2024年01月, つくば研究支援センター, 第4回TCIベンチャーアワード シーズ部門 優秀賞　　　　　　　　　　　　　　　
低価格・高耐久な白金フリー燃料電池触媒
武安光太郎

2022年10月, 日本物理学会, 第17回（2023年） 日本物理学会若手奨励賞　　　　　　　　　　　　　　　
表面反応におけるエネルギーの流れと制御因子の研究
武安光太郎

2021年07月, 筑波大学, 若手教員奨励賞　　　　　　　　　　　　　　　
武安光太郎

2021年05月, 日本表面真空学会, 講演奨励賞（若手研究者部門）　　　　　　　　　　　　　　　
ミトコンドリア電子伝達系の熱産生解析
武安光太郎

2018年09月, 日本触媒学会, 若手研究者のための海外渡航費用助成　　　　　　　　　　　　　　　
武安 光太郎

2014年, 日本真空学会, 第39回 熊谷記念真空科学論文賞　　　　　　　　　　　　　　　
杉本 敏樹;武安 光太郎;福谷 克之

2014年, 日本真空学会, 第23回 真空進歩賞　　　　　　　　　　　　　　　
武安 光太郎

2013年03月, Institute of Physics, IOP select　　　　　　　　　　　　　　　
武安 光太郎

2012年, 日本表面科学会, 講演奨励賞 スチューデント部門　　　　　　　　　　　　　　　
武安 光太郎

2010年, 日本応用物理学会, 講演奨励賞　　　　　　　　　　　　　　　
武安 光太郎

2010年, 日本真空学会, 真空に関する連合講演会 優秀ポスター賞　　　　　　　　　　　　　　　
武安 光太郎

Pentagon‐Rich Caged Carbon Catalyst for the Oxygen Reduction Reaction in Acidic Electrolytes
Guoping Chen, Miho Isegawa, Taro Koide, Yasuo Yoshida, Koji Harano, kenji Hayashida, Shusaku Fujita, Kotaro Takeyasu, Katsuhiko Ariga, Junji Nakamura
Angewandte Chemie International Edition, Wiley, 2024年09月21日
研究論文（学術雑誌）, The interaction between electron spin and oxygen molecules in non‐platinum catalysts, particularly carbon catalysts, significantly influences the catalytic performance of the oxygen reduction reaction (ORR). A promising approach to developing high‐performance catalysts involves introducing five‐membered ring structures with spin electrons into graphitic carbons. In this study, we present the successful synthesis of cage‐like cubic carbon catalysts enriched with pentagon structures using pentagon ring‐containing C60 and a NaCl template. The number of pentagons contained in the structure was increased by doping with nitrogen and annealing, and the number of electron spins also increased, thereby improving catalytic activity. The prepared catalyst exhibits remarkable activity in ORR under acidic electrolytes. Furthermore, we elucidate the correlation between the pentagon structure, the number of spin electrons, and catalytic activity, demonstrating that enhanced activity is contingent upon the presence of spin electrons. Density functional theory (DFT) calculations support the role of spin electrons in improving activity. The concept of spin electrons and the introduction of pentagon structures provide new design principles for carbon catalysts.

Critical impacts of interfacial water on C–H activation in photocatalytic methane conversion
Hiromasa Sato, Atsushi Ishikawa, Hikaru Saito, Taisuke Higashi, Kotaro Takeyasu, Toshiki Sugimoto
Communications Chemistry, 6, 1, Springer Science and Business Media LLC, 2023年01月20日
研究論文（学術雑誌）, Abstract

On-site and on-demand photocatalytic methane conversion under ambient conditions is one of the urgent global challenges for the sustainable use of ubiquitous methane resources. However, the lack of microscopic knowledge on its reaction mechanism prevents the development of engineering strategies for methane photocatalysis. Combining real-time mass spectrometry and operando infrared absorption spectroscopy with ab initio molecular dynamics simulations, here we report key molecular-level insights into photocatalytic green utilization of methane. Activation of the robust C–H bond of methane is hardly induced by the direct interaction with photogenerated holes trapped at the surface of photocatalyst; instead, the C–H activation is significantly promoted by the photoactivated interfacial water species. The interfacial water hydrates and properly stabilizes hydrocarbon radical intermediates, thereby suppressing their overstabilization. Owing to these water-assisted effects, the photocatalytic conversion rates of methane under wet conditions are dramatically improved by typically more than 30 times at ambient temperatures (~300 K) and pressures (~1 atm) in comparison to those under dry conditions. This study sheds new light on the role of interfacial water and provides a firm basis for design strategies for non-thermal heterogeneous catalysis of methane under ambient conditions.

