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Chemical speciation of third-row elements by means of high energy resolution Kβ X-ray emission spectroscopy

The partical induced X-ray emission (PIXE) is well known analytical technique for rapid multielemental detection. The technique is based on the detection of characteristic X-ray emission following inner shell ionization induced in collision with MeV protons. Solid state detectors with energy resolution around 150 eV are commonly used in PIXE technique, which is enough to separate characteristic X-ray lines from different elements. However, if the X-ray emission spectra are recorded with high-energy resolution the Kβ emission spectra start to reflect chemical environment of element. In present work, the high-energy resolution spectrometer in Johansson geometry [1] optimized for tender X-ray energy range was used to record Kβ emission spectra of several phosphorus (P), sulfur(S) and chlorine (Cl) containing compounds. In case of third-row elements Kβ emission spectra originate from valence-to-core (vtc) transition directly reflects the local symmetry of the compounds and ligand environments of the elements. The measured spectra are compared to the results of first-principle calculations based on density functional theory (DFT), included in the StoBe-deMon molecular/cluster software package. The agreement between the measured and the calculated Kβ emission spectra permits to discus valence orbitals in term of molecular orbital (MO) picture. The Kβ spectral shape of the XO 4n- and XO 3n- ions (where X is P, S or Cl) are decomposed to atomic orbitals [2]. The effects of ionic and covalent ligand bonding to PO 43- are also presented [3]. Finally, ab-initio DFT calculation of the S Kβ spectral shape of lithium polysulfide (Li 2 S x ) compounds were performed, which can be used to study Li-S batteries in operando mode. Acknowledgements: This work has been supported by Marie Curie Actions - Initial Training Networks (ITN) as an Integrating Activity Supporting Postgraduate Research with Internships in Industry and Training Excellence (SPRITE) under EC contract no. 317169.

PIXE, WDS, high energy resolutio Kβ emision line

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