The chemistry of transactinide elements

The newest elements in the periodic table are the so-called the transactinides (also referred to as superheavy elements) with atomic numbers starting from Z = 104, rutherfordium. Their chemical properties are assumed to be largely influenced by relativistic effects in their electron structure induced by the high nuclear charge Z. These elements are produced artificially in heavy-ion-induced nuclear fusion evaporation reactions using large particle accelerators. The low production rates down to single atoms per week or even month as well as their short half-lives challenge their chemical investigation on a one-atom-at-a-time level. For these investigations, we develop complete efficient and fast gas phase chemical methods.

We employ empirical thermochemical methods to predict properties of transactinides. Based on these predictions we design suitable gas chromatography setups using Monte-Carlo-based gas phase simulation tools. We work in large international collaborations with research institutions from Russia (FLNR) , Germany (GSI) , USA (LBNL, LLNL), China (IMP), Poland (ITE), Norway (OCL), and Japan (RIKEN, JAEA) to determine gas phase chemical properties of transactinide elements. Our results are used for a more comprehensive understanding of how the periodic table extends beyond known elements as well as for predicting properties of elements so far not in reach with currently available experimental techniques. The Heavy Elements group develops and employs an instrumentation pool applied for the most sensitive radioanalytical tasks, including dedicated sensor developments. We use PSI's large research facilities for the production of radioactive tracer isotopes (IP2 beamline at Injector-2 as well as the SINQ irradiation facilities). In the framework of our research, we are strongly involved in the Swiss radiochemical education, e.g., at the University of Bern.

• Chemical investigation of the elements Cn (Z = 112), Nh (Z = 113) and Fl (Z = 114).
• PureCOLD - the new PSI pile-up rejection α- and SF- spectroscopy electronics.
• Development of a vacuum chromatography system for transactinides with half-lives below one second: Hot catcher and thermal release experiments and dedicated semiconductor solid state detectors using electronic grade CVD diamond or 4H-SiC.
• Development of stable intermetallic actinide targets for high-intensity heavy-ion irradiations (synthesis of transactinides).
• Investigation of the stability of transition metal carbonyl compounds for the investigation of light transactinides at low oxidation states.
• SEARCH - Release of radionuclei from liquid and solid lead bismuth eutectica.
• MeanCorN Measurement of neutron capture cross sections and determination of half-lives of short-lived cosmogenic radio-nuclides.

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