A5015595235- Advanced Chemical Physics Studies
- Atomic and Molecular Physics
- Mass Spectrometry Techniques and Applications
- Electron and X-Ray Spectroscopy Techniques
- X-ray Spectroscopy and Fluorescence Analysis
- Photochemistry and Electron Transfer Studies
- Spectroscopy and Quantum Chemical Studies
- Spectroscopy and Laser Applications
- Laser-Matter Interactions and Applications
- Quantum, superfluid, helium dynamics
- Cold Atom Physics and Bose-Einstein Condensates
- Inorganic Fluorides and Related Compounds
- Ion-surface interactions and analysis
- Diamond and Carbon-based Materials Research
- Nuclear physics research studies
- Atmospheric Ozone and Climate
- Photocathodes and Microchannel Plates
- Atomic and Subatomic Physics Research
- Analytical chemistry methods development
- Advanced X-ray Imaging Techniques
- Advanced Electron Microscopy Techniques and Applications
- Molecular Junctions and Nanostructures
- Electrochemical Analysis and Applications
- Force Microscopy Techniques and Applications
- Phase Equilibria and Thermodynamics
Centre National de la Recherche Scientifique
2015-2024
Sorbonne Université
2015-2024
Laboratoire de Chimie Physique - Matière et Rayonnement
2015-2024
High Energy Accelerator Research Organization
1987-2020
Institute of Materials Structure Science
2020
Sophia University
2020
University of Toyama
2020
SAGA Light Source
2020
Laboratoire de Physique du Rayonnement et de la Lumière
1987-2019
Université Paris Cité
1988-2017
A new spectroscopic technique, giving complete two-dimensional e(-)-e(-) coincidence spectra in single photon double photoionization, is presented. The technique resolves the states of doubly charged ions and provides individual electrons emitted formation each final dication state. Complete for photoionization Xe, Kr, Ar at energies up to 51 eV have been recorded. Overall surprisingly, np(4) 3P, 1D, 1S are populated according their statistical weights. When evident autoionization excluded,...
The spectroscopy and the dynamics of ${\mathrm{CO}}^{2+}$ ${\mathrm{CO}}^{3+}$ in 35--150-eV energy range have been studied using various complementary experiments, such as photoionization with synchrotron radiation, ion-ion coincidence technique, ${\mathrm{H}}^{+}$ double-charge-transfer spectroscopy. In addition, ab initio calculations performed order to obtain potential-energy curves electronic states lying between 35 60 eV. lowest-energy state is shown be predissociated. metastable...
The term schemes of the doubly charged ions CO2+2, OCS2+, and CS2+2 have been calculated by CIPSI method using a new economical basis set polarized atomic orbitals difference orbitals. energies are compared with existing experimental data obtained from Auger spectra, double charge transfer, photoionization including PIPICO technique. A complete assignment manifolds singlet states is achieved good agreement between theory experiment. Only lowest ion well described simple two-hole...
A magnetic bottle spectrometer of the type recently developed by Eland et al. [Phys. Rev. Lett. 90, 053003 (2003).] has been implemented for use with synchrotron radiation, allowing multidimensional electron spectroscopy. Its application to Xe $4d$ double Auger decay reveals all energy pathways involved. The dominant path is a cascade process rapid (6 fs) ejection first followed slower ($>23\text{ }\text{ }\mathrm{fs}$) emission second electron. Weaker processes implying 3 are also...
The formation of hollow molecules (with a completely empty $K$ shell in one constituent atom) through single-photon core double ionization has been demonstrated using sensitive magnetic bottle experimental technique combined with synchrotron radiation. Detailed properties are presented such as the spectroscopy, formation, and decay dynamics $\mathrm{N}_{2}{}^{2+}$ ${K}^{\ensuremath{-}2}$ main satellite states strong chemical shifts holes on an oxygen atom CO, ${\mathrm{CO}}_{2}$,...
We observe the formation in a single-photon transition of two core holes, each at different carbon atom ${\mathrm{C}}_{2}{\mathrm{H}}_{2}$ molecule. At photon energy 770.5 eV, probability this 2-site double ionization amounts to $1.6\ifmmode\pm\else\textpm\fi{}0.4%$ 1-site ionization. A simple theoretical model based on knockout mechanism gives reasonable agreement with experiment. Spectroscopy and Auger decays associated hole states are also investigated.
Using synchrotron radiation and high-resolution electron spectroscopy, we have directly observed identified specific photoelectrons from K^{-2}V states in neon corresponding to simultaneous 1s ionization 1s→valence excitation. The natural lifetime broadening of the relative intensities different types shakeup channels been determined experimentally compared ab initio calculations. Moreover, high-energy Auger spectrum resulting decay Ne^{2+}K^{-2} Ne^{+}K^{-2}V as well participator...
Quantitative ion yields from photoionization of gaseous CO have been measured with time-of-flight mass spectrometry and photoion-photoion coincidence techniques using synchrotron radiation 270 to 360 eV 515 615 eV, in the region C 1s O excitation ionization. Dissociative multiple-ionization efficiencies, ion-branching ratios, relative all possible ionization reactions are derived. The distributions kinetic energies released (${\mathrm{C}}^{+}$+${\mathrm{O}}^{+}$)...
Single photon double ionization of CS2 has been investigated, using mass spectrometric coincidence techniques: both metastable and dissociative CS++2 states have observed; three different dissociation pathways demonstrated, including one bond (S++CS+) two bonds (S++C+S+ S++C++S) breakings; simulation the observed provided some insight into mechanisms. Monochromatized synchrotron radiation enabled us to measure excitation spectra these relatively intense processes, in 25–75 eV energy range....
