環境管理学 (奈良女子大学)

  • 衣環境学実験IV(化学) (奈良女子大学)

  • 衣環境学概論 (奈良女子大学)

  • 高分子化学 (奈良女子大学)

  • 衣環境化学実験 (奈良女子大学)

  • 生活材料物理化学 (奈良女子大学)

  • アパレル管理論演習 (奈良女子大学)

  • アパレル管理論 (奈良女子大学)

  • アパレル科学特論 (奈良女子大学)

  • アパレル洗浄論演習 (奈良女子大学)

  • アパレル洗浄論 (奈良女子大学)

  • 生活健康・衣環境学概論 (奈良女子大学)

  • 生活界面化学 (奈良女子大学)

  • 衣環境学実験II(化学) (奈良女子大学)

  • 洗浄科学 (奈良女子大学)

所属学協会

  • ナノ学会

  • 日本家政学会

  • 日本油化学会

  • 高分子学会

  • 触媒学会

  • 日本化学会

Works(作品等)

  • エチレングリコール溶液中で合成された合金ナノ粒子の構造解析

    2017年08月 - 2018年03月

  • リバースモンテカルロ法を用いた高分子に保護された金属ナノ粒子の構造解析

    2016年08月 - 2017年03月

  • 有機分子配位子で保護された複合酸化物ナノ粒子の結晶構造と磁気特性の解明

    2016年04月 - 2017年03月

  • ダイレクトメタノール形燃料電池電極用の高活性酸化触媒の研究開発

    2004年12月 - 2006年03月

  • 次世代パワー照明用蛍光体コロイド微粒子の液相合成に関する共同研究

    2002年 - 2005年

  • スーパー高分子ナノ加工体(戦略的権利化試験事業)

    2000年 - 2001年



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