Activating Nitrogen‐doped Graphene Oxygen Reduction Electrocatalysts in Acidic Electrolytes using Hydrophobic Cavities and Proton‐conductive Particles
Santosh K. Singh, Kotaro Takeyasu, Kaito Homma, Shigeharu Ito, Takashi Morinaga, Yuto Endo, Moeko Furukawa, Toshiyuki Mori, Hirohito Ogasawara, Junji Nakamura
Angewandte Chemie International Edition, Wiley, 2022年10月14日, ［査読有り］, ［筆頭著者, 責任著者］
研究論文（学術雑誌）

Critical impacts of interfacial water on the photocatalytic C–H conversion of methane
Hiromasa Sato, Atsushi Ishikawa, Hikaru Saito, Taisuke Higashi, Kotaro Takeyasu, Toshiki Sugimoto
American Chemical Society (ACS), 2022年08月24日
On-site and on-demand photocatalytic methane conversion under mild conditions is one of the urgent global challenges for the sustainable use of ubiquitous methane resources. However, the lack of accurate knowledge of the reaction mechanism prevents the development of engineering strategies for methane photocatalysis. Combining real-time mass spectrometry and operando infrared absorption spectroscopy with ab initio molecular dynamics simulations, here we report key molecular-level insights into photocatalytic green utilization of methane. The photoactivated water dramatically promotes the activation of robust C–H bond of methane, and stabilizes the •CH3 intermediates in the interfacial hydrogen-bond network of water. Owing to the moderate stabilization of •CH3, the overall photocatalytic conversion rates are dramatically improved by typically more than 30 times at ambient temperatures (~300 K) and pressures (~1 atm). The increase in reaction activity is noticeable also in C1 to C2 evolution of methane, although water is not explicitly involved in the reaction equation (2CH4 → C2H6 + H2). These marked water-assisted effects in the interfacial chemistry should affect the basic understanding and the designing strategies on the non-thermal heterogeneous catalysis of methane under ambient conditions.

Hollow Spherical Fullerene obtained by Kinetically Controlled Liquid‐Liquid Interfacial Precipitation
Guoping Chen, Flavien Sciortino, Kotaro Takeyasu, Junji Nakamura, Jonathan Patrick Hill, Lok Kumar Shrestha, Katsuhiko Ariga
Chemistry – An Asian Journal, e202200756, Wiley, 2022年08月23日, ［査読有り］
研究論文（学術雑誌）

