General Seminars

Aqueous chemistry of superheavy elements at RIKEN

by Yukiko Komori (Nishina Center for Accelerator-Based Science, RIKEN, Japan)

Monday, 21 October 2019 from to (Europe/Bucharest)
at Marius Petrascu Seminar Room (DFN)
Description Chemical characterization of superheavy elements (SHEs, atomic number Z ≥ 104) is one of the most
important and challenging subjects in nuclear chemistry. It is expected that ionic radii, oxidation states, and
chemical bonding natures are largely influenced by the strong relativistic effects on valence electrons in these
heavy elements.
At the AVF cyclotron, we produce radioisotopes of Rf (Z = 104) and Db (Z = 105) in the 248Cm(18O,5n)261Rf
(T1/2 = 68 s) and 248Cm(19F,5n)262Db (T1/2 = 34 s) reactions, respectively. Nuclear reaction products recoiling out
of the target are rapidly transported by a gas-jet method to a chemistry laboratory. We perform ion exchange,
solvent extraction, and precipitation experiments of 261Rf and 262Db using unique rapid chemical separation
apparatuses coupled to an automated rapid α/SF counting system. At the RILAC, we have developed a gasjet
transport system coupled to RIKEN GAs-filled Recoil Ion Separator (GARIS) for the heavier SHEs such as Sg
(Z = 106) and Bh (Z = 107). Toward the first aqueous chemistry of Sg and Bh, we have been developing a rapid
solvent extraction apparatus coupled to the GARIS gas-jet system.
Radiotracers of Zr/Hf, Nb/Ta, Mo/W, and Ta/Re, which are lighter homologues of Rf, Db, Sg, and Bh,
respectively, are useful for model experiments of SHEs. In this seminar, excitation function measurements for
quantitative productions of those tracers as well as no-carrier-added chemical procedure to obtain the tracer
solutions will be presented.