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Journal Articles

Density Functional Theory (DFT)-based bonding analysis correlates ligand field strength with $$^{99}$$Ru M$"o$ssbauer parameters of ruthenium-nitrosyl complexes

Kaneko, Masashi; Kato, Akane*; Nakashima, Satoru*; Kitatsuji, Yoshihiro

Inorganic Chemistry, 58(20), p.14024 - 14033, 2019/10

 Times Cited Count:3 Percentile:43.41(Chemistry, Inorganic & Nuclear)

We applied density functional theory calculations to ruthenium-nitrosyl complexes, which are known to exist in high-level radioactive waste, to give a theoretical correlation between $$^{99}$$Ru M$"o$ssbauer spectroscopic parameters ($$delta$$ and $$Delta$$$$E_{rm Q}$$) and ligand field strength ($$Delta$$$$_{rm o}$$) for the first time. The structures of the series of complexes, [Ru(NO)L$$_{5}$$] (L = Br$$^{-}$$, Cl$$^{-}$$, NH$$_{3}$$, CN$$^{-}$$), were modeled based on the corresponding single-crystal X-ray coordinates. The comparisons of the geometries and total energies between the different spin states suggested that the singlet spin state of [Ru(II)(NO$$^{+}$$)L$$_{5}$$] complexes were the most stable. The calculated results of both the $$delta$$ and $$Delta$$$$E_{rm Q}$$ values reproduced the experimental results by reported previously and increased in the order of L = Br$$^{-}$$, Cl$$^{-}$$, NH$$_{3}$$, CN$$^{-}$$. Finally, we estimated the ligand field strength ($$Delta$$$$_{rm o}$$) based on molecular orbitals, assuming C$$_{rm 4v}$$ symmetry and showed the increase of $$Delta$$$$_{rm o}$$ values in that order, being consistent with well-known spectrochemical series of ligands. The increase attributes to the strengthening of the abilities of $$sigma$$-donor and $$pi$$-acceptor of the L-ligands to the Ru atom, resulting in the increase of the $$delta$$ values.

Journal Articles

Benchmark study of DFT with Eu and Np M$"o$ssbauer isomer shifts using second-order Douglas-Kroll-Hess Hamiltonian

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

Hyperfine Interactions, 239(1), p.20_1 - 20_10, 2018/12

 Times Cited Count:2 Percentile:16.77

We optimized a mixing ratio of exchange energy between pure DFT and exact Hartree-Fock using TPSS exchange-correlation functional to estimate the accurate coordination bonds in f-block complexes by numerically benchmarking with the experimental data of M$"o$ssbauer isomer shifts for $$^{151}$$Eu and $$^{237}$$Np nuclides. Second-order Douglas-Kroll-Hess Hamiltonian with segmented all-electron relativistically contracted basis set was employed to calculate the electron densities at Eu and Np nuclei, i.e. contact densities, for each five complexes for Eu(III) and Np(IV) systems. We compared the root mean square deviation values of their isomer shifts between experiment and calculation by changing the mixing ratio of Hartree-Fock exchange parameter from 0 to 100 % at intervals of 10 %. As the result, it was indicated that the mixing ratio of 30 and 60 % for Eu and Np benchmark systems, respectively, gives the smallest deviation values. Mulliken's spin population analysis indicated that the covalency in the metal-ligand bonds for both Eu and Np complexes decreases with increasing the Hartree-Fock exchange admixture.

Journal Articles

Estimation of $$Delta$$${it R}$/${it R}$ values by benchmark study of the M$"o$ssbauer Isomer shifts for Ru, Os complexes using relativistic DFT calculations

Kaneko, Masashi; Yasuhara, Hiroki*; Miyashita, Sunao*; Nakashima, Satoru*

Hyperfine Interactions, 238(1), p.36_1 - 36_9, 2017/11

AA2016-0447.pdf:0.46MB

 Times Cited Count:2 Percentile:13.96

We aim to evaluate the validity of density functional calculations to the bonding property for Ru and Os complexes. We performed the benchmarking of theoretical computational method with $$^{99}$$Ru, $$^{189}$$Os M$"o$ssbauer isomer shifts. As the result, the computational values of the electron densities at nucleus position correlated with the experimental M$"o$ssbauer isomer shifts.

Journal Articles

Bonding study on trivalent europium complexes by combining M$"o$ssbauer isomer shifts with density functional calculations

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

Radioisotopes, 66(8), p.289 - 300, 2017/08

Scalar-relativistic density functional calculations applied to some trivalent europium complexes. Five Eu(III) complexes whose $$^{151}$$Eu M$"o$ssbauer isomer shifts vary from -1.8 to 0.5 mm/s are referred by previously reported results. Geometrical optimizations of their complexes reproduces the experimental coordination structures. Single-point calculations are applied to their optimized geometries at three density functionals, namely, BP86, B3LYP, and B2PLYP, to obtain their electron densities at Eu nucleus. A comparison of the linearity between the electron densities and the corresponding $$^{151}$$Eu M$"o$ssbauer isomer shifts reveals that B2PLYP functional shows the best linearity. Electron population and bond analyses indicate that d- and f-orbital electrons of Eu ion in the complexes are found to be correlated to the experimental $$^{151}$$Eu M$"o$ssbauer isomer shifts. This indicates that the d- and f-orbital electrons are involved in the covalent interaction of the coordination bond between the Eu ion and the ligands.

