Laser-induced electron interferences from atoms and molecules

Since discovering wave-particle duality, science has changed our perception of light and matter, especially at the subatomic level. Thanks to such discoveries, we have been able to develop and expand our scientific knowledge over the past two centuries, crossing those limits. For instance, let us take the famous double-slit experiment from T. Young (1801). This experiment has been extended after the twentieth-century quantum revolution, revealing electron and neutron diffraction used nowadays to measure the nuclei separation from complex structures. Similarly, the experiment of Michelson and Morley (1887), which follows T. Young foundations, got a fair success in astronomy, enabling high-resolution imaging of stars in the universe. In this thesis, we use light to generate electrons and produce interferences similar to the double-slit experiment, which is analyzed further to study the atomic properties. On the dynamics of an atom, that is, attoscience, we use ultrafast laser pulses to trigger motions on a femtoseconds time-scale. Together with the use of strong intense laser fields in the Mid-IR regime, the electron is ionized with zero-kinetic energy and subsequently accelerated by the laser ponderomotive energy. Strong field dynamics offer rich structures that are encoded in the photoelectron momentum distribution. Since we use two-color combined laser fields, we can gate and control those dynamics further down on the sub-cycle scale. More precisely, we show that with the help of a Reaction Microscope, we can extract both electron information and nuclear dynamics within extraordinary sub-cycle temporal resolution. Finally, the strong-field recollision model is investigated with molecules through the previously developed laser-induced electron diffraction (LIED) method. We show that backscattered electron interferences, issued from strong field at low impact parameters, embedded a particular molecular orientation that can be reproduced when the molecule is considered aligned with the laser field polarization. Those findings seem to encode a more profound property about wave diffraction in molecules until recently unexplored due to the imposed conditions given in conventional electron diffraction (CED).Desde que se descubrió la dualidad onda-partícula, la ciencia ha cambiado nuestra percepción de la luz y la materia, especialmente a nivel subatómico. Gracias a tales descubrimientos, hemos podido desarrollar y expandir nuestro conocimiento durante los últimos dos siglos, llegando ahora a estos infinitos límites de la ciencia. Por ejemplo, tomemos el famoso experimento de la doble rendija de T. Young (1801). Este experimento se ha ampliado después de la revolución cuántica del siglo XX, revelando la difracción de electrones y neutrones utilizada hoy en día para medir la separación de núcleos de estructuras complejas. De manera similar, el experimento de Michelson y Morley (1887), que sigue los fundamentos de T. Young, obtuvo un éxito considerable en astronomía, lo que permitió obtener imágenes de alta resolución de las estrellas del universo. En esta tesis, utilizamos la luz para generar electrones y producir interferencias de manera similar al experimento de doble rendija, que se analiza más a fondo para estudiar las propiedades atómicas. En la dinámica de un átomo, es decir, la attociencia, utilizamos pulsos de láser ultrarrápidos para desencadenar movimientos en una escala de tiempo de femtosegundos. Junto con el uso de campos láser intensos y fuertes en el régimen Mid-IR, OPCPA, el electrón se ioniza con energía cinética cero y, posteriormente, se acelera con la energía ponderomotriz del láser. La dinámica de campo fuerte ofrece estructuras ricas que están codificadas en la distribución de momento de fotoelectrones. Dado que usamos campos láser combinados de dos colores, podemos controlar esas dinámicas con precisiones de subciclo. Más precisamente, mostramos con la ayuda de un microscopio de reacción que podemos extraer tanto información de orbitales de electrones como dinámica nuclear dentro de una extraordinaria resolución temporal de subciclo. Finalmente, el modelo de recolisión de campo fuerte se investiga con moléculas, a través del método de difracción de electrones inducido por láser (LIED) desarrollado previamente. Mostramos que las interferencias de electrones retrodispersados, emitidas por un campo fuerte con parámetros de bajo impacto, incorporan una orientación molecular particular que se puede reproducir cuando la molécula se considera alineada con respecto a la polarización del campo láser. Esos hallazgos parecen codificar una propiedad más profunda sobre la difracción de ondas en moléculas hasta entonces inexplorada debido a las condiciones impuestas en la difracción de electrones convencional (CED).Depuis la découverte de la dualité onde-corpuscule, la science a changé notre façon de percevoir la lumière et la matière, notamment à l´échelle subatomique. C’est grâce à de telles découvertes que nous avons pu développer et élargir nos connaissances au cours des deux derniers siècles, atteignant desormais ces infimes limites de la science. Prenons par exemple la célèbre expérience de la double fente de T. Young (1801). Cette expérience a été étendue après la révolution quantique du XXe siècle, révélant la diffraction d´électrons et de neutrons utilisés aujourd’hui pour mesurer la séparation des noyaux formant des structures complexes. De même, l’expérience de Michelson et Morley (1887), qui fait suite aux fondations de T. Young, a connu un succès certain en astronomie, permettant l’imagerie à haute résolution des étoiles dans l’univers. Dans cette thèse, nous utilisons de la lumière pour générer des électrons, et ainsi produire des interférences similaires à l´expérience des fentes, qui sont par la suite analyser pour en connaître les propriétés atomiques. Sur la dynamique d’un atome, c’est-à-dire, attoscience, nous utilisons des impulsions laser ultra-rapides pour déclencher des mouvements sur une échelle de temps de la femtoseconde. Avec l’utilisation de champs laser intenses et puissants dans le régime Mid-IR, OPCPA, l’électron est ionisé avec une énergie cinétique nulle et ensuite accéléré par l’énergie pondéromotrice du laser. La dynamique des champs forts offre des structures riches qui sont encodées dans la distribution de quantité de mouvement des photoélectrons. Puisque nous utilisons des champs laser combinés à deux couleurs, nous pouvons contrôler ces dynamiques sur une échelle plus courte que la période du laser. Plus précisément, nous montrons à l’aide d’un microscope à réaction que nous pouvons extraire à la fois des informations sur les orbitales électroniques et la dynamique nucléaire avec une extraordinaire résolution temporelle. Enfin, le modèle de récollision en champ fort est étudié avec des molécules, grâce à la méthode de diffraction d’électrons induite par laser (LIED) précédemment développée. Nous montrons que les interférences électroniques rétrodiffusées, issues d’un champ fort avec faible paramètre d´impact, intègrent une orientation moléculaire particulière qui peut être reproduite lorsque la molécule est considérée alignée par rapport à la polarisation du champ électrique. Ces découvertes semblent encoder une propriété plus profonde de la diffraction d´ondes sur molécules jusqu’à alors inexplorée en raison des conditions imposées par la diffraction électronique conventionnelle (CED).Postprint (published version

