Enrichment of the Superheavy Element Rg in Natural Au

Based on the observation of the long-lived isotopes 261Rg and 265Rg (Z = 111, t(1/2) >= 10^(8) y) in natural Au, an experiment was performed to enrich Rg in 99.999% Au. 16 mg of Au were heated in vacuum for two weeks at a temperature of 1127 deg. C (63 deg. C above the melting point of Au). The content of 197Au and 261Rg in the residue was studied with high resolution inductively coupled plasma-sector field mass spectrometry (ICP-SFMS). The residue of Au was 3x10^(-6) of its original quantity. The recovery of Rg was a few percent. The abundance of Rg compared to Au in the enriched solution was about 2x10^(-6), which is a three to four orders of magnitude enrichment. It is concluded that the evaporation rate of Rg from an Au matrix in vacuum at 63 deg. C above the Au melting point is lower than that of Au. This experiment reinforces our first observation of Rg in a terrestrial material. As before it is concluded that a long-lived isomeric state exists in 261Rg and that it probably belongs to a new class of isomeric states, namely high spin super- or hyperdeformed isomeric states.

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