On the adsorption and reactivity of element 114, flerovium

Yakushev, A.*; Lens, L.*; Dllmann, Ch. E.*; Khuyagbaatar, J.*; Jger, E.*; Krier, J.*; Runke, J.*; Albers, H. M.*; Asai, Masato; Block, M.*; et al.

Frontiers in Chemistry (Internet), 10, p.976635_1 - 976635_11, 2022/08

https://doi.org/10.3389/fchem.2022.976635

Flerovium (Fl, element 114) is the heaviest element chemically studied so far. The first chemical experiment on Fl suggested that Fl is a noble-gas-like element, while the second studies suggested that Fl has a volatile-metal-like character. To obtain more reliable conclusion, we performed further experimental studies on Fl adsorption behavior on Si oxide and gold surfaces. The present results suggest that Fl is highly volatile and less reactive than the volatile metal, Hg, but has higher reactivity than the noble gas, Rn.

Study of quasielastic barrier distributions as a step towards the synthesis of superheavy elements with hot fusion reactions

Tanaka, Taiki*; Morita, Kosuke*; Morimoto, Koji*; Kaji, Daiya*; Haba, Hiromitsu*; Boll, R. A.*; Brewer, N. T.*; Van Cleve, S.*; Dean, D. J.*; Ishizawa, Satoshi*; et al.

Physical Review Letters, 124(5), p.052502_1 - 052502_6, 2020/02

https://doi.org/10.1103/PhysRevLett.124.052502

Online chemical adsorption studies of Hg, Tl, and Pb on SiO and Au surfaces in preparation for chemical investigations on Cn, Nh, and Fl at TASCA

Lens, L.*; Yakushev, A.*; Dllmann, Ch. E.*; Asai, Masato; Ballof, J.*; Block, M.*; David, H. M.*; Despotopulos, J.*; Di Nitto, A.*; Eberhardt, K.*; et al.

Radiochimica Acta, 106(12), p.949 - 962, 2018/12

AA2018-0417.pdf:0.99MB

https://doi.org/10.1515/ract-2017-2914

Online gas-solid adsorption studies with single atom quantities of Hg, Tl, and Pb on SiO and Au surfaces were carried out using short-lived radioisotopes with half-lives in the range of 4-49 s. This is a model study to measure adsorption enthalpies of superheavy elements Cn, Nh, and Fl. The short-lived isotopes were produced and separated by the gas-filled recoil separator TASCA at GSI. The products were stopped in He gas, and flushed into gas chromatography columns made of Si detectors whose surfaces were covered by SiO or Au. The short-lived Tl and Pb were successfully measured by the Si detectors with the SiO surface at room temperature. On the other hand, the Hg did not adsorb on the SiO surface, but adsorbed on the Au surface. The results demonstrated that the adsorption properties of short-lived Hg, Tl, and Pb could be studied with this setup, and that this method is applicable to the experiment for Cn, Nh, and Fl.

Study of the reaction Ca + Cm Lv at RIKEN-GARIS

Kaji, Daiya*; Morita, Kosuke*; Morimoto, Koji*; Haba, Hiromitsu*; Asai, Masato; Fujita, Kunihiro*; Gan, Z.*; Geissel, H.*; Hasebe, Hiroo*; Hofmann, S.*; et al.

Journal of the Physical Society of Japan, 86(3), p.034201_1 - 034201_7, 2017/03

https://doi.org/10.7566/JPSJ.86.034201

The fusion reaction of Ca + Cm Lv was studied using the gas-filled recoil-ion separator GARIS at RIKEN. A total of seven and spontaneous-fission decay chains were observed, which would originate from the reaction products of the element 116, Lv and Lv. Decay properties observed in the chains are in good agreement with the previously published ones. However, one of the chains showed a discrepancy, indicating the new spontaneous-fission branch in Cn or the production of the new isotope Lv.

Production of Nb and Ta for chemical studies of element 105, Db, using the GARIS gas-jet system

Huang, M.*; Haba, Hiromitsu*; Murakami, Masashi*; Asai, Masato; Kaji, Daiya*; Kanaya, Jumpei*; Kasamatsu, Yoshitaka*; Kikunaga, Hidetoshi*; Kikutani, Yuki*; Komori, Yukiko*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 304(2), p.845 - 849, 2015/05

https://doi.org/10.1007/s10967-014-3877-4

A technique to utilize radioisotopes of Nb and Ta was developed for chemical studies of element 105, Db, by coupling a gas-jet transport system to the RIKEN gas-filled recoil ion separator (GARIS). The short-lived Nb and Ta were produced with nuclear reactions using a F beam whose energy was the same as that to produce Db. Then, they were separated with GARIS and extracted to a chemistry laboratory with the gas-jet transport system. By changing only magnetic field of GARIS and inserting an energy degrader and a shutter for recoil ions, we could deliver the Nb and Ta to a chemistry device for Db without changing other experimental conditions.

