| AVS 63rd International Symposium & Exhibition | |
| Actinides and Rare Earths Focus Topic | Tuesday Sessions |
| Session AC-TuP |
| Session: | Chemistry and Physics of the Actinides and Rare Earths Poster Session |
| Presenter: | Joseph Pacold, Lawrence Berkeley National Laboratory |
| Authors: | J.I. Pacold, Lawrence Berkeley National Laboratory M.J. Kristo, Lawrence Livermore National Laboratory K.B. Knight, Lawrence Livermore National Laboratory K.S. Holliday, Lawrence Livermore National Laboratory W.W. Lukens, Lawrence Berkeley National Laboratory C.H. Booth, Lawrence Berkeley National Laboratory S.G. Minasian, Lawrence Berkeley National Laboratory T. Tyliszczak, Lawrence Berkeley National Laboratory D.K. Shuh, Lawrence Berkeley National Laboratory |
| Correspondent: | Click to Email |
The production and manipulation of nuclear material can leave distinct physical and chemical signatures, which can later be characterized to provide evidence of the origin and process history of an unidentified specimen, a field known as ‘nuclear forensics’. A broad variety of analytical chemistry techniques can provide information about interdicted and post-detonation materials. Here, we present the results of several research studies of uranium-bearing forensic specimens by soft X-ray scanning transmission X-ray microscopy (STXM). STXM yields X-ray absorption spectroscopy data with 25-nm or better spatial resolution, making it possible to quantitatively evaluate variations in oxidation state and other chemical properties across a heterogeneous specimen. Operating in the soft X-ray regime provides access to the NIV,V edges of the actinides and the oxygen K edge, which is highly sensitive to variations in U-O bonding, and consequently carries unique fingerprints of uranium oxides and their hydrates. Thus, this approach makes it possible to evaluate the oxidation state and the heterogeneity of nuclear forensic samples, yielding information on formation or process history, and/or past storage conditions. In studies of U-bearing glassy materials, the L edges of some transition metals (particularly iron, which influences the redox behavior of uranium) can provide additional insights. Technical developments in STXM operations relevant to forensics are also summarized. In particular, we report on improvements in sample preparation and rapid data analysis methods implemented in STXM experiments at Beamline 11.0.2 of the Advanced Light Source.