Molecular structure retrieval directly from laboratory-frame photoelectron spectra in laser-induced electron diffraction

Ubiquitous to most molecular scattering methods is the challenge to retrieve bond distance and angle from the scattering signals since this requires convergence of pattern matching algorithms or fitting methods. This problem is typically exacerbated when imaging larger molecules or for dynamic systems with little a priori knowledge. Here, we employ laser- induced electron diffraction (LIED) which is a powerful means to determine the precise atomic configuration of an isolated gas-phase molecule with picometre spatial and attose- cond temporal precision. We introduce a simple molecular retrieval method, which is based only on the identification of critical points in the oscillating molecular interference scattering signal that is extracted directly from the laboratory-frame photoelectron spectrum. The method is compared with a Fourier-based retrieval method, and we show that both methods correctly retrieve the asymmetrically stretched and bent field-dressed configuration of the asymmetric top molecule carbonyl sulfide (OCS), which is confirmed by our quantum- classical calculations.J.B. and group acknowledge financial support from the European Research Council for ERC Advanced Grant “TRANSFORMER” (788218), ERC Proof of Concept Grant “miniX” (840010), FET-OPEN “PETACom” (829153), FET-OPEN “OPTOlogic” (899794), Laserlab- Europe (EU-H2020 654148), MINECO for Plan Nacional FIS2017-89536-P; AGAUR for 2017 SGR 1639, MINECO for “Severo Ochoa” (SEV-2015-0522), Fundació Cellex Barce- lona, CERCA Programme/Generalitat de Catalunya, the Polish National Science Center within the project Symfonia, 2016/20/W/ST4/00314, and the Alexander von Humboldt Foundation for the Friedrich Wilhelm Bessel Prize. J.B. and K.A. acknowledge the Polish National Science Center within the project Symfonia, 2016/20/W/ST4/00314, B.B. acknowledges Severo Ochoa” (SEV-2015-0522), and A.S. acknowledges funding from the Marie Sklodowska-Curie grant agreement No. 641272. S.J.W. and C.D.L. are supported in part by Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U. S. Department of Energy under Grant No. DE-FG02- 86ER13491. M.R. and S.G. highly acknowledges support from the European Research Council (ERC) for the ERC Consolidator Grant QUEM-CHEM (772676).Peer ReviewedPostprint (published version

