Chemical Properties of Element 105 in Aqueous Solution: Extractions into Diisobutylcarbinol

Discovery of the elements with atomic numbers Z = 113, 115 and 117 (IUPAC Technical Report)

The fourth IUPAC/IUPAP Joint Working Party (JWP) on the priority of claims to the discovery of new elements 113, 115, 117 and 118 has reviewed the relevant literature pertaining to several claims. In accordance with the Criteria for the discovery of elements previously established by the 1991 IUPAC/IUPAP Transfermium Working Group (TWG), and reinforced in subsequent IUPAC/IUPAP JWP discussions, it was determined that the RIKEN collaboration has fulfilled those Criteria for element Z=113. The Dubna–Livermore–Oak Ridge collaborations claims for 115 and 117 are also in compliance. The discussion of element Z=118 will appear in a subsequent report. A synopsis of experiments and related efforts is presented along with some commentary guiding future applications of the Criteria.

Aqueous-phase chemistry of the transactinides

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-exchange- or 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.

Extraction of Nb and Ta, homolgues of Db, from sulphuric acid solutions with TOA in toluene using SISAK

Extractions of niobium and tantalum as homologues of dubnium (element 105) into tri-octylamine (TOA) in toluene from H2SO4and H2SO4/K2SO4solutions were performed to explore the possibilities of applying the automated on-line liquid–liquid extraction system SISAK to study chemical properties of dubnium in solutions. The results show that the extraction systems TOA/H2SO4and TOA/H2SO4+K2SO4are promising with respect to performing a study of Db with the SISAK system. Suggestions for performing a SISAK Db-experiment are presented. In batch experiments, Pa has also been investigated.

Chemical isolation of dubnium (element 105) in fluoride media

The isotope262Db was produced by irradiation of a248Cm target with 106-MeV19F ions at the 15 MV MP Tandem accelerator of Orsay (France). The reaction products were continuously and rapidly transported with a KCl aerosol helium jet system to the chemistry setup. They were dissolved in HF medium and the solution was passed through three successive ion exchange columns, allowing a continuous high level purification of Db from actinides on a first cation exchange column, the isolation of Db on an anion exchange one, and the retention of the long-lived decay products of262Db (3.24 h–254Fm) on a second cation exchange column. Just after the end of irradiation, the decay products were desorbed from this column, purified and α-sources were prepared on carbon foil by electrospray. In 13 effective irradiation hours, 22 events corresponding to the α-decay of254Fm were recorded. Almost 70 atoms of262Db, produced in the reaction248Cm +19F were isolated in dilute HF medium. Like its homologues/analogues Nb, Ta and Pa, dubnium forms, with fluoride ions, negatively charged complexes which are strongly retained on anion exchanger.