Laser-fluence dependence of resonance-enhanced multiphoton reduction of trivalent europium

Matsuda, Shohei; Nakashima, Nobuaki*; Yokoyama, Keiichi; Taniguchi, Seiji*; Chosrowjan, H.*; Somekawa, Toshihiro*; Yatsuhashi, Tomoyuki*

Chemical Physics Letters, 802, p.139759_1 - 139759_6, 2022/09

https://doi.org/10.1016/j.cplett.2022.139759

no abstracts in English

An Electron-capture efficiency in femtosecond filamentation

Nakashima, Nobuaki*; Yatsuhashi, Tomoyuki*; Sakota, Kenji*; Iwakura, Izumi*; Hashimoto, Sena*; Yokoyama, Keiichi; Matsuda, Shohei

Chemical Physics Letters, 752, p.137570_1 - 137570_5, 2020/08

https://doi.org/10.1016/j.cplett.2020.137570

Photo-redox reactions between Eu and Eu ions are induced by laser irradiation in alcoholic solution. Efficiency, wavelength dependence, and laser-power dependence are investigated with three different lasers. Nano second laser pulses at a wavelength of 308 nm is found to cause one-photon redox reactions with a quantum yield around 0.5. Nano second laser pulses at a wavelength of 394 nm induces two-photon reduction of Eu to form Eu. When the pulse energy is 5 mJ, the quantum yield is measured to be 0.015. Although the quantum yield is one order of magnitude lower than that of the one photon reduction, reduction phenomena can be easily observed under the moderate laser field strength. Because of the two-photon nature, there should be a room to improve the efficiency by increasing the laser field strength.

Conceptual design of multipurpose compact research reactor; Annual report FY2010 (Joint research)

Imaizumi, Tomomi; Miyauchi, Masaru; Ito, Masayasu; Watahiki, Shunsuke; Nagata, Hiroshi; Hanakawa, Hiroki; Naka, Michihiro; Kawamata, Kazuo; Yamaura, Takayuki; Ide, Hiroshi; et al.

JAEA-Technology 2011-031, 123 Pages, 2012/01

JAEA-Technology-2011-031.pdf:16.08MB

The number of research reactors in the world is decreasing because of their aging. However, the planning to introduce the nuclear power plants is increasing in Asian countries. In these Asian countries, the key issue is the human resource development for operation and management of nuclear power plants after constructed them, and also the necessity of research reactor, which is used for lifetime extension of LWRs, progress of the science and technology, expansion of industry use, human resources training and so on, is increasing. From above backgrounds, the Neutron Irradiation and Testing Reactor Center began to discuss basic concept of a multipurpose low-power research reactor for education and training, etc. This design study is expected to contribute not only to design tool improvement and human resources development in the Neutron Irradiation and Testing Reactor Center but also to maintain and upgrade the technology on research reactors in nuclear power-related companies. This report treats the activities of the working group from July 2010 to June 2011 on the multipurpose low-power research reactor in the Neutron Irradiation and Testing Reactor Center and nuclear power-related companies.

A Study of existing experimental data and validation process for evaluated high energy nuclear data; Report of task force on integral test for JENDEL high energy file in japanese nuclear data committee

Oyama, Yukio; *; Watanabe, Yukinobu*; Kawano, Toshihiko*; Numajiri, M.*; Ueki, Kotaro*; *; Yamano, Naoki*; Kosako, Kazuaki*; *; et al.

JAERI-Review 98-020, 130 Pages, 1998/11

JAERI-Review-98-020.pdf:6.4MB

no abstracts in English

Coexistence effect of molybdenum ion in the laser-induced particle formation of palladium

Saeki, Morihisa; Taguchi, Tomitsugu; Matsumura, Daiju; Nakashima, Nobuaki*; Oba, Hironori

no journal, , 

no abstracts in English

Coexistence effect of molybdenum ion in the laser-induced particle formation of palladium

Saeki, Morihisa; Taguchi, Tomitsugu; Matsumura, Daiju; Nakashima, Nobuaki*; Oba, Hironori

no journal, , 

no abstracts in English

XAFS study on effect of molybdenum addition on photo-induced particle formation of palladium

Saeki, Morihisa; Matsumura, Daiju; Yomogida, Takumi; Taguchi, Tomitsugu; Tsuji, Takuya; Kusano, Shogo*; Miyazaki, Tatsuya*; Takao, Koichiro*; Oba, Hironori; Nakashima, Nobuaki*

no journal, , 

no abstracts in English

Concept of laser-assisted separation and recovery for f-electron elements

Yokoyama, Keiichi; Nakashima, Nobuaki*; Yaita, Tsuyoshi

no journal, , 

We propose a new concept for separating f-electron elements like lanthanides or actinides. These elements have similar chemical property because only the inner shell electronic configuration is different from each other. Therefore, it is considered that chemical techniques alone is hard to complete precise mutual separation between these elements. Meanwhile, the f-f transitions exhibit drastic difference for each element in their photo absorption spectra owing to the inner shell character. There is a possibility to realize precise mutual separation by applying these f-f transitions to the separation processes. In the conference, we introduce and discuss our target and a technical feature in our study plan.

Reduction of Eu by multiphoton excitation in alcohol solutions

Matsuda, Shohei; Nakashima, Nobuaki*; Yokoyama, Keiichi; Yatsuhashi, Tomoyuki*; Chosrowjan, H.*; Taniguchi, Seiji*; Somekawa, Toshihiro*

no journal, , 

The photoredox reactions of lanthanides as a photochemical separative technique proposed in the 1970s are expected to be applied for recovery and recycling of rare metals and nuclear fuel reprocessing. In this study, Eu ions in methanol and ethanol solutions were reduced to Eu ions upon irradiation with nanosecond laser pulses. Eu was observed when the laser wavelength was tuned to f-f transition bands at 394 and 465 nm. The formation rate of Eu was proportional to the square of the incident laser intensity, indicating that the photoreduction is induced by a two-photon process. The efficiency of the photoreduction in ethanol was higher than that in methanol.

Photooxidation of trivalent americium in nitric acid

Matsuda, Shohei; Yokoyama, Keiichi; Yaita, Tsuyoshi; Kobayashi, Toru; Nakashima, Nobuaki*

no journal, , 

One of the spectroscopic properties for lanthanides and actinides is that they have f-f transitions in the visible region of their spectra. Those absorption appears at specific wavelength and has narrow line width even in the liquid phase owing to shielded f electrons. It has been reported that reduction reactions of Sm, Eu, and Yb are induced by multiphoton excitation through each f-f transition depending on conditions. This photochemical process may be applicable to mutual separation of f elements. In this study, we tried to optically control the oxidation state of americium. As a result, we found that trivalent americium (Am) in nitric acid solution is oxidized to pentavalent one (AmO) during nanosecond pulsed-laser irradiation at 503 nm corresponding to the L F transition of Am. Identification and quantification of the reactants and products were performed by absorption spectroscopy. Excitation wavelength dependence and fluence dependence of the oxidation suggest that it is initiated by a resonance-enhanced multiphoton process.