Peer-reviewed Publications |
D. Bresteau, C. Spezzani, O. Tcherbakoff, J.-F. Hergott, F. Lepetit, P. D’Oliveira, P. Salieres, R. Geneaux, M. Luttmann, I. Vadillo-Torre, J. Lenfant, S. J. Weber, M. Dehlinger, E. Meltchakov, F. Delmotte, C. Bourassin-Bouchet, J. Im, Z. Chen, J. Caillaux, J. Zhang, M. Marsi, L. Barreau, L. Poisson, D. Dowek, M. Fanciulli, O. Heckmann, M. C. Richter, K. Hricovini, M. Sebdaoui, D. Dennetiere, F. Polack, & T. Ruchon. (2023). FAB10: a user-oriented bandwidth-tunable extreme ultraviolet lightsource for investigations of femtosecond to attosecond dynamics in gas and condensed phases. Eur. Phys. J. Spec. Top., .
Résumé: We present the commissioning of the FAB10 beamline (Femtosecond to Attosecond Beamline at 10 kHz repetition rate) that has been developped and operated in the last few years at the ATTOLab facility of Paris-Saclay University. Based on the high harmonic generation process, the beamline is dedicated to investigations of ultrafast dynamics in a broad variety of systems ranging from gas phase to condensed matter in pump-probe arrangements. Its design and operation has been strongly influenced by both the laser and the large scale instruments communities, which makes it unique in several aspects. In particular, it is possible to tune the extreme ultraviolet (XUV, 10–100 eV) bandwidth from 0.2 to 20 eV – with corresponding pulse duration from 30 to 0.3 femtoseconds (fs) – thanks to an original and fully automated XUV spectral filter with three operation modes. After a general overview of the beamline features, each of those operation modes is described, characterized and illustrated with commissioning experiments.
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Elliott, E. R., Aveline, D. C., Bigelow, N. P., Boegel, P., Botsi, S., Charron, E., D'Incao, J. P., Engels, P., Estrampes, T., Gaaloul, N., Kellogg, J. R., Kohel, J. M., Lay, N. E., Lundblad, N., Meister, M., Mossman, M. E., Muller, G., Muller, H., Oudrhiri, K., Phillips, L. E., Pichery, A., Rasel, E. M., Sackett, C. A., Sbroscia, M., Schleich, W. P., Thompson, R. J., & Williams, J. R. (2023). Quantum gas mixtures and dual-species atom interferometry in space. Nature, 62366(798777), 50255–50855.
Résumé: The capability to reach ultracold atomic temperatures in compact instruments has recently been extended into space(1,2). Ultracold temperatures amplify quantum effects, whereas free fall allows further cooling and longer interactions time with gravity-the final force without a quantum description. On Earth, these devices have produced macroscopic quantum phenomena such as Bose-Einstein condensates (BECs), superfluidity, and strongly interacting quantum gases(3). Terrestrial quantum sensors interfering the superposition of two ultracold atomic isotopes have tested the universality of free fall (UFF), a core tenet of Einstein's classical gravitational theory, at the 10(-12) level(4). In space, cooling the elements needed to explore the rich physics of strong interactions or perform quantum tests of the UFF has remained elusive. Here, using upgraded hardware of the multiuser Cold Atom Lab (CAL) instrument aboard the International Space Station (ISS), we report, to our knowledge, the first simultaneous production of a dual-species BEC in space (formed from (87)Rb and (41)K), observation of interspecies interactions, as well as the production of (39)K ultracold gases. Operating a single laser at a 'magic wavelength' at which Rabi rates of simultaneously applied Bragg pulses are equal, we have further achieved the first spaceborne demonstration of simultaneous atom interferometry with two atomic species ((87)Rb and (41)K). These results are an important step towards quantum tests of UFF in space and will allow scientists to investigate aspects of few-body physics, quantum chemistry and fundamental physics in new regimes without the perturbing asymmetry of gravity.
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Huart, L., Fournier, M., Dupuy, R., Vacheresse, R., Mailhiot, M., Cubaynes, D., Ceolin, D., Herve du Penhoat, M. A., Renault, J. P., Guigner, J. - M., Kumar, A., Lutet-Toti, B., Bozek, J., Ismail, I., Journel, L., Lablanquie, P., Penent, F., Nicolas, C., & Palaudoux, J. (2023). First (e,e) coincidence measurements on solvated sodium benzoate in water using a magnetic bottle time-of-flight spectrometer. Phys Chem Chem Phys, (Advance Article).
Résumé: Understanding the mechanisms of X-ray radiation damage in biological systems is of prime interest in medicine (radioprotection, X-ray therapy...). Study of low-energy rays, such as soft-X rays and light ions, points to attribute their lethal effect to clusters of energy deposition by low-energy electrons. The first step, at the atomic or molecular level, is often the ionization of inner-shell electrons followed by Auger decay in an aqueous environment. We have developed an experimental set-up to perform electron coincidence spectroscopy on molecules in a water micro-jet. We present here the first results obtained on sodium benzoate solutions, irradiated at the oxygen and carbon K-edges.
