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Journal Articles

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Kumada, Takayuki; Iwahara, Daisuke*

Isotope News, (798), p.26 - 27, 2025/04

no abstracts in English

Journal Articles

Fluorous and organic extraction systems; A Comparison from the perspectives of coordination structures, interfaces, and bulk extraction phases

Ueda, Yuki; Micheau, C.; Akutsu, Kazuhiro*; Tokunaga, Kohei; Yamada, Masako*; Yamada, Norifumi*; Bourgeois, D.*; Motokawa, Ryuhei

Langmuir, 40(46), p.24257 - 24271, 2024/11

 Times Cited Count:0 Percentile:0.00(Chemistry, Multidisciplinary)

Microscopic structures in liquid-liquid extraction, such as structuration between extractants or extracted complexes in bulk organic phases and at interfaces, can influence macroscopic phenomena, such as the distribution behavior of solutes, including extraction efficiency, selectivity, and phase separation of the organic phase. In this study, we correlated the macroscopic behavior of the extraction of Zr(IV) ions from nitric acid solutions with microscopic structural information in order to understand at the molecular level the key factors contributing to the higher metal ion extraction performance in the fluorous extraction system comprising fluorous phosphate (TFP) in perfluorohexane as compared to the analogous organic extraction system comprising organic phosphate (THP) in n-hexane. Extended X-ray absorption fine structure, neutron reflectometry, and small-angle neutron scattering revealed the local coordination structure around the Zr(IV) ion, the accumulation of extractant molecules at the interface, and the structuration of extractant molecules in the bulk extraction phase, respectively. In the fluorous extraction system, extractant aggregates with were formed after contact with nitric acid. In contrast, in the organic extraction system, only extractant dimers were formed. We speculate that differences in the local coordination structure around the Zr(IV) ion and the structuration of the extractant molecules in the bulk extraction phase contribute to the high Zr(IV) extraction performance in the fluorous extraction system. In particular, the size of the aggregates hardly changed with increasing Zr(IV) concentration in the fluorous phase, which may be closely related to the absence of phase splitting in the fluorous extraction system.

Journal Articles

Nanostructure analysis of composite materials using polarized neutrons and polarized protons

Kumada, Takayuki

Shiki, 63, p.2 - 5, 2024/07

We introduce recent studies of spin-contrast-variation neutron scatterings, which utilizes the property that scattering power of neutron against proton remarkably depends on their relative spin directions, to reveal nanostructure of composite materials.

Journal Articles

Interpenetration of rubber and silane coupling agent on an inorganic substrate revealed by spin-contrast-variation neutron reflectivity

Kumada, Takayuki; Iwahara, Daisuke*; Nishitsuji, Shotaro*; Akutsu, Kazuhiro*; Miura, Daisuke; Motokawa, Ryuhei; Sugita, Tsuyoshi; Torikai, Naoya*; Amino, Naoya*; Oku, Takayuki; et al.

Journal of Physical Chemistry C, 128(21), p.8797 - 8802, 2024/05

 Times Cited Count:0 Percentile:0.00(Chemistry, Physical)

We elucidated the entanglement of polybutadiene and silane coupling agent (SCA) molecules bound to Si substrates using spin-contrast-variation (SCV) neutron reflectivity (NR). In an annealed integral blend film of polybutadiene and SCA, a SCA layer generated on the Si substrate was composed of 70 vol. percent SCA molecules extended perpendicularly from the silicon substrate and entangled with 30 vol. percent polybutadiene molecules. By contrast, in an SCA-precoated polybutadiene film, the SCA-precoated layer is composed of densely packed SCA molecules forming crystal-like structure, and thus did not become entangled with the postcoated polybutadiene molecules. This poor entanglement resulted in poor binding between polybutadiene and Si substrate.

Journal Articles

Foam flotation of clay particles using a bifunctional amine surfactant

Micheau, C.; Ueda, Yuki; Motokawa, Ryuhei; Bauduin, P.*; Girard, L.*; Diat, O.*

Langmuir, 39(31), p.10965 - 10977, 2023/07

 Times Cited Count:11 Percentile:71.78(Chemistry, Multidisciplinary)

Journal Articles

Neutron reflectometry analysis of condensed water layer formation at a solid interface of epoxy resins under high humidity

Liu, Y.*; Miyata, Noboru*; Miyazaki, Tsukasa*; Shundo, Atsuomi*; Kawaguchi, Daisuke*; Tanaka, Keiji*; Aoki, Hiroyuki