Hydrogenation of Formate Species Using Atomic Hydrogen on a Cu(111) Model Catalyst
Kotaro Takeyasu, Yasutaka Sawaki, Takumi Imabayashi, Septia Eka Marsha Putra, Harry Handoko Halim, Jiamei Quan, Yuji Hamamoto, Ikutaro Hamada, Yoshitada Morikawa, Takahiro Kondo, Tadahiro Fujitani, Junji Nakamura
Journal of the American Chemical Society, 144, 27, 12158, 12166, American Chemical Society (ACS), 2022年07月13日, ［査読有り］, ［筆頭著者］
英語, 研究論文（学術雑誌）, ABSTRACT: The reaction mechanism of the CH3OH synthesis by the hydrogenation of CO2 on Cu catalysts is unclear because of the challenge in experimentally detecting reaction intermediates formed by the hydrogenation of adsorbed formate (HCOOa). Thus, the objective of this study is to clarify the reaction mechanism of the CH3OH synthesis by establishing the kinetic natures of intermediates formed by the hydrogenation of adsorbed HCOOa on Cu(111). We exposed HCOOa on Cu(111) to atomic hydrogen at low temperatures of 200-250 K and observed the species using infrared reflection absorption (IRA) spectroscopy and temperature-programmed desorption (TPD) studies. In the IRA spectra, a new peak was observed upon the exposure of HCOOa on Cu(111) to atomic hydrogen at 200 K and was assigned to the adsorbed dioxymethylene (H2COOa) species. The intensity of the new peak gradually decreased with heating from 200 to 290 K, whereas the IR peaks representing HCOOa species increased correspondingly. In addition, small amounts of formaldehyde (HCHO), which were formed by the exposure of HCOOa species to atomic hydrogen, were detected in the TPD studies. Therefore, H2COOa is formed via hydrogenation by atomic hydrogen, which thermally decomposes at similar to 250 K on Cu(111). We propose a potential diagram of the CH3OH synthesis via H2COOa from CO2 on Cu surfaces, with the aid of density functional theory calculations and literature data, in which the hydrogenation of bidentate HCOOa to H2COOa is potentially the rate-determining step and accounts for the apparent activation energy of the methanol synthesis from CO2 on Cu surfaces.

Versatile nanoarchitectonics of Pt with morphology control of oxygen reduction reaction catalysts
Guoping Chen, Santosh K. Singh, Kotaro Takeyasu, Jonathan P. Hill, Junji Nakamura, Katsuhiko Ariga
Science and Technology of Advanced Materials, 23, 1, 413, 423, Informa UK Limited, 2022年06月22日, ［査読有り］
研究論文（学術雑誌）

Focusing and spin polarization of atomic hydrogen beam
Y. Nagaya, H. Nakatsu, S. Ogura, K. Shimazaki, H. Ueta, K. Takeyasu, K. Fukutani
The Journal of Chemical Physics, 155, 19, 194201, AIP Publishing, 2021年11月21日, ［査読有り］
研究論文（学術雑誌）

Role of Pyridinic Nitrogen in the Mechanism of the Oxygen Reduction Reaction on Carbon Electrocatalysts
Kotaro Takeyasu, Moeko Furukawa, Yuto Shimoyama, Santosh K. Singh, Junji Nakamura
Angewandte Chemie International Edition, 60, 10, 5121, 5124, Wiley, 2021年03月, ［査読有り］, ［筆頭著者, 責任著者］
英語, 研究論文（学術雑誌）, The introduction of pyridinic nitrogen (pyri-N) into carbon-based electrocatalysts for the oxygen reduction reaction is considered to create new active sites. Herein, the role of pyri-N in such catalysts was investigated from a mechanistic viewpoint using carbon black (CB)-supported pyri-N-containing molecules as model catalysts; the highest activity was observed for 1,10-phenanthroline/CB. X-ray photoemission spectroscopy showed that in acidic electrolytes, both pyri-N atoms of 1,10-phenanthroline could be protonated to form pyridinium ions (pyri-NH+). In O-2-saturated electrolytes, one of the pyri-NH+ species was reduced to pyri-NH upon the application of a potential; no such reduction was observed in N-2-saturated electrolytes. This behavior was ascribed to electrochemical reduction of pyri-NH+ occurring simultaneously with the thermal adsorption of O-2, as supported by DFT calculations. According to these calculations, the coupled reduction was promoted by hydrophobic environments.

CoOx electro-catalysts anchored on nitrogen-doped carbon nanotubes for the oxygen evolution reaction
Santosh K. Singh, Kotaro Takeyasu, Bappi Paul, Sachin K. Sharma, Junji Nakamura
Sustainable Energy & Fuels, 5, 3, 820, 827, Royal Society of Chemistry (RSC), 2021年01月, ［査読有り］
研究論文（学術雑誌）,

The development of high-performance, low-cost transition metal oxide nanoparticle-supported carbon catalysts for oxygen evolution reaction (OER) is one of the biggest challenges faced in the process of commercializing water electrolyzers and rechargeable metal–air batteries.

