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Your search keyword '"Lutzenkirchen-Hecht, D."' showing total 22 results
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22 results on '"Lutzenkirchen-Hecht, D."'

4. Time-resolved study of the oxidation of ethanol by cerium(IV) using combined quick-XANES, UV-vis, and Raman spectroscopies

Author

Briois, V., Lutzenkirchen-Hecht, D., Villain, F., Fonda, E., Belin, E., Griesebock, B., and Frahm, R.

Subjects
Raman spectroscopy -- Usage, Alcohol -- Chemical properties, Alcohol, Denatured -- Chemical properties, Cerium -- Chemical properties, Chemicals, plastics and rubber industries
Abstract

Time-resolved X-ray absorption spectroscopy are combined with UV-vis and Raman spectroscopies to study the in situ reduction of Ce(super 4+) to Ce(super 3+) in ethanolic solution with a time resolution of ca.4-5 s. It is observed that high quality results can be obtained simultaneously, thus giving a detailed insight into the mechanisms of the investigated chemical reaction.

Published
2005

6. Atomic and electronic bulk versus surface structure: lithium intercalation in anatase TiO2

Author

Wagemaker, M., Lutzenkirchen-Hecht, D., Well, A. A. van, and Frahm, R.

Subjects
Lithium -- Research, Lithium -- Chemical properties, Atomic structure -- Analysis, Electronic structure -- Analysis, Spectrum analysis -- Usage, Chemicals, plastics and rubber industries
Abstract

Lithium intercalation in anatase TiO2 results in structural and electronic changes. A two-phase system is completely suited in the atomic structure (EXAFS) and the electronic structure (XANES) regions of the X-ray absorption spectra of anatase TiO2 upon Li intercalation.

Published
2004

12. Lithium Storage in Amorphous TiO2 Nanoparticles

Author

Borghols, W.J.H., Lutzenkirchen-Hecht, D., Haake, U., Chan, W., Lafont, U., Kelder, E.M., Eck, E.R.H. van, Kentgens, A.P.M., Mulder, F.M., Wagemaker, M., Borghols, W.J.H., Lutzenkirchen-Hecht, D., Haake, U., Chan, W., Lafont, U., Kelder, E.M., Eck, E.R.H. van, Kentgens, A.P.M., Mulder, F.M., and Wagemaker, M.

Abstract

Contains fulltext : 83515.pdf (publisher's version ) (Closed access)

Published
2010

16. Quick scanning monochromator for millisecond in situ and in operando X-ray absorption spectroscopy.

Author

Muller, O., Lutzenkirchen-Hecht, D., and Frahm, R.

Subjects
*MONOCHROMATORS, *X-ray absorption, *OSCILLATIONS, *ELECTRIC torque motors, *EXTENDED X-ray absorption fine structure
Abstract

The design and capabilities of a novel Quick scanning Extended X-ray Absorption Fine Structure (QEXAFS) monochromator are presented. The oscillatory movement of the crystal stage is realized by means of a unique open-loop driving scheme operating a direct drive torque motor. The entire drive mechanics are installed inside of a goniometer located on the atmospheric side of the vacuum chamber. This design allows remote adjustment of the oscillation frequency and spectral range, giving complete control of QEXAFS measurements. It also features a real step-scanning mode, which operates without a control loop to prevent induced vibrations. Equipped with Si(111) and Si(311) crystals on a single stage, it facilitates an energy range from 4.0 keV to 43 keV. Extended X-ray absorption fine structure spectra up to k = 14.4 Å-1 have been acquired within 17 ms and X-ray absorption near edge structure spectra covering more than 200 eV within 10 ms. The achieved data quality is excellent as shown by the presented measurements. [ABSTRACT FROM AUTHOR]

Published
2015
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17. Corrosion of Mo in KOH:  Time Resolved XAFS Investigations

Author

Lutzenkirchen-Hecht, D. and Frahm, R.

Abstract

The corrosion products formed during the anodic polarization of molybdenum in 1 M KOH were investigated in situ with time-resolved X-ray absorption spectroscopy at the Mo K-edge. Near edge spectra (XANES) as well as EXAFS scans extending over approximately 1000 eV above the Mo absorption edge were measured as a function of the corrosion time. Time dependent values for the concentration of the dissolved Mo species in the electrolyte were calculated from the change of the absorption cofficient at the absorption edge. The detailed analysis of the XANES and EXAFS data suggests the presence of MoO42- ions in the solution.

Published
2001

18. Piezo X-ray Absorption Spectroscopy for the Investigation of Solid-State Transformations in the Millisecond Range

Author

Grunwaldt, J.-D., Lutzenkirchen-Hecht, D., Richwin, M., Grundmann, S., Clausen, B. S., and Frahm, R.

Abstract

The piezo XAFS technique in combination with an in situ cell has been used for the investigation of fast solid−solid transformations with millisecond time resolution. The technique records X-ray absorption spectra (XAFS) in a continuous mode by making use of piezo tilt tables in the X-ray monochromator, which are actuated by an oscillatory high voltage. The application of this technique in the field of solid-state chemistry and catalysis is illustrated by investigations of the X-ray absorption near-edge structure (XANES) of the Cu K edge during the autocatalytic reduction of a Cu/ZnO methanol catalyst and the spontaneous decomposition of (NH4)2Cr2O7 to Cr2O3. The reduction of Cu(II) to Cu(0) occurs within a few seconds. The existence of an intermediate Cu(I) phase could be revealed by the analysis of the preedge position and the white line intensity, but the Cu(I) intermediate is very unstable. The spontaneous decomposition of (NH4)2Cr2O7 occurs within about 30 s and shows after a short acceleration period a rather constant reaction rate and a quite long decay period.

Published
2001

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