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.

Determination of fusion barrier distributions from quasielastic scattering cross sections towards superheavy nuclei synthesis

Tanaka, Taiki*; Narikiyo, Yoshihiro*; Morita, Kosuke*; Fujita, Kunihiro*; Kaji, Daiya*; Morimoto, Koji*; Yamaki, Sayaka*; Wakabayashi, Yasuo*; Tanaka, Kengo*; Takeyama, Mirei*; et al.

Journal of the Physical Society of Japan, 87(1), p.014201_1 - 014201_9, 2018/01

https://doi.org/10.7566/JPSJ.87.014201

Excitation functions of quasielastic scattering cross sections for the Ca + Pb, Ti + Pb, and Ca + Cm reactions were successfully measured by using the gas-filled recoil-ion separator GARIS. Fusion barrier distributions were extracted from these data, and compared with the coupled-channels calculations. It was found that the peak energies of the barrier distributions for the Ca + Pb and Ti + Pb systems coincide with those of the 2n evaporation channel cross sections for the systems, while that of the Ca + Cm is located slightly below the 4n evaporation ones. This results provide us helpful information to predict the optimum beam energy to synthesize superheavy nuclei.

Complex chemistry with complex compounds

Eichler, R.*; Asai, Masato; Brand, H.*; Chiera, N. M.*; Di Nitto, A.*; Dressler, R.*; Dllmann, Ch. E.*; Even, J.*; Fangli, F.*; Goetz, M.*; et al.

EPJ Web of Conferences, 131, p.07005_1 - 07005_7, 2016/12

https://doi.org/10.1051/epjconf/201613107005

In recent years gas-phase chemical studies assisted by physical pre-separation allowed for the productions and investigations of fragile single molecular species of superheavy elements. The latest highlight is the formation of very volatile hexacarbonyl compound of element 106, Sg(CO). Following this success, second-generation experiments were performed to measure the first bond dissociation energy between the central metal atom and the surrounding ligand. The method using a tubular decomposition reactor was developed and successfully applied to short-lived Mo(CO), W(CO), and Sg(CO).

Solid-liquid extraction of Mo and W by Aliquat 336 from HCl solutions toward extraction chromatography experiments of Sg

Komori, Yukiko*; Yokokita, Takuya*; Kasamatsu, Yoshitaka*; Haba, Hiromitsu*; Toyoshima, Atsushi; Toyomura, Keigo*; Nakamura, Kohei*; Kanaya, Jumpei*; Huang, M.*; Kudo, Yuki*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 303(2), p.1385 - 1388, 2015/02

https://doi.org/10.1007/s10967-014-3476-4

We studied solid-liquid extraction behavior of carrier-free Mo and W radiotracers onto an Aliquat 336-loaded resin from HCl solutions toward extraction chromatography experiments of element 106, seaborgium(Sg). Distribution coefficients () of Mo and W on the resin were determined as a function of HCl concentration by a batch method. On-line extraction chromatography of Mo and W was also carried out in 2-8 M HCl solutions with an automated rapid chemistry apparatus. The order of extraction probability from 2 to 8 M HCl was MoW, which reflected the order of the values in the batch experiment.

Production of Db in the Cm(F,5)Db reaction and decay properties of Db and Lr

Haba, Hiromitsu*; Huang, M.*; Kaji, Daiya*; Kanaya, Jumpei*; Kudo, Yuki*; Morimoto, Koji*; Morita, Kosuke*; Murakami, Masashi*; Ozeki, Kazutaka*; Sakai, Ryutaro*; et al.

Physical Review C, 89(2), p.024618_1 - 024618_11, 2014/02

https://doi.org/10.1103/PhysRevC.89.024618

Production of Sg in the Cm(Ne,5)Sg reaction and decay properties of two isomeric states in Sg

Haba, Hiromitsu*; Kaji, Daiya*; Kudo, Yuki*; Morimoto, Koji*; Morita, Kosuke*; Ozeki, Kazutaka*; Sakai, Ryutaro*; Sumita, Takayuki*; Yoneda, Akira*; Kasamatsu, Yoshitaka*; et al.

Physical Review C, 85(2), p.024611_1 - 024611_11, 2012/02

https://doi.org/10.1103/PhysRevC.85.024611

Two isomeric states in Sg, i.e, Sg and Sg were produced in the Cm(Ne,5) reaction. Decay properties of Sg were investigated with a rotating-wheel apparatus for and spontaneous fission (SF) spectrometry under low background condition attained by a gas-jet transport system coupled to the RIKEN gas-filled recoil ion separator. Based on genetically correlated - (-) and -SF decay chains, 18 and 24 events were assigned to Sg and Sg, respectively. The half-life and -particle energy of Sg were measured to be s and MeV, respectively, and those of Sg were s and MeV.

Solvent extraction of heavy actinides (III) with HDEHP

Takayama, Reona*; Oe, Kazuhiro*; Komori, Yukiko*; Fujisawa, Hiroyuki*; Kuriyama, Ai*; Kikutani, Yuki*; Kikunaga, Hidetoshi*; Kasamatsu, Yoshitaka*; Yoshimura, Takashi*; Takahashi, Naruto*; et al.

no journal, , 

The extraction behavior of trivalent actinides (Am, Cm, Cf, Es, and Fm) into di(2-ethylhexyl)phosphoric acid, HDEHP, in benzene from HNO was studied together with lanthanides. The extraction constants, values, of lanthanides, Am, Cm, Cf, and Es were determined by a batch method using stable lanthanide isotopes and radiotracers of Am, Cm, Cf, and Es, respectively, while that of Fm was measured with Fm which was produced in the U(O,4n) reaction and was on-line supplied by a gas-jet method at the AVF cyclotron of RCNP, Osaka University. The values were determined by the slope analysis for the variation of the distribution ratio as a function of the concentration of HDEHP. We found that the of Fm is smaller than that of Dy in spite of the similar ionic radii while those of other actinides are almost the same as those of each lanthanide with a similar ionic radius.

Confirmations of the synthesis of 113 produced by the Bi(Zn,n)113 reaction

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

no journal, , 

We performed the experiment to synthesize an isotope of the element 113 produced by a Bi(Zn,n)113 reaction using a gas-filled recoil ion separator (GARIS) at RIKEN. Two decay chains were observed, and assigned to those originating from an isotope 113. Both chains were connected into the previously known decays of Bh and Db via previously unknown decays of 113, Rg, and Mt. Although the Bh was known nuclide, a number of atoms reported so far was limited. In order to study more precise decay property of the Bh, we performed the direct production of Bh by the Cm(Na,5n)Bh reaction. In this experiment, the Bh was clearly identified from the correlation of the 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.