Studying radioactive materials is notoriously difficult due to their radiation-induced toxicity and risk of contamination when handling. The cost of the radioactive isotopes used in research also is a major barrier, with some costing more than $10,000 per microgram. Certain radioisotopes also cannot be produced in sufficient quantity so it is simply impossible for researchers to study them with current laboratory techniques.
A new approach developed at Lawrence Livermore National Laboratory (LLNL) allows for the study of radioactive and/or precious elements in a much more efficient way, requiring 1,000 times less materials than previous state-of-the-art methods, without compromising the data quality.
The method and its application have recently been reported in two successive articles, one in Nature Chemistry and one in Inorganic Chemistry. The research was featured on the front cover of both journals, as well as highlighted in the journal Nature.
“This is a nice recognition that out-of-the-box ideas can, with enough work and dedication, lead to interesting breakthroughs in science, even for relatively mature research areas like radiochemistry,” said LLNL scientist and project lead Gauthier Deblonde. “The most exciting part is that this is just a beginning. Now that the proof-of-concept has been demonstrated, we will be able to move forward and apply our new method to really expand chemical knowledge on some of the most elusive and radioactive elements on Earth.”
The radiotoxicity, cost and low-availability constraints are particularly magnified for the heavy elements of the periodic table, which chemists call “actinides.” The actinides are a family of 15 radioactive elements, with the most famous ones being plutonium and uranium. Beyond plutonium, other elements include americium, curium, berkelium, californium, etc. These are the heaviest elements that can be produced on Earth and for which chemistry experiments can potentially be done. However, beyond plutonium, the availability of research isotopes drops exponentially, the elements are increasingly radioactive and the cost of producing them increases dramatically. As a result, relatively little is known about the chemical properties of these elements.
The new method involves polyoxometalate ligands (POMs), a class of molecules that has so far been largely overlooked for radiochemistry applications. The intrinsic properties of the POMs allow scientists to easily form compounds with the targeted radioisotopes, crystallize them and study them with a wide variety of spectroscopic techniques while just using a few micrograms (compared to multiple milligrams or more for previous methods). This drastically cuts costs, hastens discoveries and lowers the toxicity risk for researchers, according to Deblonde.
The new approach could be used to synthesize many new compounds containing rare isotopes, such as actinides, and study them in detail. The LLNL team plans on continuing this research to offer a new perspective on the chemistry of some of the rarest and most toxic elements on Earth, for which previous methods have remained inapplicable.
The research is funded by LLNL’s Laboratory Directed Research and Development program.
Other LLNL scientists include Ian Colliard, Jonathan Lee, Christopher Colla, April Sawvel, Mavrik Zavarin, Harris Mason (now at Los Alamos National Laboratory), as well as Oregon State University Professor May Nyman.
stark8 [at] llnl.gov