A5052957586- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Perovskite Materials and Applications
- Hemoglobin structure and function
- X-ray Spectroscopy and Fluorescence Analysis
- Quantum Dots Synthesis And Properties
- Solid-state spectroscopy and crystallography
- Mass Spectrometry Techniques and Applications
- Electron Spin Resonance Studies
- Photosynthetic Processes and Mechanisms
- Spectroscopy and Quantum Chemical Studies
- Luminescence Properties of Advanced Materials
- Electrochemical Analysis and Applications
- High-pressure geophysics and materials
- TiO2 Photocatalysis and Solar Cells
- Chalcogenide Semiconductor Thin Films
- Organometallic Complex Synthesis and Catalysis
- Iron oxide chemistry and applications
- Advanced Electron Microscopy Techniques and Applications
- Pesticide Residue Analysis and Safety
- Advanced X-ray Imaging Techniques
- Particle Accelerators and Free-Electron Lasers
- Enzyme Structure and Function
- Coordination Chemistry and Organometallics
- Quantum, superfluid, helium dynamics
École Polytechnique Fédérale de Lausanne
2016-2023
Graz University of Technology
2019
Paul Scherrer Institute
2019
Charles Humbert 8
2019
Dyenamo (Sweden)
2016
KTH Royal Institute of Technology
2016
We report on an element-selective study of the fate charge carriers in photoexcited inorganic CsPbBr3 and CsPb(ClBr)3 perovskite nanocrystals toluene solutions using time-resolved X-ray absorption spectroscopy with 80 ps time resolution. Probing Br K-edge, Pb L3-edge, Cs L2-edge, we find that holes valence band are localized at atoms, forming small polarons, while electrons appear as delocalized conduction band. No signature either electronic or structural changes is observed L2-edge. The...
A new redox couple, [Cu(bpye)<sub>2</sub>]<sup>+/2+</sup>, has been synthesized and applied in DSSCs. Overall efficiencies above 9.0% good photostability were obtained. Excellent electrolyte charge transport, fast regeneration low recombination are the major reasons for high efficiencies.
The development of next-generation perovskite-based optoelectronic devices relies critically on the understanding interaction between charge carriers and polar lattice in out-of-equilibrium conditions. While it has become increasingly evident for CsPbBr3 perovskites that Pb–Br framework flexibility plays a key role their light-activated functionality, corresponding local structural rearrangement not yet been unambiguously identified. In this work, we demonstrate photoinduced changes system...
Significance The structure–function relationship in central to biology, while the structural dynamics are driven by electronic changes. Doming of ferrous heme proteins, which is respiratory function hemoglobin, ensues from populating high-spin states. However, for ferric doming was excluded. Here, we show that states populated photoexcited cytochrome c , and present evidence doming. We also conclude photo- or thermally activated occurs a wide variety calling deeper understanding its role...
Abstract In haemoglobin the change from low-spin (LS) hexacoordinated haem to high spin (HS, S = 2) pentacoordinated domed deoxy-myoglobin (deoxyMb) form upon ligand detachment and reverse process binding are what ultimately drives respiratory function. Here we probe them in case of Myoglobin-NO (MbNO) using element- spin-sensitive femtosecond Fe K α β X-ray emission spectroscopy at an free-electron laser (FEL). We find that LS (S 1/2) MbNO HS occurs ~800 fs, it proceeds via intermediate 1)...
Anatase TiO2 (a-TiO2) exhibits a strong X-ray absorption linear dichroism with the incidence angle in pre-edge, XANES and EXAFS at titanium K-edge. In pre-edge region behaviour of A1-A3 B peaks, originating from 1s-3d transitions, is due to $p$-orbital polarization $p-d$ orbital mixing. An unambiguous assignment peak transitions made monoelectronic approximation support ab initio finite difference method calculations spherical tensor analysis quantitative agreement experiment. It found that...
A number of paramagnetic silylated d1 group 4 metallates were prepared by reaction potassium tris(trimethylsilyl)silanide with the type K[Cp2MCl2] (M = Ti, Zr, Hf). The outcomes reactions differ for all three metals. While hafnium case expected complex [Cp2Hf{Si(SiMe3)3}2]- was obtained, analogous titanium led to a product two Si(H)(SiMe3)2 ligands. zirconium caused formation dinuclear fulvalene bridged complex. desired [Cp2Zr{Si(SiMe3)3}2]- could be obtained reduction Cp2Zr{Si(SiMe3)3}2...
We report femtosecond Fe K-edge absorption (XAS) and nonresonant X-ray emission (XES) spectra of ferric cytochrome C (Cyt c) upon excitation the haem (>300 nm) or mixed tryptophan (<300 nm). The XAS XES transients obtained in both energy ranges show no evidence for electron transfer processes between photoexcited (Trp) haem, but rather an ultrafast transfer, agreement with previous optical fluorescence transient studies. reported (J. Phys. Chem. B 2011, 115 (46), 13723–13730) decay times Trp...
We review our recent results on the implementation of picosecond (ps) X-ray absorption spectroscopy to probe electronic and geometric structure centres formed by photoexcitation solar materials such as TiO2 polymorphs inorganic Cs-based perovskites. The show electron localization at Ti defects in anatase rutile small hole polaron formation valence band CsPbBr3, all within 80 ps. This method is promising for study ultrafast time scales processes, especially with advent Swiss Free Electron...
A von Hamos geometry based wavelength dispersive spectrometer combined with an <italic>in situ</italic> reactor cell has been developed to measure non-resonant sulfur Kα emission for the speciation of low concentrations sulfur.
Most chemical and biochemical reactions in nature industrial processes are driven by thermal effects that bring the reactants above energy barrier for reaction. In aqueous solutions, this process can also be triggered laser temperature jump (T-jump) method, which water vibrational (stretch, bend, or combination) modes excited a short pulse, leading to increase irradiated volume within few picoseconds. The combination of T-jump with X-ray spectroscopic probes would add element-specificity as...
X-ray absorption linear dichroism of rutile TiO 2 at the Ti K -edge provides information about electronic states involved in pre-edge transitions. Here, with high energy resolution is analyzed combination ab initio finite difference method calculations and spherical tensor analysis. It an assignment three peaks beyond octahedral crystal field splitting approximation estimates spatial extension corresponding final states. then discussed for first time (XAS) pentacoordinated titanium atoms due...
We discuss our recently reported femtosecond (fs) X-ray emission spectroscopy results on the ligand dissociation and recombination in nitrosylmyoglobin (MbNO) context of previous studies ferrous haem proteins.
The development of next generation perovskite-based optoelectronic devices relies critically on the understanding interaction between charge carriers and polar lattice in out-of-equilibrium conditions. While it has become increasingly evident for CsPbBr3 perovskites that Pb-Br framework flexibility plays a key role their light-activated functionality, corresponding local structural rearrangement not yet been unambiguously identified. In this work, we demonstrate photoinduced changes system...
We report on an element-selective study of the fate charge carriers in photoexcited inorganic CsPbBr3 and CsPb(ClBr)3 perovskite nanocrystals (NCs) toluene solutions using time-resolved X-ray absorption spectroscopy with 80 ps time resolution. Probing Br K-edge, Pb L3-edge Cs L2-edge, we find that holes valence band are localized at atoms, forming small polarons, while electrons appear as delocalized conduction band. No signature either electronic or structural changes observed L2-edge. The...