Electron-energy-loss spectroscopy and X-ray absorption spectroscopy as complementary probes for complex f-electron metals: cerium and plutonium

• Published in: Philosophical magazine (Abingdon, England) England), 2004-04, Vol.84 (10), p.1039-1056
• Main Authors: Moore, K. T., Wall, M. A., Schwartz, A. J., Chung, B. W., Morton, S. A., Tobin, J. G., Lazar, S., Tichelaar, F. D., Zandbergen, H. W., Söderlind, P., van der Laan, G.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron and ion emission by liquids and solids; impact phenomena; Electron energy loss spectra; Electron energy loss spectroscopy; Exact sciences and technology; Impact phenomena (including electron spectra and sputtering); Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Other interactions of matter with particles and radiation; Physics; X-ray absorption and absorption edges; X-ray absorption spectra
• ISSN: 1478-6435; 1478-6443
• DOI: 10.1080/14786430310001659534

In this paper, we demonstrate the power of electron-energy-loss spectroscopy (EELS) in a transmission electron microscope by investigating the electron structure of two f-electron metals: Ce and Pu. It is shown that EELS in a transmission electron microscope may be used to circumvent the difficulty of producing single-phase or single-crystal samples owing to its high spatial resolution, and that diffraction patterns and images can be acquired, providing unambiguous phase determination when acquiring spectra. EELS results are supported by synchrotron-radiation-based X-ray absorption, multielectron atomic spectral simulations, and local density approximation calculations based on density-functional theory with the generalized gradient approximation. For Ce, it is shown that changes in {111} stacking sequences can drive substantial modifications in the electronic structure of close-packed phases of Ce that have similar atomic volumes, contrary to previous assumptions in literature. For Pu, it is shown that Russell-Saunders (L-S) coupling fails for the 5f states and that either a j-j or an intermediate scheme must be used for the actinides because of the considerable spin-orbit interaction in the 5f states. We present a model showing how the 5f states behave along the light actinide series.