Actinide Science with a Soft X-ray Scanning Transmission X-ray Microscope (STXM)
- PDF / 2,529,134 Bytes
- 13 Pages / 612 x 792 pts (letter) Page_size
- 85 Downloads / 151 Views
1264-Z01-01
Actinide Science with a Soft X-ray Scanning Transmission X-ray Microscope (STXM) Per-Anders Glans,1,2 Geza Szigethy,1,3 Dustin Demoin,1,3 Tolek Tyliszczak,2 Jide Xu,3 Jinghua Guo,2 Kenneth N. Raymond,1,3 and David K. Shuh1 1
Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA 2 Advanced Light Source Division, Lawrence Berkley National Laboratory, Berkeley, CA 94720, USA 3 Department of Chemistry, University of California, Berkeley, CA 94720, USA ABSTRACT Soft x-ray scanning transmission x-ray microscope (STXM) spectromicroscopy has been developed and employed to investigate several aspects of actinide chemistry and materials science at the Advanced Light Source Molecular Environmental Science (ALS-MES) Beamline 11.0.2 STXM end station. The basic approach and fundamentals of STXM experiments for radioactive materials systems is discussed. Representative results from STXM spectromicroscopy investigations of a mixed phase uranium nitride, single crystals of Eu(III)[TREN(Me-3,2-HOPO)]3·2H2O and hydrated Pu2(III)(C2O4)3(6H2O)·3H2O complexes are presented. The STXM images and soft x-ray absorption spectra illustrate the capabilities and utility of soft x-ray STXM for providing information about actinide materials, especially the light element constituents. Lastly, new and future opportunities for actinide science utilizing soft x-ray STXM are discussed in light of the planned upgrades for the STXM end stations at the ALS. INTRODUCTION The scanning transmission x-ray microscope (STXM) end station of the Advanced Light SourceMolecular Environmental Sciences (ALS-MES) beamline provides opportunities to investigate the electronic structure of radioactive materials by near edge x-ray absorption fine structure (NEXAFS) spectromicroscopy from a regularly obtainable energy range of approximately 120 eV to 2150 eV with a spatial resolution of better than 25 nm.[1,2] This energy range spans the Kedges of C, N, O, F, Na, Mg, Al, and Si; the L2,3-edges of the first row transition metals; many of the lanthanide M5,4 edges; and the actinide N5,4-edges (4d5/2,3/2). NEXAFS probes electronic structure that yields both chemical bonding and symmetry (structural) information.[3] The electronic transitions are from element specific electron core levels to unoccupied states. Thus, NEXAFS spectra are essentially element specific contributions proportional to the unoccupied partial density of states (PDOS). NEXAFS is enhanced by the capability to successfully model near-edge data. The ALS-MES STXM can image and perform NEXAFS on extremely small amounts of contained radioactive material in a non-vacuum sample environment precluding concerns of contamination jeopardizing the end station, beamline, and storage ring.[1,4] The first scientific studies of actinide materials by NEXAFS with the ALS-MES STXM have focused on
actinide reference materials and the actinide dioxides, both at the actinide N5,4 edges and at the oxygen K-edge.[5,6] As ALS-MES STXM spectromicroscopy has been developed more re
Data Loading...
