EP Seminar

Happy landing on the island of superheavy elements

by Prof. H. W. GAEGGELER (PSI and University of Bern)

40-S2-B01** (CERN)



During the last decade the long-seeking island of superheavy elements around atomic number 114 and neutron number 184 has been discovered by Yu.Ts. Oganessian et al. from the Flerov Laboratory of Nuclear Reactions in Dubna, Russia. Meanwhile more than 30 new nuclides with atomic numbers up to 118 have been identified, many with half-lives of seconds or longer. This enabled first ever chemical investigations of these new members of the Periodic Table. These nuclides have so far exclusively been produced in complete fusion-neutron evaporation reactions between 48Ca projectiles and actinide targets. However, the drawback of such production pathways are the extremely low production rates of typically a few atoms per month of beam time. The talk summarizes recent chemical studies with elements 112 and 114. These elements are interesting for chemists since they have filled electron (sub)shells, 6d107s2 for element 112 and 6d107s27p1/22 for element 114. Due to relativistic effects on the electronic orbitals (caused by the high Coulomb attraction between the atomic electrons and the nucleus) pronounced spin-orbit coupling occurs. This leads e.g. to a strong separation of the 7p1/2 and 7p3/2 levels. This initiated speculations, that these two elements might behave more like noble gases rather than being similar to their homologues in the Periodic Table. Based on 5 atoms of element 112 it was possible to proof its similarity with Hg from the same group of Periodic Table. Ongoing studies with element 114 – currently with 4 identified atoms - do not yield evidence for a similarity with its neighbour in the same group, Pb, but rather with a very volatile element such as a heavy noble gas.
Joint PP/EP seminar - 2008
Organized by

Rolf Landua--------------------**unusual room