Promethium Characterized for the First Time using Synchrotron X-rays
September 30, 2024

Photograph of purified promethium compound. The pink-colored solid residue was obtained after several purification steps. Credit: Observation of a promethium complex in solution. Nature 629, 819–823 (2024)
The Science
First synchrotron study of a promethium (Pm) coordination complex filling the final gap in understanding of the lanthanide contraction phenomenon.
The Impact
A better understanding of rare earth elements in solution will lead to cleaner, more efficient separation techniques with applications in clean energy, medicine, and more.
Summary
Lanthanide rare-earth metals are crucial for many modern technologies, but there is one element in the series that we don't know much about. Promethium (Pm) is incredibly difficult to study due to its radioactivity, high instability, and extremely limited quantity. To address this, scientists at Oak Ridge National Laboratory produced and isolated enough of a specific isotope,147Pm, for detailed study. They used a new chemical complexing agent, bispyrrolidine diglycolamide, to stabilize the Pm in a solution. By examining this complex with advanced X-ray techniques, they were able to gather crucial data about Pm's chemical structure.
X-ray absorption spectroscopy was performed at the Beamline for Materials Measurement (BMM), a beamline funded and operated by NIST at the National Synchrotron Light Source II (NSLS-II), a DOE Office of Science user facility at DOE’s Brookhaven National Laboratory. This technique helped the team determine key details about how Pm bonds with oxygen and carbon atoms, helping to understand how Pm behaves compared to other lanthanides. They also confirmed the “lanthanide contraction” phenomenon, which describes how the size of lanthanide ions decreases as more electrons are added. Bonds between atoms were shown to shorten more quickly at the start of the lanthanide series than previously thought.
This study provides the first experimental data on Pm's coordination chemistry in solution, offering insights into its behavior and helping to complete the picture of how lanthanides interact chemically. This knowledge is valuable for improving rare-earth element separation and developing new technologies.
Download the research summary slide (PDF)
Contact
Ilja Popovs
Oak Ridge National Laboratory
popovsi@ornl.gov
Alexander Ivanov
Oak Ridge National Laboratory
ivanova@ornl.gov
Publications
Driscoll DM, White FD, Pramanik S, Einkauf JD, Ravel B, Bykov D, Roy S, Mayes RT, Delmau LH, Cary SK, Dyke T, Miller A, Silveira M, VanCleve SM, Davern SM, Jansone-Popova S, Popovs I, Ivanov AS. Observation of a promethium complex in solution. Nature 629, 819–823 (2024). https://doi.org/10.1038/s41586-024-07267-6
Funding
This research was supported by the US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division and Materials Sciences and Engineering Division under award number DE-SC00ERKCG21 (D.M.D., S.P., S.R., S.J.-P. and A.S.I.); the DOE Isotope Programme, managed by the Office of Science for Isotope R&D and Production (F.D.W., R.T.M., L.H.D., S.K.C., T.D., A.M., M.S., S.M.V., S.M.D. and I.P.); and the DOE, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division under award number DE-SC00 ERKCC08 (J.D.E.). Use of the NSLS-II (NIST beamline 6-BM) was supported by the DOE Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under contract no. DE-SC0012704. This research used resources of the Oak Ridge Leadership Computing Facility (OLCF) and the Compute and Data Environment for Science (CADES) at the Oak Ridge National Laboratory, which is supported by the Office of Science of the DOE under contract no. DE-AC05-00OR22725. This research used the hot cells and glovebox laboratories and other resources of the Radiochemical Engineering Development Centre, a DOE Office of Science research facility operated by the Oak Ridge National Laboratory. D.M.D., B.R., I.P. and A.S.I. thank K. Wehunt of Brookhaven National Laboratory for her help with handling radioactive samples at NSLS-II and E. Jahrman of the National Institute of Standards and Technology for critically reading the manuscript and providing helpful suggestions. I.P. and A.S.I. thank R. Copping, L. Harvey, N. Sims and M. Du for helpful discussions.
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