CNRS Laboratory of Physical Chemistry - Matter and Radiation

Paris, France

CNRS Laboratory of Physical Chemistry - Matter and Radiation

Paris, France

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Andre J.-M.,Paris-Sorbonne University | Andre J.-M.,CNRS Laboratory of Physical Chemistry - Matter and Radiation | Jonnard P.,Paris-Sorbonne University | Jonnard P.,CNRS Laboratory of Physical Chemistry - Matter and Radiation
Journal of Synchrotron Radiation | Year: 2017

The propagation within a one-dimensional photonic crystal of a single ultrashort and ultra-intense pulse delivered by an X-ray free-electron laser is analysed with the framework of the time-dependent coupled-wave theory in non-linear media. It is shown that the reflection and the transmission of an ultrashort pulse present a transient period conditioned by the extinction length and also the thickness of the structure for transmission. For ultra-intense pulses, non-linear effects are expected: they could give rise to numerous phenomena, bi-stability, self-induced transparency, gap solitons, switching, etc., which have been previously shown in the optical domain. © International Union of Crystallography, 2017.


Kavcic M.,Jozef Stefan Institute | Zitnik M.,Jozef Stefan Institute | Bucar K.,Jozef Stefan Institute | Mihelic A.,Jozef Stefan Institute | And 4 more authors.
Physical Review Letters | Year: 2010

We have measured a series of high-resolution x-ray spectra emitted upon resonant photoexcitation of HCl. The photon energy was tuned across the dissociative 1s→6σ* resonance and the Rydberg states converging to the Cl 1s-1 threshold, and inelastic photon scattering was observed in the region of KL emission lines. Excellent agreement is found between fully ab initio calculated and measured spectra if interferences between different excitation-emission paths are taken into account. The effect of electronic state interferences is enhanced due to dynamical broadening of the 6σ* resonance in HCl. © 2010 The American Physical Society.


Dubois A.,CNRS Laboratory of Physical Chemistry - Matter and Radiation | Carniato S.,CNRS Laboratory of Physical Chemistry - Matter and Radiation | Fainstein P.D.,Bariloche Atomic Center | Hansen J.P.,University of Bergen
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

Single-ionization cross sections of water molecules colliding with fast protons are calculated from lowest-order perturbation theory by taking all electrons and molecular orientations consistently into account. Explicit analytical formulas based on the peaking approximation are obtained for differential ionization cross sections with the partial contribution from the various electron orbitals accounted for. The results, which are in very good agreement with total and partial cross sections at high electron and projectile energies, display a strong variation on molecular orientation and molecular orbitals. © 2011 American Physical Society.


Della Picca R.,Bariloche Atomic Center | Della Picca R.,CNRS Laboratory of Physical Chemistry - Matter and Radiation | Fainstein P.D.,Bariloche Atomic Center | Dubois A.,CNRS Laboratory of Physical Chemistry - Matter and Radiation
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

We present a detailed study of the partial and total cross sections for photon-induced electron emission from H2 +. By comparing the results employing exact and approximate, bounded and continuum wave functions, for one- and two-center basis functions, we find the origin and position of the Cooper-like minima in the partial cross sections and their relationship with the Young-type interference pattern. © 2011 American Physical Society.


Guillemin R.,University Pierre and Marie Curie | Simon M.,CNRS Laboratory of Physical Chemistry - Matter and Radiation | Shigemasa E.,Japan Institute for Molecular Science
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2010

Atomic autoionization following O 1s resonant excitation in O 2 is studied using high-resolution electron spectroscopy. The resonant Auger spectrum showing evidence of ultrafast dissociation as well as the autoionization of oxygen atoms is measured and discussed. Evidence of the electronic Doppler effect is observed in both electronic decay mechanisms. ©2010 The American Physical Society.


Caillat J.,CNRS Laboratory of Physical Chemistry - Matter and Radiation | Maquet A.,CNRS Laboratory of Physical Chemistry - Matter and Radiation | Haessler S.,CEA Saclay Nuclear Research Center | Haessler S.,Vienna University of Technology | And 5 more authors.
Physical Review Letters | Year: 2011

We have simulated two-color photoionization of N2 by solving the time-dependent Schrödinger equation with a simple model accounting for the correlated vibronic dynamics of the molecule and of the ion N2+. Our results, in very good agreement with recent experiments [Haessler et al., Phys. Rev. A 80, 011404 (2009)PLRAAN1050-294710.1103/PhysRevA.80.011404], show how a resonance embedded in the molecular continuum dramatically affects the phases of the two-photon transition amplitudes. In addition, we introduce a formal relation between these measurable phases and the photoelectron release time, opening the way to attosecond time-resolved measurements, equivalent to double-slit experiments in the time domain. © 2011 American Physical Society.