Dynamical Quantum Filtering via Enhanced Scattering of para-H2 on the Orientationally Anisotropic Potential of SrTiO3(001)
Koji Shimizu, Wilson Agerico Diño, Hiroshi Nakanishi, Hideaki Kasai, Kotaro Takeyasu, Katsuyuki Fukutani, Ayako Yajima
Scientific Reports, 10, 1, 5939, Springer Science and Business Media LLC, 2020年12月
研究論文（学術雑誌）, Quantum dynamics calculation, performed on top of density functional theory (DFT)-based total energy calculations, show dynamical quantum filtering via enhanced scattering of para-H₂ on SrTiO₃(001). We attribute this to the strongly orientation-dependent (electrostatic) interaction potential between the H₂ (induced) quadrupole moment and the surface electric field gradient of ionic SrTiO₃(001). These results suggest that ionic surfaces could function as a scattering/filtering media to realize rotationally state-resolved H₂. This could find significant applications not only in H₂ storage and transport, but also in realizing materials with pre-determined characteristic properties.

窒素ドープ炭素の局所電子状態と活性
武安光太郎, 中村潤児
炭素, 2019, 290, 204, 210, The Carbon Society of Japan, 2019年11月15日, ［査読有り］, ［招待有り］, ［筆頭著者］
研究論文（学術雑誌）

Active Sites and Mechanism of Oxygen Reduction Reaction Electrocatalysis on Nitrogen-Doped Carbon Materials
Santosh K. Singh, Kotaro Takeyasu, Junji Nakamura
Advanced Materials, 31, 13, 1804297, 1804297, Wiley, 2019年03月, ［査読有り］, ［招待有り］
研究論文（学術雑誌）

Electronic and spin structure of O- and H-adsorbed Fe3O4(111) surfaces
Asakawa, Kanta, Miura, Yoshio, Nagatsuka, Naoki, Takeyasu, Kotaro, Matsumoto, Masuaki, Fukutani, Katsuyuki
PHYSICAL REVIEW B, 99, 8, 085442, AMER PHYSICAL SOC, 2019年02月, ［査読有り］
英語, 研究論文（学術雑誌）, The adsorption of O and H atoms on the Fe3O4(111) surface was investigated using ultraviolet photoemission spectroscopy (UPS) and first-principles calculations. On the FeA1-terminated surface, H adsorption decreases the work function without changing the density of states near the Fermi level. The density of states near the Fermi level decreases by O adsorption. On the O/FeA1-terminated surface, H adsorption dramatically increases the density of states near the Fermi level, indicating that the Fe 3d state is modified. The first-principles calculations showed that the electronic structure of the surface FeA on the FeA1-terminated surface is half metallic with its spin up forming an isolated spin-polarized conductive layer. By O adsorption, the up-spin band at the Fermi level of the surface FeA site is removed, and the Fermi level of the surface FeA moves to the down-spin t(2g) band. By subsequent H adsorption, electrons are doped to the FeA1 site, and the surface FeA1 layer becomes semiconducting. These results indicate that the charge and spin structure is modulated by O and H adsorption.

メタノール合成におけるCu-Zn活性点のargument　　　　　　　　　　　　　　　
武安 光太郎, 藤谷 忠宏, 中村 潤児
Accounts of Materials & Surface Research, 4, 9, 17, 2019年01月, ［査読有り］, ［招待有り］
日本語, 研究論文（学術雑誌）

Adsorption geometry of methyl chloride weakly interacting with Ag(111)
K. Takeyasu, M. Okada
J. Phys. Commun., 2, 075017, 2018年05月, ［査読有り］
英語, 研究論文（学術雑誌）

