Einsteinium

About Einsteinium

Einsteinium was identified in November 1952 in coral debris from the Ivy Mike test on Enewetak — the high neutron flux let ²³⁸U capture up to fifteen neutrons in a single pulse before sequential beta decays walked the resulting nuclide up to Z=99. That origin story is also the practical problem with the element: its longest-lived isotope, ²⁵²Es, has a 471-day half-life and decays through energetic alpha emission, so any sample is busy destroying its own coordination chemistry through radiolysis. The 2021 work at Berkeley's Heavy Element Research Lab managed to characterize the Es-O bond length in an Es(III) complex using only 233 nanograms of ²⁵⁴Es — and the team had to design the experiment around the fact that the sample's autoradiolysis was visibly degrading the surrounding ligand on the timescale of the measurement. There's no lab-scale source: production means a multi-year campaign of irradiating curium and californium targets in the High Flux Isotope Reactor at Oak Ridge, then chemical separation in shielded glove boxes. Total worldwide production runs to fractions of a milligram per decade.