Molecule of the Month
January 2004
Formation and Properties of Element 112

At GSI Darmstadt a 238U target was bombarded by 48Ca ions in order to form the isotope 283112. This nuclide is produced in a complete fusion reaction followed by the evaporation of 3 neutrons. 283112 has a half-life of several minutes and decays via spontaneous-fission (SF).
During a 17 day beam time the reaction products were collected in a He recoil chamber and continuously transported to a counting device. In addition, short-lived radioactive isotopes of Hg and Rn were added to the gas transport system. The carrier gas was injected into an array of 32 Au-covered Si detectors that were kept at different temperatures between +35 (first detector) and -185 °C (last detector). The figure depicts the results of the experiment: as expected, in the first detectors Hg is adsorbed, whereas Rn adsorbed at the very end of the array (upper part). In addition, at -170 °C 7 SF events were observed which can be assigned to the decay of 283112 (lower part). The 4 additional SF events distributed randomly along the array are considered to be back-ground. This first result on the thermochemical behaviour of element 112 indicates a Rn-like behaviour, presumably caused by relativistic effects on the atomic orbitals of this closed 7s26d10 shell element (group 12).

This work was carried out in the group of Prof. Heinz W. Gäggeler.


  • A. B. Yakushev, I. Zvara, Yu. Ts. Oganessian, A. V. Belozerov, S. N. Dmitriev, B. Eichler, S. Hübener, E. A. Sokol, A. Türler, A. V. Yeremin, G. V. Buklanov, M. L. Chelnokov, V. I. Chepigin, V. A. Gorshkov, A. V. Gulyaev, V. Ya. Lebedov, O.N. Malyshev, A. G. Popeko, S. Soverna, Z. Szeglowski, S. N. Timokhin, S. P. Tretyakova, V. M. Vasko, M. G. Itkis;
    "Chemical identification and properties of element 112"
    Radiochim. Acta, 91, 433-439, (2003); doi:10.1524/ract.91.8.433.20010.
  • H. W. Gäggeler, W. Büchle, Ch. E. Düllmann, R. Dressler, K. Eberhardt, B. Eichler, R. Eichler, C .M. Folden, T. N. Ginter, F. Glaus, K. E. Gregorich, F. Haenssler, D.C. Hoffman, E. Jäger, D. T. Jost, U. W. Kirbach, J. V. Kratz, H. Nitsche, J. B. Patin, V. Peshina, D. Piguet, Z. Qin, U. Rieth, M. Schädel, E. Schimpf, B. Schausten, S. Soverna, R. Sudowe, P. Thörle, N. Trautmann, A. Türler, A. Vahle, P. A. Wilk, G. Wirth, A. B. Yakkushev, A. von Zweidorf;
    "Chemical and nuclear studies of hassium and element 112"
    Nucl. Phys., A734, 208-212, (2004); doi:10.1016/j.nuclphysa.2004.01.036.