Peer-reviewed Publications |
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Boucher G., Eckstein A., Orieux A., Favero I., Leo G., Coudreau T., Keller A., Milman P., & Ducci S. (2014). Polarization-entanglement generation and control in a counterpropagating phase-matching geometry. Phys. Rev. A, 89, 033815.
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Fedortchenko S., Keller A., Coudreau T., & Milman P. (2014). Finite-temperature reservoir engineering and entanglement dynamics. Phys. Rev. A, 90, 042103.
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Gharaibeh, M. F., El Hassan, N., Al Shorman, M. M., Bizau, J. M., Cubaynes, D., Guilbaud, S., Sakho, I., Blancard, C., & McLaughlin, B. M. (2014). K-shell photoionization of B-like atomic nitrogen ions: experiment and theory. JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS, 47(6), 065201.
Résumé: Measurements of absolute cross sections for the K-shell photoionization of B-like atomic nitrogen ions were carried out utilizing the ion-photon merged-beam technique at the SOLEIL synchrotron radiation facility in Saint-Aubin, France. High-resolution spectroscopy with E/Delta E approximate to 13,500 was the maximum resolution achieved. We have investigated two photon energy regions: 404-409 eV and 439-442 eV. Resonance peaks found in the experimental measured cross sections are compared with theoretical estimates from the multi-configuration Dirac-Fock, R-matrix and empirical methods, allowing identification of the strong 1s -> 2p and the weaker 1s -> 3p resonances in the observed K-shell spectra of this B-like nitrogen ion.
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Helml, W., Maier, A. R., Schweinberger, W., Grguras, I., Radcliffe, P., Doumy, G., Roedig, C., Gagnon, J., Messerschmidt, M., Schorb, S., Bostedt, C., Gruener, F., DiMauro, L. F., Cubaynes, D., Bozek, J. D., Tschentscher, T., Costello, J. T., Meyer, M., Coffee, R., Duesterer, S., Cavalieri, A. L., & Kienberger, R. (2014). Measuring the temporal structure of few-femtosecond free-electron laser X-ray pulses directly in the time domain. NATURE PHOTONICS, 8(12), 950–957.
Résumé: Short-wavelength free-electron lasers are now well established as essential and unrivalled sources of ultrabright coherent X-ray radiation. One of the key characteristics of these intense X-ray pulses is their expected few-femtosecond duration. No measurement has succeeded so far in directly determining the temporal structure or even the duration of these ultrashort pulses in the few-femtosecond range. Here, by deploying the so-called streaking spectroscopy technique at the Linac Coherent Light Source, we demonstrate a non-invasive scheme for temporal characterization of X-ray pulses with sub-femtosecond resolution. This method is independent of photon energy, decoupled from machine parameters, and provides an upper bound on the X-ray pulse duration. We measured the duration of the shortest X-ray pulses currently available to be on average no longer than 4.4 fs. Analysing the pulse substructure indicates a small percentage of the free-electron laser pulses consisting of individual high-intensity spikes to be on the order of hundreds of attoseconds.
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Kennedy, E. T., Mosnier, J. - P., Van Kampen, P., Cubaynes, D., Guilbaud, S., Blancard, C., McLaughlin, B. M., & Bizau, J. - M. (2014). Photoionization cross sections of the aluminumlike Si+ ion in the region of the 2p threshold (94-137 eV). PHYSICAL REVIEW A, 90, 063409.
Résumé: We present measurements of the absolute photoionization cross section of the aluminumlike Si+ ion over the 94-137 eV photon energy range. The measurements were performed using the merged-beam setup on the PLEIADES beamline at the SOLEIL synchrotron radiation facility. Signals produced in the Si2+ and Si3+ photoionization channels of the 2p subshell of the Si+ ion from both the 1s(2)2s(2)2p(6)3s(2)3p P-2(1/2,3/2) ground levels and the 1s(2)2s(2)2p(6)3s(3)p(2 4)P metastable levels were observed. Absolute cross sections were determined. Calculations of the 2p inner-shell photoionization cross sections were carried out using the multiconfiguration Dirac-Fock and Dirac-Coulomb R-matrix theoretical approaches and are compared with experiment.
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Mandilara A., Coudreau T., Keller A., & Milman P. (2014). Entanglement classification of pure symmetric states via spin coherent states. Phys. Rev. A, 90, 050302(R).
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Marggi Poullain, S., Elkharrat, C., Li, W. B., Veyrinas, K., Houver, J. C., Cornaggia, C., Rescigno, T. N., Lucchese, R. R., & Dowek, D. (2014). Recoil frame photoemission in multiphoton ionization of small polyatomic molecules: photodynamics of NO2 probed by 400 nm fs pulses. JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS, 47(12), 124024.
