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Journal Articles

Antimony from brake dust to the combined sewer collection system via road effluent under rainy conditions

Ozaki, Hirokazu*; Yoshimura, Kazuya; Asaoka, Yoshihiro*; Hayashi, Seiji*

Environmental Monitoring and Assessment, 193(6), p.369_1 - 369_9, 2021/06

Journal Articles

${it In situ}$ optical microscopy of crystal growth of graphene using thermal radiation

Terasawa, Tomoo; Taira, Takanobu*; Obata, Seiji*; Saiki, Koichiro*; Yasuda, Satoshi; Asaoka, Hidehito

Vacuum and Surface Science, 62(10), p.629 - 634, 2019/10

Graphene, an atomically thin sheet composed of sp$$^{2}$$ carbon atoms, has been the most attractive material in this decade. The fascinating properties of graphene are exhibited when it is monolayer. Chemical vapor deposition (CVD) is widely used to produce monolayer graphene selectively in large-area. Here we introduce "radiation-mode optical microscopy" which we have developed in order to realize the ${it in situ}$ observation of the CVD growth of graphene. We show the method to observe graphene as bright contrast on Cu substrates in thermal radiation images. The growth mechanism, the nucleation site and rate limiting process, revealed by the ${it in situ}$ observation is presented. Finally, we show the CVD growth of graphene on Au substrates, resulting in the tuning of the emissivity of graphene by the pre-treatment procedures. Our method is not only a way to observe the graphene growth but also shed light on the thermal radiation property of graphene.

Journal Articles

Effect of hydrogen on chemical vapor deposition growth of graphene on Au substrates

Terasawa, Tomoo; Taira, Takanobu*; Yasuda, Satoshi; Obata, Seiji*; Saiki, Koichiro*; Asaoka, Hidehito

Japanese Journal of Applied Physics, 58(SI), p.SIIB17_1 - SIIB17_6, 2019/08

 Times Cited Count:0 Percentile:0(Physics, Applied)

Chemical vapor deposition (CVD) on substrates with low C solubility such as Cu and Au is promising to grow monolayer graphene selectively in a large scale. Hydrogen is often added to control the domain size of graphene on Cu, while Au does not require H$$_{2}$$ since Ar is inert against oxidation. The effect of H$$_{2}$$ should be revealed to improve the quality of graphene on Au. Here we report the effect of H$$_{2}$$ on the CVD growth of graphene on Au substrates using in situ radiation-mode optical microscopy. The in situ observation and ex situ Raman spectroscopy revealed that whether H$$_{2}$$ was supplied or not strongly affected the growth rate, thermal radiation contrast, and compressive strain of graphene on Au. We attributed these features to the surface reconstruction of Au(001) depending on H$$_{2}$$ supply. Our results are essential to achieve the graphene growth with high quality on Au for future applications.

Journal Articles

Recent progress in the energy recovery linac project in Japan

Sakanaka, Shogo*; Akemoto, Mitsuo*; Aoto, Tomohiro*; Arakawa, Dai*; Asaoka, Seiji*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2338 - 2340, 2010/05

Future synchrotron light source using a 5-GeV energy recovery linac (ERL) is under proposal by our Japanese collaboration team, and we are conducting R&D efforts for that. We are developing high-brightness DC photocathode guns, two types of cryomodules for both injector and main superconducting (SC) linacs, and 1.3 GHz high CW-power RF sources. We are also constructing the Compact ERL (cERL) for demonstrating the recirculation of low-emittance, high-current beams using above-mentioned critical technologies.

Journal Articles

Prototype tokamak fusion power reactor based on SiC/SiC composite material, focussing on easy maintenance

Nishio, Satoshi; Ueda, Shuzo; Kurihara, Ryoichi; Kuroda, Toshimasa*; Miura, H.*; Sako, Kiyoshi*; Takase, Kazuyuki; Seki, Yasushi; Adachi, Junichi*; Yamazaki, Seiichiro*; et al.

Fusion Engineering and Design, 48(3-4), p.271 - 279, 2000/09

 Times Cited Count:16 Percentile:72(Nuclear Science & Technology)

no abstracts in English

Oral presentation

In-situ observation of CVD growth of graphene on Au by radiation-mode optical microscopy

Terasawa, Tomoo; Taira, Takanobu*; Obata, Seiji*; Yasuda, Satoshi; Saiki, Koichiro*; Asaoka, Hidehito

no journal, , 

Monolayer selective growth of graphene was achieved by chemical vapor deposition on a Cu substrate due to its low carbon solubility. In this study, we attempted the in-situ observation of chemical vapor deposition of graphene on a Au substrate with low carbon solid solubility like Cu by a radiation-mode optical microscopy. In the radiation images, the bright contrast started the growth between the trenches of the Au foil and progressed parallel to the trenches. The result of Raman mapping measurement indiceted that this contrast corresponded to graphene. In the presentation, we will also discuss the growth mechanism of graphene on the Au substrate.

Oral presentation

Radiation-mode optical microscopy for CVD growth of graphene on gold

Terasawa, Tomoo; Taira, Takanobu*; Obata, Seiji*; Yasuda, Satoshi; Saiki, Koichiro*; Asaoka, Hidehito

no journal, , 

Since the solubility of carbon in copper is very low, monolayer graphene can be selectively grown by chemical vapor deposition (CVD) on a copper substrate. Thus, CVD growth of graphene is considered the most promising technique for the next-generation electronics. Here we report the CVD growth of graphene on gold substrates which also have the low solubility of carbon. We achieved the in-situ observation of the CVD growth of graphene on a gold foil by radiation-mode optical microscopy (Rad-OM). Figure shows the Rad-OM images of a gold foil at the growth time of 15, 30, and 40 min at 900$$^{circ}$$C under Ar, H$$_{2}$$, and CH$$_{4}$$ gas flow at 240, 8, and 5 sccm, respectively. The bright islands, corresponding to graphene confirmed by Raman spectroscopy, appeared between two trenches of the gold foil and grew parallel to the trenches. We will discuss the growth kinetics of graphene on gold, on the basis of the in-situ Rad-OM observation.

Oral presentation

In-situ observation of graphene growth on low-emissivity metal substrates using thermal radiation

Terasawa, Tomoo; Obata, Seiji*; Yasuda, Satoshi; Saiki, Koichiro*; Asaoka, Hidehito

no journal, , 

no abstracts in English

Oral presentation

Concentrations and emission source estimation of unreported harmful elements in combined sewer water during the dry and wet periods in Kooriyama, Fukushima

Ozaki, Hirokazu*; Yoshimura, Kazuya; Katayose, Yuji*; Matsumoto, Takumi*; Asaoka, Yoshihiro*; Hayashi, Seiji*

no journal, , 

no abstracts in English

Oral presentation

Concentrations of heavy metals in combined sewer water drained from urban area in Koriyama, Fukushima

Ozaki, Hirokazu*; Hayashi, Seiji*; Yoshimura, Kazuya; Katayose, Yuji*; Matsumoto, Takumi*; Asaoka, Yoshihiro*

no journal, , 

no abstracts in English

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