03.05.2007

Nature 447, 72-75 (3 May 2007) | doi:10.1038/nature05761; Received 27 July 2006; Accepted 19 March 2007

Chemical characterization of element 112

R. Eichler^1,², N. V. Aksenov³, A. V. Belozerov³, G. A. Bozhikov³, V. I. Chepigin³, S. N. Dmitriev³, R. Dressler¹, H. W. Gäggeler^1,², V. A. Gorshkov³, F. Haenssler^1,², M. G. Itkis³, A. Laube¹, V. Ya. Lebedev³, O. N. Malyshev³, Yu. Ts. Oganessian³, O. V. Petrushkin³, D. Piguet¹, P. Rasmussen¹, S. V. Shishkin³, A. V. Shutov³, A. I. Svirikhin³, E. E. Tereshatov³, G. K. Vostokin³, M. Wegrzecki⁴ & A. V. Yeremin³

Paul Scherrer Institute, 5232 Villigen, Switzerland
Department of Chemistry and Biochemistry, University of Bern, 3012 Bern, Switzerland
Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, 141980 Dubna, Russia
Insitute of Electron Technology, 02-668 Warsaw, Poland

Correspondence to: R. Eichler^1,² Correspondence and requests for materials should be addressed to R.E. (Email: robert.eichler@psi.ch).

The heaviest elements to have been chemically characterized are seaborgium¹ (element 106), bohrium² (element 107) and hassium³ (element 108). All three behave according to their respective positions in groups 6, 7 and 8 of the periodic table, which arranges elements according to their outermost electrons and hence their chemical properties. However, the chemical characterization results are not trivial: relativistic effects on the electronic structure of the heaviest elements can strongly influence chemical properties^4,^5,⁶. The next heavy element targeted for chemical characterization is element 112; its closed-shell electronic structure with a filled outer s orbital suggests that it may be particularly susceptible to strong deviations from the chemical property trends expected within group 12. Indeed, first experiments concluded that element 112 does not behave like its lighter homologue mercury^7,^8,⁹. However, the production and identification methods^10,¹¹ used cast doubt on the validity of this result. Here we report a more reliable chemical characterization of element 112, involving the production of two atoms of ²⁸³112 through the alpha decay of the short-lived ²⁸⁷114 (which itself forms in the nuclear fusion reaction¹² of ⁴⁸Ca with ²⁴²Pu) and the adsorption of the two atoms on a gold surface. By directly comparing the adsorption characteristics of ²⁸³112 to that of mercury and the noble gas radon, we find that element 112 is very volatile and, unlike radon, reveals a metallic interaction with the gold surface. These adsorption characteristics establish element 112 as a typical element of group 12, and its successful production unambiguously establishes the approach to the island of stability of superheavy elements through ⁴⁸Ca-induced nuclear fusion reactions with actinides.