Laser-induced electron diffraction of the ultrafast umbrella motion in ammonia

Visualizing molecular transformations in real-time requires a structural retrieval method with Ångström spatial and femtosecond temporal atomic resolution. Imaging of hydrogen-containing molecules additionally requires an imaging method that is sensitive to the atomic positions of hydrogen nuclei, with most methods possessing relatively low sensitivity to hydrogen scattering. Laser-induced electron diffraction (LIED) is a table top technique that can image ultrafast structural changes of gas-phase polyatomic molecules with sub-Ångström and femtosecond spatiotemporal resolution together with relatively high sensitivity to hydrogen scattering. Here, we image the umbrella motion of an isolated ammonia molecule (NH3) following its strong field ionization. Upon ionization of a neutral ammonia molecule, the ammonia cation (NH+3) undergoes an ultrafast geometrical transformation from a pyramidal (FHNH=107°) to planar (FHNH=120°) structure in approximately 8 femtoseconds. Using LIED, we retrieve a near-planar (FHNH=117±5°) field-dressed NH+3 molecular structure 7.8-9.8 femtoseconds after ionization. Our measured field-dressed NH+3 structure is in excellent agreement with our calculated equilibrium field dressed structure using quantum chemical ab initio calculations.J.B. and group acknowledge financial support from the European Research Council for ERC Advanced Grant “TRANSFORMER” (788218), ERC Proof of Concept Grant “miniX” (840010), FET-OPEN “PETACom” (829153), FET-OPEN “OPTOlogic” (899794), Laserlab- Europe (EU-H2020 654148), MINECO for Plan Nacional FIS2017-89536-P; AGAUR for 2017 SGR 1639, MINECO for “Severo Ochoa” (SEV- 2015-0522), Fundació Cellex Barcelona, CERCA Programme / Generalitat de Catalunya, and the Alexander von Humboldt Foundation for the Friedrich Wilhelm Bessel Prize. J.B., K.A. and R.Moszynski. acknowledge the Polish National Science Center within the project Symfonia, 2016/20/W/ST4/00314. J.B and B.B. acknowledge Severo Ochoa” (SEV- 2015-0522). J.B. and A.S. acknowledge funding from the Marie Sklodowska-Curie grant agreement No. 641272. C.D.L is supported in part by Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U. S. Department of Energy under Grant No. DE-FG02-86ER13491. J.S. and S.G. highly acknowledges support from the European Research Council (ERC) for the ERC Consolidator Grant QUEM-CHEM (772676). The authors thank Alejandro Saenz for helpful discussions.Peer ReviewedPostprint (author's final draft

Elastic waves in phononic monolayer granular membranes

The vibrational properties of out-of-plane elastic waves in hexagonal monolayer granular membranes were studied theoretically. The predicted propagation modes involve an out-of-plane displacement and two rotations with axes in the membrane plane. Shear and bending rigidities at the contact between beads were considered. Both the cases of freely suspended membranes and membranes coupled to a rigid substrate were analyzed. Dispersion relations and the existence of band gaps are presented and discussed for various contact properties. For freely suspended membranes with sufficient contact bending rigidity, it is shown that complete band gaps exist. The results obtained may be of interest for testing with acoustic waves the elasticity of recently developed granular membranes composed of nanoparticles (of interest because of their phoxonic properties) and more generally for the control of designing devices for membrane wave propagation.This work was supported by the STABINGRAM project (ANR-2010-BLAN-0927-03), by the MEC of the Spanish Government under project number FIS2008-06024-C03-03 and by the Jose Catillejo program. VT acknowledges the Universidad Politecnica de Valencia for support through a research visit fellowship.Tournat, V.; Pérez Arjona, I.; Merkel, A.; Sánchez Morcillo, VJ.; Gusev, V. (2011). Elastic waves in phononic monolayer granular membranes. New Journal of Physics. 13:73042-73042. https://doi.org/10.1088/1367-2630/13/7/073042S73042730421