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Issler, K., Sturm, F., Petersen, J., Flock, M., Mitric, R., Fischer I, Barreau L, & Poisson L. (2023). Time-resolved photoelectron spectroscopy of 4-(dimethylamino)benzethyne – an experimental and computational study. Phys Chem Chem Phys, 14(25), 9837–9845.
Résumé: We investigated the excited-state dynamics of 4-(dimethylamino)benzethyne (4-DMABE) in a combined theoretical and experimental study using surface-hopping simulations and time-resolved ionisation experiments. The simulations predict a decay of the initially excited S(2) state into the S(1) state in only a few femtoseconds, inducing a subsequent partial twist of the dimethylamino group within approximately 100 fs. This leads to drastically reduced Franck-Condon factors for the ionisation transition to the cationic ground state, thus inhibiting the effective ionisation of the molecule, which leads to a vanishing photoelectron signal on a similar timescale as observed in our time-resolved photoelectron spectra. From the phototoelectron spectra, an adiabatic ionisation energy of 7.17 +/- 0.02 eV was determined. The experimental decays match the theoretical predictions very well and the combination of both reveals the electronic characteristics of the molecule, namely the role of intramolecular charge transfer (ICT) states in the deactivation pathway of electronically excited 4-DMABE.
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J-N. Vigneau, O. Atabek, T.-T. Nguyen-Dang, & E. Charron. (2023). Strong field non-Franck–Condon ionization of H2: a semi-classical analysis. The European Physical Journal Special Topics, .
Résumé: Single ionization of H2 molecules exposed to strong and short laser pulses is investigated by a semi-classical method. Three laser characteristics are considered: (i) The carrier-wave frequency corresponds to wavelengths covering and bridging the two ionization regimes: From tunnel ionization (TI) at 800 nm to multiphoton ionization (MPI) at 266 nm. (ii) Values of the peak intensity are chosen within a window to eliminate competing double ionization processes. (iii) Particular attention is paid to the polarization of the laser field, which can be linearly or circularly polarized. The results and their interpretation concern two observables, namely the end-of-pulse total ionization probability and vibrational distribution generated in the cation H+2. The most prominent findings are an increased ionization efficiency in linear polarization and a vibrational distribution of the cation that favors lower-lying levels than those that would be populated in a vertical (Franck–Condon) ionization, leading to non-Franck–Condon distributions, both in linear and circular polarizations.
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L. Dakroub, T. Sinyakova, D. Cubaynes, C. Bomme, L. Chopineau, G. Garcia, O. Peyrusse, F. Quéré, C. Bourassin-Bouchet, & A. Klisnick. (2023). Laser-dressed photoionization for the temporal characterization of attosecond pulses generated from plasma mirrors. Eur. Phys. J. Spec. Top., .
Résumé: We report on the implementation of a laser-dressed photoionization method aimed at measuring the temporal structure of high-order harmonics generated from plasma mirrors at the attosecond timescale. Using numerical simulations, we show that the infrared dressing pulse induces up-down asymmetry on the angular distribution of photoelectrons. Experimentally single-shot photoelectron spectra with angular resolution were successfully detected with a velocity-map imaging spectrometer. However, the impact of the infrared dressing field in the photoelectron spectra could not be observed. We discuss several issues that potentially hampered these observations and suggest corresponding setup improvements.
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Nadoveza, N., Panades-Barrueta, R. L., Shi, L., Gatti, F., & Pelaez, D. (2023). Analytical high-dimensional operators in canonical polyadic finite basis representation (CP-FBR). J Chem Phys, (158), 114109.
Résumé: In the present work, we introduce a simple means of obtaining an analytical (i.e., grid-free) canonical polyadic (CP) representation of a multidimensional function that is expressed in terms of a set of discrete data. For this, we make use of an initial CP guess, even not fully converged, and a set of auxiliary basis functions [finite basis representation (FBR)]. The resulting CP-FBR expression constitutes the CP counterpart of our previous Tucker sum-of-products-FBR approach. However, as is well-known, CP expressions are much more compact. This has obvious advantages in high-dimensional quantum dynamics. The power of CP-FBR lies in the fact that it requires a grid much coarser than the one needed for the dynamics. In a subsequent step, the basis functions can be interpolated to any desired density of grid points. This is useful, for instance, when different initial conditions (e.g., energy content) of a system are to be considered. We show the application of the method to bound systems of increased dimensionality: H(2) (3D), HONO (6D), and CH(4) (9D).
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Panadés-Barrueta, R. L., Nadoveza, N., Gatti, F., & Peláez, D. (2023). On the sum-of-products to product-of-sums transformation between analytical low-rank approximations in finite basis representation. Eur. Phys. J. Spec. Top., 2322(121), 18971–19041.
