Refine your search:     
Report No.
 - 
Search Results: Records 1-16 displayed on this page of 16
  • 1

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

Production of $$^{266}$$Bh in the $$^{248}$$Cm($$^{23}$$Na,5$$n$$)$$^{266}$$Bh reaction and its decay properties

Haba, Hiromitsu*; Fan, F.*; Kaji, Daiya*; Kasamatsu, Yoshitaka*; Kikunaga, Hidetoshi*; Komori, Yukiko*; Kondo, Narumi*; Kudo, Hisaaki*; Morimoto, Koji*; Morita, Kosuke*; et al.

Physical Review C, 102(2), p.024625_1 - 024625_12, 2020/08

 Times Cited Count:0 Percentile:100(Physics, Nuclear)

Journal Articles

First ionization potentials of Fm, Md, No, and Lr; Verification of filling-up of 5f electrons and confirmation of the actinide series

Sato, Tetsuya; Asai, Masato; Borschevsky, A.*; Beerwerth, R.*; Kaneya, Yusuke*; Makii, Hiroyuki; Mitsukai, Akina*; Nagame, Yuichiro; Osa, Akihiko; Toyoshima, Atsushi; et al.

Journal of the American Chemical Society, 140(44), p.14609 - 14613, 2018/11

 Times Cited Count:13 Percentile:26.3(Chemistry, Multidisciplinary)

The first ionization potential (IP$$_1$$) yields information on valence electronic structure of an atom. IP$$_1$$ values of heavy actinides beyond einsteinium (Es, Z = 99), however, have not been determined experimentally so far due to the difficulty in obtaining these elements on scales of more than one atom at a time. Recently, we successfully measured IP$$_1$$ of lawrencium (Lr, Z = 103) using a surface ionization method. The result suggests that Lr has a loosely-bound electron in the outermost orbital. In contrast to Lr, nobelium (No, Z = 102) is expected to have the highest IP$$_1$$ among the actinide elements owing to its full-filled 5f and the 7s orbitals. In the present study, we have successfully determined IP$$_1$$ values of No as well as fermium (Fm, Z = 100) and mendelevium (Md, Z = 101) using the surface ionization method. The obtained results indicate that the IP$$_1$$ value of heavy actinoids would increase monotonically with filling electrons up in the 5f orbital like heavy lanthanoids.

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.

Oral presentation

Electrolytic reduction studies of Mo and W towards the reduction of seaborgium

Toyoshima, Atsushi; Asai, Masato; Attallah, M. F.*; Goto, Naoya*; Gupta, N. S.*; Haba, Hiromitsu*; Huang, M.*; Kanaya, Jumpei*; Kaneya, Yusuke; Kasamatsu, Yoshitaka*; et al.

no journal, , 

Towards electrolytic reduction of Sg, batch-wise electrolytic reduction of carrier-free $$^{93m}$$Mo and $$^{176,181}$$W radiotracers was studied using a flow electrolytic column (FEC). The electrolyzed samples from a FEC were chemically analyzed by solvent extraction with TOA and HDEHP to separate and identify reduced species from the stable Mo(VI) and W(VI) ones based on their different extraction behavior. $$^{93m}$$Mo and $$^{176, 181}$$W were applied as radiotracers. We also performed cyclic voltammetry and UV/Vis absorption spectrometry of macro amounts of Mo and W in acidic solutions to obtain information on redox reactions of these elements under given conditions. In the conference, the present status of the preparatory reduction experiments with Mo and W will be presented.

Oral presentation

Electrolytic reduction of Mo and W as lighter homologues of seaborgium

Toyoshima, Atsushi; Miyashita, Sunao*; Oe, Kazuhiro*; Kitayama, Yuta*; Lerum, H. V.*; Goto, Naoya*; Kaneya, Yusuke; Komori, Yukiko*; Mitsukai, Akina*; Vascon, A.; et al.

no journal, , 

no abstracts in English

Oral presentation

Developments towards aqueous phase chemistry of transactinide elements

Toyoshima, Atsushi; Oe, Kazuhiro*; Asai, Masato; Attallah, M. F.*; Goto, Naoya*; Gupta, N. S.*; Haba, Hiromitsu*; Kaneko, Masashi*; Kaneya, Yusuke; Kasamatsu, Yoshitaka*; et al.

no journal, , 

Due to short half-lives less than 10 s and extremely low production rates, transactinide elements heavier than seaborgium (Sg) are produced on an atom per hour scale. Therefore, a continuous rapid chemistry assembly is required to study aqueous-phase chemistry of these heaviest elements. In the present study, we started developments of a continuous chemistry assembly. Our first attempt was made in on-line experiments with Mo and W, lighter homologs of Sg, to optimize a chemistry assembly consisting of a newly developed membrane degasser as an interface between gas-jet and aqueous phase, a flow electrolytic column apparatus utilized to control oxidation states of Mo and W ions, and the continuous liquid-liquid extraction apparatus of SISAK for separation. In the conference, present status of the developments will be presented.