Effects of Hydrogen on the Electronic State and Electric Conductivity of the Rutile TiO2(110) Surface
Keisuke Fukada, Masuaki Matsumoto, Kotaro Takeyasu, Shohei Ogura, Katsuyuki Fukutani
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 84, 6, 064716, PHYSICAL SOC JAPAN, 2015年06月, ［査読有り］
英語, 研究論文（学術雑誌）, The adsorption of atomic hydrogen on a rutile TiO2(110) surface was investigated by nuclear reaction analysis (NRA), ultraviolet photoelectron spectroscopy (UPS), and conductivity measurements. The TiO2(110) surface was annealed in O-2 of 1 x 10(-4) Pa, which is regarded as a quasi-stoichiometric surface. After exposure to atomic hydrogen, UPS showed a localized in-gap state (IGS) at about 0.8 eV below the Fermi level and downward band bending with a decrease in the work function. Along with these changes, the conductivity was increased by 2.9 mu S/square. Our results indicate that hydrogen donates electrons to the substrate. The amount of charge transfer and electric conductivity are discussed on the basis of the experimental data.

Temperature dependence of hydrogen depth distribution in the near-surface region of stainless steel
Kotaro Takeyasu, Masuaki Matsumoto, Katsuyuki Fukutani
VACUUM, 109, 230, 233, PERGAMON-ELSEVIER SCIENCE LTD, 2014年11月, ［査読有り］
英語, 研究論文（学術雑誌）, The depth profile of hydrogen at a type 304 stainless steel surface was investigated with H-1(N-15,alpha gamma)C-12 nuclear reaction analysis at various temperatures. Hydrogen was predominantly distributed in the region shallower than 10 nm (surface hydrogen) with an area density of similar to 1 x 10(16) cm(-2). Hydrogen was found to also exist in a deeper region (>30 nm) with a constant volume density of similar to 4 x 10(20) cm(-3) (bulk hydrogen). While both bulk and surface components gradually decreased as the temperature rose, part of the intensities remained even at 975 K. From the temperature dependence of the amount of the surface hydrogen, the distribution of the activation energy for desorption is discussed. (C) 2014 Elsevier Ltd. All rights reserved.

Electronic structure of the SrTiO3 (001) surfaces: Effects of the oxygen vacancy and hydrogen adsorption　　　　　　　　　　　　　　　
K. Takeyasu, K. Fukada, S. Ogura, M. Matsumoto, K. Fukutani
Appl. Sci. Conv. Technol., 23, 5, 201, 210, 2014年09月, ［査読有り］, ［招待有り］
英語, 研究論文（学術雑誌）

Two charged states of hydrogen on the SrTiO3(001) surface
Kotaro Takeyasu, Keisuke Fukada, Shohei Ogura, Masuaki Matsumoto, Katsuyuki Fukutani
JOURNAL OF CHEMICAL PHYSICS, 140, 8, 084703, AMER INST PHYSICS, 2014年02月, ［査読有り］
英語, 研究論文（学術雑誌）, The effects of hydrogen exposure on the electronic structure of two types of SrTiO3(001) surfaces, oxygen-deficient (OD) and nearly-vacancy-free (NVF) surfaces, were investigated with ultraviolet photoemission spectroscopy and nuclear reaction analysis. Upon molecular hydrogen exposure to the OD surface which reveals in-gap states at 1.3 eV below the Fermi level, the in-gap state intensity was reduced to half the initial value at a hydrogen coverage of 0.9 +/- 0.7 x 10(14) cm(-2). On the NVF surface which has no in-gap state, on the other hand, atomic-hydrogen exposure induced in-gap states, and the hydrogen saturation coverage was evaluated to be 3.1 +/- 0.8 x 10(14) cm(-2). We argue that H is positively charged as H similar to 0.3+ on the NVF surface by being coordinated to the O atom, whereas H is negatively charged as H-on the OD surface by occupying the oxygen vacancy site. The stability of H-at the oxygen vacancy site is discussed. (C) 2014 AIP Publishing LLC.

