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Journal Articles

Application of photoluminescence microspectroscopy; A Study on transfer of uranyl and europium ions on dry silica gel plate

Kusaka, Ryoji; Watanabe, Masayuki

Journal of Nuclear Science and Technology, 57(9), p.1046 - 1050, 2020/09

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

Journal Articles

Journal Articles

Development of lanthanide and actinide studies toward interface chemistry using vibrational sum frequency generation spectroscopy

Kusaka, Ryoji

Hosha Kagaku, (41), p.31 - 33, 2020/03

This commentary article introduced researches involved in encouragement award 2019 of the Japan Society of Nuclear and Radiochemical Sciences. Vibrational sum frequency generation (VSFG) spectroscopy and interfacial studies of solvent extraction of lanthanides and actinides using VSFG spectroscopy were described.

Journal Articles

A Spectroscopic technique for analysis developed in the field of unclear energy

Kusaka, Ryoji

Bunko Kenkyu, 67(6), p.239 - 240, 2018/12

A spectroscopic technique for analysis developed by collaboration between Japan Atomic Energy Agency (JAEA) and Quantum and Radiological Science and Technology (QST) is discussed for readers outside the field of nuclear energy. This paper introduces a quantitative analysis for $$^{107}$$Pd radioisotope contained in a spent nuclear fuel by using laser-induced photoreduction and inductively coupled plasma mass spectrometry (ICP-MS). The importance and problems of quantitative analysis for radioisotopes in spent nuclear fuels are described, and the principle, advantages, and future applications of the spectroscopic technique are discussed.

Journal Articles

Mechanism of phase transfer of uranyl ions; A Vibrational sum frequency generation spectroscopy study on solvent extraction in nuclear reprocessing

Kusaka, Ryoji; Watanabe, Masayuki

Physical Chemistry Chemical Physics, 20(47), p.29588 - 29590, 2018/12

 Times Cited Count:6 Percentile:46.87(Chemistry, Physical)

Mechanistic understanding of solvent extraction of uranyl ions (UO$$_{2}$$$$^{2+}$$) by tributyl phosphate (TBP) will help improve the technology for the treatment and disposal of spent nuclear fuels. So far, it has been believed that uranyl ions in the aqueous phase are adsorbed to a TBP-enriched organic/aqueous interface, form complexes with TBP at the interface, and are extracted into the organic phase. Here we show that uranyl-TBP complex formation does not take place at the interface using vibrational sum frequency generation (VSFG) spectroscopy and propose an alternative extraction mechanism that uranyl nitrate, UO$$_{2}$$(NO$$_{3}$$)$$_{2}$$, passes through the interface and forms the uranyl-TBP complex, UO$$_{2}$$(NO$$_{3}$$)$$_{2}$$(TBP)$$_{2}$$, in the organic phase.

Journal Articles

The Structure of a lanthanide complex at an extractant/water interface studied using heterodyne-detected vibrational sum frequency generation

Kusaka, Ryoji; Watanabe, Masayuki

Physical Chemistry Chemical Physics, 20(4), p.2809 - 2813, 2018/01

 Times Cited Count:6 Percentile:46.87(Chemistry, Physical)

Solvent extraction plays an integral part in the separation and purification of metals. Because extractants generally used as complexing agents for metal extractions, such as di-(2-ethylhexyl)phosphoric acid (HDEHP) for lanthanide extractions, are amphiphilic, they come to the organic/water interface, and the interface plays a crucial role as the site of the formation of metal complexes and subsequent transfer reaction to an organic phase. Despite the importance of the interface for solvent extractions, however, molecular-level structure of the interface is unclear because of experimental difficulty. Here we studied structure of a trivalent europium (Eu$$^{3+}$$) complex with HDEHP formed at HDEHP monolayer/water interface by heterodyne-detected vibrational sum frequency generation (HD-VSFG) spectroscopy. The study on the HDEHP/water interface enables us to investigate the structure of the interfacial Eu$$^{3+}$$ complex by excluding the migration of Eu$$^{3+}$$ into an organic phase after the complex formation at the interface. The interface-selective vibrational Im$$chi$$$$^{(2)}$$ spectra observed by HD-VSFG of HDEHP/Eu(NO$$_{3}$$)$$_{3}$$ aqueous solution interface in the 2800-3500 cm$$^{-1}$$ region indicate that Eu$$^{3+}$$ at the HDEHP/water interface is bonded by HDEHP from the air side and by water molecules from the water side. To the best of our knowledge, such metal complex structures have not been identified in the organic or water solutions.

