Thèses sur le sujet « Physique ultrarapide »
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Arbouet, Arnaud. « RÉPONSE OPTIQUE ULTRARAPIDE DE NANO-OBJETS MÉTALLIQUES : EFFETS DE TAILLE ». Phd thesis, Université Sciences et Technologies - Bordeaux I, 2004. http://tel.archives-ouvertes.fr/tel-00803216.
Texte intégralMarceau, Claude. « Anisotropie optique ultrarapide induite par la filamentation d'impulsions femtosecondes dans les gaz ». Thesis, Université Laval, 2009. http://www.theses.ulaval.ca/2009/26889/26889.pdf.
Texte intégralGe, Xunyou. « Imagerie ultrarapide à l'échelle nanométrique par diffraction XUV cohérente ». Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00828058.
Texte intégralHanna, Marc. « Sources laser femtoseconde à fibre optique ». Habilitation à diriger des recherches, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00806296.
Texte intégralCallenaere, Mathieu. « Étude physique des poches de cavitation partielle en écoulement interne ». Grenoble INPG, 1999. http://www.theses.fr/1999INPG0090.
Texte intégralVergès, Maxime. « Thermal control of all-optical switching in magnetic heterostructures and magnetoplasmonic metasurfaces ». Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0042.
Texte intégralThe opportunity to control magnetic order at short timescale focused a lot of attention around ultrafast magnetism. This research topic is of primary importance for the development of datastorage devices that seek for faster magnetization reversal combined with energy efficiency. It has been shown over the last decade that magnetization can be reversed deterministically by means of a single ultrafast arbitrary polarized laser pulse, so-called All Optical Helicity-Independent Switching (AO-HIS). This kind of light-induced magnetization reversal is restricted to a few ferrimagnetic materials such as GdFeCo or MnRuGa. Since AO-HIS can be performed with linearly polarized ultrafast laser pulses, it is believed that the underlying physics stands for a pure thermal effect, meaning that only the amount of energy transfered from the incoming light to the electronic system matters. In this work we propose various strategies to control this thermal effect. First we consider a periodic arrangement of [Co/Gd/Pt] nanodisks on glass substrate. These structures have been shown to exhibit surface lattice resonances in visible range, characterized by a strong absorption enhancement. In this way we demonstrate that the excitation of such optical mode leads to a reduction of the threshold fluence for observing AO-HIS by 400 %. Also, such collective resonances enhance the magneto-optical activity by 5000 %, promising for a reliable readout sensivity. Probing the magneto-optical behaviour of the metasurfaces with an oblique angle ofincidence reveals the existence of magnetism-induced surfce lattice resonances. We believe that this latter result is important from fundamental point of view. The other strategy involves the multilayer system GdFeCo/Cu. We show that thicker Cu layers allows the electronic system to cool down more efficiently so that AO-HIS can be observed for a larger range of fluencies for a given pulse duration. Thus this adjacent Cu layer plays therole of a heat sink. A direct consequence is the possibility, for samples with thick Cu layers, toextend AO-HIS to larger pulse durations, until 25 picoseconds. This study must facilitate the integration of AO-HIS in future magnetism-based data storage devices
Hajlaoui, Mahdi. « Entre métal et isolant : Dynamique ultrarapide dans l'isolant topologique Bi2Te3 et domaines microscopiques à la transition De Mott Dans V203 ». Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00924392.
Texte intégralCanva, Michael. « Étude des propriétés optiques de molécules organiques encagées dans des matrices solides synthétisées par procede sol-gel. Applications : lasers accordables, mémoire optique ». Phd thesis, Université Paris Sud - Paris XI, 1992. http://pastel.archives-ouvertes.fr/pastel-00713718.
Texte intégralBeaulieu, Nathan. « Propriétés électroniques et magnétiques sous excitation laser femtoseconde, du Gd monocristallin aux alliages ferrimagnétiques ». Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00953656.
Texte intégralNag, Lipsa. « Internal dynamics of flavoproteins studied by femtosecond spectroscopy ». Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLX121/document.
