Physical preseparation for chemistry experiments

Summary. The chemistry of superheavy elements -or transactinides from their position in the Periodic Table -is summarized. After giving an overview over historical developments, nuclear aspects about synthesis of neutron-rich isotopes of these elements, produced in hot-fusion reactions, and their nuclear decay properties are briefly mentioned. Specific requirements to cope with the one-atom-at-a-time situation in automated chemical separations and recent developments in aqueous-phase and gas-phase chemistry are presented. Exciting, current developments, first applications, and future prospects of chemical separations behind physical recoil separators ("pre-separator") are discussed in detail. The status of our current knowledge about the chemistry of rutherfordium (Rf, element 104), dubnium (Db, element 105), seaborgium (Sg, element 106), bohrium (Bh, element 107), hassium (Hs, element 108), copernicium (Cn, element 112), and element 114 is discussed from an experimental point of view. Recent results are emphasized and compared with empirical extrapolations and with fully-relativistic theoretical calculations, especially also under the aspect of the architecture of the Periodic Table.

Section: Physical Pre-separatorsmentioning

confidence: 99%

Chemistry of superheavy elements

Schädel

2012

“…Though still relatively new, short overview articles on preseparation can be found, see, e.g. [24,25].…”

Section: Thermalization and Jet-transport Directly Behind The Targetmentioning

confidence: 99%

Superheavy element studies with preseparated isotopes

Düllmann¹

2011

Self Cite

Superheavy elements / Transactinides / Physical preseparation / Recoil separatorSummary. In recent years, significant progress in the field of superheavy element research has been achieved thanks to a novel combination of techniques from different fields. This "physical preseparation" approach includes the coupling of an ancillary setup -typically a chemistry apparatus or a counting setup -to a physical recoil separator. This latter preseparator removes unwanted nuclear reaction products as well as the intense heavy-ion beam associated with superheavy element experiments and thus isolates the evaporation residues of the nuclear fusion reactions. These are guided to the separators's focal plane, where they are extracted and available for further transport to external setups, e.g., by a gas-jet. In this overview, the development of physical preseparation is described, and experimental results from nuclear chemistry and physics that were achieved with "preseparated" isotopes are summarized, with an emphasis on results relevant for superheavy element research. The covered topics range from chemical studies in the liquid as well as in the gas phase, the measurement of nuclear decay properties and of atomic masses. Preseparation was already shown to be a very powerful approach in these studies and promises to allow further progress in superheavy element research.

“…Recently, the method of physical preseparation [11][12][13][14] has been developed to overcome these technical limitations. In this technique, the EVRs are spatially separated in a physical recoil separator from unwanted nuclear reaction products as well as the intense heavy-ion beam.…”

Section: Physical Preseparation For Chemistry Experimentsmentioning

confidence: 99%

Gas chemical investigation of hafnium and zirconium complexes with hexafluoroacetylacetone using preseparated short-lived radioisotopes

Düllmann

Gregorich²,

Pang

et al. 2009

Zirconium / Hafnium / Hexafluoroacetylacetonates / Thermochromatography / Isothermal gas chromatogaphy / Physical preseparation Summary. Volatile metal complexes of the group 4 elements Zr and Hf with hexafluoroacetylacetonate (hfa) have been studied using short-lived radioisotopes of the metals. The new technique of physical preseparation has been employed where reaction products from heavy-ion induced fusion reactions are isolated in a physical recoil separator -the Berkeley Gas-filled Separator in our work -and made available for chemistry experiments. Formation and decomposition of M(hfa) 4 (M = Zr, Hf) has been observed and the interaction strength with a fluorinated ethylene propylene (FEP) Teflon surface has been studied. From the results of isothermal chromatography experiments, an adsorption enthalpy of −ΔH a = (57 ± 3) kJ/mol was deduced. In optimization experiments, the time for formation of the complex and its transport to a counting setup installed outside of the irradiation cave was minimized and values of roughly one minute have been reached. The half-life of 165 Hf , for which conflicting values appear in the literature, was measured to be (73.9 ± 0.8) s. Provided that samples suitable for α-spectroscopy can be prepared, the investigation of rutherfordium (Rf), the transactinide member of group 4, appears possible. In the future, based on the studies presented here, it appears possible to investigate short-lived single atoms produced with low rates (e.g., transactinide isotopes) in completely new chemical systems, e.g., as metal complexes with organic ligands as used here or as organometallic compounds.