Langmuir, 39(29), p.10154 - 10162, 2023/06

 Times Cited Count:11 Percentile:74.82(Chemistry, Multidisciplinary)

Journal Articles

Structure analysis of asymmetric interface using spin-contrast-variation neutron reflectometry

Kumada, Takayuki; Miura, Daisuke*; Akutsu, Kazuhiro*; Oku, Takayuki; Torikai, Naoya*; Niizeki, Tomotake*

Hamon, 32(4), p.165 - 168, 2022/11

We demonstrated the advantage of spin-contrast-variation neutron reflectometry on the structure analysis of buried interface between resin and porous silica layers. The interface structure was not reproduced by the normal Gaussian model, but by the asymmetric interface model where crosslinked polymer chains neither permeate the pore nor follow the surface roughness of the silica layer.

Journal Articles

Structure analysis of a buried interface between organic and porous inorganic layers using spin-contrast-variation neutron reflectivity

Kumada, Takayuki; Miura, Daisuke*; Akutsu, Kazuhiro*; Oishi, Kazuki*; Morikawa, Toshiaki*; Kawamura, Yukihiko*; Suzuki, Junichi*; Oku, Takayuki; Torikai, Naoya*; Niizeki, Tomotake*

Journal of Applied Crystallography, 55(5), p.1147 - 1153, 2022/10

AA2021-0903.pdf:1.06MB

 Times Cited Count:2 Percentile:30.55(Chemistry, Multidisciplinary)

Spin-contrast-variation neutron reflectivity obtains multiple reflectivity curves from a single sample and a single beam source. We used the strong point of the technique to reveal that, although methylated-perhydropolysilazane-derived silica layer has a higher porosity near the interface with acrylic urethane resin, the resin did not permeate the pore network.

Journal Articles

Analysis of the electric double layer structure formed in an ionic liquid using neutron reflectivity

Tamura, Kazuhisa; Akutsu-Suyama, Kazuhiro*; Cagnes, M.*; Darwish, T. A.*

ECS Advances (Internet), 1(2), p.020503_1 - 020503_5, 2022/06

AA2021-0622.pdf:1.08MB

The ionic liquid/Si electrode interface was investigated using neutron reflectivity. We precisely elucidated the structure of the electrical double layer formed at 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([BMIM]TFSA)/Si(100) electrode interface with the orientation of the [BMIM]TFSA molecule using a partially deuterated [BMIM]TFSA. The results revealed that [BMIM]TFSA molecules form a layered structure. Cation and anion molecules are alternatingly stacked and molecules in the first three layers are horizontally oriented to the electrode surface at E = -1.2 V, i.e., on the negatively charged electrode surface. It was also revealed that the imidazole ring in [BMIM] cation is parallel to the electrode surface.

Journal Articles

New design of a sample cell for neutron reflectometry in liquid-liquid systems and its application for studying structures at air-liquid and liquid-liquid interfaces

Akutsu-Suyama, Kazuhiro*; Yamada, Norifumi*; Ueda, Yuki; Motokawa, Ryuhei; Narita, Hirokazu*

Applied Sciences (Internet), 12(3), p.1215_1 - 1215_10, 2022/02

 Times Cited Count:6 Percentile:60.96(Chemistry, Multidisciplinary)

no abstracts in English

Journal Articles

Deep learning approach for an interface structure analysis with a large statistical noise in neutron reflectometry

Aoki, Hiroyuki; Liu, Y.*; Yamashita, Takashi*

Scientific Reports (Internet), 11(1), p.22711_1 - 22711_9, 2021/11

 Times Cited Count:12 Percentile:64.13(Multidisciplinary Sciences)

Journal Articles

SUIREN (polarized neutron reflectometer)

Takeda, Masayasu

Hamon, 31(1), p.18 - 19, 2021/02

no abstracts in English

Journal Articles

Development of spin-contrast-variation neutron reflectometry for structural analyses of multilayer films

Kumada, Takayuki; Miura, Daisuke*; Akutsu, Kazuhiro*; Suzuki, Junichi*; Torikai, Naoya*

Hamon, 30(4), p.207 - 211, 2020/11

We developed a technique of spin-contrast-variation neutron reflectivity (SCV-NR) for structural analyses of multilayer films. The SCV-NR curves of the polystyrene monolayer film were precisely reproduced using a common set of structural parameters and neutron scattering length density at each proton polarization. This result ensures that SCV-NR curves are not deformed by inhomogeneous PH due to the spin-diffusion mechanism. The number of structural parameters of the lamellar microphase-separated poly(styrene-block-isoprene) thin film is too large to determine with a single unpolarized reflectivity curve only. However, these parameters converged through the global analysis of the SCV-NR curves. In this manner, SCV-NR determines the structure of multilayer films while excluding the incorrect structural model that accidentally accounts for a single unpolarized reflectivity curve only.