Oral presentation

First ionization potentials of heavy actinides

Sato, Tetsuya; Asai, Masato; Kaneya, Yusuke*; Tsukada, Kazuaki; Toyoshima, Atsushi; Mitsukai, Akina*; Takeda, Shinsaku*; Vascon, A.*; Sakama, Minoru*; Sato, Daisuke*; et al.

no journal, , 

The first ionization potential (IP$$_1$$) yields information on valence electronic structure of an atom. IP$$_1$$ values of heavy actinides beyond einsteinium (Es, Z = 99), however, have not been determined experimentally so far due to the difficulty in obtaining these elements on scales of more than one atom at a time. Recently, we successfully measured IP$$_1$$ of lawrencium (Lr, Z = 103) using a surface ionization method. The result suggests that Lr has a loosely-bound electron in the outermost orbital. In contrast to Lr, nobelium (No, Z = 102) is expected to have the highest IP$$_1$$ among the actinide elements owing to its full-filled 5f and the 7s orbitals. In the present study, we have successfully determined IP$$_1$$ values of No as well as fermium (Fm, Z = 100) and mendelevium (Md, Z = 101) using the surface ionization method. The obtained results indicate that the IP$$_1$$ value of heavy actinoids would increase monotonically with filling electrons up in the 5f orbital like heavy lanthanoids.

Oral presentation

Adsorption behavior of lawrencium (Lr) on a tantalum surface

Sato, Tetsuya; Kaneya, Yusuke*; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Mitsukai, Akina*; Osa, Akihiko; Makii, Hiroyuki; Nishio, Katsuhisa; Hirose, Kentaro; et al.

no journal, , 

The ground state electronic configuration of lawrencium (Lr, Z =103) is predicted to be [Rn]$$5f^{14}7s^27p_{1/2}$$, which is different from that of the lanthanide homolog Lu [Xe]$$4f^{14}6s^25d$$ due to strong relativistic effects. According to semi-empirical considerations, volatility of Lr is expected to be higher than that of Lu. We have investigated adsorption behavior of $$^{256}$$Lr, which was produced in the reaction of $$^{249}$$Cf($$^{11}$$B, 4n), on a tantalum (Ta) metal surface using a surface ion-source installed into the isotope separator on-line (ISOL) at the JAEA tandem accelerator facility. The observed adsorption behavior of $$^{256}$$Lr was similar to those of Tb and Lu which have relatively higher adsorption enthalpy on Ta surface. It implies that Lr would have low volatility like such as Lu and Tb.

Oral presentation

Adsorption behavior of lawrencium (Lr, Z = 103) on a tantalum surface

Sato, Tetsuya; Kaneya, Yusuke*; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Mitsukai, Akina*; Osa, Akihiko; Makii, Hiroyuki; Hirose, Kentaro; Nagame, Yuichiro; et al.

no journal, , 

Our experimental results on the first ionization potential measurement of lawrencium (Lr, element 103) have strongly suggested that the Lr atom has a [Rn]$$7s^25f^{14}7p_{1/2}$$ configuration as a result of the influence of strong relativistic effects. The configuration is different from that expected from the lanthanide homologue, lutetium (Lu). According to a semi-empirical consideration, it is expected that the change of the electronic configuration leads higher volatility of Lr than that of Lu. In this work, adsorption behaviors of Lr and various short-lived rare earth isotopes on a tantalum surface were investigated via observation of their surface ionization efficiencies. It was found that Lr would behave like low volatile rare earth elements such as Lu contrary to the semi-empirical expectation.

Oral presentation

Measurement of mass-symmetric spontaneous fission of $$^{259}$$Lr

Asai, Masato; Kamada, Hiroki*; Shigekawa, Yudai*; Tsukada, Kazuaki; Sato, Tetsuya; Toyoshima, Atsushi; Mitsukai, Akina; Nagame, Yuichiro; Nishio, Katsuhisa; Hirose, Kentaro; et al.

no journal, , 

To clarify the fission mechanism of mass-symmetric spontaneous fissions observed around the neutron-rich Fm region, we have measured kinetic energies and mass distribution of spontaneous-fission fragments in this nuclear region precisely. The experiment was performed at the JAEA tandem accelerator facility using an on-line isotope separator (ISOL). The mass-separated $$^{259}$$Lr nuclei were implanted into thin foil, and two fragments of their spontaneous fission were coincidently measured with two Si detectors. The spontaneous fission of $$^{259}$$Lr was found to show a narrow symmetric mass distribution. On the other hand, their total kinetic energy TKE was found to be low, which is apparently different from the high-TKE symmetric fissions observed in the Fm isotopes. This indicates that the fission mechanisms of these two symmetric fissions are different.

