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For the first time, chemical separations of element 106 (Seaborgium, Sg) were performed in aqueous solutions. The isotopes 265 Sg and 266 Sg were produced in the 248 Cm + 22 Ne reaction at a beam energy of 121 MeV. The reaction products were continuously transported by a He(KCl)-jet to the computer-controlled liquid chromatography system ARCA. In 0.1 M HNO3/5 X ΙΟ -4 M HF, Sg was found to be eluted within 10 s from 1.6X8 mm cation-exchange columns (Aminex A6, 17.5±2 μπι) together with the hexavalent Mo-and W-ions, while hexavalent U-ions and tetravalent Zr-, Hf-, and element 104 ions were strongly retained on the column. Element 106 was detected by measuring correlated α-decays of the daughter isotopes 78-s 261 104 and 26-s 257 102. For the isotope 266 Sg, we have evidence for a spontaneous fission branch. It yields a partial spontaneousfission half-life which is in agreement with recent theoretical predictions. The chemical results show that the most stable oxidation state of Sg in aqueous solution is +6, and that like its homologs Mo and W, Sg forms neutral or anionic oxo-or oxohalide-compounds under the present condition. In these first experiments, Sg exhibits properties very characteristic of group 6 elements, and does not show U-like properties.

On-line gas chromatography / Group 5 elements / Hahnium (element 105) / Chlorides / Relativistic effects SummaryThe retention behavior of volatile chlorides and oxychlorides of short-lived isotopes of group 5 elements Nb and 105 (Ha = hahnium) in quartz columns was studied using on-line isothermal gas chromatography. The 15-s " 8 Nb was produced from a 215 U-fission target at a reactor neutron beam line and 34-s 262 Ha in fusion reactions of ' 8 0 + 249 Bk. The reaction products were continuously and rapidly transported to the chromatography apparatus with a carbon aerosol gas-jet system using He as carrier gas. Volatile chloride molecules were formed in a 900°C reaction oven by adding HCl as reactive gas. Depending on trace amounts of 0 2 in the system, either the pentachlorides or the oxytrichlorides, or a mixture thereof, were formed. The isotopes "»Nb and 262 Ha were unambiguously identified after gas chromatographic separation by measuring the characteristic y-lines of " g Nb and by registering 262 Ha-25 *Lr mother-daughter a-a correlations as well as spontaneous fission decays, respectively. The adsorption enthalpies of the investigated species on quartz surfaces were determined by analyzing the measured retention curves with a Monte Carlo model. Using an empirical correlation, the adsorption enthalpies were converted to sublimation enthalpies. The sublimation enthalpies of 95 ± 16 kJ-mol" 1 and 124± 16 kJ · mol"' determined for NbCl s and NbOCl 3 , respectively, were in good agreement with literature data. In experiments with Ha-chlorides a yield curve with two components was observed. Sublimation enthalpies of ^ 120 kJ · mol -1 and 152 ±18 kJ-mol"' were estimated for HaCl 5 and HaOCl 3 , respectively. The estimated sublimation enthalpies were compared with theoretical predictions from relativistic calculations and with empirical extrapolations of chemical properties. In agreement with empirical extrapolations, a lower volatility was found for HaOCl 3 than for NbOCl·,.

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