A5059300118- X-ray Spectroscopy and Fluorescence Analysis
- Spectroscopy and Quantum Chemical Studies
- Advanced Chemical Physics Studies
- Photochemistry and Electron Transfer Studies
- Electron and X-Ray Spectroscopy Techniques
- Crystallography and Radiation Phenomena
- Advanced X-ray Imaging Techniques
- CO2 Reduction Techniques and Catalysts
- Mass Spectrometry Techniques and Applications
- Advanced NMR Techniques and Applications
- Magnetism in coordination complexes
- Electrochemical Analysis and Applications
- Metal-Catalyzed Oxygenation Mechanisms
- X-ray Diffraction in Crystallography
- Radical Photochemical Reactions
- NMR spectroscopy and applications
- Laser-Matter Interactions and Applications
- Material Dynamics and Properties
- Enzyme Structure and Function
- Lanthanide and Transition Metal Complexes
- Iron oxide chemistry and applications
- Catalytic C–H Functionalization Methods
- Chemical Reactions and Mechanisms
- Advanced Electron Microscopy Techniques and Applications
- Nuclear Physics and Applications
Helmholtz-Zentrum Berlin für Materialien und Energie
2016-2025
University Hospital Bonn
2023-2024
Max-Born-Institute for Nonlinear Optics and Short Pulse Spectroscopy
2019-2022
University of Potsdam
2016-2021
Institut für angewandte Photonik
2021
Malteser Krankenhaus St. Anna
2017
Universität Hamburg
2017
Center for Free-Electron Laser Science
2017
Local probes of the electronic ground state are essential for understanding hydrogen bonding in aqueous environments. When tuned to dissociative core-excited at O1s pre-edge water, resonant inelastic X-ray scattering back exhibits a long vibrational progression due ultrafast nuclear dynamics. We show how coherent evolution OH bonds around oxygen provides access high levels liquid water. The stretch into long-range part potential energy curve, which makes probe more sensitive than infra-red...
We present a setup combining liquid flatjet sample delivery and MHz laser system for time-resolved soft X-ray absorption measurements of samples at the high brilliance undulator beamline UE52-SGM Bessy II yielding unprecedented statistics in this spectral range. demonstrate that efficient detection transient changes transmission mode enables identification photoexcited species dilute samples. With iron(II)-trisbipyridine aqueous solution as benchmark system, we various edges regime. In...
Significance Water is the matrix of life and behaves anomalously in many its properties. Since Wilhelm Conrad Röntgen, two distinct separate phases have been argued to coexist ambient water, competing with alternative view single-phase liquid, footing on X-ray scattering experiment theory. We conducted a quantitative high-resolution spectroscopic multimethod investigation analysis (X-ray absorption, emission, resonant inelastic scattering). find that all known observables can be fully...
We present a flexible and compact experimental setup that combines an in vacuum liquid jet with x-ray emission spectrometer to enable static femtosecond time-resolved resonant inelastic soft scattering (RIXS) measurements from liquids at free electron laser (FEL) light sources. demonstrate the feasibility of this type experiments performed Linac Coherent Light Source FEL facility. At we observed changes RIXS spectra high peak fluences which currently sets limit maximum attainable count rate...
Abstract The dynamics of fragmentation and vibration molecular systems with a large number coupled degrees freedom are key aspects for understanding chemical reactivity properties. Here we present resonant inelastic X-ray scattering (RIXS) study to show how it is possible break down such complex multidimensional problem into elementary components. Local multimode nuclear wave packets created by excitation different core-excited potential energy surfaces (PESs) will act as spatial gates...
Soft X-ray spectroscopies are ideal probes of the local valence electronic structure photocatalytically active metal sites. Here, we apply selectivity time-resolved resonant inelastic scattering at iron L-edge to transient charge distribution an optically excited charge-transfer state in aqueous ferricyanide. Through comparison steady-state spectra and quantum chemical calculations, coupled effects valence-shell closing ligand-hole creation experimentally theoretically disentangled described...
Air lasing from single ionized N_{2}^{+} molecules induced by laser filamentation in air has been intensively investigated and the mechanisms responsible for are currently highly debated. We use ultrafast nitrogen K-edge spectroscopy to follow strong field ionization fragmentation dynamics of N_{2} upon interaction with an ultrashort 800 nm pulse. Using probe pulses generated extreme high-order harmonic generation, we observe transitions indicative formation electronic ground X^{2}Σ_{g}^{+},...
Photoassisted catalysis using Ni complexes is an emerging field for cross-coupling reactions in organic synthesis. However, the mechanism by which light enables and enhances reactivity of these often remains elusive. Although optical techniques have been widely used to study ground excited states photocatalysts, they lack specificity interrogate electronic structural changes at specific atoms. Herein, we report metal-specific studies transient L- K-edge X-ray absorption spectroscopy a...
<strong class="journal-contentHeaderColor">Abstract.</strong> Integrated Ocean Drilling Program (IODP) Expedition 331 drilled into the Iheya North hydrothermal system in middle Okinawa Trough order to investigate active subseafloor microbial ecosystems and their physical chemical settings. We five sites during using special guide bases at three holes for reentry, casing, capping, including installation of a steel mesh platform with valve controls postcruise sampling fluids. At Site C0016,...