Résumé: We report a general method for the complete analysis of the recoil frame photoelectron angular distribution (RFPAD) in n-photon dissociative ionization of small polyatomic molecules, resulting from (n – 1) bound-to-bound transitions plus one-photon ionization of a neutral excited state of the target. This method relies on the decomposition of the RFPAD in terms of the R-K (chi, theta(e)) recoil frame azimuthal harmonics (RFAHs) which are the components of its Fourier expansion in phi(e), where chi and theta(e) are the polar angles referring to the polarization axis P and the photoelectron momentum k relative to the ion fragment recoil direction, respectively, and fe is the azimuth of k relative to P. The RFAH expansion method is illustrated by a detailed experimental and theoretical study of one-colour multiphoton dissociative and non-dissociative ionization of the NO2 molecule of C-2v symmetry induced by 400 nm fs laser pulses, which involve electronic and nuclear dynamics within the pulse duration of the order of 70 fs. The reaction mechanism proposed to account for five-photon dissociative ionization of NO2 involves the role of [R*(6a(1))(-1)] Rydberg states populated by three-photon absorption, subsequently ionized by a fourth photon into the NO2+ (X-1 Sigma(+)(g), upsilon(1),upsilon(2),upsilon(3)) manifold involving autoionization of [R*(4b(2))(-1)] Rydberg states, and linear versus bent geometry selective dissociation of NO2+ (X-1 Sigma(+)(g), upsilon(1),upsilon(2),upsilon(3)) by a fifth photon. The reported calculations provide a coherent picture of the experimental findings although all features are not yet well reproduced.
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McLaughlin, B. M., Bizau, J. M., Cubaynes, D., Al Shorman, M. M., Guilbaud, S., Sakho, I., Blancard, C., & Gharaibeh, M. F. (2014). K-shell photoionization of B-like oxygen (O3+) ions: experiment and theory. JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS, 47(11), 115201.
Résumé: Absolute cross sections for the K-shell photoionization of boron-like (B-like) O3+ ions were measured by employing the ion-photon merged-beam technique at the SOLEIL synchrotron-radiation facility in Saint-Aubin, France. High-resolution spectroscopy with E/Delta E approximate to 5000 (approximate to 110 meV, full width half maximum) was achieved with photon energy from 540 up to 600 eV. Several theoretical approaches, including R-matrix, multi-configuration Dirac-Fock and screening constant by unit nuclear charge were used to identify and characterize the strong 1s -> 2p and the weaker 1s -> 3p resonances observed in the K-shell spectra of this ion. The trend of the integrated oscillator strength and autoionization width (natural line width) of the strong 1s -> 2p resonances along the first few ions of the B-like sequence is discussed.
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Perez-Torres, J. F., Sanz-Vicario, J. L., Veyrinas, K., Billaud, P., Picard, Y. J., Elkharrat, C., Marggi Poullain, S., Saquet, N., Lebech, M., Houver, J. C., Martin, F., & Dowek, D. (2014). Circular dichroism in molecular-frame photoelectron angular distributions in the dissociative photoionization of H-2 and D-2 molecules. PHYSICAL REVIEW A, 90(4), 043417.
Résumé: The presence of net circular dichroism in the photoionization of nonchiral homonuclear molecules has been put in evidence recently through the measurement of molecular-frame photoelectron angular distributions in dissociative photoionization of H-2 [Dowek et al., Phys. Rev. Lett. 104, 233003 (2010)]. In this work we present a detailed study of circular dichroism in the photoelectron angular distributions of H-2 and D-2 molecules, oriented perpendicularly to the propagation vector of the circularly polarized light, at different photon energies (20, 27, and 32.5 eV). Circular dichroism in the angular distributions at 20 and to a large extent 27 eV exhibits the usual pattern in which inversion symmetry is preserved. In contrast, at 32.5 eV, the inversion symmetry breaks down, which eventually leads to total circular dichroism after integration over the polar emission angle. Time-dependent ab initio calculations support and explain the observed results for H-2 in terms of quantum interferences between direct photoionization and delayed autoionization from the Q(1) and Q(2) doubly excited states into ionic states (1s sigma(g) and 2p sigma(u)) of different inversion symmetry. Nevertheless, for D-2 at 32.5 eV, there is a particular case where theory and experiment disagree in the magnitude of the symmetry breaking: when D+ ions are produced with an energy of around 5 eV. This reflects the subleties associated to such simple molecules when exposed to this fine scrutiny.
