The Experts below are selected from a list of 192 Experts worldwide ranked by ideXlab platform
Stefan Düsterer - One of the best experts on this subject based on the ideXlab platform.
-
Time-resolved inner-shell photoelectron spectroscopy: From a bound molecule to an Isolated Atom
Physical Review A, 2018Co-Authors: Felix Brauße, Gildas Goldsztejn, Kasra Amini, Rebecca Boll, Sadia Bari, Michael Burt, Barbara Cunha De Miranda, Cedric Bomme, Mark Brouard, Stefan DüstererAbstract:Due to its element and site specificity, inner-shell photoelectron spectroscopy is a widely used technique to probe the chemical structure of matter. Here, we show that time-resolved inner-shell photoelectron spectroscopy can be employed to observe ultrafast chemical reactions and the electronic response to the nuclear motion with high sensitivity. The ultraviolet dissociation of iodomethane (CH3I) is investigated by ionization above the iodine 4d edge, using time-resolved inner-shell photoelectron and photoion spectroscopy. The dynamics observed in the photoelectron spectra appear earlier and are faster than those seen in the iodine fragments. The experimental results are interpreted using crystal-field and spin-orbit configuration interaction calculations, and demonstrate that time-resolved inner-shell photoelectron spectroscopy is a powerful tool to directly track ultrafast structural and electronic transformations in gas-phase molecules.
Michael I. Bell - One of the best experts on this subject based on the ideXlab platform.
-
INCLUSION OF LOCAL STRUCTURE EFFECTS IN THEORETICAL X-RAY RESONANT SCATTERING AMPLITUDES USING AB INITIO X-RAY-ABSORPTION SPECTRA CALCULATIONS
Physical Review B, 1998Co-Authors: Julie O. Cross, Matthew Newville, John J. Rehr, Larry B. Sorensen, Charles E. Bouldin, G. M. Watson, Thomas Gouder, G. H. Lander, Michael I. BellAbstract:Improved calculations of Bragg peak intensities near Atomic resonance are obtained by including the effect of the local environment around the resonant Atoms on the resonant scattering amplitudes $\ensuremath{\Delta}{f=f}^{\ensuremath{'}}{+if}^{\ensuremath{''}}.$ Theoretical absorption cross sections calculated by the ab initio x-ray-absorption code FEFF are used to obtain the imaginary part ${f}^{\ensuremath{''}}$ by extension of the optical theorem to nonforward scattering under the dipole approximation. The real part ${f}^{\ensuremath{'}}$ is obtained by a limited range Kramers-Kronig transform of the difference between ${f}^{\ensuremath{''}}$ based on FEFF and existing theoretical calculations of ${f}^{\ensuremath{''}}$ based on an Isolated-Atom model. The Atomic part of $\ensuremath{\Delta}f$ calculated by FEFF for the resonant Atom embedded in the local potential is assumed to have spherical symmetry; however, no restriction is placed on the spectral features due to multiple scattering of the intermediate-state virtual photoelectron. Bragg peak intensities calculated in the kinematic approximation using the FEFF-based $\ensuremath{\Delta}f$ are compared to intensities calculated using the Isolated-Atom $\ensuremath{\Delta}f$ and to experimental data for Cu metal and ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{6.8}$ at the Cu K absorption edge, and for ${\mathrm{UO}}_{2}$ at the U ${M}_{\mathrm{IV}}$ absorption edge.
Alessandro Mirone - One of the best experts on this subject based on the ideXlab platform.
-
X-ray Resonant Magnetic Scattering : Polarisation Dependence in the non-spherical case
Acta crystallographica. Section A Foundations of crystallography, 2007Co-Authors: Alessandro MironeAbstract:A simple tensorial contraction method has been developed to obtain analytical formulae for X-ray resonant magnetic scattering. First, the method has been applied considering electric dipole-dipole and electric quadrupole-quadrupole scattering in the Isolated-Atom approximation. The results have been compared with previous work. The same method has then been extended to non-spherical systems by deriving new phenomenological formulae.
Felix Brauße - One of the best experts on this subject based on the ideXlab platform.
-
Time-resolved inner-shell photoelectron spectroscopy: From a bound molecule to an Isolated Atom
Physical Review A, 2018Co-Authors: Felix Brauße, Gildas Goldsztejn, Kasra Amini, Rebecca Boll, Sadia Bari, Michael Burt, Barbara Cunha De Miranda, Cedric Bomme, Mark Brouard, Stefan DüstererAbstract:Due to its element and site specificity, inner-shell photoelectron spectroscopy is a widely used technique to probe the chemical structure of matter. Here, we show that time-resolved inner-shell photoelectron spectroscopy can be employed to observe ultrafast chemical reactions and the electronic response to the nuclear motion with high sensitivity. The ultraviolet dissociation of iodomethane (CH3I) is investigated by ionization above the iodine 4d edge, using time-resolved inner-shell photoelectron and photoion spectroscopy. The dynamics observed in the photoelectron spectra appear earlier and are faster than those seen in the iodine fragments. The experimental results are interpreted using crystal-field and spin-orbit configuration interaction calculations, and demonstrate that time-resolved inner-shell photoelectron spectroscopy is a powerful tool to directly track ultrafast structural and electronic transformations in gas-phase molecules.
Julie O. Cross - One of the best experts on this subject based on the ideXlab platform.
-
INCLUSION OF LOCAL STRUCTURE EFFECTS IN THEORETICAL X-RAY RESONANT SCATTERING AMPLITUDES USING AB INITIO X-RAY-ABSORPTION SPECTRA CALCULATIONS
Physical Review B, 1998Co-Authors: Julie O. Cross, Matthew Newville, John J. Rehr, Larry B. Sorensen, Charles E. Bouldin, G. M. Watson, Thomas Gouder, G. H. Lander, Michael I. BellAbstract:Improved calculations of Bragg peak intensities near Atomic resonance are obtained by including the effect of the local environment around the resonant Atoms on the resonant scattering amplitudes $\ensuremath{\Delta}{f=f}^{\ensuremath{'}}{+if}^{\ensuremath{''}}.$ Theoretical absorption cross sections calculated by the ab initio x-ray-absorption code FEFF are used to obtain the imaginary part ${f}^{\ensuremath{''}}$ by extension of the optical theorem to nonforward scattering under the dipole approximation. The real part ${f}^{\ensuremath{'}}$ is obtained by a limited range Kramers-Kronig transform of the difference between ${f}^{\ensuremath{''}}$ based on FEFF and existing theoretical calculations of ${f}^{\ensuremath{''}}$ based on an Isolated-Atom model. The Atomic part of $\ensuremath{\Delta}f$ calculated by FEFF for the resonant Atom embedded in the local potential is assumed to have spherical symmetry; however, no restriction is placed on the spectral features due to multiple scattering of the intermediate-state virtual photoelectron. Bragg peak intensities calculated in the kinematic approximation using the FEFF-based $\ensuremath{\Delta}f$ are compared to intensities calculated using the Isolated-Atom $\ensuremath{\Delta}f$ and to experimental data for Cu metal and ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{6.8}$ at the Cu K absorption edge, and for ${\mathrm{UO}}_{2}$ at the U ${M}_{\mathrm{IV}}$ absorption edge.
