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西本 究*; Tang, J.*; 小川 修一*; 吉越 章隆; 石塚 眞治*; 渡辺 大輝*; 寺岡 有殿; 高桑 雄二*
no journal, ,
Metastable oxygen molecule has long lifetime of dissociation on Si(111) surface. We reported that the number of adsorbed oxygen atoms at the completion of Langmuir-type adsorption on Si(111) surface increases about three times with increasing temperature from room temperature to 873 K. In this study to clarify the role of metastable oxygen molecules in the initial oxide growth, real-time photoelectron spectroscopy techniques were used to measure time evolutions of oxygen uptake on partially oxidized Si(111) surface after oxygen supply was stopped. We concluded that the decrease of work function is ascribed to dissociation of metastable oxygen molecules, suggesting metastable oxygen molecules are concerned with the oxide growth until Langmuir-type adsorption is completed.
7 studied by real-time photoelectron spectroscopy and theoretical calculationsTang, J.*; 西本 究*; 小川 修一*; 吉越 章隆; 石塚 眞治*; 渡辺 大輝*; 寺岡 有殿; 高桑 雄二*
no journal, ,
To clarify the influence of adsorbed oxygen molecules; O
in the oxidation of Si(111)77 surface, the initial oxidation kinetics were investigated by real-time photoelectron spectroscopy using He resonance line and synchrotron radiation at SPring-8, and theoretical calculations. The O2p uptakes indicate that Langmuir-type adsorption is in progress. When the supply of O
gas was stopped at the oxide coverage of 50%, however, the O2p uptakes has almost no decrease and slightly decreased at 863 K and 883 K, respectively, while it steeply decreased at 913 K and eventually no oxide remained on Si(111) after 5000 s. O2p intensities decrease at slower rate when O supply was stopped at the larger oxide coverage. The observed changes of decomposition rate are ascribed to those of oxygen adsorption states. A surface reaction model is proposed to make clear the phase transition taking into account the role of O.
朝岡 秀人; 魚住 雄輝; 横山 有太; 山口 憲司
no journal, ,
自己組織化によるナノ構造制御には、成長カイネティクスを左右する表面ストレス制御がキーテクノロジーとなる。われわれは複雑なSi(111)再構成構造に内在する等方ストレスを、レーザーによる基板のたわみを実測したストレス遷移と、電子線を利用したRHEEDの同時測定を通して評価した。その結果、バルク構造を持つ水素終端表面と、水素終端のない清浄再構成表面とのストレス差を実験的に捉えることに成功するなど、ナノ構造とストレスとの密接な関係を見いだした。
-FeSi thin film fabricated on Si and silicon-on-insulator substrates笹瀬 雅人*; 山本 博之; 志村 憲一郎*; 山口 憲司
no journal, ,
本研究では、Si及びSOI(silicon on insulator)基板上に成膜した-FeSi薄膜について薄膜及び界面の差異を透過型電子顕微鏡(TEM)断面観察,X線元素マッピングにより検証したものである。ナノレベルの構造、化学状態を含む元素分布の差異を解析するとともに発光特性に及ぼす影響について議論を行う。
横山 有太; 魚住 雄輝; 朝岡 秀人
no journal, ,
本研究では、ストライプ構造を有するSi(110)-162再構成表面へGe原子をMBEにより蒸着することで、新たなSi-Geナノ構造の作製を目指した。室温のSi表面へGeをおよそ1原子層蒸着した後、700
Cで加熱することで、基板の162構造とは異なる方向、間隔をもつ新たなストライプ構造が形成されることを見いだした。これは、表面のSi原子とGe原子が混ざり合ったSi-Geによる構造であると考えられる。また、Geの蒸着量や加熱温度により、ストライプの方向や間隔が変化することも明らかとなった。この表面は、特定の方向のみに沿ったストライプ構造により構成されており、大きな異方性をもつ。本表面上へ薄膜を作製した場合、薄膜への異方的ストレス印加が期待される。薄膜へのストレス印加による表面物性の変化は非常に興味深い分野であり、本研究で得られた表面を用いることで、今後さらなる研究の発展が期待される。
Al foil catalystsXu, Y.*; Ma, Y.*; 櫻井 惇也*; 寺岡 有殿; 吉越 章隆; 出村 雅彦*; 平野 敏幸*
no journal, ,
We found that NiAl shows high catalytic activity for methanol decomposition and methane steam reforming as catalysts of hydrogen production. It is possible to enhance catalytic activity by modifying the NiAl foil by a pre-steam treatment followed by a reduction with H gas flow. We investigated the effect of the steam treatment and H reduction on the surface morphology of NiAl foil using synchrotron radiation X-ray photoemission spectroscopy. Although the metallic Ni2p
and 2p
peaks were detected before the steam treatment, the metallic Ni was significantly decreased and NiO appeared after the steam treatment, suggesting that most of the metallic Ni was oxidized. After the hydrogen reduction, the metallic Ni increased again, indicating that the NiO was reduced. These fine metallic Ni particles formed on the foil surface contribute to the enhanced catalytic activity.
