A5032706535- Advanced X-ray Imaging Techniques
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced Electron Microscopy Techniques and Applications
- Particle Accelerators and Free-Electron Lasers
- Crystallography and Radiation Phenomena
- Advanced X-ray and CT Imaging
- Medical Imaging Techniques and Applications
- Electron and X-Ray Spectroscopy Techniques
- Laser-Matter Interactions and Applications
- Metal-Catalyzed Oxygenation Mechanisms
- Nuclear Physics and Applications
- Particle accelerators and beam dynamics
- Advanced Chemical Physics Studies
- Spectroscopy and Quantum Chemical Studies
- Photochemistry and Electron Transfer Studies
- Muon and positron interactions and applications
- Enzyme Structure and Function
- Atomic and Molecular Physics
- Lanthanide and Transition Metal Complexes
- Mass Spectrometry Techniques and Applications
- ZnO doping and properties
- X-ray Diffraction in Crystallography
- Magnetism in coordination complexes
- Gyrotron and Vacuum Electronics Research
- Metal complexes synthesis and properties
Paul Scherrer Institute
2013-2023
Swiss Light Source
2004-2017
University of Bern
2017
ETH Zurich
2014-2015
Center for Free-Electron Laser Science
2015
Universität Hamburg
2015
Bellingham Technical College
2015
École Polytechnique Fédérale de Lausanne
2006-2008
Lib4RI - Library for the Research Institutes within the ETH Domain: Eawag, Empa, PSI & WSL
2008
Joint Institute for Laboratory Astrophysics
2008
X-ray absorption spectroscopy is a powerful probe of molecular structure, but it has previously been too slow to track the earliest dynamics after photoexcitation. We investigated ultrafast formation lowest quintet state aqueous iron(II) tris(bipyridine) upon excitation singlet metal-to-ligand-charge-transfer (1MLCT) by femtosecond optical pump/x-ray techniques based on x-ray near-edge structure (XANES). By recording intensity characteristic XANES feature as function laser time delay, we...
Brown algae of the Laminariales (kelps) are strongest accumulators iodine among living organisms. They represent a major pump in global biogeochemical cycle and, particular, source iodocarbons coastal atmosphere. Nevertheless, chemical state and biological significance accumulated have remained unknown to this date. Using x-ray absorption spectroscopy, we show that form is iodide, which readily scavenges variety reactive oxygen species (ROS). We propose here its role an inorganic...
The following topics are dealt with: TTF/FLASH in the XFEL context, general layout of facility, accelerator, undulators for SAES and spontaneous emission, photon beamlines scientific instruments, infrastructure auxiliary systems, commissioning operation, project management organization, cost time schedule. (HSI)
Synchrotron-based X-ray Tomographic Microscopy (SRXTM) is nowadays a powerful technique for non-destructive, high-resolution investigations of broad kind materials. High-brilliance and high-coherence third generation synchrotron radiation facilities allow micrometer sub-micrometer, quantitative, three-dimensional imaging within very short time extend the traditional absorption to edge-enhanced phase-sensitive measurements. At Swiss Light Source TOMCAT, new beamline TOmographic Coherent...
Structural changes of the iron(II)-tris-bipyridine ([Fe(II)(bpy)(3)](2+)) complex induced by ultrashort pulse excitation and population its short-lived (< or =0.6 ns) quintet high spin state have been detected picosecond x-ray absorption spectroscopy. The structural relaxation from to low was followed over entire lifetime excited state. A combined analysis x-ray-absorption near-edge structure extended fine spectroscopy features delivers an Fe-N bond elongation 0.2 in compared singlet ground
We report on the temporal and spatial stability of first tunable femtosecond undulator hard-x-ray source for ultrafast diffraction absorption experiments. The 2.5-1 Angstrom output radiation is driven by an initial 50 fs laser pulse employing laser-electron slicing technique. By using x-ray to probe laser-induced coherent optical phonons in bulk bismuth, we estimate duration 140+/-30 FWHM with timing drifts below 30 rms measured over 5 days. Optical control lattice motion demonstrated.
L(2,3) X-ray absorption spectra of aqueous [Ru(II)(bpy)3]2+ have been recorded in its ground and excited states, 50 ps after short pulse laser excitation. Significant changes both the XANES (X-ray Near-Edge Absorption Structure) EXAFS (Extended Fine regions state complex are detected. The line shapes quantitatively simulated using a crystal field multiplet code trigonal symmetry. In addition, spectral region states analyzed order to extract structural parameters their corresponding molecular...
The Linac Coherent Light Source has added a self-seeding capability to the soft x-ray range using grating monochromator system. We report demonstration of with measured resolving power 2000--5000, wavelength stability ${10}^{\ensuremath{-}4}$, and an increase in peak brightness by factor 2--5 across photon energy 500--1000 eV. By avoiding need for at experimental station, self-seeded beam can deliver as much 50-fold higher users.
We report the implementation of a method which can yield 3D distribution phase (refractive index) weakly absorbing object from single tomographic data set.In order to reduce residual absorption artifact (due fact that only one set is used) original algorithm presented by A. V. Bronnikov amended adding in filter factor found using semi empirical approach.The quality reconstruction largely sufficient for optimal segmentation and further postprocessing even though correction based on assumption...
