Einsteinium Es

Discovery

On 1 November 1952 the United States detonated 'Ivy Mike', the first full-scale thermonuclear device, at Enewetak Atoll in the Pacific. In the instant of the explosion, uranium-238 nuclei were drenched in neutrons so intensely that some absorbed as many as fifteen, then beta-decayed repeatedly into much heavier elements.

Analysing filter papers flown through the mushroom cloud and coral debris from nearby islands, a team led by Albert Ghiorso, drawing on Berkeley, Argonne and Los Alamos, found in December 1952 a new alpha emitter with a half-life of about 20 days. It was element 99, einsteinium-253. Element 100, fermium, turned up in the same debris soon afterwards.

Because the bomb test was classified, the discovery could not be published until 1955. When a group in Sweden prepared to report element 99 from accelerator experiments, the American team published reactor-based results to protect its priority. In 2021 researchers at Lawrence Berkeley National Laboratory used about 200 nanograms of einsteinium to measure one of its chemical bond lengths for the first time.

Origin of the name

The element honours Albert Einstein, the most celebrated physicist of the twentieth century. The symbol is Es. The name was proposed while Einstein was alive but made public only after the discovery was declassified, following his death in April 1955. Because the bomb programme had been code-named Project PANDA, the team briefly nicknamed element 99 'pandemonium'.

Main uses

• Making new elements: In 1955 a target of roughly a billion einsteinium-253 atoms was bombarded with alpha particles to create the first atoms of mendelevium, element 101.
• Basic research: Einsteinium helps scientists probe electron structure and bonding among the heavy actinides. Its radioactivity is so intense that samples damage their own crystal lattices and steadily transmute into berkelium and californium, which makes pure samples hard to keep.
• There are no industrial or medical uses.

Isotopes

Einsteinium has no stable isotopes. The most commonly used, einsteinium-253, has a half-life of about 20.5 days; it is made in a few high-flux reactors from the decay of californium-253. The longest-lived, einsteinium-252, has a half-life of about 472 days but is extremely hard to produce and available only in minute quantities. Einsteinium-254 (about 276 days) was used in the 2021 bond-length study.

In everyday life

Einsteinium has no presence in nature or in daily life. Batches are smaller than a speck of dust, and very few people have ever seen the metal. Small samples have been reported to glow in the dark from their own radiation. As a strongly radioactive material it can accumulate in bone if taken into the body, and research on it is carried out only behind shielding.