A5018473095- X-ray Spectroscopy and Fluorescence Analysis
- Advanced X-ray Imaging Techniques
- Advanced Electron Microscopy Techniques and Applications
- Advanced Chemical Physics Studies
- Photochemistry and Electron Transfer Studies
- Magnetism in coordination complexes
- Electron and X-Ray Spectroscopy Techniques
- Spectroscopy and Quantum Chemical Studies
- Enzyme Structure and Function
- Metal-Catalyzed Oxygenation Mechanisms
- Crystallography and Radiation Phenomena
- CO2 Reduction Techniques and Catalysts
- Iron oxide chemistry and applications
- Ion-surface interactions and analysis
- Liquid Crystal Research Advancements
- X-ray Diffraction in Crystallography
- Chemical Thermodynamics and Molecular Structure
- Laser-Matter Interactions and Applications
- Phase Equilibria and Thermodynamics
- Mass Spectrometry Techniques and Applications
- Diamond and Carbon-based Materials Research
- Thermodynamic properties of mixtures
- Metal complexes synthesis and properties
- Particle Accelerators and Free-Electron Lasers
- Radioactive element chemistry and processing
Helmholtz-Zentrum Berlin für Materialien und Energie
2012-2022
Diamond Light Source
2020-2022
Albert Einstein College of Medicine
2017
Max Planck Institute for Biophysical Chemistry
2008-2015
Massachusetts Institute of Technology
2014
Max Planck Society
2008-2013
Max Planck Institute for Dynamics and Self-Organization
2011
University at Buffalo, State University of New York
2011
Institut für Nanophotonik
2010
Argonne National Laboratory
2008
We present a liquid flatjet system for solution phase soft-x-ray spectroscopy. The set-up utilises the phenomenon of formation stable sheets upon collision two identical laminar jets. Colliding single water jets, coming out nozzles with 50 μm orifices, under an impact angle 48° leads to double sheet formation, which first is 4.6 mm long and 1.0 wide. operates fully functional vacuum conditions (<10−3 mbar), allowing spectroscopy aqueous solutions in transmission mode. analyse...
The valence-excited states of ferric and ferrous hexacyanide ions in aqueous solution were mapped by resonant inelastic X-ray scattering (RIXS) at the Fe L2,3 N K edges. Probing both central ligand atoms enabled identification metal- ligand-centered excited states, as well ligand-to-metal metal-to-ligand charge-transfer states. Ab initio calculations utilizing RASPT2 method used to simulate L2,3-edge RIXS spectra quantification covalencies occupied empty orbitals π σ symmetry. We found that...
In a multifaceted investigation combining local soft X-ray and vibrational spectroscopic probes with ab initio molecular dynamics simulations, hydrogen-bonding interactions of two key principal amine compounds in aqueous solution, ammonia (NH3) ammonium ion (NH4+), are quantitatively assessed terms electronic structure, solvation dynamics. From the measurements complementary determination IR-active hydrogen stretching bending modes NH3 NH4+ picture emerges comparatively strongly...
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...
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...
The ambient-pressure endstation and branchline of the Versatile Soft X-ray (VerSoX) beamline B07 at Diamond Light Source serves a very diverse user community studying heterogeneous catalysts, pharmaceuticals biomaterials under realistic conditions, liquids ices, novel electronic, photonic battery materials. instrument facilitates studies near-surface chemical composition, electronic geometric structure variety samples using photoelectron spectroscopy (XPS) near-edge absorption fine-structure...
L-edge spectroscopy of 3d transition metals provides important electronic structure information and has been used in many fields. However, the use this method for studying dilute aqueous systems, such as metalloenzymes, not prevalent because severe radiation damage lack suitable detection systems. Here we present spectra from a Mn solution using high-transmission zone-plate spectrometer at Linac Coherent Light Source (LCLS). The optimized discriminating signal overwhelming O K-edge...
Determining covalent and charge-transfer contributions to bonding in solution has remained an experimental challenge. Here, the quenching of fluorescence decay channels as expressed dips L-edge X-ray spectra solvated 3d transition-metal ions complexes was reported a probe. With full set theoretical ab initio aqueous Cr(3+), including resonant inelastic scattering, we address covalency charge transfer for this prototypical ion solution. We dissect local atomic effects from intermolecular...
