A5089425402- 2D Materials and Applications
- Porphyrin and Phthalocyanine Chemistry
- Rare-earth and actinide compounds
- Magnetic properties of thin films
- MXene and MAX Phase Materials
- Graphene research and applications
- Topological Materials and Phenomena
- Crystallography and Radiation Phenomena
- Perovskite Materials and Applications
- Gas Sensing Nanomaterials and Sensors
- Photodynamic Therapy Research Studies
- Magnetic Properties of Alloys
- Metal complexes synthesis and properties
- Metal-Catalyzed Oxygenation Mechanisms
- Metal and Thin Film Mechanics
- Advanced Electron Microscopy Techniques and Applications
- Photochemistry and Electron Transfer Studies
- Chalcogenide Semiconductor Thin Films
University of Potsdam
2021-2023
Helmholtz-Zentrum Berlin für Materialien und Energie
2019-2023
The central moiety of porphyrins is shown to control the charge state inner complex and links it by covalent interaction peripheral substituents. This link, which enables versatile functions porphyrins, not picked up in established, reduced four orbital picture [Gouterman, J. Mol. Spectrosc., 1961, 6, 138]. X-ray absorption spectroscopy at N K-edge with density functional theory approaches gives access full electronic structure, particular π* manifold beyond Gouterman orbitals. Systematic...
Free base 5,10,15,20-tetrakis(4-carboxylatophenyl)porphyrin stands for the class of powerful porphyrin photosensitizers singlet oxygen generation and light-harvesting. The atomic level selectivity dynamic UV pump - N K-edge probe X-ray absorption spectroscopy in combination with time-dependent density functional theory (TD-DFT) gives direct access to crucial excited molecular states within unusual relaxation pathway. efficient intersystem crossing, that is El-Sayed forbidden not facilitated...
The electron–phonon scattering is one of the main microscopic mechanisms responsible for spin-flip in transient state ultrafast demagnetization. Here, we present an experimental determination temperature-dependent rate Gd. Using a static x-ray emission spectroscopy method, where reduction decay peak intensities when increasing temperature quantified, measure independently electron-phonon 5d and 4f electrons. We deduce dependence electrons, while no effect on phonon population observed Our...
Abstract Synthetic single crystals of bulk molybdenum disulphide cleaved in ultrahigh vacuum are mapped across a large (≈25 mm 2 ) area by X‐ray photoelectron spectroscopy, both statically and transiently following above‐bandgap excitation an ultrafast laser. This work finds that: I) A surface typically displays spatially inhomogeneous properties, manifested (≈1 eV) variations binding energy band bending variable degrees stability those over time as result gas uptakes from the residual...
Black phosphorus possesses useful two-dimensional (2D) characteristics of van der Waals coupled materials but additionally features an in-plane anisotropic puckered layer structure that deviates from common 2D materials. Three distinct directions exist within the lattice black phosphorus: armchair and zigzag out-of-plane direction, with each 3p partial density states. This structural anisotropy is imprinted onto various collective long-range properties, while extent to which local electronic...
Abstract While extensive work has been dedicated to the measurement of demagnetization time following an ultra-short laser pulse, experimental studies its underlying microscopic mechanisms are still scarce. In transition metal ferromagnets, one main mechanism is spin-flip conduction electrons driven by electron-phonon scattering. Here, we present original method monitor mediated scattering rate in nickel through stringent atomic symmetry selection rules x-ray emission spectroscopy....
How different microscopic mechanisms of ultrafast spin dynamics coexist and interplay is not only relevant for the development spintronics but also thorough description physical systems out-of-equilibrium. In pure crystalline ferromagnets, one main mechanism relaxation electron-phonon (el-ph) driven spin-flip, or Elliott-Yafet, scattering. Unexpectedly, recent experiments with ferro- ferrimagnetic alloys have shown sublattices. These distinct sublattice are contradictory to Elliott-Yafet...
The layered dichalcogenide MoS[Formula: see text] is relevant for electrochemical Li adsorption/intercalation, in the course of which material undergoes a concomitant structural phase transition from semiconducting 2H-MoS[Formula: to metallic 1T-Li[Formula: text]MoS[Formula: text]. With core hole clock approach at S L[Formula: X-ray absorption edge we quantify ultrafast directional charge transfer excited S3p electrons in-plane ([Formula: text]) and out-of-plane as [Formula: fs fs. isotropic...
Room-Temperature Hydrogen Treatment The surface of a cleaved bulk MoS2 crystal presents electronic binding energies and band bending which typically varies both spatially across the sample with time elapsed since cleavage even under ultrahigh vacuum atmosphere. In article 2300392, Giangrisostomi co-workers demonstrate that room temperature exposure to atomic hydrogen freshly annealed results in homogenized stable S 2p3/2 energy ∼162.0 eV Fermi level close mid-gap. Cover design by Martin Künstin.