Département de Physique Nucléaire

SuperHeavy Elements (SHE) provide unique possiblities to study the influence
 of relativistic effects on the electronic structure. However, until
 recently, only a limited number of thermally stable, inorganic compounds
 of SHEs have been accessible due to technical restrictions [1]. Thanks to
 the approach of physical preseparation [2], many limitations could be
 overcome. We have developed in experiments at the TRIGA reactor in Mainz
 and at the TASCA separator at GSI a method to synthesize carbonyl
 complexes of short-lived isotopes [3]. This method has now been
 successfully applied at the GARIS separator at RIKEN to synthesize for the
 first time a carbonyl complex of a superheavy element - Seaborgium
 hexacarbonyl [4].

 ²⁶⁵Sg was synthesized in the reaction ²⁴⁸Cm(²²Ne,5n), separated from the
 primary beam, and was thermalized in a He/CO mixture behind GARIS. This
 way it formed a volatile complex and was transported in the gas stream to
 a COMPACT gas-chromatography detector[6], where its adsorption on SiO₂ was
 studied. The chemical properties of seaborgium were compared to its
 lighter homologs molybdenum and tungsten. The combination of physical and
 chemical separation allowed studying the decay of ²⁶⁵Sg  under background-
 free conditions. Our results indicate the observation of Sg(CO)₆ and
 provide new information on the nuclear properties of ²⁶⁵Sg.

Experimental details and results will be presented in the seminar. An
 outlook on future applications of CO chemistry in superheavy element
 research and as a new tool for background-free decay spectroscopy will be
 given.

[1] A. Tuerler and V. Pershina, Chem. Rev. 113, 1237-1312 (2013).

[2] Ch.E. Duellmann et al., Nucl. Instr. Meth. A 551, 528539 (2005).

[3] J. Even et al., Inorg.Chem. 51, 6431-6422 (2012).

[4] J. Even et al, accepted for publication in Science (2014).

[5] H. Haba et al., Phys. Rev. C 85, 024611(2012).

[6] A. Yakushev et al., Inorg. Chem. 53, 1624 (2014).