A5051642490- Advanced Chemical Physics Studies
- Electron and X-Ray Spectroscopy Techniques
- X-ray Spectroscopy and Fluorescence Analysis
- Atomic and Molecular Physics
- Spectroscopy and Quantum Chemical Studies
- Mass Spectrometry Techniques and Applications
- Photochemistry and Electron Transfer Studies
- Semiconductor materials and devices
- Spectroscopy and Laser Applications
- Molecular Junctions and Nanostructures
- Advanced X-ray Imaging Techniques
- Laser-Matter Interactions and Applications
- Ion-surface interactions and analysis
- Surface and Thin Film Phenomena
- Inorganic Fluorides and Related Compounds
- Advanced Electron Microscopy Techniques and Applications
- Nuclear Physics and Applications
- Semiconductor materials and interfaces
- Catalytic Processes in Materials Science
- Crystallography and Radiation Phenomena
- Silicon Nanostructures and Photoluminescence
- Surface Chemistry and Catalysis
- Quantum, superfluid, helium dynamics
- Atmospheric Ozone and Climate
- Laser-Plasma Interactions and Diagnostics
Laboratoire de Chimie Physique - Matière et Rayonnement
2016-2025
Sorbonne Université
2016-2025
Centre National de la Recherche Scientifique
2016-2025
Uppsala University
2014-2023
Université Paris Cité
2013-2023
Sorbonne University Abu Dhabi
2023
SPring-8
2017-2021
Délégation Paris 6
2015-2020
Hyogo University
2019
RIKEN
2019
Theory predicts that double-core-hole (DCH) spectroscopy can provide a new powerful means of differentiating between similar chemical systems with sensitivity not hitherto possible. Although DCH ionization on single site in molecules was recently measured double- and single-photon absorption, double-core holes vacancies two different sites, allowing unambiguous analysis, have remained elusive. Here we report direct observation sites produced via sequential two-photon using short, intense...
We have performed x-ray two-photon photoelectron spectroscopy using the Linac Coherent Light Source free-electron laser in order to study double core-hole (DCH) states of CO2, N2O, and N2. The experiment verifies theory behind chemical sensitivity two-site DCH by comparing a set small molecules with respect energy shift state extracting relevant parameters from this shift.
The nonlinear interaction of x rays with matter is at the heart understanding and controlling ultrafast molecular dynamics from an atom-specific viewpoint, providing new scientific analytical opportunities to explore structure small quantum systems. At increasingly high x-ray intensity, sensitivity ultrashort pulses specific electronic states emerging short-lived transient intermediates particular relevance for our fundamental multiphoton absorption processes. In this work, intense...
Synchrotron radiation was used to excite an inner-shell electron into a Rydberg orbital at the Ar 2p ns, nd, Kr 3d np and Xe 4d n p resonances. The resonant decay shake-off channels studied by three different measurements. Firstly, threshold scans were obtained over resonances thresholds. On first resonance for each atom, photoelectron spectra collected. intensity distribution of low kinetic energy electrons also determined few Finally, shake calculation carried out compare with experimental...
When exposed to ultraintense x-radiation sources such as free electron lasers (FELs) the innermost electronic shell can efficiently be emptied, creating a transient hollow atom or molecule. Understanding femtosecond dynamics of systems is fundamental achieving atomic resolution in flash diffraction imaging noncrystallized complex biological samples. We demonstrate capacity correlation method called "partial covariance mapping" probe neon atoms intense 8 fs pulses 1062 eV photons. A complete...
Electronic core levels in molecules are highly localized around one atomic site. However, single-photon ionization of symmetric molecules, the question core-hole localization versus delocalization over two equivalent atoms has long been debated as answer lies at heart quantum mechanics. Here, using a joint experimental and theoretical study core-ionized carbon disulfide (CS2), we demonstrate that it is possible to experimentally select distinct molecular-fragmentation pathways which hole can...
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...
Abstract We publish three Roadmaps on photonic, electronic and atomic collision physics in order to celebrate the 60th anniversary of ICPEAC conference. In Roadmap I, we focus light–matter interaction. this area, studies ultrafast molecular dynamics have been rapidly growing, with advent new light sources such as attosecond lasers x-ray free electron lasers. parallel, experiments established synchrotron radiation femtosecond using cutting-edge detection schemes are revealing scientific...
By exploiting the core-excitation-induced dissociation of ${\mathrm{O}}_{2}$, we find that Auger emission exhibits a Doppler-like energy shift. We show this to be manifestation localization core hole and propose problem core-hole versus delocalization in spectroscopies may resolved by considering nature measurement.