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Picard, Y. J., Manschwetus, B., Geleoc, M., Bottcher, M., Casagrande, E. M. S., Lin, N., Ruchon, T., Carre, B., Hergott, J. F., Lepetit, F., Taieb, R., Maquet, A., & Huetz, A. (2014). Attosecond evolution of energy- and angle-resolved photoemission spectra in two-color (XUV plus IR) ionization of rare gases. Physical Review A, 89(3), 031401.
Résumé: We have analyzed the angular distributions of the photoelectrons emitted upon photoionization of rare gases by a comb of harmonics in the extreme ultraviolet range, in the presence of a “dressing” infrared (IR) field with controlled delay tau, stabilized down to about +/-60 as. The measurements have been performed with the help of the coincidence momentum imaging technique. We evidence marked differences in the measured angular distributions of the photoelectrons, depending on the number of IR photons exchanged. Joined to a theoretical interpretation, these observations bring new insights into the dynamics of this class of two-color photoionization processes that are a key step towards studying photoionization in the time domain, with attosecond time resolution.
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Puthumpally-Joseph, R., Sukharev, M., Atabek, O., & Charron, E. (2014). Dipole-Induced Electromagnetic Transparency. Phys. Rev. Lett., 113, 163603.
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Sugny, D., Vranckx, S., Ndong, M., Vaeck, N., Atabek, O., & Desouter-Lecomte, M. (2014). Control of molecular dynamics with zero-area fields: Application to molecular orientation and photofragmentation. Physical Review A, 90, 053404.
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Tarakeshwar P., Palma J. L., Finkelstein-Shapiro D., Keller A., Urdaneta I., Calatayud M., Atabek O., & Mujica V. (2014). SERS as a probe of charge-transfer pathways in hybrid dye/molecule-metal oxide complexes. J. Phys. Chem. C, 118, 3774.
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Urdaneta I., Keller A., Atabek O., Palma J. L., Finkelstein-Shapiro D., Tarakeshwar P., Mujica V., & Calatayud M. (2014). Dopamine Adsorption on TiO2 Anatase Surfaces. J. Phys. Chem. C, 118, 20688.
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Urdaneta I., Pilmé J., Keller A., Atabek O., Tarakeshwar P., Mujica V., & Calatayud M. (2014). Probing Raman enhancement in Dopamine-Ti2O4 hybrid using stretched molecular geometries. J. Phys. Chem. A, 118, 1196.
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Vernaz-Gris P., Ketterer A., Keller A., Walborn S. P., Coudreau T., & Milman P. (2014). Continuous discretization of in nite-dimensional Hilbert spaces. Phys. Rev. A, 89, 052311.
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Actes de Conférences |
Calisti, A., Ferri, S., Mosse, C., Talin, B., Klisnick, A., Meng, L., Benredjem, D., & Guilbaud, O. (2014). Study of Particle Correlation Effects on Line Profiles of Ni-Like Collisional XUV Laser Amplifier. In X-RAY LASERS 2012 (Vol. 147, pp. 49–53).
Résumé: We discuss the effects of particle correlations on the spectral broadening due to the radiator motion (Doppler broadening) for a Ni-like XUV laser line pumped in two different regimes (transient and quasi-steady state regimes) of collisional excitation. In a medium with gain, radiative transport effects modify the observed profile and these modifications depend on the homogeneous or inhomogeneous nature of the intrinsic profile (before amplification). The intrinsic line profile is usually described by a Voigt profile, which is the convolution of a Lorentzian profile due to the different homogeneous broadenings (electron collision-induced transitions and spontaneous emission) and an inhomogeneous Gaussian profile due to Doppler shifts (due to the radiator motion in the free-particle limit). In this paper, it is shown that accounting for the correlations between particles modifies noticeably the radiator-motion broadened profiles, whatever the densities and temperatures values.
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Kozlova, M., Nejdl, J., Krus, M., Prokupek, J., Dostal, J., Rus, B., Klisnick, A., Meng, L., Tissandier, F., Stehle, C., Lefevre, R., Chaulagain, U., Champion, N., Barroso, P., Reix, F., Jagourel, P., Larour, J., Delmotte, F., Constancias, C., Suzuki-Vidal, F., & Acef, O. (2014). Characterization of Zn X-Ray Laser at PALS Centre, Its Applications in Dense Plasma Probing and Astrophysics. In X-RAY LASERS 2012 (Vol. 147, pp. 151–159).