Résumé: In this work, we analyze and compare different possible strategies for the transformations among low-rank (i.e., few number of terms) tensor approximations. The motivation behind this is to achieve compact yet accurate representations of potential-like operators (scalar fields) in symbolic or analytical form. We do this analysis from a formal and from a numerical perspective. Specifically, we concentrate on Tucker and Canonic Polyadic ansätze. We introduce the sum-of-product finite basis representations (SOP-FBR) for both. Here, the factor matrices (aka single-particle functions) are approximated through a set of auxiliary basis functions, specific to the system. In this way, analytical, grid-independent, low-rank expressions can be obtained. We illustrate how finite-precision arithmetic hinders transformations among all these forms. The solution to this issue seems to adapt current algorithms to high-precision arithmetic at the expense of an increase in CPU times.
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Shi, L., Schroder, M., Meyer, H. - D., Pelaez, D., Wodtke, A. M., Golibrzuch, K., Schonemann, A. - M., Kandratsenka, A., & Gatti, F. (2023). Quantum and classical molecular dynamics for H atom scattering from graphene. J Chem Phys, 15911(1911).
Résumé: This work presents systematic comparisons between classical molecular dynamics (cMD) and quantum dynamics (QD) simulations of 15-dimensional and 75-dimensional models in their description of H atom scattering from graphene. We use an experimentally validated full-dimensional neural network potential energy surface of a hydrogen atom interacting with a large cell of graphene containing 24 carbon atoms. For quantum dynamics simulations, we apply Monte Carlo canonical polyadic decomposition to transform the original potential energy surface (PES) into a sum of products form and use the multi-layer multi-configuration time-dependent Hartree method to simulate the quantum scattering of a hydrogen or deuterium atom with an initial kinetic energy of 1.96 or 0.96 eV and an incident angle of 0 degrees , i.e., perpendicular to the graphene surface. The cMD and QD initial conditions have been carefully chosen in order to be as close as possible. Our results show little differences between cMD and QD simulations when the incident energy of the H atom is equal to 1.96 eV. However, a large difference in sticking probability is observed when the incident energy of the H atom is equal to 0.96 eV, indicating the predominance of quantum effects. To the best of our knowledge, our work provides the first benchmark of quantum against classical simulations for a system of this size with a realistic PES. Additionally, new projectors are implemented in the Heidelberg multi-configuration time-dependent Hartree package for the calculation of the atom scattering energy transfer distribution as a function of outgoing angles.
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Tajouo Tela, H., Quintas-Sanchez, E., Dubernet, M. - L., Scribano, Y., Dawes, R., Gatti, F., & Ndengue, S. (2023). Rovibrational states calculations of the H(2)O-HCN heterodimer with the multiconfiguration time dependent Hartree method. Phys Chem Chem Phys, 2522(4644), 3181333–3182433.
Résumé: Water and hydrogen cyanide are two of the most common species in space and the atmosphere with the ability of binding to form dimers such as H(2)O-HCN. In the literature, while calculations characterizing various properties of the H(2)O-HCN cluster (equilibrium distance, vibrational frequencies and rotational constants) have been done in the past, extensive calculations of the rovibrational states of this system using a reliable quantum dynamical approach have yet to be reported. In this work, we intend to mend that by performing the first calculation of the rovibrational states of the H(2)O-HCN van der Waals complex on a recently developed potential energy surface. We use the block improved relaxation procedure implemented in the Heidelberg MultiConfiguration Time-Dependent Hartree (MCTDH) package to compute the states of the H(2)O-HCN isomer, from which we extract the transition frequencies and rotational constants of the complex. We further adapt an approach first suggested by Wang and Carrington-and supported here by analysis routines of the Heidelberg MCTDH package-to properly characterize the computed rovibrational states. The subsequent assignment of rovibrational states was done by theoretical analysis and visual inspection of the wavefunctions. Our simulations provide a Zero Point Energy (ZPE) and intermolecular vibrational frequencies in good agreement with past ab initio calculations. The transition frequencies and rotational constants obtained from our simulations match well with the available experimental data. This work has the broad aim to propose the MCTDH approach as a reliable option to compute and characterize rovibrational states of van der Waals complexes such as the current one.
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Voute, A., Dörfler, A., Wiesenfeld, L., Dulieu, O., Gatti, F., Peláez, D., & Willitsch, S. (2023). Charge transfer of polyatomic molecules in ion-atom hybrid traps: Stereodynamics in the millikelvin regime. Phys. Rev. Research, 5(3).
Résumé: Rate constants for the charge-transfer reaction between N2H+ and Rb in the millikelvin regime are measured in an ion-atom hybrid trap and are found to be lower than the Langevin capture limit. Multireference ab initio computation of the potential energy surfaces involved in the reaction reveals that the low-temperature charge transfer is hindered by short-range features highly dependent on the collision angle and is promoted by a deformation of the molecular frame. The present study highlights the importance of polyatomic effects and of stereodynamics in cold molecular ion-neutral collisions.
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