Aqueous-phase chemistry of the transactinides

Abstract

Rapid automated chemical separations / Liquid-liquid extraction / Ion exchange /Reversed-phase extraction chromatography / α-particle spectroscopy / Relativistic effects Summary. The experimental techniques developed to perform rapid chemical separations of the heaviest elements in the aqueous phase are presented. In general, these include transport of the nuclear reaction products to a separation device by the gas-jet technique and dissolution in an aqueous solution containing inorganic ligands for complex formation. The complexes are chemically characterized by a partition method which can be liquid-liquid extraction, ion-exchangeor reversed-phase extraction chromatography. The separated fractions are quickly evaporated to dryness for the preparation of samples for α-particle spectroscopy. Comments are given on the special situation in which chemistry has to be studied with single atoms. Theoretical predictions of chemical properties are compared to the presently known chemical behaviour of rutherfordium, Rf (element 104), dubnium, Db (element 105), seaborgium, Sg (element 106), and hassium, Hs (element 108) and to that of their lighter homologs in the Periodic Table in order to assess the role of relativistic effects in the chemistry of the heaviest elements.

Chemistry of superheavy elements

“…Consequently, three to five neutrons are emitted before the compound nucleus has cooled. Still, because of the neutron-richness of actinides targets, these reactions yield the more neutron-rich, rela- tively long-lived isotopes used in chemical investigations of SHE; see Table 2 for used nuclides and [25,32,37,38,60,78,79] for more details.…”

“…With typical beam intensities of 3 × 10 12 heavyions per second and targets of about 0.8 mg/cm 2 thickness (≈ 2 × 10 18 atoms/cm 2 ), production yields range from a few atoms per minute for Rf and Db isotopes to eight atoms per hour for 265 Sg, less than two atoms per hour for 267 Bh, and a few atoms per day for 269 Hs and element 114 isotopes. As half-lives are too short to accumulate many atoms produced at such rates, all chemical separations are performed with single atoms on an atom-at-a-time scale [25,60]. Alpha decay, the most prominent decay mode for these nuclides, see Fig.…”

“…Such characterizations of the behavior of a single atom yields information approximating the equilibrium constant that would be obtained from macroscopic amounts of this element. More detailed information on this situation can be found in [25,54,56,60,61,89].…”

“…Chemistry with SHE in the liquid phase has been performed mostly in discontinuous, batch-wise operations with a large numbers of cyclic repetitions [25,60,132]. While in a few experiments on Rf and Db manual procedures were used [100,133] most transactinide separations were carried out with the Automated Rapid Chemistry Apparatus (ARCA) [134] and the more advanced Automated Ionexchange separation apparatus coupled with the Detection system for Alpha spectroscopy (AIDA) [135][136][137].…”

“…The role of physical recoil separators will be outlined. Reviews on the experimental results of SHE chemistry experiments can be found in [25,[54][55][56][57][58][59][60][61] and the comprehensive work of [62].…”