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John D Bozek - One of the best experts on this subject based on the ideXlab platform.
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photoabsorption photoionization and Auger processes at the carbon k edge in c h 3 i
Physical Review A, 2020Co-Authors: John D Bozek, Ruaridh Forbes, Stephen T Pratt, Alberto De Fanis, Aleksandar R Milosavljevic, Christophe Nicolas, Nicholas A Besley, D M P HollandAbstract:The dynamics of photoabsorption, photoionization, and the associated Auger decay have been investigated at the carbon $K$ edge in methyl iodide ($\mathrm{C}{\mathrm{H}}_{3}\mathrm{I}$) using linearly polarized synchrotron radiation. Ion yield measurements were used to investigate transitions in the pre-edge region due to excitations into either unoccupied valence or Rydberg states. The assignment of these transitions was achieved through comparison with theoretical x-ray absorption spectra calculated using time-dependent density functional theory, within the Tamm-Dancoff approximation. Several of the Rydberg states belonging to series converging onto the $\mathrm{C}1s$ ionization limit exhibit significant vibrational structure that is also interpreted using theoretical calculations. The $\mathrm{C}1s$ in $\mathrm{C}{\mathrm{H}}_{3}\mathrm{I}$ photoElectron Spectrum was measured, and the observed vibrational structure was assigned with the aid of theoretical predictions. Polarization dependent, resonantly excited, valence shell photoElectron spectra were recorded at photon energies coinciding with the $\mathrm{C}\phantom{\rule{0.16em}{0ex}}1s\ensuremath{\rightarrow}{\ensuremath{\sigma}}^{*}, \mathrm{C}\phantom{\rule{0.16em}{0ex}}1s\ensuremath{\rightarrow}6s{a}_{1}$ and $\mathrm{C}\phantom{\rule{0.16em}{0ex}}1s\ensuremath{\rightarrow}6pe$ transitions in $\mathrm{C}{\mathrm{H}}_{3}\mathrm{I}$, thereby allowing photoElectron angular distributions to be determined. The nonresonantly excited C(KVV) Auger Electron Spectrum was measured and some of the features observed at high kinetic energies were attributed to transitions into valence orbitals possessing significant iodine character. The contributions of participator and spectator Auger decay to the resonantly excited photoElectron spectra have been assessed. The influence of participator decay appears minor whereas spectator decay results in the enhanced population of satellite states.
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molecular frame Auger Electron energy Spectrum from n2
Journal of Physics B, 2012Co-Authors: James P Cryan, J M Glownia, Jakob Andreasson, A Belkacem, N Berrah, Cosmin I Blaga, Christoph Bostedt, John D BozekAbstract:Here we present the first angle-resolved, non-resonant (normal) Auger spectra for impulsively aligned nitrogen molecules. We have measured the angular pattern of Auger Electron emission following K-shell photoionization by 1.1 keV photons from the Linac Coherent Light Source (LCLS). Using strong-field-induced molecular alignment to make molecular frame measurements is equally effective for both repulsive and quasi-bound final states. The capability to resolve Auger emission angular distributions in the molecular frame of reference provides a new tool for spectral assignments in congested Auger Electron spectra that takes advantage of the symmetries of the final diction states. Based on our experimental results and theoretical predictions, we propose the assignment of the spectral features in the Auger Electron Spectrum.
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angle resolved Electron spectroscopy of laser assisted Auger decay induced by a few femtosecond x ray pulse
Physical Review Letters, 2012Co-Authors: M Meyer, P Radcliffe, T Tschentscher, J T Costello, Adrian L Cavalieri, Ivanka Grguras, Andreas Maier, Reinhard Kienberger, John D BozekAbstract:Two-color ($\mathrm{x}\mathrm{\text{\ensuremath{-}}}\mathrm{ray}+\mathrm{\text{infrared}}$) Electron spectroscopy is used for investigating laser-assisted $KLL$ Auger decay following $1s$ photoionization of atomic Ne with few-femtosecond x-ray pulses from the Linac Coherent Light Source. In an angle-resolved experiment, the overall width of the laser-modified Auger-Electron Spectrum and its structure change significantly as a function of the emission angle. The spectra are characterized by a strong intensity variation of the sidebands revealing a gross structure. This variation is caused, as predicted by theory, by the interference of Electrons emitted at different times within the duration of one optical cycle of the infrared dressing laser, which almost coincides with the lifetime of the Ne $1s$ vacancy.