Journal Articles

Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex, 2; Neutron scattering instruments

Nakajima, Kenji; Kawakita, Yukinobu; Ito, Shinichi*; Abe, Jun*; Aizawa, Kazuya; Aoki, Hiroyuki; Endo, Hitoshi*; Fujita, Masaki*; Funakoshi, Kenichi*; Gong, W.*; et al.

Quantum Beam Science (Internet), 1(3), p.9_1 - 9_59, 2017/12

The neutron instruments suite, installed at the spallation neutron source of the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC), is reviewed. MLF has 23 neutron beam ports and 21 instruments are in operation for user programs or are under commissioning. A unique and challenging instrumental suite in MLF has been realized via combination of a high-performance neutron source, optimized for neutron scattering, and unique instruments using cutting-edge technologies. All instruments are/will serve in world-leading investigations in a broad range of fields, from fundamental physics to industrial applications. In this review, overviews, characteristic features, and typical applications of the individual instruments are mentioned.

Journal Articles

Present status of the negative ion based neutral beam injector for JT-60U

Oga, Tokumichi; Umeda, Naotaka; Akino, Noboru; Ebisawa, Noboru; Grisham, L. R.*; Hikida, Shigenori*; Honda, Atsushi; Ito, Takao; Kawai, Mikito; Kazawa, Minoru; et al.

Review of Scientific Instruments, 73(2), p.1058 - 1060, 2002/02

 Times Cited Count:12 Percentile:42.55(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Study of increasing the beam power on the negative ion based neutral beam injector for JT-60U

Kuriyama, Masaaki; Akino, Noboru; Ebisawa, Noboru; Grisham, L. R.*; Hikida, Shigenori*; Honda, Atsushi; Ito, Takao; Kawai, Mikito; Kazawa, Minoru; Kusaka, Makoto*; et al.

Fusion Engineering and Design, 56-57(Part.A), p.523 - 527, 2001/10

 Times Cited Count:5 Percentile:59.28(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Development of negative ion based NBI system for JT-60U

Umeda, Naotaka; Akino, Noboru; Ebisawa, Noboru; Grisham, L. R.*; Hikida, Shigenori*; Honda, Atsushi; Ito, Takao; Kawai, Mikito; Kazawa, Minoru; Kusaka, Makoto*; et al.

Fusion Technology, 39(2-Part2), p.1135 - 1139, 2001/03

no abstracts in English

Journal Articles

Operation of the positive-ion based NBI system for JT-60U

Ohara, Hiroshi; Akino, Noboru; Ebisawa, Noboru; Hikida, Shigenori*; Honda, Atsushi; Ito, Takao; Kawai, Mikito; Kazawa, Minoru; Kusaka, Makoto*; Kuriyama, Masaaki; et al.

Fusion Technology, 39(2-Part2), p.1140 - 1144, 2001/03

no abstracts in English

Journal Articles

Beam performance of negative-ion based NBI system for JT-60

Ito, Takao; Akino, Noboru; Ebisawa, Noboru; Grisham, L. R.*; Honda, Atsushi; Hu, L.*; Kawai, Mikito; Kazawa, Minoru; Kuriyama, Masaaki; Kusaka, Makoto*; et al.

Fusion Engineering and Design, 51-52, p.1039 - 1047, 2000/11

 Times Cited Count:14 Percentile:31.29(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Power flow in the negative-ion based neutral beam injection for JT-60

Kuriyama, Masaaki; Akino, Noboru; Ebisawa, Noboru; Grisham, L. R.*; Hikida, Shigenori*; Honda, Atsushi; Ito, Takao; Kawai, Mikito; Kazawa, Minoru; Kusaka, Makoto*; et al.

Review of Scientific Instruments, 71(2), p.751 - 754, 2000/02

 Times Cited Count:17 Percentile:30.63(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Increasing the beam power of the JT-60 negative ion based neutral beam system

Kuriyama, Masaaki; Akino, Noboru; Ebisawa, Noboru; Grisham, L. R.*; Hikida, Shigenori*; Honda, Atsushi; Ito, Takao; Kawai, Mikito; Kazawa, Minoru; Kusaka, Makoto*; et al.