Hydrogen-Induced Dipoles and Sensing Principles of Pt-Ti-O gate Si-MISFET Hydrogen Gas Sensors
Toshiyuki Usagawa, Kotaro Takeyasu, Katsuyuki Fukutani
28TH EUROPEAN CONFERENCE ON SOLID-STATE TRANSDUCERS (EUROSENSORS 2014), 87, 1015, 1018, ELSEVIER SCIENCE BV, 2014年, ［査読有り］
英語, 研究論文（国際会議プロシーディングス）, Distribution of hydrogen-induced dipoles in platinum-titanium-oxygen (Pt-Ti-O) gate structures of Si-MISFET hydrogen gas sensors has been observed by H-specific H-1(N-15, alpha gamma) C-12 nuclear reaction analysis (NRA). The sheet number of hydrogen-induced dipoles under N-2-diluted 1% H2 atmosphere @ 50 degrees C is estimated as 2.2x10(14)/cm(2). The averaged vertical components of dipole-moments is estimated as 82.5D, if the relative dielectric constant of modified TiOx layer and the sensing amplitude Delta V-g (V) are assigned by 114 and 624.4mV. We have found that the hydrogen-induced dipoles are generated in Pt-side modified TiOx layer, and also localized around specific thick pathway of the corridor originated from platinum grain-boundaries. (C) 2014 Published by Elsevier Ltd.

Analytical Formula for Calculating Adsorption Density of States on Chamber Surfaces from Measured Pressure Change
Takeyasu, Kotaro, Sugimoto, Toshiki, Fukutani, Katsuyuki
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 82, 11, 114602, PHYSICAL SOC JAPAN, 2013年11月, ［査読有り］
英語, 研究論文（学術雑誌）, Pressure decay during an evacuation process of a vacuum chamber often shows a power-law dependence on time, which is considered to reflect the distribution of the adsorption energy of particles on the surface of the chamber. We derive an analytical formula that directly transforms the pressure change into the adsorption density of states. This method shows that the power-law behavior is equivalent to the situation in which the chamber surface has a constantor exponential-type adsorption density of states for particles under a quasi-static condition.

Control of the surface electronic structure of SrTiO3(001) by modulation of the density of oxygen vacancies
Kotaro Takeyasu, Keisuke Fukada, Masuaki Matsumoto, Katsuyuki Fukutani
JOURNAL OF PHYSICS-CONDENSED MATTER, 25, 16, 162202, IOP PUBLISHING LTD, 2013年04月, ［査読有り］
英語, 研究論文（学術雑誌）, The influence of electron irradiation and the subsequent oxygen adsorption on the electronic structure of an SrTiO3(001) surface was investigated by ultraviolet photoemission spectroscopy (UPS). Electron irradiation induced an in-gap state (IGS) as observed by UPS keeping the surface 1 x 1, which is considered to originate from oxygen vacancies on the topmost surface due to the electron-stimulated desorption (ESD) of oxygen. Electron irradiation also caused a downward shift of the valence band maximum, indicating downward band bending and the formation of a conductive layer on the surface. Adsorption of oxygen on the electron-irradiated surface, on the other hand, reduced the intensity of the IGS along with yielding upward band bending, which points to disappearance of the conductive layer. The results show that ESD and oxygen adsorption can be used to control the surface electronic structure switching between semiconducting and metallic regimes by changing the density of the oxygen vacancies.

Gas dynamics in the vacuum chamber with a single adsorption site on the wall surface: Origin of the exponential pressure decay with the time constant of sub-kilo seconds
Toshiki Sugimoto, Kotaro Takeyasu, Katsuyuki Fukutani
Journal of the Vacuum Society of Japan, 56, 8, 322, 329, 2013年, ［査読有り］
日本語, 研究論文（学術雑誌）, During pumping down of water molecules in a typical laboratory vaccum chamber (evacuation time constant: τp<
1 s), we obserbed that the pressure decays exponentially on a time scale of sub-kilo seconds before it starts to decrease with nearly t-1 time dependence. On the basis of the Henry-type adsorption-desorption rate equation on the chamber wall and the equation of evacuation, we discuss here that such an exponential decay curve can be realized in the quasi-steady state for pressure by the mathematical phase-space analysis. By applying this analysis to obserbed decay curves, we also show that the pressure decay is dominated by the chemisorbed water with an activation energy for desorption of ∼890 meV, which is in good agreement with the recent results of water adsorbed on oxide surfaces as investigated by surface science techniques. Our results establish a firm basis to describe evacuation process.

