| AVS 60th International Symposium and Exhibition | |
| Actinides and Rare Earths Focus Topic | Tuesday Sessions |
| Session AC+AS+SS-TuM |
| Session: | The Surface Science of Actinides and Rare Earths |
| Presenter: | J.J. Joyce, Los Alamos National Laboratory |
| Correspondent: | Click to Email |
The understanding of complex materials has made remarkable advances in recent years. Much of this understanding has been realized through new spectroscopy capabilities at synchrotron facilities. While the vast majority of materials can take advantage of public synchrotrons, transuranic materials are excluded when multiple containment barriers are incompatible with the chosen spectroscopy. Photoemission requires no physical barrier between photons, sample surface and the electron analyzer, thus photoemission on Pu materials is generally not allowed at public synchrotrons.
The Laser Plasma Light Source has been developed at Los Alamos for transuranic photoemission. Using several different variants of photoemission we have explored a range of Pu materials which has lead to a significant improvement in our understanding of transuranic electronic structure. Examples of these successes will be given along with details of the unique facility. Using the capabilities of our transuranic photoemission system we exploit opportunities in angle-resolved photoemission (ARPES) providing insight into the details of both the energy and crystal momentum for a material. Additional information is obtained using tunable photons used to isolate the 5f electron contribution to the valence electronic structure. Between ARPES and tunable photoemission, we construct a fairly detailed picture of the bonding and hybridization for transuranic materials. By adding temperature-dependent photoemission to the experimental tools, we cross over phase transition boundaries as well as quantify electron-phonon coupling. We also have the capability for 1.5 and 3 keV core-level spectroscopy using a monochromatized x-ray source.
By combining the above photoemission tools with a variety of surface preparation capabilities including cleaving, laser ablation, and thermal desorption, we have a flexible photoemission facility that provides unique insight into the electronic structure of transuranic materials. We will show photoemission results for PuCoGa5, PuCoIn5, PuO2, PuTe and Pu metal that span the range of materials from Mott insulators to heavy fermion superconductors. The latest developments in Pu electronic structure combine a multivalent configuration for Pu with ongoing efforts to quantify the localized/delocalized 5f electron boundary. We will discuss details of Pu electronic structure in light of both valence configurations and localization.
Work supported by the U.S. DOE Basic Energy Science, Materials Sciences and Engineering; LANL LDRD program, and Science Campaign 2.