Chemical isolation of dubnium (element 105) in fluoride media

The isotope 2 6 2 Db was produced by irradiation of a 2 4 8 Cm target with 106-MeV 1 9 F ions at the 15MV MP Tandem accelerator of Orsay (France). The reaction products were continuously and rapidly transported with a KClaerosol 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 of 2 6 2 Db (3.24 h- 2 5 4 Fm) 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 of 2 5 4 Fm were recorded. Almost 70 atoms of 2 6 2 Db, produced in the reaction 2 4 8 Cm + 1 9 F 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.