Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 26

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Theoretical elucidation of Am(III)/Cm(III) separation mechanism with diamide-type ligands using relativistic density functional theory calculation

Kaneko, Masashi; Suzuki, Hideya; Matsumura, Tatsuro

Inorganic Chemistry, 57(23), p.14513 - 14523, 2018/12

 Times Cited Count:4 Percentile:50.9(Chemistry, Inorganic & Nuclear)

We elucidated the separation mechanism between Am(III) and Cm(III) ions by using two different types of diamide ligands, diglycolamide (DGA) and alkylated diamide amine (ADAAM), by means of the density functional theory technique and electron density analysis. The molecular geometries and formation reactions of the metal-ligand complexes were modeled by using [M(DGA)$$_{3}$$]$$^{3+}$$ and [M(ADAAM)(NO$$_{3}$$)$$_{3}$$(H$$_{2}$$O)]. We successfully reproduced Cm(III) selectivity over Am(III) with DGA and Am(III) selectivity over Cm(III) with ADAAM. Furthermore, we analyzed the bonding properties between the metal ion and the diamide-type ligands by using model complexes, [M(DGA)$$_{3}$$]$$^{3+}$$ and [M(ADAAM)(NO$$_{3}$$)$$_{3}$$(H$$_{2}$$O)], and revealed the differences in terms of the bond dissociation energy and the metal 5f-orbital participation in the covalency between the Am(III) and the Cm(III) complexes. It was suggested that the differences were key factors to understand the Am(III)/Cm(III) selectivity.

Journal Articles

Computational chemical analysis of Eu(III) and Am(III) complexes with pnictogen-donor ligands using DFT calculations

Kimura, Taiki*; Kaneko, Masashi; Watanabe, Masayuki; Miyashita, Sunao*; Nakashima, Satoru*

Dalton Transactions (Internet), 47(42), p.14924 - 14931, 2018/11

 Times Cited Count:2 Percentile:73.48(Chemistry, Inorganic & Nuclear)

We demonstrated density functional calculations of Eu(III) and Am(III) complexes with pnictogen-donor (X) ligands, CH$$_{3}$$)$$_{2}$$X-CH$$_{2}$$-CH$$_{2}$$-X(CH$$_{3}$$)$$_{2}$$ (X = N, P, As and Sb). We investigated the optimized structures of the cmoplexes and the Gibbs energy differences in the complex formation reactions. Those results indicated that the N- and P-donor ligands have Am(III) ion selectivity over Eu(III) ion, especially, the P-donor ligand showed the highest selectivity. The tendency of the Am(III)/Eu(III) selectivity by the pnictogen-dono ligands was found to be comparable to that of soft acid classification in hard and soft acids and bases rule. Mulliken's spin population analysis indicated that the bonding property between the metal ion and the pnictogen atoms correlated with the Am(III)/Eu(III) selectivity. In particular, the participation of f-orbital electrons of the metal ion in the covalency was indicated to have an important role for the selectivity.

Journal Articles

Variation of half-life and internal-conversion electron energy spectrum between $$^{235m}$$U oxide and fluoride

Shigekawa, Yudai*; Kasamatsu, Yoshitaka*; Yasuda, Yuki*; Kaneko, Masashi; Watanabe, Masayuki; Shinohara, Atsushi*

Physical Review C, 98(1), p.014306_1 - 014306_5, 2018/07

 Times Cited Count:1 Percentile:78.75(Physics, Nuclear)

The nuclear half-life of $$^{235m}$$U has been reported to vary depending on the chemical environment. In this study, both the half-life and the internal-conversion (IC) electron energy spectrum were measured for $$^{235m}$$U with identical chemical environments for the first time. $$^{235m}$$U oxide and fluoride samples were subjected to these measurements, and clear differences in the half-life and the energy spectrum between these samples were observed. The peaks in the energy spectra were identified with the relativistic density functional theory calculation, and the molecular orbital states of the $$^{235m}$$U oxide and fluoride estimated from the energy spectra and the calculation qualitatively explained the difference in the half-lives between the samples.

