A5044136716- Magnetism in coordination complexes
- Electron Spin Resonance Studies
- Advanced X-ray Imaging Techniques
- Organic and Molecular Conductors Research
- Metal-Catalyzed Oxygenation Mechanisms
- Porphyrin and Phthalocyanine Chemistry
- Nuclear reactor physics and engineering
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced Electron Microscopy Techniques and Applications
- Nuclear Physics and Applications
- X-ray Diffraction in Crystallography
- Nuclear Materials and Properties
- Crystallization and Solubility Studies
- Enzyme Structure and Function
- Advanced Chemical Physics Studies
- Porphyrin Metabolism and Disorders
- Solid-state spectroscopy and crystallography
- Magnetic properties of thin films
- Lanthanide and Transition Metal Complexes
- Advanced Memory and Neural Computing
- Advanced Chemical Sensor Technologies
- Quantum and electron transport phenomena
- Surface Chemistry and Catalysis
- Assisted Reproductive Technology and Twin Pregnancy
- Folate and B Vitamins Research
European X-Ray Free-Electron Laser
2020-2025
Max Planck Institute for the Structure and Dynamics of Matter
2014-2022
University of Toronto
2014-2021
École Polytechnique Fédérale de Lausanne
2020-2021
CEA Cadarache
2021
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2021
Center for Free-Electron Laser Science
2013-2019
Universität Hamburg
2013-2019
Changzhou University
2013
Beijing University of Chemical Technology
2013
Abstract A comprehensive insight into ultrafast dynamics of photo-switchable materials is desired for efficient control material properties through light excitation. Here, we study a polycrystalline spin crossover thin film as prototypical example and reveal the sequential photo-switching dynamics, from local molecular rearrangement to global lattice deformation. On earliest femtosecond timescale, structural occurs within constant unit-cell volume two-step process, involving initial...
Time-resolved X-ray methods are widely used for monitoring transient intermediates over the course of photochemical reactions. Ultrafast absorption and emission spectroscopies as well elastic scattering deliver detailed electronic structural information on chemical dynamics in solution phase. In this work, we describe opportunities at Femtosecond Experiments (FXE) instrument European XFEL. Guided by idea combining spectroscopic techniques one experiment, FXE has completed initial...
We demonstrate a method of time-stamping Radio Frequency compressed electron bunches for Ultrafast Electron Diffraction experiments in the sub-pC regime. use an in-situ ultra-stable photo-triggered streak camera to directly track time arrival each pulse and correct timing jitter radio frequency synchronization. show that we can down 30 fs root-mean-square with minimal distortion diffraction patterns, performed proof-of-principle experiment by measuring ultrafast electron-phonon coupling...
Abstract Photoexcitation of spin crossover (SCO) complexes can trigger extensive electronic transitions and transformation molecular structure. However, the precise nature associated ultrafast structural dynamics remains elusive, especially in solid state. Here, we studied a single‐crystal SCO material with femtosecond electron diffraction (FED). The unique capability FED allows us to directly probe atomic motions track changes within crystal lattice. By monitoring time‐dependent Bragg...
Single-ion magnets (SIMs) constitute the ultimate size limit in quest for miniaturizing magnetic materials. Several bottlenecks currently hindering breakthroughs quantum information and communication technologies could be alleviated by new generations of SIMs displaying multifunctionality. Here, ultrafast optical absorption spectroscopy X-ray emission are employed to track photoinduced spin-state switching prototypical complex [Co(terpy)
New synthetic hybrid materials and their increasing complexity have placed growing demands on crystal growth for single-crystal X-ray diffraction analysis. Unfortunately, not all chemical systems are conducive to the isolation of single crystals traditional characterization. Here, small-molecule serial femtosecond crystallography (smSFX) at atomic resolution (0.833 Å) is employed characterize microcrystalline silver n-alkanethiolates with various alkyl chain lengths free electron laser...
Achieving ultrafast photomagnetic switching of single-molecule magnets (SMMs) could lead to simultaneous fast and dense data storage devices. To facilitate this, a thorough understanding the dynamics emerging after ultrashort laser pulse excitation is essential. However, complex nature these materials means there lack established experimental techniques that can probe spin in SMMs. Herein, we perform femtosecond time-resolved Mn K-edge X-ray emission spectroscopy on Mn(III)-based trinuclear...
Abstract One of the most basic molecular photophysical processes is that spin transitions and intersystem crossing between excited states surfaces. The change in affects spatial distribution electron density through orbit coupling interaction. subsequent nuclear reorganization reports on full extent induced distribution, which can be treated similarly to intramolecular charge transfer with effective reaction coordinates depicting transition. Here, single-crystal [Fe II (bpy) 3 ](PF 6 ) 2 , a...