Oral presentation

Adsorption of lawrencium (Lr) on a metallic tantalum (Ta) surface

Kaneya, Yusuke*; Tomitsuka, Tomohiro; Sato, Tetsuya; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Mitsukai, Akina; Makii, Hiroyuki; Hirose, Kentaro; Osa, Akihiko; et al.

no journal, , 

Oral presentation

First ionization energies of heavy actinides

Nagame, Yuichiro; Sato, Tetsuya; Asai, Masato; Kaneya, Yusuke*; Makii, Hiroyuki; Mitsukai, Akina; Osa, Akihiko; Sch$"a$del, M.*; Toyoshima, Atsushi; Tsukada, Kazuaki; et al.

no journal, , 

Oral presentation

Adsorption of lawrencium on a metallic tantalum surface at high temperature

Kaneya, Yusuke*; Asai, Masato; Sato, Tetsuya; Tomitsuka, Tomohiro; Tsukada, Kazuaki; Toyoshima, Atsushi; Mitsukai, Akina; Makii, Hiroyuki; Hirose, Kentaro; Osa, Akihiko; et al.

no journal, , 

To study the influence of the valence 7p$$_{1/2}$$ electronic orbital on chemical properties of lawrencium, a measurement of the adsorption enthalpy of lawrencium was carried out. A new method using a surface ionization technique coupled to an on-line isotope separator was developed, which enabled one to measure temperature dependence of lawrencium surface adsorption on a metallic tantalum surface at high temperature up to 2800 K. The temperature dependences of adsorption of lawrencium as well as various lanthanide elements were investigated with this method, and the adsorption enthalpy of lawrencium was successfully extracted.

Oral presentation

Adsorption behavior of lawrencium on a tantalum surface

Sato, Tetsuya; Kaneya, Yusuke*; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Mitsukai, Akina*; Osa, Akihiko; Makii, Hiroyuki; Hirose, Kentaro; Nagame, Yuichiro; et al.

no journal, , 

Our experimental results on the first ionization potential measurement of lawrencium (Lr, element 103) have strongly suggested that the Lr atom has a [Rn]$$7s^25f^{14}7p_{1/2}$$ configuration as a result of the influence of strong relativistic effects. The configuration is different from that expected from the lanthanide homologue, lutetium (Lu). According to a semi-empirical consideration, it is expected that the change of the electronic configuration leads higher volatility of Lr than that of Lu. In this work, adsorption behaviors of Lr and various short-lived rare earth isotopes on a tantalum surface were investigated via observation of their surface ionization efficiencies. It was found that Lr would behave like low volatile rare earth elements such as Lu contrary to the semi-empirical expectation.

Oral presentation

Measurements of the first ionization potentials of heavy actinides

Sato, Tetsuya; Asai, Masato; Kaneya, Yusuke*; Tsukada, Kazuaki; Toyoshima, Atsushi; Mitsukai, Akina*; Takeda, Shinsaku*; Vascon, A.*; Sakama, Minoru*; Sato, Daisuke*; et al.

no journal, , 

The first ionization potential (IP$$_1$$) yields information on valence electronic structure of an atom. IP$$_1$$ values of heavy actinides beyond einsteinium (Es, Z = 99), however, have not been determined experimentally so far due to the difficulty in obtaining these elements on scales of more than one atom at a time. Recently, we successfully measured IP$$_1$$ of lawrencium (Lr, Z = 103) using a surface ionization method. The result suggests that Lr has a loosely-bound electron in the outermost orbital. In contrast to Lr, nobelium (No, Z = 102) is expected to have the highest IP$$_1$$ among the actinide elements owing to its full-filled 5f and the 7s orbitals. In the present study, we have successfully determined IP$$_1$$ values of No as well as fermium (Fm, Z = 100) and mendelevium (Md, Z = 101) using the surface ionization method. The obtained results indicate that the IP$$_1$$ value of heavy actinoids would increase monotonically with filling electrons up in the 5f orbital like heavy lanthanoids.

Oral presentation

Anion-exchange behavior of Db in HF/HNO$$_{3}$$ solution

Kato, Mizuho*; Adachi, Sadia*; Toyoshima, Atsushi*; Tsukada, Kazuaki; Asai, Masato; Haba, Hiromitsu*; Yokokita, Takuya*; Komori, Yukiko*; Shigekawa, Yudai*; Sueki, Keisuke*

no journal, , 

A few studies have been so far performed on aqueous chemistry of Db, the group-5 superheavy element, by anion-exchange experiments in HF and HF/HNO$$_{3}$$ mixture solutions. Although the distribution coefficient (Kd) of Db was shown to trend to Ta $$>$$ Nb $$>$$ Db $$>$$ Pa in the group-5 homologs and pseudo-homolog elements, its chemical species has not been clarified. In this work, for identification of fluoride species of Db, we performed anion-exchange experiments of Nb, Ta, and Db in HF/1.0 M HNO$$_{3}$$ mixture solutions by using an automated rapid chemistry apparatus, ARCA.

16 (Records 1-16 displayed on this page)
  • 1