Résumé: This report presents the results from experiments at PALS Centre using a Zn X-ray laser with the pulse length of 0.15 ns and the wavelength of 21.2 nm, working in single or double pass regime with the output energy of 0.4 mJ or 4 mJ per pulse, respectively. The current X-ray laser was experimentally examined to obtain its temporal coherence and spectral width using a path-difference interferometer. The double pass regime shows that QSS plasma based source-amplifier is promising for “short” fs soft X-ray pulses. The X-ray laser is commonly used for user's experiments. Its advantages can be shown in applications such as probing of dense plasmas (up to 2.5 x 10(24) cm(-3)) or single shot experiments (4 x 10(14) photons/pulse). The simple technique based on Talbot effect was used to obtain the gradients of electron densities of line plasmas produced under conditions corresponding to XRL's amplifiers operating in TCE and QSS regime. To investigate radiative shock wave in laboratory is challenging in aspects of the optimization of experimental parameters. Due to the high electron density (10(22) cm(-3)) produced in the gas medium propagated by the shock wave, the velocity of the shock wave, and the absorption losses on optical elements, it is necessary to use the energetic single shot probe.
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Meng, L., Calisti, A., Ferri, S., Mosse, C., Talin, B., Benredjem, D., Guilbaud, O., & Klisnick, A. (2014). Spectral Broadening of Ni-Like XUV Laser Lines. In X-RAY LASERS 2012 (Vol. 147, pp. 181–184).
Résumé: We have used the PPP lineshape code to calculate the intrinsic (i.e. before amplification) line profile of the Mo XUV laser over an extended range of plasma densities and temperatures, chosen to cover conditions for collisional excitation pumping in the transient and quasi-steady state regimes. The calculated profiles were then used to simulate the amplified line profile, using a detailed 1D-radiative transfer code, taking into account the effect of saturation. We discuss the possibility to achieve a gain bandwidth that would support pulse amplification below 1 ps.
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Meng, L., Klisnick, A., Kozlova, M., Bohacek, K., Krus, M., Prokupek, J., Urbanski, L., Marconi, M. C., Berrill, M., Rocca, J. J., Guilbaud, O., Tissandier, F., Sebban, S., Zeitoun, P., Calisti, A., Ferri, S., Mosse, C., & Talin, B. (2014). Temporal Coherence and Spectral Linewidth of Neon-Like XUV Lasers Pumped in the Quasi-steady State Regime. In X-RAY LASERS 2012 (Vol. 147, pp. 175–180).
Résumé: We report recent experimental progress in the characterization of the temporal coherence and related spectral linewidth of plasma-based soft X-ray lasers (SXRL). New measurements were carried out with two types of SXRLs pumped in the quasi-steady state (QSS) regime, in a capillary-discharge plasma and in a laser-produced plasma. We describe the main results obtained from both experiments and compare them to dedicated numerical simulations. We discuss the results in the context of the possibility to achieve XUV lasers with pulse duration below 1 picosecond.
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Tissandier, F., Sebban, S., Kozlova, M., Gautier, J., Zeitoun, P., Klisnick, A., & Maynard, G. (2014). High Density Optical-Field-Ionization Soft X-Ray Lasers. In X-RAY LASERS 2012 (Vol. 147, pp. 243–255).
Résumé: Generating an optical-field-ionization (OFI) collisional soft X-ray laser amplifier in a high density plasma would allow a significant increase of the saturation intensity, laser gain, and reduction of the emitted pulse duration. Due to strong refraction of the pump infrared beam in the plasma, guiding techniques have to be implemented. Using an optically preformed plasma waveguide, we successfully achieved guiding of J-energy pulses in a near-critical density krypton plasma with 50 % total transmission over 5 to 10 mm. X-ray lasing at 32.8 nm has also been demonstrated. This technique is a step towards OFI recombination soft X-ray lasers. This pumping scheme requires the production of a cold and dense plasma. We propose to pump a high density neon VIII plasma by a frequency doubled intense Ti:Sa laser. Guiding of the 405 nm pump pulse has already been achieved at LOA.
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Urbanski, L., Marconi, M. C., Meng, L. M., Berrill, M., Guilbaud, O., Klisnick, A., & Rocca, J. J. (2014). Spectral Linewidth Measurement of a Ne-Like Ar Capillary Discharge Soft X-Ray Laser. In X-RAY LASERS 2012 (Vol. 147, pp. 257–261).
Résumé: We report on the measurement of spectral linewidth of a Ne-like Ar tabletop capillary discharge laser. The linewidth was measured as a function of the gain medium length. Due to inhomogeneous character of the linewidth, saturation rebroadening is expected. However no such behavior was observed while the amplifier length was extended beyond saturation. This situation is compared with a numerical model, identifying that even a small amount of collisional broadening effectively homogenizes the line profile.
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