研究者詳細 - 石田　高史

論文 - 石田　高史

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Development of silicon-on-insulator direct electron detector with analog memories in pixels for sub-microsecond imaging 招待有り査読有り

Takafumi Ishida , Kosei Sugie , Toshinobu Miyoshi , Yuichi Ishida , Koh Saitoh , Yasuo Arai , Makoto Kuwahara

Microscopy 73 巻 ( 6 ) 頁： 511 - 516 2024年12月

Carbonization of a Molybdenum Substrate Surface and Nanoparticles by a One-Step Method of Femtosecond Laser Ablation in a Hexane Solution 査読有り

Yoshiki Tanaka, Xi Yu, Shusaku Terakawa, Takafumi Ishida, Koh Saitoh, Hongwei Zhang, Toru Asaka, Fumihiro Itoigawa, Makoto Kuwahara, Shingo Ono

ACS Omega 8 巻 ( 8 ) 頁： 7932 - 7939 2023年2月

Static Hydrophobic Cuprous Oxide Surface Fabricated via One-Step Laser-Induced Oxidation of a Copper Substrate 査読有り

Xi Yu, Yoshiki Tanaka, Tomoki Kakiuchi, Takafumi Ishida, Koh Saitoh, Fumihiro Itoigawa, Makoto Kuwahara, Shingo Ono

Micromachines 14 巻 ( 1 ) 頁： 185 2023年1月

Extension of focal depth by electron quasi-Bessel beam in atomic-resolution scanning transmission electron microscopy 査読有り

Ishida Takafumi, Owaki Takeshi, Ohtsuka Masahiro, Kuwahara Makoto, Saitoh Koh, Kawasaki Tadahiro

APPLIED PHYSICS EXPRESS 15 巻 ( 11 ) 頁： 115001 2022年11月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Applied Physics Express

Extension of the focal depth of a sub-nanometer-sized electron probe in a scanning transmission electron microscope was demonstrated using an electron Bessel beam. We observed atomically-resolved annular dark-field scanning transmission electron microscope images of SrTiO3 in the [001] direction with defocus using an electron quasi-Bessel beam generated by a ring-shaped aperture in an aberration-corrected probe-forming system. The experimental results show that the defocus range over which images with a 0.2 nm spatial resolution can be acquired using the electron quasi-Bessel beam is three times longer than the corresponding defocus range for a conventional beam.

DOI： 10.35848/1882-0786/ac96ce

Web of Science

Scopus

Transient electron energy-loss spectroscopy of optically stimulated gold nanoparticles using picosecond pulsed electron beam 査読有り

Kuwahara Makoto, Mizuno Lira, Yokoi Rina, Morishita Hideo, Ishida Takafumi, Saitoh Koh, Tanaka Nobuo, Kuwahara Shota, Agemura Toshihide

APPLIED PHYSICS LETTERS 121 巻 ( 14 ) 頁： 143503 2022年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Applied Physics Letters

Ultrafast phenomena in gold nanotriangles (AuNTs) were investigated using a transient electron energy-loss spectroscopy (TEELS) technique under irradiation from a 150-fs pulse laser with a wavelength of 780 nm. This investigation was conducted using a time-resolved transmission electron microscopy method that was developed to measure the dynamics of nanomaterials. Enhancement of the intensity and energy-width broadening of the energy loss were observed at the EEL peaks associated with surface and bulk plasmons on the AuNTs. The TEELS measurement revealed two decay processes of 7.8 ps and longer than 100 ps that compensate for relaxation times of excited surface plasmons using transient absorption spectroscopy. The results show that the bulk and surface plasmons have the same time evolution, i.e., that the excited electrons on the surface and in the bulk have the same relaxation processes in both electron-phonon and phonon-phonon interactions. The time evolution of electronic and lattice temperatures was also estimated based on the measured relaxation time using a two-temperature model, which revealed the volume expansion of the AuNTs and clarified the energy shifts of plasmons. Details of excited electrons in nanoparticles investigated via plasmon energy loss are expected to facilitate improvement in the performance for energy harvesting of photons in nanostructure-controlled materials.

DOI： 10.1063/5.0108266

Web of Science

Scopus

Thin film growth of Ba(Zn,Fe)(2)As-2 by molecular beam epitaxy 査読有り

Ikegami R., Hatano T., Kiyozawa T., Ishida T., Tomizawa Y., Iida K., Ikuta H.

THIN SOLID FILMS 758 巻 2022年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Thin Solid Films

We have grown Ba(Zn1-xFex)2As2 thin films by molecular beam epitaxy. Epitaxial thin films with various Fe contents up to x = 0.16 were obtained by employing fluoride substrates and supplying Zn and As in excess. The film of the parent compound BaZn2As2 showed a metallic behavior in the temperature range of 50–300 K, although semiconducting behavior with a bandgap of 0.23 eV has been reported for a polycrystalline bulk sample. The metallic behavior can be ascribed to a defect layer near the film/substrate interface that was found by a cross-sectional microstructure observation. For the Fe-substituted films, on the other hand, no such defect layer was observed, and the temperature dependence of resistivity showed semiconducting behavior. BaZn2As2 is known as a parent compound of diluted magnetic semiconductors, but the magnetization measurements of the Fe doped films showed no evidence of ferromagnetic order.

