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Einsteinium is elusive, but scientists just got smarter about it

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Feb 11, 2021, 10:38 AM EST

You know things are going to get freaky when you try to study an element that emerged in the wake of the first hydrogen bomb to ever explode.

Unlike its genius namesake, einsteinium has a difficult temperament. Nuclear reactors can only produce microscopic amounts. Artificially created and at the edge of the periodic table, the 99th element is extremely radioactive and has a half-life (the time it takes for half of it to decay) of barely over 20 days. Getting a better look at it has always been just out of reach. Scientists from UC Berkeley and Georgetown University were finally able to create a more stable isotope of it, which stuck around long enough to demystify some of its hidden properties.

“Understanding the properties of these heavy elements has been restricted by their scarcity and radioactivity,” said Rebecca Abergel, who co-led a study recently published in Nature. “This is especially true for einsteinium (Es), the heaviest element on the periodic table that can currently be generated in quantities sufficient to enable classical macroscale studies.”

Einsteinium is invisible without a microscope, but one of the heaviest elements that exists — or at least can be made to exist. It is an actinide, part of a group of elements that includes uranium, though anything heavier than uranium is not naturally occurring. It’s also the type of radioactive poison that is often portrayed as glowing green sludge in comics and movies. So what would anyone want with this stuff? While it can’t be put to much use outside a research lab yet, it could eventually be used to make advances in technology and radiopharmaceuticals.

Making einsteinium involves zapping curium (element 96) with neurons and one of the few nuclear reactors in the world actually capable of that. Neuron-bombing curium sets off a succession of nuclear reactions, but in the end, you don’t get pure einsteinium.

The Oak Ridge nuclear reactor, one of the few that can make einsteinium, and the one that this team used to create it. Credit: Atomic Energy Commission/PhotoQuest/Getty Images

What Abergel and her team found was that any einsteinium produced was heavily contaminated with californium. Since californium is element 98, with only one nuclear proton less than einsteinium, this was not totally unexpected, but it meant they needed to change their plans.

X-ray crystallography was originally going to be used to find out more about einsteinium's structure. In this method, X-rays are scattered by the crystals to determine their 3D structures, which is why scientists usually rely on it, except it needs a pure sample of the substance in question. There was obviously a problem with that. The issue of radioactive decay was also in the way. Using isotope einsteinium-254, which has a half-life of 276 days, would answer that. Then the pandemic hit and most of it disappeared before anyone could get back to the lab.

Wearing masks that look like they were made for a post-apocalyptic disaster zone, the team was finally able to observe what little they had of this elusive element. They were able to reveal something that could have major implications for future research. The bond length of einsteinium, or the average distance from nucleus to nucleus in a pair of bonded atoms, can give away how it will interact with other substances.

Having an idea of its bonding tendencies tells scientists what they should merge it with for a particular purpose and adds to the knowledge of how actinides behave. Experimentation with einsteinium could also someday prove the theorized “island of stability” is for real. This is a point past which scientists believe that isotopes of superheavy elements may have longer half-lives, making them ideal for experimentation without scrambling to finish everything before they vanish.

By the way, einsteinium does glow from radioactive decay, but not in the way Toxic Avenger would make you think. It’s more like this.