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Auger Electron angular distribution of double core hole states in the molecular reference frame
Physical Review Letters, 2010Co-Authors: James P Cryan, J M Glownia, Jakob Andreasson, A Belkacem, N Berrah, Cosmin I Blaga, Christoph Bostedt, John D Bozek, Christian Buth, L F DimauroAbstract:The Linac Coherent Light Source free Electron laser is a source of high brightness x rays, 2 × 10 11 photons in a ∼5 fs pulse, that can be focused to produce double core vacancies through rapid sequential ionization. This enables double core vacancy Auger Electron spectroscopy, an entirely new way to study femtosecond chemical dynamics with Auger Electrons that probe the local valence structure of molecules near a specific atomic core. Using 1.1 keV photons for sequential x-ray ionization of impulsively aligned molecular nitrogen, we observed a rich single-site double core vacancy Auger Electron Spectrum near 413 eV, in good agreement with ab initio calculations, and we measured the corresponding Auger Electron angle dependence in the molecular frame.
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Auger Electron angular distribution of double core hole states in the molecular reference frame
Physical Review Letters, 2010Co-Authors: James P Cryan, J M Glownia, Jakob Andreasson, A Belkacem, N Berrah, Cosmin I Blaga, Christoph Bostedt, John D Bozek, Christian Buth, L F DimauroAbstract:The Linac Coherent Light Source free Electron laser is a source of high brightness x rays, $2\ifmmode\times\else\texttimes\fi{}{10}^{11}$ photons in a $\ensuremath{\sim}5\text{ }\text{ }\mathrm{fs}$ pulse, that can be focused to produce double core vacancies through rapid sequential ionization. This enables double core vacancy Auger Electron spectroscopy, an entirely new way to study femtosecond chemical dynamics with Auger Electrons that probe the local valence structure of molecules near a specific atomic core. Using 1.1 keV photons for sequential x-ray ionization of impulsively aligned molecular nitrogen, we observed a rich single-site double core vacancy Auger Electron Spectrum near 413 eV, in good agreement with ab initio calculations, and we measured the corresponding Auger Electron angle dependence in the molecular frame.
L F Dimauro - One of the best experts on this subject based on the ideXlab platform.
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Auger Electron angular distribution of double core hole states in the molecular reference frame
Physical Review Letters, 2010Co-Authors: James P Cryan, J M Glownia, Jakob Andreasson, A Belkacem, N Berrah, Cosmin I Blaga, Christoph Bostedt, John D Bozek, Christian Buth, L F DimauroAbstract:The Linac Coherent Light Source free Electron laser is a source of high brightness x rays, 2 × 10 11 photons in a ∼5 fs pulse, that can be focused to produce double core vacancies through rapid sequential ionization. This enables double core vacancy Auger Electron spectroscopy, an entirely new way to study femtosecond chemical dynamics with Auger Electrons that probe the local valence structure of molecules near a specific atomic core. Using 1.1 keV photons for sequential x-ray ionization of impulsively aligned molecular nitrogen, we observed a rich single-site double core vacancy Auger Electron Spectrum near 413 eV, in good agreement with ab initio calculations, and we measured the corresponding Auger Electron angle dependence in the molecular frame.