Salieres P.,CEA Saclay Nuclear Research Center | Maquet A.,CNRS Laboratory of Physical Chemistry - Matter and Radiation | Haessler S.,Vienna University of Technology | Caillat J.,CNRS Laboratory of Physical Chemistry - Matter and Radiation | Taieb R.,CNRS Laboratory of Physical Chemistry - Matter and Radiation
Reports on Progress in Physics | Year: 2012

The recently developed attosecond light sources make the investigation of ultrafast processes in matter possible with unprecedented time resolution. It has been proposed that the very mechanism underlying the attosecond emission allows the imaging of valence orbitals with Ångström space resolution. This controversial idea together with the possibility of combining attosecond and Ångström resolutions in the same measurements has become a hot topic in strong-field science. Indeed, this could provide a new way to image the evolution of the molecular electron cloud during, e.g. a chemical reaction in real time. Here we review both experimental and theoretical challenges raised by the implementation of these prospects. In particular, we show how the valence orbital structure is encoded in the spectral phase of the recombination dipole moment calculated for Coulomb scattering states, which allows a tomographic reconstruction of the orbital using first-order corrections to the plane-wave approach. The possibility of disentangling multi-channel contributions to the attosecond emission is discussed as well as the necessary compromise between the temporal and spatial resolutions. © 2012 IOP Publishing Ltd.


Haessler S.,CEA Saclay Nuclear Research Center | Caillat J.,CNRS Laboratory of Physical Chemistry - Matter and Radiation | Boutu W.,CEA Saclay Nuclear Research Center | Giovanetti-Teixeira C.,CNRS Laboratory of Physical Chemistry - Matter and Radiation | And 8 more authors.
Nature Physics | Year: 2010

A strong laser field may tunnel ionize a molecule from several orbitals simultaneously, forming an attosecond electron-hole wavepacket. Both temporal and spatial information on this wavepacket can be obtained through the coherent soft X-ray emission resulting from the laser-driven recollision of the liberated electron with the core. By characterizing the emission from aligned N 2 molecules, we demonstrate the attosecond contributions of the two highest occupied molecular orbitals. We determine conditions where they are disentangled in the real and imaginary parts of the emission dipole moment. This allows us to carry out a tomographic reconstruction of both orbitals with angstrom spatial resolution. Their coherent superposition provides experimental images of the attosecond wavepacket created in the ionization process. Our results open the prospect of imaging ultrafast intramolecular dynamics combining attosecond and angstrom resolutions. © 2010 Macmillan Publishers Limited. All rights reserved.


Strocov V.N.,Paul Scherrer Institute | Schmitt T.,Paul Scherrer Institute | Flechsig U.,Paul Scherrer Institute | Patthey L.,Paul Scherrer Institute | Chiuzbaian G.S.,CNRS Laboratory of Physical Chemistry - Matter and Radiation
Journal of Synchrotron Radiation | Year: 2011

Operation of an X-ray spectrometer based on a spherical variable-line-spacing (VLS) grating is analyzed using dedicated ray-tracing software allowing fast optimization of the grating parameters and spectrometer geometry. The analysis is illustrated with optical design of a model spectrometer to deliver a resolving power above 20400 at a photon energy of 930 eV (Cu L-edge). With this energy taken as reference, the VLS coefficients are optimized to cancel the lineshape asymmetry (mostly from the coma aberrations) as well as minimize the symmetric aberration broadening at large grating illuminations, dramatically increasing the aberration-limited vertical acceptance of the spectrometer. For any energy away from the reference, corrections to the entrance arm and light incidence angle on the grating are evaluated to maintain the exactly symmetric lineshape. Furthermore, operational modes when these corrections are coordinated are evaluated to maintain either energy-independent focal curve inclination or maximal aberration-limited spectrometer acceptance. The results are supported by analytical evaluation of the coma term of the optical path function. This analysis thus gives a recipe for designing a high-resolution spherical VLS grating spectrometer operating with negligible aberrations at large acceptance and over an extended energy range. © 2011 International Union of Crystallography.


Dahlstrom J.M.,Albanova University Center | L'Huillier A.,Lund University | Maquet A.,CNRS Laboratory of Physical Chemistry - Matter and Radiation
Journal of Physics B: Atomic, Molecular and Optical Physics | Year: 2012

This tutorial presents an introduction to the interaction of light and matter on the attosecond timescale. Our aim is to detail the theoretical description of ultra-short time delays and to relate these to the phase of extreme ultraviolet (XUV) light pulses and to the asymptotic phaseshifts of photoelectron wave packets. Special emphasis is laid on time-delay experiments, where attosecond XUV pulses are used to photoionize target atoms at well-defined times, followed by a probing process in real time by a phase-locked, infrared laser field. In this way, the laser field serves as a clock to monitor the ionization event, but the observable delays do not correspond directly to the delay associated with single-photon ionization. Instead, a significant part of the observed delay originates from a measurement induced process, which obscures the single-photon ionization dynamics. This artefact is traced back to a phaseshift of the above-threshold ionization transition matrix element, which we call the continuum-continuum phase. It arises due to the laser-stimulated transitions between Coulomb continuum states. As we shall show here, these measurement-induced effects can be separated from the single-photon ionization process, using analytical expressions of universal character, so that eventually the attosecond time delays in photoionization can be accessed. © 2012 IOP Publishing Ltd.

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