Sulfate complexation of element 104, Rf, in HSO/HNO mixed solution

Li, Z.*; Toyoshima, Atsushi; Asai, Masato; Tsukada, Kazuaki; Sato, Tetsuya; Sato, Nozomi; Kikuchi, Takahiro; Nagame, Yuichiro; Schdel, M.; Pershina, V.*; et al.

Radiochimica Acta, 100(3), p.157 - 164, 2012/03

https://doi.org/10.1524/ract.2012.1898

Decay properties of Bh and Db produced in the Cm + Na reaction

Morita, Kosuke*; Morimoto, Koji*; Kaji, Daiya*; Haba, Hiromitsu*; Ozeki, Kazutaka*; Kudo, Yuki*; Sato, Nozomi*; Sumita, Takayuki*; Yoneda, Akira*; Ichikawa, Takatoshi*; et al.

Journal of the Physical Society of Japan, 78(6), p.064201_1 - 064201_6, 2009/06

https://doi.org/10.1143/JPSJ.78.064201

Decay properties of an isotope Bh and its daughter nucleus Db produced by the Cm(Na,5) reaction were studied by using a gas-filled recoil separator coupled with a position-sensitive semiconductor detector. Bh was clearly identified from the correlation of the known nuclide, Db. The obtained decay properties of Bh and Db are consistent with those observed in the 113 chain, which provided further confirmation of the discovery of 113.

Production and decay properties of Bh and its daughter nuclei

Morimoto, Koji*; Morita, Kosuke*; Kaji, Daiya*; Haba, Hiromitsu*; Ozeki, Kazutaka*; Kudo, Yuki*; Sato, Nozomi; Sumita, Takayuki*; Yoneda, Akira*; Ichikawa, Takatoshi*; et al.

no journal, , 

A nuclide, Bh, is the great-grand-daughter of 113 that is produced in the Bi + Zn reaction. The identification was based on a genetic link to the known daughter nucleus Db by alpha-decays. The main purpose of this work is to provide further confirmation of the production and identification of the isotope 113. As a present result, a state in Bh, which decays by an alpha emission with the energies ranging from 9.05 to 9.23 MeV, feeds a state in Db, which decays by alpha emission and by SF with a previously known half-life. The result provided a further confirmation of the production and identification of the isotope of the 113th element, 113, studied by a research group at RIKEN.

Sulfate complexation of element 104, Rf, in HSO/HNO mixed solution ([H] = 1.0 M)

Li, Z.; Toyoshima, Atsushi; Asai, Masato; Tsukada, Kazuaki; Sato, Tetsuya; Sato, Nozomi; Kikuchi, Takahiro; Schdel, M.*; Nagame, Yuichiro; Liang, X. H.*; et al.

no journal, , 

Cation-exchange behavior of Rf (T = 78 s) produced in the Cm(O, 5n) reaction was studied on a "one-atom-at-a-time" scale in HSO (0.15-0.69 M)/HNO mixed solutions ([H] = 1.0 M) using an automated ion-exchange separation apparatus coupled with the detection system for alpha-spectroscopy. It was found that adsorption probability (%ads) of Rf on cation-exchange resin decreases with increasing [HSO], showing a successive formation of its sulfate complexes. Rf exhibited much weaker formation of the complexes than the lighter homologues Zr and Hf, which is qualitatively in good agreement with theoretical calculations including relativistic effects.

Production of Sg via the Cm(Ne,5)Sg reaction

Haba, Hiromitsu*; Oe, Kazuhiro*; Ozeki, Kazutaka*; Kasamatsu, Yoshitaka*; Kaji, Daiya*; Kikunaga, Hidetoshi*; Kudo, Hisaaki*; Kudo, Yuki*; Komori, Yukiko*; Sato, Nozomi; et al.

no journal, , 

RIKEN group has investigated the performance of the system using an isotope of element 106, Sg, produced in the Cm(Ne,5) reaction. Alpha-particles of Sg separated with a GAs-filled Recoil Ion Separator (GARIS) and extracted to a chemistry laboratory were successfully identified with a rotating wheel system for -spectrometry under low background conditions. As a result, two isomeric states in Sg, Sg (-particle energy MeV, half-life s) and Sg ( MeV, s), were identified. The cross sections for the Cm(Ne,5) reactions at 118 MeV were roughly evaluated to be 200 pb for Sg and 170 pb for Sg.