Abstract Spin‐crossover (SCO) complexes have drawn significant attention for the possibility to photoswitch their electronic spin state on a sub‐picosecond timescale at molecular level. However, multi‐step mechanism of laser‐pulse‐induced switching in solid is not yet fully understood. Here, time‐resolved synchrotron X‐ray diffraction used follow dynamics crystal lattice response picosecond laser excitation nanometric thin films SCO complex [Fe(HB(1,2,4‐triazol‐1‐yl) 3 ) 2 ]. The observed...
A water vapor induced phase separation (WVIPS) electrospinning process for the preparation of core–shell nanofibers with a single capillary is described. The PAN–PVP were fabricated by WVIPS polyvinylpyrrolidone (PVP)–polyacrylonitrile (PAN) homogeneous solution. solvent solubility parameter liquid jets was altered vapor, which subsequently before rapidly volatilized, and caused formation structured nanofibers. scanning electron microscope (SEM) transmission (TEM) applied to characterize...
Femtosecond time-resolved X-ray absorption (XANES) at the Co K-edge, emission (XES) in Kβ and valence-to-core regions, broadband UV–vis transient are combined to probe femtosecond picosecond sequential atomic electronic dynamics following photoexcitation of two vitamin B12 compounds, hydroxocobalamin aquocobalamin. Polarized XANES difference spectra allow identification structural evolution involving first equatorial then axial ligands, with latter showing rapid coherent bond elongation...
The Femtosecond X-ray Experiments (FXE) instrument at the European Free-Electron Laser (EuXFEL) provides an optimized platform for investigations of ultrafast physical, chemical and biological processes. It operates in energy range 4.7-20 keV accommodating flexible versatile environments a wide samples using diverse spectroscopic, scattering diffraction techniques. FXE is particularly suitable experiments taking advantage sub-MHz repetition rates provided by EuXFEL. In this paper dedicated...
X-ray Free Electron Lasers (XFELs) allow the collection of high-quality serial femtosecond crystallography data. The next generation megahertz superconducting FELs promises to drastically reduce data times, enabling capture more structures with higher signal-to-noise ratios and facilitating complex experiments. Currently, gas dynamic virtual nozzles (GDVNs) stand as sole delivery method capable best utilizing repetition rate sources for crystallography. However, their substantial sample...
Abstract A detailed understanding of the ultrafast dynamics halogen-bonded materials is desired for designing supramolecular and tuning various electronic properties by external stimuli. Here, a prototypical multifunctional material containing spin crossover (SCO) cations paramagnetic radical anions studied as model system photo-switchable SCO hybrid systems using electron diffraction two complementary optical spectroscopic techniques. Our results reveal sequential from to dimer softening,...
The safety improvement of nuclear reactors requires continuous efforts in understanding the fundamental physical quantities related to fission process. In neutronic models, reactor dynamics is covered by kinetic parameters characterize temporal behavior neutron population subject perturbations. transfer function a frequency domain analogy this description. It can be measured experimentally through analysis via noise or modulation, for study stability and parameters. This paper summarizes...
Abstract Photoexcitation of spin crossover (SCO) complexes can trigger extensive electronic transitions and transformation molecular structure. However, the precise nature associated ultrafast structural dynamics remains elusive, especially in solid state. Here, we studied a single‐crystal SCO material with femtosecond electron diffraction (FED). The unique capability FED allows us to directly probe atomic motions track changes within crystal lattice. By monitoring time‐dependent Bragg...
The present article summarizes the development and testing of a reactivity modulation device developed by French Atomic Alternative Energies Commission (CEA). It was installed in CROCUS reactor Swiss Federal Institute Technology Lausanne (EPFL). Experimental tests were performed framework collaboration between CEA EPFL. so-called PISTIL aims at measuring nuclear transfer function frequency range interest 1 mHz 200 Hz, order to probe in-core kinetic behavior prompt delayed neutrons. is...
X-ray free-electron lasers (XFEL) provide unique opportunities for hard emission spectroscopy (XES) in solution phase by enabling femtosecond temporal resolution. The high brilliance and MHz repetition rate of such sources drive the development specialized sample delivery systems to overcome challenges degradation, as well major advances multiple-gain detectors fully utilize dynamic range required detection. This paper addresses experimental limitations that arise a typical XES experiment...
In nuclear research reactors, integral experiments are powerful tools to measure core parameters, such as the delayed neutron fraction. Within scope of point kinetic approximation, reactivity modulation can be used for probing reactor transfer function and then infer parameters core. this context, Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA) Ecole Polytechnique Fédérale de Lausanne (EPFL) have been collaborating developing a probe device (PISTIL) measurement setup...
The present article describes the preliminary validation study of simulated in-core and reflector n eutron spectra in preparation oncoming experimental programs zeropower reactor CROCUS at EPFL. For this purpose, a set activation foils were irradiated three characteristic positions reactor, subsequent activities analyzed via γ spectrometry. setup was then modeled with Monte Carlo neutron transport code Serpent2 associated an analysis tool to include effect power history during experiments....
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