Using three new coincidence experiments to study the dynamics of double photoionization a complex atom we demonstrate that (1) indirect processes contribute up 20% ionization Ar near threshold and (2) population final states depends on symmetry electron-pair wave function as correctly predicted by theory. The energy distribution photoelectrons is found be essentially flat at 12.7 eV above threshold.
The emission of one or two Auger electrons, following Kr $3d$ inner-shell ionization by synchrotron light, has been investigated both experimentally and theoretically. All electrons emitted in the process are detected coincidence analyzed energy thanks to a magnetic-bottle electron time-of-flight spectrometer. In addition, noncoincident high-resolution spectra have measured characterize cascade double-Auger paths more fully. Combination experimental approaches our calculations allows full...
We have observed single photon double $K$-shell photoionization in the ${\mathrm{C}}_{2}{\mathrm{H}}_{2n}$ ($n=1--3$) hydrocarbon sequence and ${\mathrm{N}}_{2}$ CO, using synchrotron radiation electron coincidence spectroscopy. Our previous observations of ${K}^{\ensuremath{-}2}$ process these molecules are extended by a with one core hole created at each two neighboring atoms molecule (${K}^{\ensuremath{-}1}{K}^{\ensuremath{-}1}$ process). In sequence, spectroscopy...
Due to its element- and site-specificity, inner-shell photoelectron spectroscopy is a widely used technique probe the chemical structure of matter. Here we show that time-resolved can be employed observe ultrafast reactions electronic response nuclear motion with high sensitivity. The ultraviolet dissociation iodomethane (CH$_3$I) investigated by ionization above iodine 4d edge, using photoion spectroscopy. dynamics observed in spectra appear earlier are faster than those seen fragments....
Properties of the interatomic Coulombic decay (ICD) process in Ne dimers have been obtained by tracking formation energetic Ne+ ions. The double photoionization cross section, deduced from Ne+/Ne+ coincidence signal, is dominated ICD and presents a threshold 280 meV below atomic Ne+2s(-1) threshold. Rydberg excitation 2s electron dimer creates molecular states whose Sigma Pi symmetries resolved. These excited resonant releasing an ion neutral Ne* fragment. Subsequent autoionization fragment...
Energy and angle resolved measurements have been performed in the double photoionization of helium. Whereas angular distributions do not depend much on energy sharing $({E}_{1}{,E}_{2})$ at 4 eV above threshold, a strong effect is observed $E\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}18.6$ eV. These results can be analyzed qualitatively if total amplitude split into two parts which are, respectively, symmetric $({a}_{g})$ antisymmetric $({a}_{u})$ interchange ${E}_{1}$ ${E}_{2}$,...
The spectroscopy and metastability of the carbon dioxide doubly charged ion, CO(2) (2+) dication, have been studied with photoionization experiments: time-of-flight photoelectron coincidence (TOF-PEPECO), threshold photoelectrons (TPEsCO), ion (TPEsCO coincidence) spectroscopies. Vibrational structure is observed in TOF-PEPECO TPEsCO spectra ground first two excited states. vibrational dominated by symmetric stretch except spectrum state where an antisymmetric progression observed. All three...
Simultaneous core ionization and excitation have been observed in the C(2)H(2n) (n=1, 2, 3) molecular series using synchrotron radiation a magnetic bottle time-of-flight electron spectrometer. Rich satellite patterns corresponding to (K(-2)V) excited states of K(-1) ions identified by detecting coincidence photoelectron with two Auger electrons resulting from double hole relaxation. A theoretical model is proposed providing absolute photoionization cross sections revealing clear signatures...
We present in detail a theoretical model that provides absolute cross sections for simultaneous core-ionization core-excitation (K−2V ) and compare its predictions with experimental results obtained on the water molecule after photoionization by synchrotron radiation. Two resonances of different symmetries are assigned main K−2V peak comparable contributions from monopolar (direct shake-up) dipolar (conjugate core-valence excitations identified. The is observed much greater width than total...
We have observed, for the first time, $\mathrm{LS}$-forbidden triplet doubly excited states, in single photon excitation of ground state helium, below second ionization threshold. These states are identified as $^{3}D^{o}$ and $^{3}P^{o}$ their is due to spin-orbit interaction that mixes them with optically allowed $^{1}P^{o}$ states. This observation possible very high efficiency detecting metastable atoms created after fluorescence decay new capabilities third generation synchrotron vacuum...
A new toroidal analyser has been used to study the double photoionization of helium, for energies down 4 eV above threshold. The two electrons are detected with equal energies, and coincidences between them various angles emission can be obtained simultaneously. plane detection contains photon beam, in contrast recent experiments performed perpendicular beam. angular correlation function is extracted directly from present measurements, which shown insensitive Stokes parameters width that not...
Photoelectron spectroscopy and photoion-photoion coincidence technique are combined for the first time to show, in a molecule, selectivity of electronic decay channels resonances near core edge. Tetramethylsilane is studied ${\mathrm{L}}_{\mathrm{I}\mathrm{I},\mathrm{I}\mathrm{I}\mathrm{I}}$ level silicon, by use monochromatized synchrotron radiation 100--120-eV range. Autoionization simple double-resonant Auger processes explain formation one-hole multiple-hole excited configurations final...