NSLS-II Seminar

Some new developments in x-ray absorption (XAS) and resonant inelastic x-ray scattering (RIXS) will be discussed. An introduction is given of XAS, including the oxygen K edge, metal K edge and metal L edge [1,2]. The main part of the talk deals with resonant inelastic x-ray scattering (RIXS) In 2p3d RIXS one scans through the 2p XAS edge and measures the low energy excitations, including phonons, magnons, dd-excitations and charge transfer. The 100 meV resolved 2p3d RIXS spectra of ruby (Cr3+ in Al2O3), Fe3O4 and LaCoO3 will be discussed [3,4]. The present experimental resolution of 30 to 100 meV allows the detailed observation of the electronic structure, including the determination of crystal field parameters, covalency parameters and spin-orbit coupling, but also the momentum dependence of magnons and other low energy excitations. Related to the RIXS measurements is the analysis of Fluorescence yield (FY) detected x-ray absorption spectra (XAS), including the intrinsic deviations of FY-XAS spectral shape from the XAS spectrum that is important for measurements with x-ray free electron lasers [5,6]. [1] Core Level Spectroscopy of Solids Frank de Groot and Akio Kotani (Taylor & Francis CRC press, 2008) [2] Download the x-ray spectroscopy simulation software at http://www.anorg.chem.uu.nl/CTM4XAS/ [3] Huang et al. Nature Comm. 8, 15929 (2017). [4] Tomiyasu et al. Phys. Rev. Lett. 119, 196402 (2017) [5] F.M.F. de Groot, Nature Chemistry 4, 766 (2012) [6] Mitzner et al. J. Phys. Chem. Lett. 4, 3641 (2013)