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Auger Electron angular distribution of double core hole states in the molecular reference frame
Physical Review Letters, 2010Co-Authors: James P Cryan, J M Glownia, Jakob Andreasson, A Belkacem, N Berrah, Cosmin I Blaga, Christoph Bostedt, John D Bozek, Christian Buth, L F DimauroAbstract:The Linac Coherent Light Source free Electron laser is a source of high brightness x rays, $2\ifmmode\times\else\texttimes\fi{}{10}^{11}$ photons in a $\ensuremath{\sim}5\text{ }\text{ }\mathrm{fs}$ pulse, that can be focused to produce double core vacancies through rapid sequential ionization. This enables double core vacancy Auger Electron spectroscopy, an entirely new way to study femtosecond chemical dynamics with Auger Electrons that probe the local valence structure of molecules near a specific atomic core. Using 1.1 keV photons for sequential x-ray ionization of impulsively aligned molecular nitrogen, we observed a rich single-site double core vacancy Auger Electron Spectrum near 413 eV, in good agreement with ab initio calculations, and we measured the corresponding Auger Electron angle dependence in the molecular frame.
James P Cryan - One of the best experts on this subject based on the ideXlab platform.
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molecular frame Auger Electron energy Spectrum from n2
Journal of Physics B, 2012Co-Authors: James P Cryan, J M Glownia, Jakob Andreasson, A Belkacem, N Berrah, Cosmin I Blaga, Christoph Bostedt, John D BozekAbstract:Here we present the first angle-resolved, non-resonant (normal) Auger spectra for impulsively aligned nitrogen molecules. We have measured the angular pattern of Auger Electron emission following K-shell photoionization by 1.1 keV photons from the Linac Coherent Light Source (LCLS). Using strong-field-induced molecular alignment to make molecular frame measurements is equally effective for both repulsive and quasi-bound final states. The capability to resolve Auger emission angular distributions in the molecular frame of reference provides a new tool for spectral assignments in congested Auger Electron spectra that takes advantage of the symmetries of the final diction states. Based on our experimental results and theoretical predictions, we propose the assignment of the spectral features in the Auger Electron Spectrum.
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Auger Electron angular distribution of double core hole states in the molecular reference frame
Physical Review Letters, 2010Co-Authors: James P Cryan, J M Glownia, Jakob Andreasson, A Belkacem, N Berrah, Cosmin I Blaga, Christoph Bostedt, John D Bozek, Christian Buth, L F DimauroAbstract:The Linac Coherent Light Source free Electron laser is a source of high brightness x rays, 2 × 10 11 photons in a ∼5 fs pulse, that can be focused to produce double core vacancies through rapid sequential ionization. This enables double core vacancy Auger Electron spectroscopy, an entirely new way to study femtosecond chemical dynamics with Auger Electrons that probe the local valence structure of molecules near a specific atomic core. Using 1.1 keV photons for sequential x-ray ionization of impulsively aligned molecular nitrogen, we observed a rich single-site double core vacancy Auger Electron Spectrum near 413 eV, in good agreement with ab initio calculations, and we measured the corresponding Auger Electron angle dependence in the molecular frame.
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Auger Electron angular distribution of double core hole states in the molecular reference frame
Physical Review Letters, 2010Co-Authors: James P Cryan, J M Glownia, Jakob Andreasson, A Belkacem, N Berrah, Cosmin I Blaga, Christoph Bostedt, John D Bozek, Christian Buth, L F DimauroAbstract:The Linac Coherent Light Source free Electron laser is a source of high brightness x rays, $2\ifmmode\times\else\texttimes\fi{}{10}^{11}$ photons in a $\ensuremath{\sim}5\text{ }\text{ }\mathrm{fs}$ pulse, that can be focused to produce double core vacancies through rapid sequential ionization. This enables double core vacancy Auger Electron spectroscopy, an entirely new way to study femtosecond chemical dynamics with Auger Electrons that probe the local valence structure of molecules near a specific atomic core. Using 1.1 keV photons for sequential x-ray ionization of impulsively aligned molecular nitrogen, we observed a rich single-site double core vacancy Auger Electron Spectrum near 413 eV, in good agreement with ab initio calculations, and we measured the corresponding Auger Electron angle dependence in the molecular frame.
Bernd Winter - One of the best experts on this subject based on the ideXlab platform.
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Aqueous Solution Chemistry of Ammonium Cation in the Auger Time Window.