In this combined theoretical and experimental study we report a full analysis of the resonant inelastic X-ray scattering (RIXS) spectra H2O, D2O HDO. We demonstrate that electronically-elastic RIXS has an inherent capability to map potential energy surface perform vibrational electronic ground state in multimode systems. show control selection excitation can be performed by tuning frequency across core-excited molecular bands is clearly reflected spectra. Using high level ab initio structure...
In this combined theoretical and experimental study we report on an analysis of the resonant inelastic X-ray scattering (RIXS) spectra gas phase water via lowest dissociative core-excited state |1s-1O4a11. We focus spectral feature near dissociation limit electronic ground state. show that narrow atomic-like peak consists overlapping contribution from RIXS channels back to first valence excited |1b-114a11 molecule. The has signatures ultrafast (UFD) in state, as by means ab initio...
Abstract The femtosecond excited‐state dynamics following resonant photoexcitation enable the selective deformation of N−H and N−C chemical bonds in 2‐thiopyridone aqueous solution with optical or X‐ray pulses. In combination multiconfigurational quantum‐chemical calculations, orbital‐specific electronic structure its ultrafast accessed inelastic scattering at N 1s level using synchrotron radiation soft free‐electron laser LCLS provide direct evidence for this controlled photoinduced...
The structure of bulk liquid water was recently probed by x-ray scattering below the temperature limit homogeneous nucleation (TH) ∼232 K [J. A. Sellberg et al., Nature 510, 381-384 (2014)]. Here, we utilize a similar approach to study TH using oxygen K-edge emission spectroscopy (XES). Based on previous XES experiments [T. Tokushima Chem. Phys. Lett. 460, 387-400 (2008)] at higher temperatures, expected ratio 1b1′ and 1b1″ peaks associated with lone-pair orbital in change strongly upon deep...
We report on a combined theoretical and experimental study of core-excitation spectra gas liquid phase methanol as obtained with the use X-ray absorption spectroscopy (XAS) resonant inelastic scattering (RIXS). The electronic transitions are studied computational methods that include strict extended second-order algebraic diagrammatic construction [ADC(2) ADC(2)-x], restricted active space perturbation theory, time-dependent density functional theory—providing complete assignment near oxygen...
The room temperature conversion of gaseous methanol to carbon monoxide and hydrogen on a polycrystalline Au film at ambient pressure has been triggered characterized by oxygen K-edge excitation vibrationally resolved resonant inelastic X-ray scattering. rate-limiting first dehydrogenation step is driven ultrafast O-H dissociation deprotonation O excited CH3OH. surface further dehydrogenates the CH3O+ photoradical created X-rays via electron transfer from surface. With scattering, we trace CO...
Time-resolved L-edge X-ray absorption spectroscopy is shown to be a state-selective probe by identifying the formation of spin-flip excited state in Cr( iii ).
In a comparative synchrotron X-ray absorption, non-resonant emission and resonant inelastic scattering investigation of the aqueous nitrite nitrate ions, we access both, their unoccupied occupied valence...
We report on oxygen $K$-edge soft x-ray emission spectroscopy from a liquid water jet at the Linac Coherent Light Source. observe significant changes in spectral content when tuning over wide range of incident fluences. In addition total yield decreases high These modifications result reabsorption by valence-excited molecules generated Auger cascade. Our observations have major implications for future studies intense sources. highlight importance pulse length with respect to core-hole lifetime.
Inversion-symmetry separation of electronic state manifolds in RIXS enables identification transient species photo-chemical dynamics.
Truncation of orbital subspaces in TD-DFT yields an accurate description RIXS spectra for soft X-ray K-edges.
We demonstrate for the case of photoexcited [Ru(2,2'-bipyridine)3]2+ how femtosecond resonant inelastic X-ray scattering (RIXS) at ligand K-edge allows one to uniquely probe changes in valence electronic structure following a metal-to-ligand charge-transfer (MLCT) excitation. Metal-ligand hybridization is probed by nitrogen-1s resonances providing information on both electron-accepting MLCT state and hole density metal center. By comparing spectrum calculations based functional theory, we...
The impact of ligand substitution on metal-ligand covalency and the valence excited state landscape is investigated using resonant inelastic soft X-ray scattering.
The speciation of 2-Mercaptopyridine in aqueous solution has been investigated with nitrogen 1s Near Edge X-ray Absorption Fine Structure spectroscopy and time dependent Density Functional Theory. prevalence distinct species as a function the solvent basicity is established. No indications dimerization towards high concentrations are found. determination different molecular structures put into context proton-transfer keto-enol thione–thiol tautomerisms.
We present a novel soft x-ray spectrometer for ultrafast absorption spectroscopy utilizing table-top femtosecond high-order harmonic sources. Where most commercially available spectrometers rely on spherical variable line space gratings with typical efficiency the order of 3% in first diffractive order, this spectrometer, based Hettrick-Underwood design, includes reflective zone plate as dispersive element. An improved 12% at N K-edge is achieved, accompanied by resolving power 890. The high...