Analysis of a pumping curve of water with the conversion equation from pressure to adsorption density of states
Kotaro Takeyasu, Toshiki Sugimoto, Katsuyuki Fukutani
Journal of the Vacuum Society of Japan, 56, 11, 457, 460, 2013年, ［査読有り］, ［招待有り］
日本語, 研究論文（学術雑誌）, A pumping-down curve of a vacuum chamber often shows a power-law dependence on time, which has been attributed to a distribution of the adsorption energy of molecules on the chamber wall. We have recently derived an analytical formula that directly converts pressure changes as a function of time into the adsorption density of states (ADOS). In the present paper, on the basis of this formula, we analyzed the pumping-down curves reported in literatures to obtain ADOS of water molecules. The ADOS was dependent on the initial exposure pressure of water. The origin of the pressure dependence is discussed.

Theoretical analysis of a spin-polarized atomic hydrogen beam optics
Shohei Ogura, Kotaro Takeyasu, Katsuyuki Fukutani
Journal of the Vacuum Society of Japan, 54, 3, 192, 195, 2011年, ［査読有り］
日本語, 研究論文（国際会議プロシーディングス）, We have analyzed an optical system for a spin-polarized atomic hydrogen beam. By calculating the model emittance of atomic hydrogen beams, we simulated the beam profile. We predicted that a hexapole magnet with a length of 75 mm and magnetic flux density of 0.65 T results in a spin polarization of 95% and a beam separation of 9 mm, which is sufficient for our purpose. We also found that the longer hexapole manget results in a higher spin polarization and smaller beam separation.

Structural study of clean and gas adsorbed metal surfaces by low-energy electron diffraction
K. Takeyasu, K. Fukada, S. Ogura, M. Matsumoto, K. Fukutani
SEISAN KENKYU, 61, 5, 945, 948, 東京大学生産技術研究所, 2010年02月
日本語, 本研究では, 低速電子線回折法(LEED)を用いてイリジウム(Ir)(111)清浄表面及び一酸化窒素(NO)吸着表面の二つの試料について, スポット強度の温度依存性の解析と動力学的解析によってデバイ温度を評価した．LEEDスポット強度の温度依存性を用いた解析ではIr (111)清浄表面におけるデバイ温度は250～280K, NO吸着表面におけるデバイ温度は220～235K程度であることが分かった．また動力学的解析結果からはIr (111)清浄表面におけるデバイ温度は310K, バルクのデバイ温度が440 Kとなり, 表面ではバルクよりも低い値となることが分かった．表面でのデバイ温度が低いことは表面原子の振動振幅がバルク内部に比べて大きいことを示しており, さらに表面にNOが吸着することによりさらに増大すると考えられる．［本要旨はPDFには含まれない］

混成電位駆動型触媒反応の理論的枠組みと実験的検証　　　　　　　　　　　　　　　
武安光太郎
第134回触媒討論会, 2024年09月13日, 口頭発表（招待・特別）
［招待講演］

窒素ドープカーボン触媒の活性低下メカニズムに基づく高性能化　　　　　　　　　　　　　　　
武安光太郎
第31回燃料電池シンポジウム, 2024年05月24日, 口頭発表（招待・特別）
2024年05月24日 - 2024年05月24日, ［招待講演］

ミトコンドリア呼吸鎖における反応駆動由来の熱産生解析　　　　　　　　　　　　　　　
武安光太郎, Nuning Anugrah, Putri Namari, 中村潤児
第21回ミトコンドリア学会 年会, 2023年03月08日, 口頭発表（招待・特別）
2023年03月08日 - 2023年03月08日, ［招待講演］

Mechanism of thermogenesis in mitochondrial respiratory chain　　　　　　　　　　　　　　　
武安光太郎
生物物理学会 年会シンポジウム, 2022年09月18日, 英語, 口頭発表（招待・特別）
［招待講演］, ［国際会議］

Detection of unstable intermediates for CO2 conversion into methanol on a Cu(111) model catalyst　　　　　　　　　　　　　　　
武安光太郎
6th International Conference on Catalysis and Chemical Engineering, 2022年02月22日, 英語, 口頭発表（招待・特別）
［招待講演］, ［国際会議］