Scientific reports, 2017Co-Authors: Daniel Hollas, Marvin Nicolas Pohl, Robert Seidel, Emad F. Aziz, Petr Slavíček, Bernd WinterAbstract:We report on chemical reactions triggered by core-level ionization of ammonium ( $${{\rm{NH}}}_{4}^{+}$$ ) cation in aqueous solution. Based on a combination of photoemission experiments from a liquid microjet and high-level ab initio simulations, we identified simultaneous single and double proton transfer occurring on a very short timescale spanned by the Auger-decay lifetime. Molecular dynamics simulations indicate that the proton transfer to a neighboring water molecule leads to essentially complete formation of H3O+ (aq) and core-ionized ammonia $${({{\rm{NH}}}_{3}^{+})}^{\ast }$$ (aq) within the ~7 fs lifetime of the nitrogen 1s core hole. A second proton transfer leads to a transient structure with the proton shared between the remaining NH2 moiety and another water molecule in the hydration shell. These ultrafast proton transfers are stimulated by very strong hydrogen bonds between the ammonium cation and water. Experimentally, the proton transfer dynamics is identified from an emerging signal at the high-kinetic energy side of the Auger-Electron Spectrum in analogy to observations made for other hydrogen-bonded aqueous solutions. The present study represents the most pronounced charge separation observed upon core ionization in liquids so far.
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relaxation of Electronically excited hydrogen peroxide in liquid water insights from Auger Electron emission
Journal of Physical Chemistry C, 2013Co-Authors: Stephan Thurmer, Petr Slavíček, Isaak Unger, Bernd WinterAbstract:Autoionization Electron spectroscopy is applied to study nonradiative relaxation processes of hydrogen peroxide aqueous solution irradiated by soft X-rays. The high kinetic energy part of the oxygen 1s H2O2(aq) Auger-Electron Spectrum reveals dicationic final states with considerably lower energy than for neat liquid water. Assisted by quantum chemical calculations, it is argued that such lower-energy states arise from two fundamentally different relaxation processes. One is (local) Auger decay, yielding H2O22+(aq) species, and here the low final-state energy arises from charge delocalization across the molecular O–O bond. Alternatively, nonlocal dicationic states can form, corresponding to a charge-separated complex comprising H2O2 and a neighboring water molecule. Different charge-separation mechanisms, depending on whether or not proton dynamics of the core-level excited or ionized H2O2 molecule is involved, are discussed. We also present for the first time the partial Electron yield X-ray absorption s...
S. Fritzsche - One of the best experts on this subject based on the ideXlab platform.
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Selectivity of the Br 3d−1 Auger decays in HBr
Physical Review A, 2018Co-Authors: J. Palaudoux, T. Kaneyasu, L. Andric, S. Carniato, G. Gamblin, F. Penent, Y. Hikosaka, E. Shigemasa, K. Ito, S. FritzscheAbstract:The Auger decay of the spin-orbit and molecular-field split Br 3d−1 core holes in HBr is investigated, both by a photoElectron–Auger-Electron coincidence experiment and by ab initio calculations based on the one-center approximation. The branching ratios for the Auger decay of the five different core-hole states to the 4p(σ,π)−2 dicationic final states are determined. Experimental and theoretical data are in good agreement and conform to results for the 4pπ−2 final states from a previous analysis of the high-resolution conventional Auger-Electron Spectrum. The branching ratios for the Br 3d−1 Auger decay to the 4p(σ,π)−2 with Σ symmetry follow the propensity rule of L2,3VV Auger decay [S. Svensson, A. Ausmees, S. J. Osborne, G. Bray, F. Gel'mukhanov, H. Ågren, A. Naves de Brito, O.-P. Sairanen, A. Kivimäki, E. Nõmmiste, H. Aksela, and S. Aksela, Phys. Rev. Lett. 72, 3021 (1994)] stating that the oriented core holes decay preferentially by involving a valence Electron from an orbital with the same spatial orientation. For the M4,5VV decay in HBr this propensity rule has to be supplemented by the requirement that the Auger-Electron channel and the other valence orbital have the same preferential orientation. We also probe the influence of the Auger kinetic energy on the distortion of the photoline caused by the postcollision interaction effect. For small kinetic energies, differences between experimental results and theoretical predictions are identified.