In this review, high-resolution X-ray emission and X-ray absorption spectroscopy will be discussed. The focus is on the 3d transition-metal systems. To understand high-resolution X-ray emission and reso-nant X-ray emission, it is first necessary to spend some time discussing the X-ray absorption process. Section II discusses 1s X-ray absorption, i.e., the K edges, and section III deals with 2p X-ray absorption, the L edges. X-ray emission is discussed in, respectively, the L edges. X-ray emission is discussed in, respec-tively, and section V on 2p3s and 2p3d X-ray emission. Section VI focuses on magnetic dichroism effects, and in section VII selective X-ray absorption experiments are discussed. To limit the scope of this review paper, many related topics (for example, EELS, XPS, and resonant photoemission, phonon-oriented inelastic X-ray scat-tering, and X-ray microscopy) will not be discussed. In addition, many aspects of X-ray absorption, such as reflection experiments, diffraction absorption fine structure, and related experiments, will remain untouched. EXAFS will be discussed very briefly, and its X-ray emission analogue EXEFS 69,71 will not be discussed.

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High-Resolution X-ray Emission and X-ray Absorption Spectroscopy

http://www.anorg.chem.uu.nl/PDF/degroot04a.pdf

Multiplet effects in X-ray spectroscopy

We measured the spin state of iron in ferropericlase (Mg0.83Fe0.17)O at high pressure and found a high-spin to low-spin transition occurring in the 60- to 70-gigapascal pressure range, corresponding to depths of 2000 kilometers in Earth's lower mantle. This transition implies that the partition coefficient of iron between ferropericlase and magnesium silicate perovskite, the two main constituents of the lower mantle, may increase by several orders of magnitude, depleting the perovskite phase of its iron. The lower mantle may then be composed of two different layers. The upper layer would consist of a phase mixture with about equal partitioning of iron between magnesium silicate perovskite and ferropericlase, whereas the lower layer would consist of almost iron-free perovskite and iron-rich ferropericlase. This stratification is likely to have profound implications for the transport properties of Earth's lowermost mantle.

https://science.sciencemag.org/content/sci/300/5620/789.full.pdf

Iron partitioning in Earth's Mantle: Toward a deep lower mantle discontinuity

We report X-ray emission spectra of Fe, Fe, and Cospin-crossover compounds in their high-spin and low-spin forms. It is shown that all X-ray emission features are sensitive to the spin state. Variations of the K

/pdf/probing-the-3d-spin-momentum-with-x-ray-emission-2i9z9e3b8o.pdf

Probing the 3d Spin Momentum with X-ray Emission Spectroscopy: The Case of Molecular-Spin Transitions

Knowledge of the structure of catalysts is essential to understand their behavior, which further facilitates development of an active, selective, and stable catalyst. Determining the structure of a functioning catalyst is essential in this regard. The structure of a catalyst is prone to change during the catalytic process and needs to be determined in its working conditions. In this tutorial review, we have summarized studies done at synchrotron radiation facilities that illustrate the capability to determine catalyst structure using X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES). These studies aim at facilitating the determination of the dynamic structure-performance relationships during a catalytic process.

/pdf/advanced-x-ray-absorption-and-emission-spectroscopy-in-situ-4i9uzf7b35.pdf

Advanced X-ray absorption and emission spectroscopy: in situ catalytic studies

This paper demonstrates that spin-polarized x-ray-excitation spectra can be obtained using K alpha emission as well as K beta lines. A spin-polarized analysis of K alpha x-ray emission and the excitation spectra by K alpha detection on a Ni compound is reported. A systematic analysis of the first-row transition-metal ions using the ligand-field multiplet calculation is presented for K alpha and K beta emission spectra.

Xin Wang

Papers

Spin-polarized x-ray emission of 3d transition-metal ions : A comparison via K alpha and K beta detection

Spin-polarized and site-selective X-ray absorption. Demonstration with Fe porphyrins and Kβ detection

X-ray magnetic circular dichroism spectra and distortions at Fe2+ L2,3 edges