First conceived in the combustion of a hydrogen bomb on the island of Elugelab in the South Pacific in 1952, the heavy element einsteinium is one of the strictest members of the periodic table; it does not occur naturally and is so unstable that it is difficult to get enough things, long enough, to study them.
Now, a team of chemists from Lawrence Berkeley National Laboratory, Los Alamos National Laboratory and Georgetown University have succeeded. They inspected a microscopic amount of einsteinium-254 to better understand the fundamental chemical properties and behavior of the elusive element. His research is published today in the journal Nature.
Einsteinium is manufactured in the Oak Ridge National Laboratory High flow isotope reactor as a by-product of the biannual production of californi-252 (another heavy element, synthesized in the laboratory, but of commercial use.) Technological advances have made it possible for these radioactive elements to be manufactured in laboratory environments, without the destructive pyrotechnics of mid-20th century. The Oak Ridge, Tennessee reactor is one of the few suppliers of california-252.
“The reason they can create these elements is because they have a really high neutron flux, so they can push out more and more. [of their nucleon shells]” Katherine Shield, a chemist at Lawrence Berkeley National Laboratory and co-author of the paper, said in a video call. The initial product of the reactor is “just an absolute mess, a combination of all sorts of things,” said Shield, who explained that “it’s not just about making the element or making the isotope, it’s also about purifying. -so that we can do chemistry “with him”.
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Heavy, radioactive elements such as einsteinium and californium, as well as well-known names such as uranium and plutonium, are part of the actinide group: elements 89 to 103 of the periodic table. Only a few are synthesized, such as einsteinium and california. Once a research team goes beyond the logistical work of safety protocols (to ensure that radioactive elements, like any other laboratory material, are handled safely), the problems are primarily to ensure that they have enough material to work with and that the material is pure enough to provide useful results. Extracted from the California production process, einsteini can often be contaminated by 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, a chemist at the University of Iowa and lead author of the study, it was previously believed that one microgram (1,000 nanograms) was the lower limit for a sample size.
“There were questions,‘ Will the show survive? “that we could prepare as best we could,” Carter said in a video call. “Incredibly, incredibly, it worked.”
The team was able to measure the binding distance of einsteinium-254 by X-ray absorption spectroscopy, in which it bombarded the sample with X-rays (this line of research also required the creation of a specialized support for in the sample, which did not collapse) under X-ray bombardment for about three days). The researchers examined what happened to the light that was absorbed by the sample and found that the light that was subsequently emitted changed to blue, meaning that the wavelengths were shortened slightly. This was a surprise, because they had expected a shift toward red (longer wavelengths) and this suggests that einsteinium electrons may pair differently than other elements close to the periodic table. Unfortunately, the team was unable to obtain X-ray diffraction data due to California contamination in their sample, which would tarnish the results of the method.
Researchers previously assumed that they could extrapolate certain observed trends in lighter elements to heavier actinide elements, such as how they absorb light and how the atoms and ions of other elements, called lanthanides, decrease as their atomic numbers increase. But the new results suggest that the extrapolation may not be real.
“There’s been a lot of work over the last 20 years to progress progressively toward the actinide series, proving that … actinide chemistry is happening more,” Carter said. “The rules we’ve developed for smaller things may not work so well.”
Radioanalytical work had been done on the einsteinium shortly after its discovery in the 1950s, but little was studied at that time. on actinides in general beyond their radioactive properties). Recent research has shown that einsteine bond distances — the average length of the connection between the nuclei of two atoms in a molecule—they were a little shorter than expected. The result, Carter said, is a “significant first data point.”
Like so many other scientists during this pandemic, the team was unable to conduct the research follow-up experiments they had planned. When they finally returned to the lab, most of their sample had decayed. But, as with any first step, this is sure to be followed by progress. It’s just a matter of when.