First formed in the combing of a hydrogen bomb on the South Pacific island of Elugelab in 1952, the heavy element einsteinium is one of the most obvious members of the Periodic Table; it does not occur naturally and is so unstable that it is difficult to find enough of the material, for long enough, to study it.
Now, a team of pharmacists at Lawrence Berkeley National Laboratory, Los Alamos National Laboratory, and Georgetown University have made the case. They examined the microscopic size of einsteinium-254 to better understand the basic chemical properties and behavior of the accessible element. They have their research published today in the journal Nature.
Einsteinium is manufactured at Oak Ridge National Laboratory High Isotope Flux Reactor as a by-product of biennial californium-252 production (another heavy element, synthesized by laboratory, but one with a commercial facility.) Technological advances have meant that these radioactive elements can be produced there. their laboratory conditions, in the absence of destructive pyrotechnics in the mid-20th century. The reactor in Oak Ridge, Tennessee, is one of very few suppliers of californium-252.
“The reason they can create these elements is because they have a very high neutron flux, so they can just push farther and farther and farther out. [of their nucleon shells], ” Katherine Shield, a chemist at Lawrence Berkeley’s national laboratory and co-author of the paper, said in a video call. The first product of the reactor is “just a complete mess, a mix of all sorts of things,” Shield said, explaining “it’s not just about making the element or making the isotope, but also cleaning it so we can do chemistry with it. ”
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Such heavy, radioactive elements as einsteinium and californium, as well as household names such as uranium and plutonium, are part of the actinide group: elements 89 to 103 on the Periodic Table. Only a few of them, such as einsteinium and californium, are synthesized. Once a research team gets past the logical work of safety protocols (to ensure that the radioactive elements, like any other lab material, are handled safely), the issues are largely resolved. make sure they have enough material to work with and that the material is pure. enough to offer useful results. Extracted from the californium production process, einsteinium can be contaminated with the former.
The research team worked with just 200 nanograms of einsteinium, an amount about 300 times lighter than a grain of salt. According to Korey Carter, now a chemist at the University of Iowa and lead author of the study, a microgram (1,000 nanograms) was previously thought to be the minimum for sample size.
“There were questions about, ‘Is the sample going to survive? ‘we could prepare as best we could,’ ‘Carter said in a video call. “Amazingly, surprisingly, it worked. ”
The team was able to measure the binding speed of einsteinium-254 using X-ray spectroscopy, in which you explode the sample with X-rays (this line of study also wanted to build a special retainer for the sample, one that would not crumble under X-ray bombs over about three days). The researchers looked at what happened to light captured by the sample and found that the light emitted later was dried, causing the waves to be slightly shortened. This was surprising, as they were expected to regenerate – longer waves – and this indicates that einsteinium electrons may pair differently than other elements near the Periodic Table. Unfortunately, the team was unable to obtain X-ray isolation data due to californium contamination in their sample, which would mutate their results from the method.
Previously, researchers accepted that they could transmit specific movements seen in lighter elements to the heavier actinide elements, such as how they absorb light and the size of atoms and ions of other elements, called lanthanides, reduction as their atomic numbers go up. But the new findings suggest that extrapolation may not be true.
“A lot of good work has been done over the last 20 years as they move further into the actinide series, showing that there is … more than actinide chemistry,” Carter said. “The rules we’ve developed for smaller things may not work as well.”
Radioanalytical work on einsteinium was carried out shortly after its discovery in the 1950s, but at the time, little has been studied. about actinides in general beyond their radioactive properties). Recent research has shown that the binding speed of einsteinium – the average length of bonding between the nuclei of two atoms in a molecule—there were slightly shorter than expected. The result, Carter said, is “a meaningful first point of data. ”
Like so many other scientists during this pandemic, the team was unable to follow-up tests they had planned. When they returned to the last laboratory, most of their sample had shrunk. But as with any first step, this one is sure to follow steps. It’s just a matter of when.