Search

Your search keyword '"Nachtegaal, M."' showing total 3 results
Start Over Author "Nachtegaal, M." Topic xanes
3 results on '"Nachtegaal, M."'

1. The dedicated QEXAFS facility at the SLS: Performance and Scientific Opportunities.

Author

Frahm, R., Nachtegaal, M., Stötzel, J., Harfouche, M., van Bokhoven, J. A., and Grunwaldt, J.-D.

Subjects
*LIGHT sources, *MONOCHROMATORS, *CRYSTALS, *SPECTRUM analysis, *FORCE & energy
Abstract

The SuperXAS beamline at the Swiss Light Source (SLS) features a permanently installed monochromator for quick scanning EXAFS (QEXAFS) spectroscopy in series with a conventional double crystal monochromator (DCM). All installed optical components like collimating and focussing mirrors can be used by both devices. The remote exchange of the monochromators is possible in less than five minutes while maintaining the beam geometry on the sample. The QEXAFS system allows fast absorption scans down to the millisecond range for the investigation of time dependent processes. Using a Si(111) channel cut crystal the energy range from 5–16 keV can be covered, with a Si(311) cut the range 9.5–30 keV. Usually a quick scanning interval of 0.1°–2° in Bragg angle is selected, thus covering XANES, full EXAFS or multiple edge scans of e.g. all L-edges of a heavy element. Up to about 80 spectra per second can be collected, corresponding to a time resolution of 12.5 ms. The high intensity of the beamline even facilitates fluorescence measurements on dilute samples. [ABSTRACT FROM AUTHOR]

Published
2010
Full Text
View/download PDF

2. Influence of the muffin-tin approximation on the simulation of titanium K-edge X-ray absorption spectra of TiO2 (rutile and anatase phases)

Author

Kravtsova, A.N., Soldatov, A.V., Nachtegaal, M., Tew, M.W., and van Bokhoven, J.A.

Subjects
*MUFFIN pans, *SIMULATION methods & models, *TITANIUM compounds, *ABSORPTION spectra, *X-ray absorption near edge structure, *MULTIPLE scattering (Physics)
Abstract

Abstract: X-Ray absorption near-edge structure (XANES) spectra at the Ti K-edge of TiO2 (rutile and anatase phases) have been analyzed. Theoretical analyses of the experimental data have been performed on the basis of both real-space full multiple scattering theory with muffin-tin approximation for potential shape and full-potential (beyond muffin-tin approximation) finite difference method. A full potential is required to satisfactorily reproduce experimental Ti K-edge XANES spectra in the TiO2. [Copyright &y& Elsevier]

Published
2010
Full Text
View/download PDF

3. Microsecond X-ray absorption spectroscopy identification of Co(I) intermediates in cobaloxime-catalyzed hydrogen evolution

Author

Jeroen A. van Bokhoven, Grigory Smolentsev, Alexander A. Guda, Vincent Artero, Bianca Cecconi, Maarten Nachtegaal, Murielle Chavarot-Kerlidou, Paul Scherrer Institute (PSI), Dipartimento di Scienza dei Materiali = Department of Materials Science [Milano-Bicocca], Università degli Studi di Milano-Bicocca = University of Milano-Bicocca (UNIMIB), Laboratoire de Chimie et Biologie des Métaux (LCBM - UMR 5249), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Southern Federal University [Rostov-on-Don] (SFEDU), Institute for Chemical and Bioengineering [ETH Zurich] (ICB), Department of Chemistry and Applied Biosciences [ETH Zürich] (D-CHAB), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)- Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), ANR-11-LABX-0003,ARCANE,Grenoble, une chimie bio-motivée(2011), European Project: 290605,EC:FP7:PEOPLE,FP7-PEOPLE-2011-COFUND,PSI-FELLOW(2012), European Project: 306398,EC:FP7:ERC,ERC-2012-StG_20111012,PHOTOCATH2ODE(2012), Smolentsev, G, Cecconi, B, Guda, A, Chavarot Kerlidou, M, van Bokhoven, J, Nachtegaal, M, Artero, V, Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Università degli Studi di Milano-Bicocca [Milano] (UNIMIB), and International Research Center 'Smart Materials', Southern Federal University, 344090 Rostov-on-Don (Russia)

Subjects
Absorption spectroscopy, solar fuels, chemistry.chemical_element, transient X-ray absorption, 010402 general chemistry, Photochemistry, 7. Clean energy, 01 natural sciences, Article, Catalysis, photocatalysi, Organic chemistry, [CHIM.COOR]Chemical Sciences/Coordination chemistry, Hydrogen production, X-ray absorption spectroscopy, solar fuel, 010405 organic chemistry, Chemistry, Organic Chemistry, General Chemistry, [CHIM.CATA]Chemical Sciences/Catalysis, XANES, 0104 chemical sciences, Microsecond, Catalytic cycle, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], Cobalt, photocatalysis
Abstract

Rational development of efficient photocatalytic systems for hydrogen production requires understanding the catalytic mechanism and detailed information about the structure of intermediates in the catalytic cycle. We demonstrate how time-resolved X-ray absorption spectroscopy in the microsecond time range can be used to identify such intermediates and to determine their local geometric structure. This method was used to obtain the solution structure of the CoI intermediate of cobaloxime, which is a non-noble metal catalyst for solar hydrogen production from water. Distances between cobalt and the nearest ligands including two solvent molecules and displacement of the cobalt atom out of plane formed by the planar ligands have been determined. Combining in situ X-ray absorption and UV/Vis data, we demonstrate how slight modification of the catalyst structure can lead to the formation of a catalytically inactive CoI state under similar conditions. Possible deactivation mechanisms are discussed. Distinct CoI states are generated under light-driven conditions depending on the structure of two cobaloxime complexes (see figure). Only one is catalytically active for H2 evolution and its structure is determined using quantitative analysis of time-resolved XANES spectra.

Published
2015

Catalog

Books, media, physical & digital resources
See catalog results