We utilized femtosecond time-resolved resonant inelastic X-ray scattering and ab initio theory to study the transient electronic structure photoinduced molecular dynamics of a model metal carbonyl photocatalyst Fe(CO)5 in ethanol solution. propose mechanistic explanation for parallel ultrafast intra-molecular spin crossover ligation Fe(CO)4 which are observed following charge transfer photoexcitation as reported our previous [Wernet et al., Nature 520, 78 (2015)]. find that branching...
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...
X-ray absorption spectroscopy at the L-edge of 3d transition metals provides unique information on local metal charge and spin states by directly probing 3d-derived molecular orbitals through 2p-3d transitions. However, this soft x-ray technique has been rarely used synchrotron facilities for mechanistic studies metalloenzymes due to difficulties x-ray-induced sample damage strong background signals from light elements that can dominate low signal. Here, we combine femtosecond pulses a...
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...
Bonding of the Ni(2+)(aq) complex is investigated with an unprecedented combination resonant inelastic X-ray scattering (RIXS) measurements and ab initio calculations at Ni L absorption edge. The spectra directly reflect relative energies ligand-field charge-transfer valence-excited states. They give element-specific access atomic resolution to ground-state electronic structure allow quantification strength 3d-3d electron correlation interactions in complex. experimentally determined 10Dq =...
In resonant inelastic soft x-ray scattering (RIXS) from molecular and liquid systems, the interplay of ground state structural core-excited dynamical contributions leads to complex spectral shapes that partially allow for ambiguous interpretations. this work, we dissect these in oxygen K-edge RIXS alcohols. We use into electronic as an accurate measure nuclear dynamics intermediate process. determine characteristic time until give a measurable contribution profiles τdyn = 1.2 ± 0.8 fs. By...
Hydration shells around ions are crucial for many fundamental biological and chemical processes. Their local physicochemical properties quite different from those of bulk water hard to probe experimentally. We address this problem by combining soft X-ray spectroscopy using a liquid jet molecular dynamics (MD) simulations together with ab initio electronic structure calculations elucidate the water–ion interaction in MgCl2 solution at level. Our results reveal that salt mainly affect...
Background The prosthetic socket is a key component that influences prosthesis satisfaction, with poorly fitting linked to abandonment and reduced community participation.This paper reviews adjustable designs, as they have the potential improve fit comfort through accommodating residual limb volume fluctuations alleviating undue pressure.Methods Systematic literature patent searches were conducted across multiple databases identify articles patents discussed sockets.The used find companies,...
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.
In the current work, X-ray emission spectra of aqueous solutions different inorganic salts within Hofmeister series are presented. The results reflect direct interaction ions with water molecules and therefore, reveal general properties salt-water interactions. Within experimental precision a significant effect on structure has been observed but no ordering according to maker/structure breaker concept could be mirrored in indicating that effect-if existent-may caused by more complex
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.
Liquid-jet photoelectron spectroscopy was applied to determine the first acid dissociation constant (pKa) of aqueous-phase glucose while simultaneously identifying spectroscopic signature respective deprotonation site. Valence spectra from solutions at pH values below and above pKa reveal a change in glucose's lowest ionization energy upon neutral subsequent emergence its anionic counterpart. Site-specific insights into solution-pH-dependent molecular structure changes are also shown be...
The discovery of ultrafast X-ray induced optical reflectivity changes enabled the development X-ray/optical cross correlation techniques at free electron lasers worldwide. We have now linked through experiment and theory fundamental excitation relaxation steps with transient properties in finite solid samples. Therefore, we gain a thorough interpretation an optimized detection scheme to refractive index response.
Ultrafast electronic and structural dynamics of matter govern rate selectivity chemical reactions, as well phase transitions efficient switching in functional materials. Since x-rays determine properties with elemental, chemical, orbital magnetic selectivity, short pulse x-ray sources have become central enablers ultrafast science. Despite these strengths, been poor at picking up excited state moieties from the unexcited ones. With time-resolved anti-Stokes resonant Raman scattering...
Ambient pressure x-ray photoelectron spectroscopy (APXPS) can provide a compelling platform for studying an analyte's oxidation and reduction reactions in solutions. This paper presents proof-of-principle operando measurements of model organometallic complex, iron hexacyanide, aqueous solution using the dip-and-pull technique. The data demonstrates that electrochemically active liquid meniscuses on working electrodes undergo controlled redox which were observed APXPS. A detailed discussion...