Journal Articles

New progress in the observation and application of the laser-plasma in the semiconductors and dielectrics, 2; Study of non-thermal effects on femtosecond laser ablation of transparent dielectrics through the measurements of spallation dynamics

Kumada, Takayuki

Purazuma, Kaku Yugo Gakkai-Shi, 96(4), p.176 - 180, 2020/04

AA2019-0379.pdf:0.66MB

We have developed time-resolved reflectivity measurement system using femtosecond laser pulses, which can measure structure of thin films generated by non-thermal effect.

Journal Articles

Development of spin-contrast-variation neutron reflectometry for the structural analysis of multilayer films

Kumada, Takayuki; Akutsu, Kazuhiro*; Oishi, Kazuki*; Morikawa, Toshiaki*; Kawamura, Yukihiko*; Sahara, Masae*; Suzuki, Junichi*; Torikai, Naoya*

Journal of Applied Crystallography, 52(5), p.1054 - 1060, 2019/10

AA2018-0116.pdf:0.86MB

 Times Cited Count:4 Percentile:36.02(Chemistry, Multidisciplinary)

We developed a technique of spin-contrast-variation neutron reflectometry (SCV-NR). Polarized-neutron reflectivity curves of film samples vary as a function of their proton-polarization P. The P-dependent reflectivity curves of a polystyrene film was precisely reproduced using a common set of structure parameters and the P-dependent neutron scattering length. The reflectivity curve of poly (styrene-block-isoprene) (PSPI) presented a shoulder attributed to holes with the depth corresponding to one period of periodic lamellae on the free surface only at a specific P. In this way, structural information about specific surfaces or interfaces can be obtained by controlling the P.

Journal Articles

Development of dynamic nuclear polarization system for spin-contrast-variation neutron reflectometry

Kumada, Takayuki; 7 of others*

JPS Conference Proceedings (Internet), 22, p.011015_1 - 011015_5, 2018/11

Journal Articles

Magnetic field dependence of the canted spin moment around the interface between ferromagnetic Ni and antiferromagnetic FeMn revealed by the polarized neutron reflectivity

Amemiya, Kenta*; Sakamaki, Masako*; Mizusawa, Mari*; Takeda, Masayasu

JPS Conference Proceedings (Internet), 8, p.034004_1 - 034004_6, 2015/09

Journal Articles

Neutron reflectometers in J-PARC

Yamada, Norifumi*; Takeda, Masayasu; Yamazaki, Dai

Hamon, 24(4), p.288 - 295, 2014/11

no abstracts in English

Journal Articles

Neutron reflectometer

Takeda, Masayasu; Yamazaki, Dai; Hino, Masahiro*

Hamon, 24(3), p.200 - 205, 2014/08

no abstracts in English

JAEA Reports

Development of multilayer mirrors for use in the wavelength region of 4 nm

Ishino, Masahiko; Yoda, Osamu*; Koike, Masato

JAERI-Research 2005-019, 13 Pages, 2005/09

JAERI-Research-2005-019.pdf:1.46MB

We have developed soft X-ray multilayer mirrors for use around the wavelength region of 4 nm including the K-absorption edge of carbon ($$lambda = 4.4 nm$$). We have chosen Co$$_3$$O$$_4$$ and Cr as the final candidate materials for absorber layers, and SiO$$_2$$ and Sc for the spacer materials as the result of theoretical invitation. Co$$_3$$O$$_4$$/SiO$$_2$$, Co$$_3$$O$$_4$$/Sc and Cr/Sc multilayer mirrors have been fabricated by means of an ion beam sputtering (IBS) method. As the result of structure evaluations with X-ray diffraction measurement, we have found that the fabricated Co$$_3$$O$$_4$$/Sc and Cr/Sc multilayer mirrors have stable structures. Soft X-ray reflectivity measurements for fabricated multilayer mirrors are carried out in the wavelength region of 4 nm with a synchrotron radiation source. We have found that the Cr/Sc multilayer mirror has a high soft X-ray reflectivity. However, soft X-ray reflectivities below the absorption edge of carbon are reduced. The analyses obtained by EPMA and SIMS suggested that this phenomenon was attributed to contamination of carbon.

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