Chemical studies on rutherfordium (Rf) at JAERI

Abstract

Chemical studies on element 104, rutherfordium (Rf), at JAERI (Japan Atomic Energy Research Institute) are reviewed. The transactinide nuclide 261 Rf has been produced in the reaction 248 Cm( 18 O, 5n) at the JAERI tandem accelerator with the production cross section of about 13 nb. On-line anion-exchange experiments on Rf together with the lighter homologues, group-4 elements Zr and Hf, in acidic solutions have been conducted with a rapid ion-exchange separation apparatus. From the systematic study of the anion-exchange behavior of Rf, it has been found that the properties of Rf in HCl and HNO 3 solutions are quite similar to those of Zr and Hf, definitely confirming that Rf is a member of the group-4 elements. However, we have observed an unexpected chemical behavior of Rf in HF solutions; the fluoride complex formation of Rf is significantly different from those of the homologues. Prospects of extending chemical studies on transactinide elements in the near future at JAERI are briefly considered.

Chemical studies of elements with Z≥ 104 in liquid phase

“…1, the liquid-phase experiments with the transactinide elements are carried out on the basis of the following steps: i) synthesis of a specific isotope of a transactinide element, ii) rapid transport of this nuclide to chemical separation devices by a gas-jet transport technique, iii) fast chemical characterization that includes dissolution in an aqueous solution containing inorganic/organic ligands for complex formation, iv) preparation of a sample suitable for nuclear spectroscopy ( -spectroscopy) which usually requires the evaporation of aqueous solution to dryness, and v) detection of nuclides through their characteristic nuclear decay properties for unambiguous identification. For characterization of the transactinide elements, recent partition experiments have been conducted using the automated rapid ionexchange separation apparatus ARCA II (Automated Rapid Chemistry Apparatus) with a miniaturized computer-controlled liquid chromatography system [41] and AIDA (Automated Ion-exchange separation apparatus coupled with the Detection system for Alpha spectroscopy) [42]; AIDA consists of ARCA II and an automated on-line -particle detection system. AIDA enables cyclic discontinuous column chromatographic separations of short-lived nuclides in liquid phases and automated detection ofparticles within a typical cycle time of 60 s. As mentioned before, the experimental approach generally involves comparative studies on the chemical properties of the transactinide elements with those of their lighter homologs and pseudohomologs; i.e., elements with at least partially similar chemical properties but placed in a different group of the Periodic Table. Thus, all chemical experiments on the transactinide elements should be conducted together with their lighter homologs under identical conditions.…”

Chemistry of superheavy elements

“…After first results from ARCA II, these studies were predominantly carried out with AIDA at the Japan Atomic Energy Agency (JAEA) Tandem accelerator in Tokai, Japan [137]. MCT experiments probing the behavior of cationic species of Rf in dilute HF and mixed HF/HNO 3 solutions yielded results which are in agreement with the quantitative studies of ARCA and AIDA; see [60].…”

“…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]. Both allow fast, repetitive chromatographic separations in miniaturized columns (8 mm long, 1.6 mm i.d.)…”

Development of an automated batch-type solid-liquid extraction apparatus and extraction of Zr, Hf, and Th by triisooctylamine from HCl solutions for chemistry of element 104, Rf

“…Automated Slider-type dissOlution equipment (ASO) was based on the dissolution section of ARCA [4,5].…”

“…Various rapid chemical methods were reviewed in the literature [3]. Indeed, the ion-exchange chromatography apparatuses, Automated Rapid Chemistry Apparatus (ARCA) [4] and Automated Ion-exchange separation apparatus coupled with the Detection system for Alpha-spectroscopy (AIDA) installing the modified ARCA [5], and the solvent extraction apparatus, Short-lived Isotopes Studied by the AKUFVEtechnique (SISAK) [6] have been widely used as solution chemistry apparatuses for the transactinide elements. In experiments using the ion-exchange chromatography apparatus ARCA (AIDA), the formation of complexes of elements 104 (Rf ) and 105 (Db) with several ligands has been investigated systematically in various concentrations of acidic solutions [1,2,[7][8][9][10][11][12][13][14][15][16].…”