We employ grazing-incidence femtosecond x-ray diffraction to characterize the coherent, laser-induced lattice motion of a bismuth crystal as function depth from surface with temporal resolution 193+/-8 fs. The data show direct consequences on carrier diffusion and electron-hole interaction, allowing us estimate an effective rate D=2.3+/-0.3 cm(2)/s for highly excited carriers interaction time 260+/-20
The Paul Scherrer Institute is planning the construction of a hardx-ray free-electron laser, SwissFEL, by 2016, which will produce intense, ultrashort pulses transversely coherent radiation in wavelength range 0.1-7 nm, with future extensions to cover 0.08-30 nm.Special design considerations include (a) compact construction, compatible status national facility, (b) uniform 100 Hz repetition rate, well suited sample manipulations and detector readout, (c) flexible tuning electron beam energy...
We present a static and picosecond X-ray absorption study at the Cu K-edge of bis(2,9-dimethyl-1,10-phenanthroline)copper(I) ([Cu(dmp)2](+); dmp = 2,9-dimethyl-1,10-phenanthroline) dissolved in acetonitrile dichloromethane. The steady-state photoluminescence spectra dichloromethane are also presented show shift to longer wavelengths for latter, which points stronger stabilization excited complex. fine structure features transient allow an unambiguous assignment electronic geometric molecule...
Nanostructures of transition metal oxides, such as zinc oxide, have attracted considerable interest for solar-energy conversion and photocatalysis. Both applications are sensitive to the transport trapping photoexcited charge carriers. The probing electron has recently become possible using time-resolved element-sensitive methods, X-ray spectroscopy. However, valence-band-trapped holes so far escaped observation. Herein we use absorption spectroscopy combined with a dispersive emission...
In liquid phase chemistry dynamic solute-solvent interactions often govern the path, ultimate outcome, and efficiency of chemical reactions. These steps involve many-body movements on subpicosecond time scales thus ultrafast structural tools capable capturing both intramolecular electronic changes, local solvent changes are desired. We have studied intra- intermolecular dynamics a model chromophore, aqueous [Fe(bpy)3](2+), with complementary X-ray in single experiment exploiting intense XFEL...
Accurate determination of the transient electronic structures, which drive photochemical reactions, is crucial in chemistry and biology. We report detection chemical changes on picosecond time scale by x-ray-absorption near-edge structure photoexcited aqueous [Ru(bpy)(3)](2+). Upon ultrashort laser pulse excitation a charge transfer excited state having 300 ns lifetime formed. detect change oxidation central Ru atom at its L3 L2 edges, temporal resolution 100 ps with zero unambiguously determined.
Metallica: A large contraction of the Pt-Pt bond in triplet excited state photoreactive [Pt(2)(P(2)O(5)H(2))(4)](4-) ion is determined by time-resolved X-ray absorption spectroscopy (see picture). The strengthening interaction accompanied a weakening ligand coordination bonds, resulting an elongation platinum-ligand that for first time.
We present the extension of time-resolved optical pump/x-ray absorption spectroscopy (XAS) probe experiments towards data collection at MHz repetition rates. The use a high-power picosecond laser operating an integer fraction rate storage ring allows exploitation up to two orders magnitude more x-ray photons than in previous schemes based on kHz lasers. Consequently, we demonstrate order increase signal-to-noise XAS molecular systems solution. This makes it possible investigate highly dilute...
Synchrotron‐based X‐ray Tomographic Microscopy (SRXTM) is nowadays a powerful technique for non‐destructive, high‐resolution investigations of broad kind materials. High‐brilliance and high‐coherence third generation synchrotron radiation facilities allow micrometer sub‐micrometer, quantitative, three‐dimensional imaging within very short time extend the traditional absorption to edge‐enhanced phase‐sensitive measurements. At Swiss Light Source, new, tomography dedicated beamline called...
Ultrafast spin probe: A short-lived transient species of light-excited [Fe(bpy)3]2+ (bpy=2,2′-bipyridine) shows geometry variations that correspond to excitation a high-spin state, in which the momentum FeII has now been directly determined be S=2 by spin-sensitive ultrafast X-ray emission spectroscopy. Detailed facts importance specialist readers are published as "Supporting Information". Such documents peer-reviewed, but not copy-edited or typeset. They made available submitted authors....
Abstract Serial femtosecond crystallography (SFX) using X-ray free-electron laser sources is an emerging method with considerable potential for time-resolved pump-probe experiments. Here we present a lipidic cubic phase SFX structure of the light-driven proton pump bacteriorhodopsin (bR) to 2.3 Å resolution and investigate protein dynamics modest sample requirement. Time-resolved (TR-SFX) delay 1 ms yields difference Fourier maps compatible dark M state transition bR. Importantly, very...
The SwissFEL soft X-ray free-electron laser (FEL) beamline Athos will be ready for user operation in 2021. Its design includes a novel layout of alternating magnetic chicanes and short undulator segments. Together with the APPLE X architecture undulators, branch can operated different modes producing FEL beams unique characteristics ranging from attosecond pulse length to high-power modes. Further space has been reserved upgrades including modulators an external seeding better timing...
Abstract Time-resolved X-ray absorption fine structure (XAFS) spectroscopy with picosecond temporal resolution is a new method to observe electronic and geometric structures of short-lived reaction intermediates. It combines an intense femtosecond laser source synchronized the pulses delivered by synchrotron Swiss light (SLS). We present key experiments on charge transfer reactions as well spin-crossover processes in coordination chemistry compounds next solvation dynamics studies...