Imaging an isolated water molecule with an attosecond electron wave packet

We use laser-induced electron diffraction (LIED) to self-image the molecular structure of an isolated water molecular ion using its own retuning attosecond electron wave packet (EWP). Using LIED’s sub-femtosecond and picometre spatio-temporal resolution imaging capabilities, we observe the symmetric stretching of the O-H and H-H internuclear distances with increasing laser field strength.Postprint (published version

Ultrafast imaging of the Renner-Teller effect in a field-dressed molecule

We present experimental results of linear-to-bent transition of field-dressed molecules, mediated by Renner-Teller effect. Using the state-of-the-art laser-induced electron diffraction (LIED) technique, we image a bent and symmetrically stretched carbon disulfide (CS2) molecule populating an excited electronic state under the influence of strong laser field. Our findings are well-supported by ab initio quantum mechanical calculations.Peer ReviewedPostprint (published version

Fermi Large Area Telescope Constraints on the Gamma-ray Opacity of the Universe

The Extragalactic Background Light (EBL) includes photons with wavelengths from ultraviolet to infrared, which are effective at attenuating gamma rays with energy above ~10 GeV during propagation from sources at cosmological distances. This results in a redshift- and energy-dependent attenuation of the gamma-ray flux of extragalactic sources such as blazars and Gamma-Ray Bursts (GRBs). The Large Area Telescope onboard Fermi detects a sample of gamma-ray blazars with redshift up to z~3, and GRBs with redshift up to z~4.3. Using photons above 10 GeV collected by Fermi over more than one year of observations for these sources, we investigate the effect of gamma-ray flux attenuation by the EBL. We place upper limits on the gamma-ray opacity of the Universe at various energies and redshifts, and compare this with predictions from well-known EBL models. We find that an EBL intensity in the optical-ultraviolet wavelengths as great as predicted by the "baseline" model of Stecker et al. (2006) can be ruled out with high confidence.Comment: 42 pages, 12 figures, accepted version (24 Aug.2010) for publication in ApJ; Contact authors: A. Bouvier, A. Chen, S. Raino, S. Razzaque, A. Reimer, L.C. Reye

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Solve-RD: systematic pan-European data sharing and collaborative analysis to solve rare diseases.

For the first time in Europe hundreds of rare disease (RD) experts team up to actively share and jointly analyse existing patient's data. Solve-RD is a Horizon 2020-supported EU flagship project bringing together >300 clinicians, scientists, and patient representatives of 51 sites from 15 countries. Solve-RD is built upon a core group of four European Reference Networks (ERNs; ERN-ITHACA, ERN-RND, ERN-Euro NMD, ERN-GENTURIS) which annually see more than 270,000 RD patients with respective pathologies. The main ambition is to solve unsolved rare diseases for which a molecular cause is not yet known. This is achieved through an innovative clinical research environment that introduces novel ways to organise expertise and data. Two major approaches are being pursued (i) massive data re-analysis of >19,000 unsolved rare disease patients and (ii) novel combined -omics approaches. The minimum requirement to be eligible for the analysis activities is an inconclusive exome that can be shared with controlled access. The first preliminary data re-analysis has already diagnosed 255 cases form 8393 exomes/genome datasets. This unprecedented degree of collaboration focused on sharing of data and expertise shall identify many new disease genes and enable diagnosis of many so far undiagnosed patients from all over Europe

Solving unsolved rare neurological diseases-a Solve-RD viewpoint.

Funder: Durch Princess Beatrix Muscle Fund Durch Speeren voor Spieren Muscle FundFunder: University of Tübingen Medical Faculty PATE programFunder: European Reference Network for Rare Neurological Diseases | 739510Funder: European Joint Program on Rare Diseases (EJP-RD COFUND-EJP) | 44140962