Advanced Photon Source

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Theory and Software Group - Highlights 2015

Highlights

bookThe Theory of Inelastic Scattering and Absorption of X-rays
M. van Veenendaal, Cambridge University Press, Cambridge, United Kingdom, ISBN-13: 978-1107033559.

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This comprehensive, self-contained guide to X-ray spectroscopy will equip you with everything you need to begin extracting the maximum amount of information available from X-ray spectra. Key topics such as the interaction between X-rays and matter, the basic theory of spectroscopy, and selection and sum rules, are introduced from the ground up, providing a solid theoretical grounding. The book also introduces core underlying concepts such as atomic structure, solid-state effects, the fundamentals of tensor algebra and group theory, many-body interactions, scattering theory, and response functions, placing spectroscopy within a broader conceptual framework, and encouraging a deep understanding of this essential theoretical background. Suitable for graduate students, researchers, materials scientists and optical engineers, this is the definitive guide to the theory behind this powerful and widely used technique.

PuSbThe Ground State Wavefunction of Plutonium in PuSb as determined via X-ray Magnetic Circular Dichroism
M. Janoschek, D. Haskel, J. Fernandez-Rodriguez, M. van Veenendaal, Y. Choi, J. Rebizant, G. E. Lander, J.-X. Zhu, J. D. Thompson, and E. D. Bauer, Phys. Rev. B. 91, 035117 (2015).

APS HIGHLIGHT

Measurements of x-ray magnetic circular dichroism (XMCD) and x-ray absorption near-edge structure (XANES) spectroscopy at the Pu M4,5 edges of the ferromagnet PuSb are reported. Using bulk magnetization measurements and a sum rule analysis of the XMCD spectra, we determine the individual orbital [μL =2.8(1)μB/Pu] and spin moments [μS = −2.0(1)μB/Pu] of the Pu 5f electrons. Atomic multiplet calculations of the XMCD and XANES spectra reproduce well the experimental data and are consistent with the experimental
value of the spin moment. These measurements of Lz and Sz are in excellent agreement with the values that have been extracted from neutron magnetic form factor measurements, and confirm the local character of the 5f electrons in PuSb. Finally, we demonstrate that a split M5 as well as a narrow M4 XMCD signal may serve as a signature of 5f electron localization in actinide compounds.

XClaimXclaim: a graphical interface for the calculation of core-hole spectroscopies
J. Fernández-Rodríguez, B. Toby, and M. van Veenendaal, J. El. Spec. and Rel. Phenom. 202, 81 (2015).

Xclaim (X-ray core level atomic multiplets) is a graphical interface for the calculation of core-hole spec-troscopy and ground state properties within a charge-transfer multiplet model taking into account amany-body Hamiltonian with Coulomb, spin–orbit, crystal-field, and hybridization interactions. UsingCoulomb and spin–orbit parameters calculated in the Hartree–Fock limit and ligand field parameters(crystal-field, hybridization and charge-transfer energy) the program calculates X-ray absorption spec-troscopy (XAS), X-ray photoemission spectroscopy (XPS), photoemission spectroscopy (PES) and inversephotoemission (IPES). The program runs on Linux, Windows and MacOS platforms.

For software, click here