Contact

Porträt Dr. habil. Scheinost, Andreas; FWOS

Dr. habil. Andreas Scheinost

Head
Molecular Structures

Phone: +33 476 88 2462
+33 6 340 358 18

Department of Molecular Structures


Molecular Structures

Research

  • Synchrotron-based research on the short-range structure, oxidation state and bonding of actinides, using the following methods:
  • EXAFS: Extended X-ray absorption fine-structure spectroscopy to determine the short-range structure of a target element, i.e. the elemental identity, number and radial distance of atoms in its coordination shell and beyond (typically to radial distances of up to 5 A, in well ordered systems even to 10 A).
  • HERFD-XANES: High-energy-resolution fluoresence-detected X-ray absorption near-edge structure spectroscopy to derive oxidation states of the target element
  • XES and RIXS: X-ray emission and resonant inelastic X-ray spectroscopy to derive information on the bonding character (covalent <-> ionic)
  • P-XRD: Powder X-ray diffraction offering much higher resolution or faster speed (in-situ/in-operando) than with lab sources
  • SX-XRD: Single-crystal diffraction
  • Surface-sensitive techniques like CTR (crystal truncation rods) and RAXR (resonant anomalous X-ray reflectivity)  
  • EXAFS, HERFD-XANES, XES and RIXS is not restricted to crystalline solids, but can be applied to a wide range of samples, to derive
    information on e.g. aqueous speciation, complexation with dissolved inorganic ligands like chloride, sulfate or nitrate, complexation with organic ligands like acetate or humic acid, interaction with bacteria and plants, sorption to mineral and rock surfaces for actinides an other metals and metalloids.
  • Due to the high penetration depth of the employed hard X-rays, the methods are suited to study chemical reactions in-situ/in-operando, for instance at very low or high temperatures, under special atmospheres, or under electrochemical potentials.

Latest Publication

Stabilization mechanism of molecular orbital crystals in IrTe2

Ritschel, T.; Stahl, Q.; Kusch, M.; Trinckauf, J.; Garbarino, G.; Svitlyk, V.; Mezouar, M.; Yang, J.; Cheong, S.-W.; Geck, J.

Doped IrTe2 is considered a platform for topological superconductivity and therefore receives currently a lot of interest. In addition, the superconductivity in these materials exists in close vicinity to electronic order and the formation of molecular orbital crystals, which we explore here by means of high-pressure single crystal x-ray diffraction in combination with density functional theory. Our crystallographic refinements provide detailed information about the structural evolution as a function of applied pressure up to 42 GPa. Using this structural information for density functional theory calculations, we show that the local multicenter bonding in IrTe2 is driven by changes in the Ir-Te-Ir bond angle. When the electronic order sets in, this bond angle decreases drastically, leading to a stabilization of a multicenter molecular orbital bond. This unusual local mechanism of bond formation in an itinerant material provides a natural explanation for the different electronic orders in IrTe2. It further illustrates the strong coupling of the electrons with the lattice and is most likely relevant for the superconductivity in this material.

Publications


Equipment


Staff

Most team members are permanently at the ESRF in Grenoble (France).

ROBL Group Picture 2017/12 ©Copyright: HZDR/Denis Morel

ROBL Group Picture 2017/12

Foto: HZDR/Denis Morel

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Head

NameBld./Office+49 351 260Email
Dr. habil. Andreas ScheinostROBL/21.6.04+33 476 88 2462
+33 6 340 358 18

Employees

NameBld./Office+49 351 260Email
Dr. Nils BaumannROBL/21.6.03+33 476 88 2849
n.baumannAthzdr.de
Jörg ExnerROBL/BM20+33 476 88 2372
Dr. Christoph HennigROBL/21.6.02a+33 476 88 2005
Dr. Kristina KvashninaROBL/21.6.01+33 476 88 2367
k.kvashnina@hzdr.de
Damien NaudetROBL/BM20+33 476 88 1941
d.naudetAthzdr.de
Dr. Damien PrieurROBL/21.6.04+33 476 88 2849
d.prieurAthzdr.de
Dr. André Roßberg801/P3162758
Dr. Volodymyr Svitlykv.svitlykAthzdr.de
Thomas Zimmermann801/P2543487
t.zimmermannAthzdr.de


Contact

Dr. habil. Andreas Scheinost

Head
Molecular Structures

Phone: +33 476 88 2462
+33 6 340 358 18