2023 APS Fellow. Talk Title: Spectroscopy and Structure of the Simplest Actinide Bonds

Processing and remediation of nuclear waste requires the development of efficient chemical separation processes. The exploration of suitable chelating agents for such separations processes is challenging as actinide chemistry is not well-understood. This is, in part, due to the technical difficulties and expense of working with radiologically hazardous elements. Theoretical modeling of actinide chemistry is highly desirable, but this task poses a severe challenge for computational quantum chemistry models due to the large numbers of metal-centered electrons and the presence of strong relativistic effects. For the development of computational models with truly predictive capabilities it is essential that they can be tested and validated by comparisons with accurate experimental data.

We are using multiple resonance spectroscopy and jet cooling techniques to unravel the complex electronic spectra of Th and U compounds. Recent results for the oxides, sulfides, nitrides and halides will be discussed. The patterns of electronic states for these molecules provide information concerning the occupation of the 5f orbitals and their participation in bond formation.