Gas chemical properties of heaviest elements

Chemistry of the superheavy elements

The quest for superheavy elements (SHEs) is driven by the desire to find and explore one of the extreme limits of existence of matter. These elements exist solely due to their nuclear shell stabilization. All 15 presently 'known' SHEs (11 are officially 'discovered' and named) up to element 118 are short-lived and are man-made atom-at-a-time in heavy ion induced nuclear reactions. They are identical to the transactinide elements located in the seventh period of the periodic table beginning with rutherfordium (element 104), dubnium (element 105) and seaborgium (element 106) in groups 4, 5 and 6, respectively. Their chemical properties are often surprising and unexpected from simple extrapolations. After hassium (element 108), chemistry has now reached copernicium (element 112) and flerovium (element 114). For the later ones, the focus is on questions of their metallic or possibly noble gas-like character originating from interplay of most pronounced relativistic effects and electron-shell effects. SHEs provide unique opportunities to get insights into the influence of strong relativistic effects on the atomic electrons and to probe 'relativistically' influenced chemical properties and the architecture of the periodic table at its farthest reach. In addition, they establish a test bench to challenge the validity and predictive power of modern fully relativistic quantum chemical models.

Chemistry of superheavy elements

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.

Fast chemical separations and laser mass spectrometry – tools for nuclear research

Fast chemical separation procedures applied in nuclear research require dedicated experimental techniques. Rapid discontinuous separation procedures are illustrated by an example to isolate technetium from fission products. The use of a gas jet and its combination with a thermochromatographic separation and with the continuous solvent extraction technique SISAK is described and examples are given for the investigation of short-lived fission products. The potential of resonance ionization mass spectrometry (RIMS) as a highly sensitive technique using different experimental systems is outlined for ultra trace analysis of long-lived plutonium and neptunium isotopes, including isotope ratio measurements of the plutonium isotopes. In addition, the precise determination of the first ionization potentials (IP) of ten actinide elements up to einsteinium and of technetium carried out by using the photoionization threshold method and requiring sample sizes of ∼ 1012atoms is presented.