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

A Spin-crossover phenomenon depending on the environment around an iron atom for the assembled coordination polymers

Nakashima, Satoru*; Kaneko, Masashi

Advances in Chemistry Research, Vol.36, p.171 - 195, 2017/01

Spin-crossover (SCO) phenomena of the assembled coordination polymers are introduced. When the bridging ligand is flexible like 1,2-bis(4-pyridyl)ethane, 1,3-bis(4-pyridyl)propane, a variety of assembled structure can be obtained, depending on the conformer of the ligand and the guest molecules. Guest-dependent SCO phenomena of the assembled iron complexes are shown. Density functional theory is applied to know the cause of guest-dependent SCO phenomena. The validity of an iron mono-nucleus model is evaluated for the coordination polymers. It is shown that SCO occurs or not depends on the local structure around iron ion.

Journal Articles

$$^{61}$$Ni synchrotron radiation-based M$"o$ssbauer spectroscopy of nickel-based nanoparticles with hexagonal structure

Masuda, Ryo*; Kobayashi, Yasuhiro*; Kitao, Shinji*; Kurokuzu, Masayuki*; Saito, Makina*; Yoda, Yoshitaka*; Mitsui, Takaya; Hosoi, Kohei*; Kobayashi, Hirokazu*; Kitagawa, Hiroshi*; et al.

Scientific Reports (Internet), 6, p.20861_1 - 20861_8, 2016/02

 Times Cited Count:6 Percentile:57.99(Multidisciplinary Sciences)

Journal Articles

Attempt to measure magnetic hyperfine fields in metallic thin wires under spin Hall conditions using synchrotron-radiation M$"o$ssbauer spectroscopy

Mibu, Ko*; Mitsui, Takaya; Tanaka, Masaaki*; Masuda, Ryo*; Kitao, Shinji*; Kobayashi, Yasuhiro*; Yoda, Yoshitaka*; Seto, Makoto*

Journal of Applied Physics, 117(17), p.17E126_1 - 17E126_4, 2015/05

 Times Cited Count:2 Percentile:87.26(Physics, Applied)

Journal Articles

$$^{57}$$Fe polarization dependent synchrotron M$"o$ssbauer spectroscopy using a diamond phase plate and an iron borate nuclear Bragg monochromator

Mitsui, Takaya; Imai, Yasuhiko*; Masuda, Ryo*; Seto, Makoto*; Mibu, Ko*

Journal of Synchrotron Radiation, 22(2), p.427 - 435, 2015/03

 Times Cited Count:5 Percentile:61.85(Instruments & Instrumentation)

Journal Articles

High-pressure radiative conductivity of dense silicate glasses with potential implications for dark magmas

Murakami, Motohiko*; Goncharov, A. F.*; Hirao, Naohisa*; Masuda, Ryo*; Mitsui, Takaya; Thomas, S. M.*; Bina, C. R.*

Nature Communications (Internet), 5, p.5428_1 - 5428_6, 2014/11

 Times Cited Count:13 Percentile:47.97(Multidisciplinary Sciences)

Journal Articles

Development of $$^{125}$$Te synchrotron-radiation-based M$"o$ssbauer spectroscopy

Kurokuzu, Masayuki*; Kitao, Shinji*; Kobayashi, Yasuhiro*; Saito, Makina*; Masuda, Ryo*; Mitsui, Takaya; Yoda, Yoshitaka*; Seto, Makoto*

Hyperfine Interactions, 226(1), p.687 - 691, 2014/04

 Times Cited Count:2 Percentile:36.51

Journal Articles

$$^{125}$$Te synchrotron-radiation-based M$"o$ssbauer spectroscopy of Fe$$_{1.1}$$Te and FeTe$$_{0.5}$$Se

Kurokuzu, Masayuki*; Kitao, Shinji*; Kobayashi, Yasuhiro*; Saito, Makina*; Masuda, Ryo*; Mitsui, Takaya; Yoda, Yoshitaka*; Seto, Makoto*

Journal of the Physical Society of Japan, 83(4), p.044708_1 - 044708_4, 2014/04

 Times Cited Count:1 Percentile:85.88(Physics, Multidisciplinary)

Journal Articles

Synchrotron radiation-based M$"o$ssbauer spectra of $$^{174}$$Yb measured with internal conversion electrons

Masuda, Ryo*; Kobayashi, Yasuhiro*; Kitao, Shinji*; Kurokuzu, Masayuki*; Saito, Makina*; Yoda, Yoshitaka*; Mitsui, Takaya; Iga, Fumitoshi*; Seto, Makoto

