[en] We developed a gas-jet transport system coupled to the GAs-filled Recoil Ion Separator GARIS at the RIKEN Linear Accelerator as a novel technique for superheavy element (SHE) chemistry. The isotopes of ²⁶¹Rf (atomic number Z = 104), ²⁶²Db (Z = 105), and ²⁶⁵Sg (Z = 106) useful for chemistry studies were produced in the ²⁴⁸Cm(¹⁸O,5n), ²⁴⁸Cm(¹⁹F,5n), and ²⁴⁸Cm(²²Ne,5n) reactions, respectively, and they were extracted to a chemistry laboratory by the gas-jet method after the separation by GARIS (1-4). The production and decay properties of those isotopes were investigated in detail for future chemistry studies using a rotating wheel apparatus for α and SF spectrometry. Recently, the chemical synthesis and gas-chromatographic analysis of the first organometallic compound of SHEs, Sg(CO)₆, were successfully conducted with preseparated ²⁶⁵Sg. In the conference, preliminary results on the production of Bh (Z = 107) isotopes in the ²⁴⁸Cm(²³Na,xn) reactions will also be presented. (author)

[en] A gas-jet transport system has been installed to the RIKEN GAs-filled Recoil Ion Separator, GARIS to start up SuperHeavy Element (SHE) chemistry. This system is a promising approach for exploring new frontiers in SHE chemistry: background radioactivities from unwanted by-products are suppressed, a high gas-jet transport yield is achieved, and new chemical reactions can be investigated. Useful radioisotopes of "2"6"1Rf"a","b, "2"6"2Db, and "2"6"5Sg"a","b for chemical studies were produced in the reactions of "2"4"8Cm("1"8O,5n)"2"6"1Rf"a","b, "2"4"8Cm("1"9F,5n)"2"6"2Db, and "2"4"8Cm("2"2Ne,5n)"2"6"5Sg"a","b, respectively. They were successfully extracted to a chemistry laboratory by the gas-jet method. Production and decay properties of "2"6"1Rf"a","b, "2"6"2Db, and "2"6"5Sg"a","b were investigated in detail with the rotating wheel apparatus for α- and spontaneous fission spectrometry. Present status and perspectives of the SHE chemistry at GARIS are also briefly presented.

[en] An isothermal gas-chromatographic (IGC) device has been developed and tested for on-line gas phase studies of volatile oxychlorides of short-lived group-5 transition metals. Radioisotopes of niobium and tantalum, produced in nuclear fusion evaporation reactions, are directly flushed into the IGC setup by an inert gas-jet. Oxychloride compounds are formed by the addition of SOCl₂ and O₂. Parameters influencing the formation and transport of NbOCl₃ and TaOCl₃ are discussed. For nuclides with half-lives (t_1/2) of about 30 s, an overall efficiency of 7% is obtained, rendering the IGC setup suitable for the chemical exploration of ²⁶²Db (t_1/2 = 34 s). (author)

[en] An isothermal gas-chromatographic (IGC) device has been developed and tested for on-line gas phase studies of volatile oxychlorides of short-lived group-5 transition metals. Radioisotopes of niobium and tantalum, produced in nuclear fusion evaporation reactions, are directly flushed into the IGC setup by an inert gas-jet. Oxychloride compounds are formed by the addition of SOCl₂ and O₂. Parameters influencing the formation and transport of NbOCl₃ and TaOCl₃ are discussed. For nuclides with half-lives (t_1/2) of about 30 s, an overall efficiency of 7% is obtained, rendering the IGC setup suitable for the chemical exploration of ²⁶²Db (t_1/2 = 34 s).

[en] The radioisotopes of ²⁶¹Rf, ²⁶²Db, and ²⁶⁵Sg were produced in the reactions of ²⁴⁸Cm(¹⁸O,5n)²⁶¹Rf, ²⁴⁸Cm(¹⁹F,5n)²⁶²Db, and ²⁴⁸Cm(²²Ne,5n)²⁶⁵Sg, respectively, using a gas-jet transport system coupled to the RIKEN gas-filled recoil ion separator, GARIS. Production and decay properties of those nuclides were investigated in detail with a rotating wheel apparatus for ∼ and spontaneous fission spectrometry under low background conditions. (author)

[en] Extraction behavior of carrier-free Nb and Ta with tributyl phosphate (TBP) from HF solutions was studied by a batch method. Tantalum is extracted well to an organic phase, while Nb is left in an aqueous phase at 0.053-1.0 M HF concentrations. The similar extraction trends of Nb and Ta are shown in the solid phase extraction using a TBP resin. The extraction equilibria in the solid phase extraction are attained within ∼10 s. (author)

[en] Several experiments have been made to study the aqueous chemistry of element 105, dubnium. Although difference of the complex formation strength among Db and its lighter homologues was deduced from some of the experiments in HF solution, enough data have not been accumulated to discuss in detail the fluoride complexations and/or relativistic effects. In the present work, we have investigated the chemical behavior of Db together with its group-5 homologues by anion-exchange chromatography in HF. (orig.)

[en] The isotopes of ²⁶¹Rf, ²⁶²Db, and ²⁶⁵Sg were produced in the ²⁴⁸Cm(¹⁸O,5n)²⁶¹Rf, ²⁴⁸Cm(¹⁹F,5n)²⁶²Db, and ²⁴⁸Cm(²²Ne,5n)²⁶⁵Sg reactions, respectively, using a gas-jet transport system coupled to the gas-filled recoil ion separator, GARIS at RIKEN. Production and decay properties of those nuclides were investigated in detail with a rotating wheel apparatus for α and spontaneous fission spectrometry under low background conditions. (author)

[en] We report on the characteristic anion-exchange behavior of the superheavy element dubnium (Db) with atomic number Z=105 in HF/HNO₃ solution at the fluoride ion concentration [F^-]=0.003 M. The result clearly demonstrates that the fluoro complex formation of Db is significantly different from that of the group-5 homologue Ta in the 6th period of the periodic table while the behavior of Db is similar to that of the lighter homologue Nb in the 5th period. (author)

No abstract available