Over the course of 70 years, isotopes of einsteinium have proven to be very difficult to study. Either they are too hard to make, or they have a very fast half-life.
Scientists have recently successfully studied einsteinium – one of the most elusive and heaviest elements on the periodic table – for the first time in decades. This achievement brings chemists closer to the discovery of a so-called “island of stability ” – a term used to describe a mysterious region somewhere on the periodic table of super-heavy elements. less likely to decay.
It is known that the US Department of Energy first discovered einsteinium (named after Albert Einstein) during the first hydrogen bomb test in 1952.
This element does not occur naturally on Earth and can only be produced in extremely small quantities by specialized nuclear reactors. It is also difficult to separate from other elements, is highly radioactive, and decays rapidly, making research difficult.
Named after Albert Einstein, the chemical element einsteinium has 99 electrons revolving around its nucleus.
However, researchers from the Lawrence Berkeley National Laboratory (Berkeley Lab) at the University of California, which carried out the first experiments on einsteinium since the 1970s, have recently created a sample of einsteinium. pure is 233 nanogram in size. In this way, they were able to discover for the first time some of the basic chemical properties of einsteinium.
For a long time since its discovery, physicists knew almost nothing about einsteinium.
Co-author Korey Carter, an assistant professor at the University of Iowa and a former scientist at Berkeley Lab, told Live Science : “It’s hard to study einsteinium just because of where it is on the periodic table.”
Like the other elements in the actinide series – a group of 15 metallic elements found at the bottom of the periodic table – einsteinium is made by bombarding a target element, in this case curium, with neutrons and protons to form heavier elements. The team used a specialized nuclear reactor at Oak Ridge National Laboratory in Tennessee, one of the few places in the world that can produce einsteinium.
However, this reaction is designed to produce californium – an important element commonly used in nuclear power plants. It therefore produces only very small amounts of einsteinium as a by-product. Extracting a sample of pure einsteinium from californium is challenging because of the similarities between the two elements, meaning the researchers obtained only a small sample of einsteinium-254, one of the stable isotopes or versions of this element.
“It’s a very small amount of matter. You can’t see it, and the only way you can tell it is from its radioactivity ,” Carter said.
However, how to create einsteinium only solves half the problem. The remaining problem is how to store it.
Over the course of 70 years, isotopes of einsteinium have proven to be very difficult to study. Either they are too hard to make, or they have a very fast half-life.
Essentially, Einsteinium-254 has a half-life of 276 days. It will decompose into berkelium-250, emitting gamma radiation that is potentially dangerous to humans. So, researchers at Los Alamos National Laboratory in New Mexico designed a special 3D-printed sample holder to house einsteinium and protect Berkeley Lab scientists from this radiation.
However, the decay of Einsteinium-254 also creates other problems for researchers. “It decays continuously, leading to a loss of about 7.2% in mass per month when studying it,” the study’s authors said.
“You have to take this into account when planning the test”.
The team at Berkeley Lab are used to dealing with other elements with short half-lives. Even so, the team began its work shortly before the outbreak of the Covid-19 pandemic. This means, they lost valuable time and were unable to complete all the planned experiments.
The main finding from the study was the measurement of the einsteinium bond length – the average distance between two bonded atoms.
A sample of pure einsteinium measures 233 nanograms.
This is a fundamental chemical property that helps scientists predict how einsteinium will interact with other elements. They found that the bond lengths of einsteinium go against the general trend of the actinides (the special group of metallic radioactive elements at the bottom of the periodic table). This is something that has been theoretically predicted in the past, but has never been proven in practice before. Compared to the rest of the actinide series, einsteinium also has a very different glow pattern when exposed to light, which the team describes as “an unprecedented physical phenomenon”.
Further experiments are needed to determine the reason. The new study “lays the groundwork for doing studies with really small samples of the element,” says Carter.
The team’s research may also make it easier to create einsteinium in the future. In particular, einsteinium has the potential to be used as a target element to create even heavier elements, including undiscovered ones like the hypothetical element 119, also known as ununennium .
The study was published February 3 in the journal Nature.