Role of pyridinic nitrogen as an active site of carbon catalysts　　　　　　　　　　　　　　　
武安光太郎
物理学会 2021年秋季大会 企画シンポジウム, 2021年09月18日, 英語, 口頭発表（招待・特別）
［招待講演］, ［国際会議］

窒素ドープグラフェンモデル触媒における酸素吸着状態　　　　　　　　　　　　　　　
武安光太郎
第128回触媒討論会 若手シンポジウム, 2021年09月16日, 日本語, 口頭発表（招待・特別）
［招待講演］, ［国際会議］

疎水性による窒素ドープグラフェン触媒の酸素還元反応に関する最近の発展　　　　　　　　　　　　　　　
武安光太郎
第12回新電極シンポジウム・宿泊セミナー, 2019年11月01日, 日本語, 口頭発表（招待・特別）
［招待講演］, ［国際会議］

窒素ドープカーボン材料のORR活性点　　　　　　　　　　　　　　　
武安光太郎
文部科学省 ポスト「京」重点課題５ 若手研究者によるワークショップ, 2019年08月29日, 日本語, 口頭発表（招待・特別）
［招待講演］, ［国際会議］

Effective local structure and reaction mechanisms for bottom-up designed metal-free ORR catalyst　　　　　　　　　　　　　　　
K. Takeyasu
International Congress on Pure and Applied Chemistry, 2019年08月06日, 英語, 口頭発表（招待・特別）
［招待講演］, ［国際会議］

芳香族分子ベース触媒での吸着水素がアクティベートする酸素還元反応　　　　　　　　　　　　　　　
武安光太郎, 下山雄人, 古川萌子, S. K. Singh, 中村潤児
第一回ハイドロジェノミクス研究会, 2018年11月16日, 日本語, 口頭発表（一般）
［国内会議］

Effective local structure for pyridinic nitrogen in carbon-based ORR catalyst synthesized with a bottom-up approach　　　　　　　　　　　　　　　
K. Takeyasu, Y. Shimoyama, M. Furukawa, S. K. Singh, J. Nakamura
Southeast Asia Collaborative Symposium on Energy Materials 2018, 2018年11月08日, 英語, 口頭発表（招待・特別）
［招待講演］, ［国際会議］

Effective Local Structure for Bottom-up Designed ORR Catalyst Using Pyridinic Nitrogen Containing Molecules　　　　　　　　　　　　　　　
K. Takeyasu, Y. Shimoyama, M. Furukawa, S. K. Singh, J. Nakamura
American Vacuum Society 60th Symposium, 2018年10月23日, 英語, 口頭発表（一般）
［国際会議］

ピリジン型窒素含有分子を用いた 酸素還元反応触媒における活性機構　　　　　　　　　　　　　　　
武安光太郎, 下山雄人, 古川萌子, S. K. Singh, 中村潤児
第122回触媒討論会, 2018年09月27日, 口頭発表（一般）
［国内会議］

酸化物表面で散乱された水素分子の散乱角異方性 -原子核スピンフィルタリング-　　　　　　　　　　　　　　　
武安 光太郎
光科学若手研究会, 2016年04月09日, 日本語, 口頭発表（招待・特別）
［招待講演］, ［国内会議］

分子の表面散乱・反応過程における立体効果　　　　　　　　　　　　　　　
武安 光太郎
第九回 紀州吉宗セミナー, 2016年02月12日, 日本語, 口頭発表（招待・特別）
［招待講演］, ［国内会議］

真空容器内壁での分子の脱離と圧力変化 -表面吸着状態密度の導出　　　　　　　　　　　　　　　
武安 光太郎
日本真空学会 研究例会, 2012年07月13日, 日本語, 口頭発表（招待・特別）
［招待講演］, ［国内会議］

排気曲線による真空容器内壁の吸着状態密度の導出　　　　　　　　　　　　　　　
武安 光太郎
KEK加速器セミナー, 2011年12月20日, 日本語, 口頭発表（招待・特別）
［招待講演］, ［国内会議］