Proceedings of the 18th IEEE/NPSS Symposium on Fusion Engineering (SOFE '99), p.133 - 136, 1999/00

no abstracts in English

Oral presentation

A Spectroscopic study on interface toward improvement of solvent extraction method for high-level liquid waste

Kusaka, Ryoji; Watanabe, Masayuki

no journal, , 

no abstracts in English

Oral presentation

A Heterodyne-detected vibrational sum frequency generation study on structure of a lanthanide complex at metal extractant monolayer/water interfaces

Kusaka, Ryoji; Watanabe, Masayuki

no journal, , 

Solvent extraction (liquid-liquid extraction) is a significantly important technique for the separation and purification of lanthanides. Because of the amphiphilic nature of extractants, such as di-(2-ethylhexyl)phosphoric acid (HDEHP) used for the solvent extraction of lanthanides, the interface plays a crucial role as the site of the formation of lanthanide-extractant complexes and the subsequent transfer reaction to an organic phase. Here we studied the structure of a europium(III) (Eu$$^{3+}$$) complex with HDEHP formed at an HDEHP monolayer/water interface by heterodyne-detected vibrational sum frequency generation (HD-VSFG) spectroscopy. The vibrational spectra of the interface observed by HD-VSFG in the CH and OH stretching region demonstrate that not only HDEHP but also water molecules are bonded to Eu$$^{3+}$$ at the interface. This structure of the interfacial Eu$$^{3+}$$ complex is intermediated between those of the complexes in the aqueous and organic bulk phases, suggesting that in the process of the solvent extraction of Eu$$^{3+}$$ by HDEHP extractant, Eu$$^{3+}$$ forms the intermediate complex with HDEHP and water at the interface and, subsequently, the transfer of Eu$$^{3+}$$ into an organic phase occurs.

Oral presentation

Surface of uranyl aqueous solution studied by heterodyne-detected vibrational sum frequency generation spectroscopy

Kusaka, Ryoji; Watanabe, Masayuki

no journal, , 

The solvent extraction utilizing the complex formation between uranyl and tributyl phosphate (TBP) is important as a method for treating spent nuclear fuel. Since TBP is surface active, it is believed that the uranyl-TBP complex is formed at the organic/TBP/water interface, and the complex is extracted into the organic phase. However, the structure of the uranyl-TBP complex formed at the interface is controversial. In this study, the structure of the uranyl-TBP complex was investigated by heterodyne-detected vibrational sum frequency generation spectroscopy at the surface of an aqueous solution of uranyl and TBP (TBP molecular layer/aqueous solution interface). Surprisingly, it is found that uranyl-TBP complex does not form at the interface.

Oral presentation

Mechanism of liquid-liquid solvent extraction of uranyl by tributyl phosphate; A Study using vibrational sum frequency generation spectroscopy

Kusaka, Ryoji; Watanabe, Masayuki

no journal, , 

Liquid-liquid solvent extraction of uranyl using tributyl phosphate (TBP) is a significantly important technique in treatments of spent nuclear fuels. In the solvent extraction, TBP comes to an organic/aqueous interface and forms an organic/TBP monolayer/aqueous interface because of the surface activity of TBP. At the interface, it is believed that the complex formation between uranyl and TBP takes place, and subsequently the uranyl-TBP complex transfers to an organic phase. However, the structure of the uranyl-TBP complex formed at the interface is controversial. This is partly because of no experimental studies on molecular-level structure at interfaces pertaining to the solvent extraction of uranyl. Recently, we proposed that an extractant/aqueous interface, formed on the surface of an aqueous solution, is a good model of an organic/extractant/aqueous interface, to investigate the structure of interfacial metal complexes using vibrational sum frequency generation (VSFG) spectroscopy. In the present study, we investigated the structure of theuranyl-TBP complex at the TBP/uranyl aqueous solution interface by VSFG spectroscopy. Surprisingly, interface-selective vibrational spectra obtained by VSFG suggests that uranyl does not form a complex with TBP at the TBP/uranyl aqueous solution interface. This result proposes that we should reconsider the mechanism of the solvent extraction of uranyl by TBP.

Oral presentation

Solvent extraction mechanism studied by vibrational sum frequency generation spectroscopy

Kusaka, Ryoji; Watanabe, Masayuki

no journal, , 

In general solvent extraction, an aqueous phase where metal ions are dissolved and an organic phase where an extractant is dissolved are brought into contact with each other, and the metal is extracted from the aqueous phase to the organic phase as a metal complex. Since the extractant used is poorly soluble in water and surface active, it is considered that complex formation between metal and extractant takes place at the interface and then the metal is extracted into the organic phase. However, due to experimental difficulties, the phase transfer mechanism occurring at the interface is unknown. One of the reasons for the difficulties to observe the metal complex at the interface is that the metal complex moves to the organic phase after the complex formation at the interface. In order to observe the metal complex at the interface, we removed the organic phase so that we can trap the metal complex at the extractant/water interface (the surface of aqueous solution). The structure of the metal complex at the interface is investigated using sum frequency generation (VSFG) spectroscopy to elucidate the solvent extraction mechanism.

Oral presentation

Solvent extraction mechanism of uranium studied by sum frequency generation spectroscopy

Kusaka, Ryoji; Watanabe, Masayuki

no journal, , 

no abstracts in English

39 (Records 1-20 displayed on this page)