Applied Physics Letters, 104(8), p.082411_1 - 082411_5, 2014/02

 Times Cited Count:10 Percentile:49.6(Physics, Applied)

A detection system for synchrotron-radiation (SR)-based M$"o$ssbauer spectroscopy was developed to enhance the nuclear resonant scattering counting rate and thus increase the available nuclides. In the system, a windowless avalanche photodiode (APD) detector was combined with a vacuum cryostat to detect the internal conversion (IC) electrons and fluorescent X-rays accompanied by nuclear de-excitation. As a feasibility study, the SR-based M$"o$ssbauer spectrum using the 76.5 keV level of $$^{174}$$Yb was observed without $$^{174}$$Yb enrichment of the samples. The counting rate was five times higher than that of our previous system, and the spectrum was obtained within 10 h. This result shows that nuclear resonance events can be more efficiently detected by counting IC electrons for nuclides with high IC coefficients. Furthermore, the windowless detection system enables us to place the sample closer to the APD elements and is advantageous for nuclear resonant inelastic scattering measurements. Therefore, this detection system can not only increase the number of nuclides accessible in SR-based M$"o$ssbauer spectroscopy but also allows the nuclear resonant inelastic scattering measurements of small single crystals or enzymes with dilute probe nuclides that are difficult to measure with the previous detection system.

Journal Articles

Correlation between $$^{237}$$Np M$"o$essbauer parameter and crystal structure of neptunyl compounds

Saeki, Masakatsu

Nippon Kessho Gakkai-Shi, 46(6), p.415 - 420, 2004/12

no abstracts in English

JAEA Reports

Radiochemical studies of iodine, tritium and neptunium

Saeki, Masakatsu

JAERI-Review 2004-011, 54 Pages, 2004/03

JAERI-Review-2004-011.pdf:5.21MB

In this review, experimental results on studies of radioactive iodine, tritium and neptunium are summarized. On studies of radioactive iodine, from various experimental results, the process establishing the formation mechanism of organic iodides was fully described. On the basis of formation mechanism, possibilities for the formation of organic iodides under nuclear reactor accidents and so on were also discussed. On studies of tritium, three topics were concisely described on the isotopic composition of tritium gases, the chemical forms and the diffusivity of tritium in various materials, and the sorption and desorption behaviors of tritium on surfaces of various materials. On the neptunium chemistry, the relationship between the structure of neptunium compound and the Moessbauer isomer shift and experimental results on neptunyl(VI) hydroxides were discussed.

Journal Articles

$$^{238}$$U and $$^{57}$$Fe M$"o$ssbauer spectroscopic study of UFe$$_{2}$$

Tsutsui, Satoshi; Nakada, Masami; Kobayashi, Yasuhiro*; Nasu, Saburo*; Haga, Yoshinori; Onuki, Yoshichika

Hyperfine Interactions, 133(1-4), p.17 - 21, 2001/11

no abstracts in English

Journal Articles

$$^{238}$$U M$"o$ssbauer study of UPt$$_{3}$$

Tsutsui, Satoshi; Nakada, Masami; Nasu, Saburo*; Haga, Yoshinori; Yamamoto, Etsuji; Kimura, Noriaki*; Onuki, Yoshichika

Journal of Magnetism and Magnetic Materials, 226-230(Part.1), p.87 - 88, 2001/05

no abstracts in English

Journal Articles

$$^{238}$$U M$"o$ssbauer spectroscopic study of UX$$_{2}$$(X=Ga, P, As, Sb)

Tsutsui, Satoshi; Nakada, Masami; Nasu, Saburo*; Haga, Yoshinori; Homma, Tetsuo; Yamamoto, Etsuji; Tokiwa, Yoshifumi; Aoki, Dai*; Wi$'s$niewski, P.*; Onuki, Yoshichika

Journal of the Physical Society of Japan, Vol.70, Supplement A, p.34 - 36, 2001/05

no abstracts in English

Journal Articles

$$^{238}$$U M$"o$ssbauer study on the magnetic properties of uranium-based heavy fermion superconductors

Tsutsui, Satoshi; Nakada, Masami; Nasu, Saburo*; Haga, Yoshinori; Homma, Tetsuo; Yamamoto, Etsuji; Okuni, Hitoshi*; Onuki, Yoshichika

Hyperfine Interactions, 126(1-4), p.335 - 340, 2000/07

 Times Cited Count:6 Percentile:60.9

no abstracts in English

Journal Articles

$$^{57}$$Fe M$"o$ssbauer spectroscopic study of U$$_{6}$$Fe

Tsutsui, Satoshi; Kobayashi, Yasuhiro*; Nakada, Masami; Nasu, Saburo*; Yamamoto, Etsuji; Haga, Yoshinori; Onuki, Yoshichika

Journal of the Physical Society of Japan, 69(6), p.1764 - 1768, 2000/06

 Times Cited Count:2 Percentile:73.94(Physics, Multidisciplinary)

no abstracts in English

39 (Records 1-20 displayed on this page)