DOI： 10.1016/j.tsf.2022.139420

Web of Science

Scopus

Observation of domain wall bimerons in chiral magnets 査読有り

T. Nagase, Y. So, H. Yasui, T. ishida, H. Yoshida, Y. Tanaka, K. Saitoh, N. Ikarashi, Y. Kawaguchi, M. Kuwahara, M. Nagao

Nature Communications 12 巻 ( 1 ) 頁： 3490 2021年6月

Performance of a silicon-on-insulator direct electron detector in a low-voltage transmission electron microscope 査読有り

Takafumi Ishida, Akira Shinozaki, Makoto Kuwahara, Toshinobu Miyoshi, Koh Saitoh, Yasuo Arai

Microscopy 70 巻 ( 3 ) 頁： 321 - 325 2021年6月

Intensity Interference in a Coherent Spin-Polarized Electron Beam 査読有り

M. Kuwahara, Y. Yoshida, W. Nagata, K. Nakakura, M. Furui, T. Ishida, K. Saitoh, T. Ujihara, N. Tanaka

Physical Review Letters 126 巻頁： 125501 2021年3月

Development of a voltage-applicable heating specimen holder for in situ observations of solid oxide fuel cells with an environmental transmission electron microscope 査読有り

Ishida Takafumi, Hiroshima Hideto, Higuchi Kimitaka, Tomita Masahiro, Saitoh Koh, Tanji Takayoshi

SURFACE AND INTERFACE ANALYSIS 52 巻 ( 9 ) 頁： 584 - 590 2020年8月

パルス電子波を用いた時間分解透過電子顕微鏡

桑原真人, 横井里奈, 水野りら, 冨樫将孝, 吉田優也, 永田渉, 古井雅人, 中蔵虎二郎, 石田高史

顕微鏡 55 巻 ( 3 ) 頁： 131 - 138 2020年

記述言語：日本語出版者・発行元：公益社団法人日本顕微鏡学会

<p>透過電子顕微鏡（TEM）にナノ秒を越える時間分解能を獲得させるため，パルスレーザーにより駆動する光陰極型電子源を搭載した時間分解TEMの開発が精力的に進められている．この世界の動向を俯瞰しつつ，時間分解測定により計測が可能となる計測対象を解説する．また，光陰極材料の種類と特性，それに関わる電子線特性を評価する物理量について，相対論的量子力学を復習しつつ見ていく．つぎに，負の電子親和性表面をもつ半導体フォトカソードを用いた，時間分解TEMによる実験結果を用いながら量子力学と電子波の関わりについて理解を深めていく．また，それらに内在する量子性を活用する新しい電子顕微鏡についても触れ，時間分解電子顕微鏡の高度化により期待される計測対象を解説する．</p>

DOI： 10.11410/kenbikyo.55.3_131

Efficient Measurement of the Orbital-Angular-Momentum Spectrum of an Electron Beam via a Dammann Vortex Grating 査読有り

Noguchi Yuuki, Nakayama Shota, Ishida Takafumi, Saitoh Koh, Uchida Masaya

PHYSICAL REVIEW APPLIED 12 巻 ( 6 ) 2019年12月

Smectic Liquid-Crystalline Structure of Skyrmions in Chiral Magnet Co8.5Zn7.5Mn4(110) Thin Film 査読有り

Nagase T., Komatsu M., So Y. G., Ishida T., Yoshida H., Kawaguchi Y., Tanaka Y., Saitoh K., Ikarashi N., Kuwahara M., Nagao M.

PHYSICAL REVIEW LETTERS 123 巻 ( 13 ) 2019年9月

Enhanced Hollow-cone Illumination TEM technique for Dynamical Observations of Light-elemens in Matereials 査読有り

T. Kawasaki, T. Ishida, A. Kuwabara and Y. Ikuhara

AMTC Letters 6 巻頁： 114-115 2019年

Operando STEM-EELS Observation of Anodic Reactions in Solid Oxide Fuel Cells 査読有り

6 巻頁： 112-113 2019年

環状分割検出器を用いたホローコーンSTEMによる位相再生

石田高史, 川﨑忠寛, 丹司敬義, 生田孝

顕微鏡 52 巻 ( 1 ) 頁： 13 - 18 2017年

記述言語：日本語出版者・発行元：公益社団法人日本顕微鏡学会

<p>走査透過電子顕微鏡において，試料を透過した電子波の位相変化を回復する手法の1つとして円環絞りと環状アレイ検出器を用いた位相コントラスト環状明視野法を開発した．本手法は，円環絞りを用いてホローコーンビームを作ることにより分解能を維持したまま焦点深度を拡大することができるため，運動学的な近似が成立する範囲で厚い試料の定量的な投影ポテンシャルの再生に期待が持てる．本稿では，本手法で用いる電子光学系及び位相再生のプロセスの概要，実際に開発した装置，結晶性試料を用いた原理検証結果及びイメージシミュレーションを用いた本手法の応用可能性についての検討結果について紹介する．</p>

DOI： 10.11410/kenbikyo.52.1_13

Development of electrostatic spherical aberration corrector using annular and circular electrodes 査読有り

T. Kawasaki, T. Ishida, Y. Takai, Y. Ogawa, M. Lomita, T. Matsutani, T. Kodama, T. Ikuta

Surface and Interface Analysis 48 巻 ( 11 ) 頁： 1160-1165 2016年

In situ Observation of Interfaces between Metal Electrode and Solid Oxide Electrolyte Prepared by FIB 査読有り

T. Ishida, T. Tanji, M. Tomita, K, Higuchi, K. Saitoh

AMTC Letters 5 巻頁： 46-47 2016年

Phase reconstruction in annular bright-field scanning transmission electron microscopy 査読有り

T. Ishida, T. Kawasaki, T. Tanji, T. Kodama, T. Matsutani, K. Ogai, T. Ikuta

Microscopy 64 巻頁： 69–76 2015年

Quantitative evaluation of annular bright-field phase images in STEM 査読有り

T. Ishida, T. Kawasaki, T. Tanji, T. Ikuta

Microscopy 64 巻頁： 121–128 2015年

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