No abstract

We present a setup exploiting a von Hámos spectrometer in order to study (resonant) X-ray emission of matter exposed to high pressure. The capabilities of this setup are demonstrated for the case of FeO at pressures between 13 GPa and 75 GPa. The setup provides high-quality Kβ 1,3 X-ray emission spectra at high pressures for iron spin state analysis within minutes and iron valence-to-core spectra in less than one hour. Resonant X-ray emission maps can be obtained on a timescale of one hour with 1.0 eV and in approximately 3 hours with 0.2 eV incident energy resolution. Both Kα and Kβ emission can be utilized to gain L-edge and M-edge-like information, respectively, with the option of measuring both simultaneously. The spin state results on FeO between 13 GPa and 75 GPa are in accordance with recent literature. The structural distortion is reflected in both, valence-to-core spectra and resonant X-ray emission maps, which showcase the great potential of the presented setup. The achieved data acquisition times are promising to couple pressure with temperature by laser heating.

Large area manufacturing processes of thin films such as large-area vacuum roll-to-roll coating of dielectric and gas permeation barrier layers in manufacturing industry require a precise control of e.g. film thickness, homogeneity, chemical compositions, crystallinity and surface roughness. In order to determine these properties in real time, hyperspectral imaging is a novel, cost-efficient, and fast tool as in-line technology for large-area quality control. We demonstrate the application of hyperspectral imaging to characterize the thickness of thin films of the multilayer system ZTO/Ag/ITO produced by roll-to-roll magnetron sputtering on 220 mm wide PET substrate. X-ray reflectivity measurements are used to determine the thickness gradients of roll-to-roll produced foils with sub nanometer accuracy that serve as ground truth data to train a machine learning model for the interpretation of the hyperspectral imaging spectra. Based on the model, the sub-layer thicknesses on the complete substrate foil area were predicted which demonstrates the capabilities of this approach for large-scale in-line real-time quality control for industrial applications.

<p>The determination of the electronic structure of iron-bearing compounds at high pressure and high temperature (HPHT) conditions is of crucial importance for the understanding of the Earth’s interior and planetary matter. Information on their electronic structure can be obtained by X-ray emission spectroscopy (XES) measurements, where the iron’s Kβ<sub>1,3</sub> emission provides information about the spin state and the valence-to-core region focusses on the coordination chemistry around the iron and its electronic state. Furthermore, resonant XES (RXES) at the iron’s K-edge reveals even more detailed information about the electronic structure [1].</p><p>We present a setup to investigate the electronic structure of iron-bearing compounds <em>in situ</em> at HPHT conditions using XES and RXES. The HPHT conditions are accomplished by diamond anvil cells (DACs) in combination with a portable double-sided Yb:YAG-laser heating setup [2]. The spectroscopy setup contains a wavelength dispersive von Hamos spectrometer in combination with a Pilatus 100K area detector [3]. This setup provides a full Kβ<sub>1,3</sub> emission spectrum including valence-to-core emission in a single shot fashion. In combination with a dedicated sample preparation and use of highly intense synchrotron radiation of beamline P01 at PETRA III, the duration of the measurements is shortened to an extend that <em>in situ</em> XES, including valence-to-core, as well as <em>in situ</em> spin state imaging becomes feasible. The use of miniature diamonds [4] enables RXES measurements at the Fe-K edge. By using different analyzer crystals for the von Hamos spectrometer, simultaneous Kα and Kβ detection are feasible, which provides L-edge and M-edge like information.</p><p>The presented sample is siderite (FeCO<sub>3</sub>), which is in focus of recent research as it is a candidate for the carbon storage in the deep Earth. Siderite exhibits a complex chemistry at pressures above 50 GPa and temperatures above 1400 K resulting in the formation of carbonates featuring tetrahedrally coordinated CO<sub>4</sub>-groups instead of the typical triangular-planar CO<sub>3</sub>-coordination. These carbonates are well understood on a structural level but information on their electronic structure is scarce [5-7]. We present information on the sample’s spin state at <em>in situ</em> conditions of about 75 GPa and 2000 K XES Kβ<sub>1,3</sub> imaging  as well as RXES measurements for low and high pressure siderite at ambient temperature conditions for Kα and Kβ emission.</p><p>[1] M. L. Baker et al., <em>Coordination Chemistry Reviews </em>345, 182 (2017)</p><p>[2] G. Spiekermann et al.<em>,  Journal of Synchroton Radiation,</em> 27, 414 (2020)</p><p>[3] C. Weis et al., <em>Journal of Analytical Atomic Spectroscopy</em> 34, 384 (2019)</p><p>[4] S. Petitgirard et al., <em>J. Synchrotron Rad</em>. , 24, 276 (2017)</p><p>[5] J. Liu et al., <em>Scientific Reports, </em>5, 7640 (2015)</p><p>[6] M. Merlini et al., <em>American Mineralogist</em>, 100, 2001, (2015)</p><p>[7] V. Cerantola et al., <em>Nature Communications</em> 8, 15960 (2017)</p>

No abstract