ENRICHMENT OF THE SUPERHEAVY ELEMENT ROENTGENIUM (Rg) IN NATURAL Au

Abstract

Based on the observation of the long-lived isotopes of roentgenium, 261 Rg and 265 Rg (Z = 111, t1/2≥108 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° C (63° C above the melting point of Au ). The content of 197 Au and 261 Rg in the residue was studied with high resolution inductively coupled plasma-sector field mass spectrometry (ICP-SFMS). The residue of Au was 3×10-6 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 2×10-6, 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° 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 261 Rg and that it probably belongs to a new class of isomeric states, namely high spin (K-type) super- or hyperdeformed isomeric states.