Journal Articles

Bonding study on d- and f-block coordination compounds by combining density functional calculations with M$"o$ssbauer spectroscopic parameters

Kaneko, Masashi

Hosha Kagaku, (35), p.36 - 39, 2017/03

This paper is an article for research introduction by winner of the Japan Society of Nuclear and Radiochemical Sciences Encouragement Price 2016. It was mentioned about the achievements which revealed the spin transition behavior of iron complex and the separation mechanism of actinides from lanthanides.

Journal Articles

Soft X-ray emission and absorption spectra in the C K region of sputtered amorphous carbon films

Muramatsu, Yasuji; Hirono, Shigeru*; Umemura, Shigeru*; Ueno, Yuko*; Hayashi, Takayoshi*; Grush, M. M.*; Gullikson, E. M.*; Perera, R. C. C.*

Carbon, 39(9), p.1403 - 1407, 2001/06

 Times Cited Count:17 Percentile:40.83(Chemistry, Physical)

no abstracts in English

Journal Articles

Soft X-ray emission and absorption spectra in the O K region of oxygen incorporated in microporous carbon

Muramatsu, Yasuji; Ueno, Yuko*; Ishiwata, Yoichi*; Eguchi, Ritsuko*; Watanabe, Masamitsu*; Shin, S.*; Perera, R. C. C.*

Carbon, 39(9), p.1359 - 1402, 2001/06

no abstracts in English

Journal Articles

Relativistic density functional calculations for potential energy curves of uranyl nitrate hydrate

Hirata, Masaru; Bastug, T.*; Tachimori, Shoichi; Sekine, Rika*; Onoe, Jun*; Nakamatsu, Hirohide*

Advances in Quantum Chemistry, Volume 37, p.325 - 333, 2001/00

no abstracts in English

Journal Articles

Electronic structures and chemical bonding of actinyl nitrates dihydrates

Hirata, Masaru; Tachimori, Shoichi; Sekine, Rika*; Onoe, Jun*; Nakamatsu, Hirohide*

Advances in Quantum Chemistry, Volume 37, p.335 - 351, 2001/00

no abstracts in English

Journal Articles

Chemical bonding state analysis of silicon carbide layers in Mo/SiC/Si multilayer mirrors by soft X-ray emission and absorption spectroscopy

Muramatsu, Yasuji; Takenaka, Hisataka*; Ueno, Yuko*; Gullikson, E. M.*; Perera, R. C. C.*

Applied Physics Letters, 77(17), p.2653 - 2655, 2000/10

 Times Cited Count:12 Percentile:49.08(Physics, Applied)

no abstracts in English

Journal Articles

Chemical effect on X-ray spectra induced by multiple inner-shell ionization, 2

Kawatsura, Kiyoshi*; Takeshima, Naoki*; Terazawa, Norihisa*; Aoki, Yasushi; Yamamoto, Shunya; Nashiyama, Isamu; Narumi, Kazumasa; Naramoto, Hiroshi

JAERI-Review 99-025, TIARA Annual Report 1998, p.188 - 190, 1999/10

no abstracts in English

Journal Articles

Chemical bonding of new molecules containing lithium atoms

Kudo, Hiroshi

Kagaku To Kogyo, 45(5), p.941 - 944, 1992/00

no abstracts in English

Journal Articles

Exotic molecules violating the octet rule

Kudo, Hiroshi

Kagaku, 46(11), p.748 - 752, 1991/00

no abstracts in English

Journal Articles

Morphologies of CVD ZrC crystals

Phys.Status Solidi A, 66, p.175 - 181, 1981/00

 Times Cited Count:2 Percentile:76.22(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Chemical effects on beryllium K X-ray spectra produced by heavy ion bombardment

