Experimental identification of spin-parities and single-particle configurations in 257No and its alpha-decay daughter 253Fm

Co-precipitation behaviour of single atoms of rutherfordium in basic solutions

All superheavy elements (SHEs), with atomic numbers (Z) ≥104, have been artificially synthesized one atom at a time and their chemical properties are largely unknown. Because these heavy nuclei have short lifetimes as well as extremely low production rates, chemical experiments need to be carried out on single atoms and have mostly been limited to adsorption and extraction. We have now investigated the precipitation properties of the SHE Rf (Z = 104). A co-precipitation method with samarium hydroxide had previously established that the co-precipitation behaviour of a range of elements reflected these elements' tendency to form hydroxide precipitates and/or ammine complex ions. Here we investigated co-precipitation of Rf in basic solutions containing NH₃ or NaOH. Comparisons between the behaviour of Rf with that of Zr and Hf (lighter homologues of Rf) and actinide Th (a pseudo-homologue of Rf) showed that Rf does not coordinate strongly with NH₃, but forms a hydroxide (co)precipitate that is expected to be Rf(OH)₄.

Observation of the chemical reaction equilibria of element 104, rutherfordium: solid-liquid extraction of Rf, Zr, Hf and Th with Aliquat 336 resin from HCl

We successfully observed the equilibrium state of the chemical reactions for superheavy elements on a one-atom-at-a-time scale; we investigated the time dependence of the extraction behaviour of element 104, Rf. The distribution coefficient of Rf in 9 M HCl was found to be higher than those of its homologous elements, probably due to differences in the chloride complexation of Rf.

Coprecipitation experiment with Sm hydroxide using a multitracer produced by nuclear spallation reaction: A tool for chemical studies with superheavy elements

To establish a new methodology for superheavy element chemistry, the coprecipitation behaviors of 34 elements with samarium hydroxide were investigated using multitracer produced by a spallation of Ta. The chemical reactions were rapidly equilibrated within 10s for many elements. In addition, these elements exhibited individual coprecipitation behaviors, and the behaviors were qualitatively related to their hydroxide precipitation behaviors. It was demonstrated that the ammine and hydroxide complex formations of superheavy elements could be investigated using the established method.

Recent great impact by an Isotope Separator On-Line (ISOL) in nuclear and radiochemistry

On April 9 2015, the Letter article titled "Measurement of the first ionization potential of lawrencium, element 103" is now published at News and Views on Nature (2015) which has been performed by our remarkably Japanese colleagues of nuclear and radiochemistry at JAEA (Japan Atomic Energy Agency). In this review, the author will state that the isotope separator on-line (ISOL) our regularly used, one of mass separation techniques, with a thermal surface ionization makes possible for determining the ionization potential of lawrencium based on the fruitful fundations of developing the ISOL system until now and also ever studying searches for unknown nuclei and these nuclear decay properties around actinide region in the past 20 years.

Sulfate complexation of element 104, Rf, in H2SO4/HNO3 mixed solution

The cation-exchange behavior of 261Rf (T 1/2= 78 s) produced in the 248Cm(18O, 5n) reaction was studied on a “one-atom-at-a-time” scale in 0.15–0.69 M H2SO4/HNO3 mixed solutions ([H+]=1.0 M) using an automated ion-exchange separation apparatus coupled with the detection system for alpha-spectroscopy (AIDA). It was found that adsorption probabilities ( decrease with an increase of [HSO4 −], showing a successive formation of Rf sulfate complexes. Rf exhibits a weaker complex formation tendency compared to the lighter homologues Zr and Hf. This is in good agreement with theoretical predictions including relativistic effects.

Production and properties of transuranium elements

We summarize historical perspective of the transuranium elements, neptunium (Np) through lawrencium (Lr), and recent progress on production, and nuclear and chemical properties of these elements. Exotic decay properties of heavy nuclei are also introduced. Chemical properties of transuranium elements in aqueous and solid states are summarized based on the actinide concept.

Theoretical description of superheavy nuclei

A short review of the studies of superheavy nuclei (SHN), done recently in our theoretical group of Warsaw, is presented. Main attention is given to description of the properties of SHN. The description is performed by macroscopic–microscopic methods. Such properties as mass, α-decay energy and α-decay half-life are considered. Special attention is devoted to the analysis of the half-life. Although mainly treated in a phenomenological way, the role of the microscopic structure of a nucleus in this quantity is tested. It is found that this structure may significantly change the half-life of nuclei with the odd nucleon (or nucleons).

Extraction behavior of rutherfordium into tributylphosphate from hydrochloric acid

The extraction behavior of rutherfordium (Rf) into tributylphosphate (TBP) from hydrochloric acid (HCl) has been studied together with those of the lighter group-4 elements Zr and Hf. The extractability of261Rf,169Hf, and85Zr into TBP was investigated under identical conditions in 7.2–8.0 M HCl by on-line reversed-phase extraction chromatography. The percent extractions of Rf, Hf, and Zr into the TBP resin increase steeply with increasing HCl concentration, and the order of extraction is Zr > Hf ≈ Rf. By considering the order of chloride complexation among these elements, it is suggested that the stability of the TBP complex of Rf tetrachloride is lower than those of Zr and Hf.