神谷 潤一郎; 荻原 徳男; 發知 英明; 林 直樹; 金正 倫計
no journal, ,
J-PARC 3GeVシンクロトロンにおける一つの課題は、周回ビーム軌道への不必要な磁場の影響を遮断し、安定したビーム軌道を得ることである。ビームに対して不必要な磁場を最も効果的に遮蔽をする最善の方法は、最もビームに近い場所でビームの周りを磁性材料で完全に覆うことである。つまりビームラインの真空容器を磁性材料化することが、完全な磁場遮蔽であるといえる。我々は、現在漏洩磁場によりビーム軌道に影響がでているJ-PARC 3GeVシンクロトロン出射部の真空容器に対し、磁性材料化を適用することとした。良い磁気性能及び真空性能を達成するためには真空中での高温熱処理が効果的であることを発見し、詳細な条件出しを行った。フランジ,ビームパイプ,ベローズという全ての部品を磁性体材料で製作を行い、最終的に上前述の熱処理を行った。それらの真空容器をビームラインへ設置することで、ビーム軌道のズレ及びビームロスを低減することに成功した。この結果、加速器運転の安定性が向上した。
荻原 徳男; 引地 裕輔; 神谷 潤一郎; 金正 倫計
no journal, ,
The 3 GeV Rapid Cycling Synchrotron (RCS) in the Japan Accelerator Research Complex (J-PARC) project is planned to generate a high-power beam of 1 MW. In order to supply continuously the beam of 1 MW it is important to reduce the beam loss thoroughly. Thus the non-disruptive and fast-response beam diagnostic tools for extensive researches have been strongly required. To realize the fast non-disruptive beam profile detection, we intended to apply the molecular beam technique for making the compact and large-scale gas-sheet target. Monte Carlo simulations demonstrate the generation of large-scale gas-sheet targets in a vacuum by a thin concentric slit with a large aperture. Here gas is introduced from the outside toward the center, leading to the appearance of a large-scale gas sheet around the center. With inner and outer diameters of 200 and 400, respectively, and a gap of 0.1, the generated gas sheet had a diameter of 130 and thickness of less than 0.4 (half width), where all the valuables are expressed in ratio.
小泉 欧児*; 井上 勝*; 荻原 徳男; 神谷 潤一郎; 金正 倫計
no journal, ,
In the 3 GeV Rapid Cycling Synchrotron (RCS) in the Japan Accelerator Research Complex (J-PARC) project, large-scale bellows were needed to adjust the gap between the ceramic ducts and between the ceramic ducts and the transport ducts. The space for setting the bellows are so narrow that the requirements for the bellows were severe. Typical free length and inner diameter of the bellows were 100 mm and 300-400 mm, respectively; nevertheless, the spring rate of less than 100 N/mm was needed. Then pure Ti and SUS 316L steel were selected as materials for bellows; Ti bellows were set in the high radiation field because of its small residual radioactivity, and the SUS 316L bellows in the other area. We have developed the hydro-formed bellows as flexible as welded bellows. Then, we have developed the new polishing method "wet mechanical polishing". Using the fluid containing the minute particles of abrasive we have succeeded to polish the inner-surface of the complicated shape. The average roughness factor Ra of 0.05 
m was obtained. After assembling, mainly to reduce the hydrogen inventory in the bellows, all the bellows have been vacuum-fired for 10h at 650C for Ti bellows, and at 750C for SUS316L bellows, respectively. Thus we have succeeded in developing the large-scale hydro-formed bellows with the inner-surface polishing, as flexible as welded bellows.