A discussion is presented on the general nature of shape resonances in small molecules and how they may relate to molecular bond lengths. Criteria for assigning photoabsorption features as are described, usefulness photoemission experiments such assignments highlighted. Based these criteria, all unambiguously identified K-shell shape-resonance containing B, C, N, O, F examined an attempt identify empirically a energy/bond length relationship. Although available data insufficient establish...
Significance Electrons emitted from equivalent centers in isolated molecules via the photoelectric effect interfere, providing an atomic-scale of celebrated Young’s double-slit experiment. We have developed a theoretical and experimental framework to characterize such interference phenomena accurately, we applied it simplest hydrocarbons with different bond lengths bonding types. demonstrate that fundamental observations can be related crucial structural information, as chemical lengths,...
The dynamics following laser-induced molecular photodissociation of gas-phase ${\mathrm{CH}}_{2}\mathrm{BrI}$ at 271.6 nm were investigated by time-resolved Coulomb-explosion imaging using intense near-IR femtosecond laser pulses. observed delay-dependent photofragment momenta reveal that undergoes C-I cleavage, depositing 65.6% the available energy into internal product states, and absorption a second UV photon breaks C-Br bond ${\mathrm{CH}}_{2}\mathrm{Br}$. Simulations confirm this...
The photodissociation dynamics of CH3I and CH2ClI at 272 nm were investigated by time-resolved Coulomb explosion imaging, with an intense non-resonant 815 probe pulse. Fragment ion momenta over a wide m/z range recorded simultaneously coupling velocity map imaging spectrometer pixel mass spectrometry camera. For both molecules, delay-dependent pump-probe features assigned to ultraviolet-induced carbon-iodine bond cleavage followed explosion. Multi-mass also allowed the sequential...
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....
The C and O $1s$ photoelectron lines of the C${\mathrm{O}}_{2}$ molecule in gas phase have been measured with vibrational resolution threshold region. fine structure on line is completely dominated by antisymmetric stretching mode a frequency 307 $(\ifmmode\pm\else\textpm\fi{}3)\mathrm{meV}$. This can be excited only via vibronic coupling, as predicted Domcke Cederbaum [Chem. Phys. 25, 189 (1977)], provides mechanism for dynamic core-hole localization. Relaxation effects are found to affect...
Partial photoelectron cross sections σ and angular distribution parameters β were obtained for the first five valence orbitals in CF4: 1t1, 4t2, 1e, 3t2, 4a1, as a function of photon energy from 17 to 70 eV. These data taken with aid angle-resolved spectroscopy synchrotron radiation. The results compared earlier on CCl4. Substantial differences found. are explained partly terms absence Cooper minimum fluorine compound opposed presence chlorine compounds position shape resonances. Data CF4...
Direct measurements of ${\mathrm{Ar}}^{+}$ $1{s}^{\ensuremath{-}1}2{p}^{\ensuremath{-}1}nl$ double-core-hole shake-up states are reported using conventional single-channel photoemission, offering a new and relatively easy means to study such species. The high-quality results yield accurate energies lifetimes the states. Their photoemission spectrum also can be likened $1s$ absorption an exotic argon ion with $2p$ core vacancy, providing information about spectroscopy both this unusual ionic...
Creation of deep core holes with very short (τ≤1 fs) lifetimes triggers a chain relaxation events leading to extensive nuclear dynamics on few-femtosecond time scale. Here we demonstrate general multistep ultrafast dissociation an example HCl following Cl 1s→σ^{*} excitation. Intermediate states one or multiple in the shallower electron shells are generated course decay cascades. The repulsive character and large gradients potential energy surfaces these intermediates enable fragmentation...
The ultrafast structural dynamics of water following inner-shell ionization is a crucial issue in high-energy radiation chemistry. We have exposed isolated molecules to short x-ray pulse from free-electron laser and detected momenta all produced ions coincidence. By combining experimental results theoretical modeling, we can image dissociation individual unprecedented detail. reveal significant molecular H2O2+, such as asymmetric deformation bond-angle opening, leading two-body or three-body...
Resonant photofragmentation of core-excited water molecules has been studied with high-resolution partial-ion-yield spectroscopy. Both the single and coincidence channels were monitored simultaneously. A steep increase in yield curves above ionization threshold, where normal Auger decay produces doubly charged or multiply species that two more fragments, observed. By comparing relative weight H neutral fragments qualitatively assessed, found to be higher for O...
The femtosecond dissociation of HCl after core excitation has been studied through the resonant Auger decay. spectra contain contributions from decay occurring at both ``molecular'' and ``atomic'' internuclear distances. We have observed a new interference mechanism in these spectra: An atomic spectral line develops into negative contribution, ``hole,'' when detuning energy maximum $\mathrm{Cl}{2p}^{\ensuremath{-}1}{\ensuremath{\sigma}}^{*}$ resonance. Resonant x-ray scattering theory...