Kawatsura, Kiyoshi; Ozawa, K.; *; *

Phys.Lett.,A, 60(4), p.327 - 329, 1977/04

no abstracts in English

Journal Articles

Effects of the chemical bond in neutron resonance

KURRI-TR-55, p.31 - 33, 1969/00

no abstracts in English

Oral presentation

Bonding properties of Eu and Am complexes with chalcogen donor ligands exhibiting the same coordination geometries

Kaneko, Masashi; Watanabe, Masayuki; Miyashita, Sunao*; Nakashima, Satoru*

no journal, , 

In this study, we discussed the stability and bonding property of Eu and Am complexes with imidodiphosphinic acid which shows the same coordination geometry for both O- and S-donor ligands. We performed the geometry optimizations by referring to single crystal structures as their starting coordinates and calculated the Gibbs energy for the stabilization toward the hydrated complex. As the results, the calculated Eu and Am complexes have the same coordination geometries for O- and S-donor complexes and reproduced the metal-ligand distances of single crystal structures. The results of Gibbs energy indicated that O-donor preferably coordinates to Eu over Am, meanwhile, S-donor selectively coordinates to Am over Eu.

Oral presentation

Separation mechanism of Am(III) from Eu(III) based on chemical bonding

Kaneko, Masashi

no journal, , 

Density functional theory (DFT) calculations have been employed to understand the equilibrium structures, electronic states, and stabilities of minor-actinides (MA) and lanthanides (Ln) complexes. An previous application of DFT calculation to the MA/Ln separation has indicated that the Am/Eu selectivity can be explained by the stability in complexation reaction. However, the origin of Am/Eu selectivity remains unclear. This study aims to understand the origin by correlating the stability of their complexes with the covalency in metal-ligand coordination bonds by means of scalar-relativistic DFT calculations. After an optimization of DFT method using benchmark study with M$"o$ssbauer spectroscopic parameters, we applied the DFT method to the separation of Am from Eu and analyzed the bonding states between metal and ligands in Eu and Am complexes. As a result, it was found that the wave functions of Eu ion with ligands have syn-phase overlap not depending on donor atoms, whereas those of Am ion have syn-phase overlap in the case of sulfur donors and anti-phase in the case of oxygen donors. This indicates that the difference in bonding states between metal and ligands is an origin in the Am/Eu selectivity.

Oral presentation

Construction of chemical bonding database for development of separation prediction code of minor-actinides

Kaneko, Masashi; Kimura, Taiki; Watanabe, Masayuki; Miyashita, Sunao*; Nakashima, Satoru*

no journal, , 

We aim to developt the prediction code for separation performance of minor-actinides from lanthanides. In this study, we constructed a chemical bonding database of Am and Eu with Group 15 and 16 element donor ligands. As the result of energy analysis using density functional theory calculations, the trend of separation behavior of Am from Eu with group 15 and 16 donor ligands correlated with the trend of soft acid classification of hard and soft acids and bases principle. As the result of bonding analysis, the donor ligands which strongly bond to Am were indicated to possess the high selectivity to Am.

Oral presentation

Benchmarking of DFT with M$"o$ssbauer isomer shift values for heavy metal complexes

Kaneko, Masashi; Watanabe, Masayuki

no journal, , 

A linear relationship between M$"o$ssbauer isomer shift values and electron densities at nucleus position assures the quantitative evaluation of the covelant interaction between a M$"o$ssbauer element and the surroundings. The evaluation of the linearity between experimental isomer shift values and estimated electron densities via quantum chemical calculation helps us to validate the computational method for estimating the bonding property. Our recent studies have demonstrated the benchmarking with the linear relationship using density functional calculations for heavy metal complexes, including $$^{99}$$Ru, $$^{151}$$Eu, $$^{189}$$Os and $$^{237}$$Np M$"o$ssbauer nuclides. The linearity was obtained with high correlation coefficient by mixing exact exchange potential into density functional. We will also present the bonding properties for the heavy metal complexes, as well as the application possibility of the computational method to the field of minor actinide partitioning.

26 (Records 1-20 displayed on this page)