After 69 years, the chemist finally takes a good look at Einsteinium


Hydrogen bomb tests in the Pacific yielded new elements.

Hydrogen bomb tests in the Pacific yielded new elements.
Photo: Keystone / Getty Images ()Getty Images)

First conceived in 1952 in the combustion of a hydrogen bomb on the South Pacific island of Elugulab, the heavy element Einsteinium is one of the Shire members of the periodic table; It does not happen naturally and is so unstable that it is difficult to get enough stuff for a long time to actually study it.

Now, Lawrence Berkeley National Laboratory, Los Alamos National Laboratory and a team of chemists at Georgetown University have succeeded in doing so. He inspected a microscopic amount of Einsteinium-254 to better understand the fundamental chemical properties and behavior of the elusive element. His research is Posted on Today in the journal Nature.

Einsteinium is made at Oak Ridge National Laboratory High flow isotope reactor Biological Californium-252 production (another heavy, laboratory-synthesized element, but as a by-product with commercial utility) technological advancements means that these radioactive elements can be produced in laboratory settings, with no disastrous fireworks in the middle. to make. 20th century. The reactor at Oak Ridge, Tennessee is one of the very few suppliers of California-252.

“The reason they can make these elements is that they have this really high flow of neutrons, so they can push back and forth and forward. [of their nucleon shells], “ Said Katherine Shield, a chemist at Lawrence Berkeley National Laboratory and co-author of the paper in a video call. The initial product of the reactor is “just a complete mess, a combination of all kinds of things”, Shield said, “It’s not just about making elements or making isotopes, but also purifying it so that we can do chemistry. . with this.”

High Flux Isotope Reactor in Oak Ridge, Tennessee.

High Flux Isotope Reactor in Oak Ridge, Tennessee.
The image: Wikimedia Commons ()fair use)

Such heavy, radioactive elements such 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 is past the logistic work of the security protocol (to ensure radioactive elements are handled safely, like any other laboratory material), it is primarily to ensure that their There is enough material to work and the material is pure enough to produce useful results. Extracted from the process of producing Californium, Einsteinium can often be contaminated by the former.

The research team was working with only 200 nanograms of Einsteinium, which was about 300 times lighter than salt grains. According to Corey Carter, a chemist at the University of Iowa and the lead author of the study, a microgram (1,000 nanograms) was previously considered a lower limit for a sample size.

“There were questions, ‘Is the specimen going to survive?” “We can prepare as best we can,” Carter said in a video call. “Surprisingly, surprisingly, it worked.”

The team succeeded in measuring the bond distance to Einsteinium-254 using X-ray absorption spectroscopy, in which you bombard the sample with an X-ray (this line of probe is also used for a special holder for the sample. Requires construction, which is uprooted. Under X-ray bombardment during approximately three days). The researchers looked at what happened to the light absorbed by the sample and found that the light emitted later was blue, meaning that the wavelength was shortened slightly. This was a surprise, as they expected the riddift-wave wavelengths — and this suggests that Einsteinium’s electrons may be different from those of its other elements near the periodic table. Unfortunately, the team was unable to obtain X-ray diffraction data due to a Californium contamination in their sample, which would worsen their results with the method.

Chemists inspect a laboratory sample of Einsteinium-254.

Chemists inspect a laboratory sample of Einsteinium-254.
Photo: Merlin Sergeant / Berkeley Lab

Earlier, researchers assumed that they could take some of the trends seen in lighter elements to heavier actinide elements, such as how they absorb light and the shape of atoms and ions of other elements, called lanthanides. , Lack As their atomic numbers increase. But new results suggest that extrapolation may not be correct.

“Over the last 20 years, there has been a lot of work on progressively progressing the actinide series, indicating that … actinide chemistry is more ongoing,” Carter said. “The rules that we have developed for small things probably don’t work too much.”

Shortly after its discovery in the 1950s, radioanalytical work was done on Einsteinium, but at that time, very little study was done. About actinides in general) beyond their radioactive properties. Recent research has shown that the bond distance of Einsteinium – the average length of the relationship between the nuclei of two atoms in a molecule –Were Slightly less than expected. The result, Carter said, “is a meaningful first data point.”

Like many other scientists during this epidemic, the team was not able to conduct Follow-up experiments he planned. When they finally returned to the laboratory, most of their samples were rotting. But as any first step, it is definitely after progress. It is a matter of when

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