Technical Feature

Spectroscopic characterization of actinide materials

R. Caciuffo^a1, E. C. Buck^a2, D. L. Clark^a3 and G. van der Laan^a4

^a1 Actinide Research Department, Institute for Transuranium Elements, Karlsruhe, Germany; roberto.caciuffo@ec.europa.eu

^a2 Pacific Northwest National Laboratory, Richland, WA 99354, USA; edgar.buck@pnl.gov

^a3 Los Alamos National Laboratory, NM 87545, USA; dlclark@lanl.gov

^a4 Diamond Light Source, UK; gerrit.vanderlaan@stfc.ac.uk

Abstract

Advanced spectroscopic techniques provide new and unique tools for unraveling the nature of the electronic structure of actinide materials. Inelastic neutron scattering experiments, which address temporal aspects of lattice and magnetic fluctuations, probe electromagnetic multipole interactions and the coupling between electronic and vibrational degrees of freedom. Nuclear magnetic resonance clearly demonstrates different magnetic ground states at low temperature. Photoemission spectroscopy provides information on the occupied part of the electronic density of states and has been used to investigate the momentum-resolved electronic structure and the topology of the Fermi surface in a variety of actinide compounds. Furthermore, x-ray absorption and electron energy-loss spectroscopy have been used to probe the relativistic nature, occupation number, and degree of localization of 5f electrons across the actinide series. More recently, element- and edge-specific resonant and non-resonant inelastic x-ray scattering experiments have provided the opportunity of measuring elementary electronic excitations with higher resolution than traditional absorption techniques. Here, we will discuss results from these spectroscopic techniques and what they tell us of the electronic and magnetic properties of selected actinide materials.

Roberto Caciuffo Actinide Research Department, Institute for Transuranium Elements, Karlsruhe, Germany; tel. 49-7247-951382; and e-mail roberto.caciuffo@ec.europa.eu. Caciuffo is head of the Actinide Research Department at the Institute for Transuranium Elements in Karlsruhe, Germany, and former full professor of experimental physics at the Università Politecnica delle Marche, Ancona, Italy. He is a member of advisory boards of several international institutions. Caciuffo's current research is focused on the study of magnetic correlations and multipolar order in f-electron systems by neutron and synchrotron radiation x-ray scattering. He also has authored and co-authored more than 200 publications in leading international journals.

Edgar C. Buck Radiochemical Sciences and Engineering Group, Pacific Northwest National Laboratory, 902 Battelle Blvd., Richland, WA 99354, USA; tel. 509-376-7101; and e-mail edgar.buck@pnl.gov. Buck is a staff scientist at the Pacific Northwest National Laboratory (PNNL). He received his MS degree in radiochemistry from Salford University, UK, and his PhD degree in materials science from the University of Birmingham, UK, in 1991. Buck worked at the Chemical Technology Division at Argonne National Laboratory from 1991 to 2000 before moving to PNNL. He is an adjunct teaching professor at Washington State University, Tricities, and has published more than 50 scientific papers. Buck's research interests concern the application of transmission electron microscopy to the study of the long-term behavior of spent nuclear fuels, post-irradiation examination of nuclear reactor components, and the alteration behavior of nuclear waste forms.

David L. Clark Los Alamos National Laboratory, Low Alamos, NM 87545, USA; tel. 505-665-6690; and e-mail dlclark@lanl.gov. Clark is director of the Glen T. Seaborg Institute, and a fellow of Los Alamos National Laboratory (LANL). He is a consulting faculty member at the Stanford Synchrotron Radiation Laboratory, a fellow of the American Association for the Advancement of Science, and a Plutonium Science Strategy leader for LANL. His research interests are in the structure and bonding of actinide materials, applications of synchrotron radiation to actinide science, behavior of actinides in the environment, and in the aging effects of nuclear weapons materials. Clark also has published 140 scientific papers.

Gerrit van der Laan Diamond Light Source, Didcot OX11 0DE, UK; tel. 44-1235-778925; and e-mail Gerrit.vanderlaan@stfc.ac.uk. Van der Laan is an Individual Merit Research Scientist at the Science and Technology Facilities Council based at the synchrotron facility Diamond Light Source, UK, and an honorary professor at the Universities of York and Manchester, UK. His research interests include magnetic spectroscopy, many-electron calculations, and actinides. Van der Laan has published 375 scientific papers and received the Agilent Technologies Europhysics Award in 2000 for “pioneering work in establishing the field of magnetic x-ray dichroism.” He also is a fellow of both the Institute of Physics and the American Physical Society.