Seminars Archive

High-resolution x-ray absorption and x-ray emission (theory, catalysis and magnetism)

Abstract


Tuesday, May 18, 2004, 14:30
Seminar Room, ground floor, Building "T"
Sincrotrone Trieste, Basovizza

High-resolution x-ray absorption and x-ray emission


(theory, catalysis and magnetism)


Frank de Groot

(Utrecht University)
Abstract
The talk starts with an introduction of x-ray absorption spectroscopy, including the multiplet interpretation of XAS spectral shapes. The atomic multiplet, crystal field and charge transfer effects will, in short, be explained. Some recent developments include the determination of the differential-orbital covalence [1] and the analysis of the charge transfer multiplet ground state into single-particle components. Over the last few years, we have been applied soft x-ray absorption spectra under catalytic reaction conditions. In-situ XAS has been applied to study the iron redox behavior in Fe/ZSM5 [2] and the sample reduction of a Co/Mn/TiO2 Fisher-Tropsch catalyst. The second part of my talk discusses Resonant Inelastic X-ray Scattering (RIXS) [3]. RIXS is a combination of x-ray absorption and x-ray emission. The principle of RIXS will be explained and some examples will be given of possible applications. For hard x-ray RIXS this includes the measurement of soft x-ray spectra with hard x-rays [4], valence selective x-ray absorption [5], spectral sharpening effects [6], EXAFS measurements over an extended range through other edges. An example of soft x-ray RIXS discusses the measurements of dd-transitions and spin-flip transitions to determine the super-exchange energy [7,8]. [1] J. Am. Chem. Soc. 125, 12894 (2003). [2] J. Phys. Chem. B, 107, 13069 (2003) [3] Chem. Rev. 101, 1779 (2001) [4] Phys. Rev. B. 58, 13452 (1998) [5] Inorg. Chem. 41, 3121 (2002) [6] Phys. Rev. B. 66, 195112 (2002) [7] Phys. Rev. Lett. 80, 5204 (1998) [8] Phys. Rev. B. 57, 14584 (1998)