Texte intégralNature employs charge transfer reactions in many biological functions. Redox-active cofactors like flavins (FAD and FMN) are often implicated in such reactions. Charge transfer in proteins often proceeds via formation of radical intermediates. The amino acid radicals of tyrosine (TyrOH) and tryptophan are thought to play important roles as intermediates in intra- and interprotein charge transfer reactions. Tryptophanyl radicals (both protonated cation and deprotonated neutral forms), had been characterized before. However, tyrosyl radicals had only been characterized in the neutral form, and were thought to be formed by concerted electron extraction and deprotonation of tyrosine. Short-lived intermediates are often difficult to observe in biochemical reactions, but may be populated when they can be photochemically formed using short light pulses.In this work, we have characterized intermediates in non-functional charge transfer reactions in flavoproteins using femtosecond time-resolved fluorescence and absorption spectroscopy. Excited states and product states formed in the wild type and mutant forms of the methyltransferase flavoenzyme TrmFO from Thermus thermophilus were investigated. In the TrmFO active site, a tyrosine (Tyr343), is closely stacked on the FAD isoalloxazine ring and a cysteine (Cys51) can form a highly fluorescent adduct with the FAD. In the mutant C51A, FADox fluorescence is strongly quenched by electron transfer from the Tyr343 in ~1ps. The resulting product state displayed a distinct spectral feature- a strong absorption band at ~490 nm unlike any previously characterized radical species. It was assigned to the radical cation of tyrosine (TyrOH•+) which had never been observed before. The FAD•-TyrOH•+ intermediate, is very short-lived as it decays in ~3ps, through charge recombination. As a general conclusion, despite the very low pKa of TyrOH•+, electron transfer from tyrosine can occur without concomitant proton transfer.Using polarization photoselection experiments, we estimated the dipole moment direction for this new transition. The resultant angle between the excited FADox transition and the probed TyrOH•+ transition in C51A TrmFO was 31º±5º. This result sets the orientation of the dipole moment of the transition in the molecular frame of the phenol ring. The finding of distinct directions for the excited FAD transition band and the 490 nm transition confirms their origin in different molecular entities.Following the results from TrmFO, we reinvestigated the photochemistry in the model flavoprotein glucose oxidase (GOX). Here, both tryptophan and tyrosine residues are located in the vicinity of FAD and the photoproduct evolution on the picosecond timescale is more complex. Distinct phases of excited state decay with time constants of 1ps and ~4ps were observed, as well as phases of ~4ps, ~37 ps and a longer-lives phase for product state evolution. Consequently, a comprehensive model for the involvement of radicals of tyrosine and tryptophan and, the different FAD redox states, in the light-induced charge separation and recombination in GOX was made. Partial involvement of the TyrOH•+ radical cation, spectrally similar to C51A TrmFO, was required for the 4 ps and 37 ps phases to account for the ensemble of data. This result explains previous enigmatic features and indicates the involvement of TyrOH•+ in a variety of protein systems.So far, only the deprotonated tyrosyl radical TyrO• had been observed as a functional intermediate in several systems. The visualization of protonated TyrOH•+ radical in TrmFO C51A and GOX suggests the possibility of its intermediate formation as a precursor of TyrO• in functional biochemical reactions.Finally, in TrmFO the construction of specific variants with site-directed mutagenesis was initiated to study active-site flexibility using electron transfer rates as conformational markers. Further experimental and modeling work is required to pursue this goal
Varin, Charles. « Impulsions d'électrons relativistes ultrarapides à l'aide d'un schéma d'accélération par laser dans le vide ». Thesis, Université Laval, 2006. http://www.theses.ulaval.ca/2006/23911/23911.pdf.
Texte intégralElias, Philippe. « Structure spatio-temporelle de la matière éjectée par une surface soumise a une onde de choc ». Phd thesis, Université Paris Sud - Paris XI, 1988. http://pastel.archives-ouvertes.fr/pastel-00716490.
Texte intégralTorresin, Olivier. « Etude comparée de l'émission d'électrons de nanopointes de tungstène et de diamant : émission de champ et photoémission induite par laser femtoseconde ». Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30253.
Texte intégralThis thesis presents electron emission from metallic (tungsten) and dielectric (diamond) nanotips under femtosecond laser illumination. The behavior of DC emission and laser induced photoemission from tungsten nanotips has been widely studied and we use it to benchmark diamond measurements. In the first part, we study DC emission and photoemission from tungsten nanotips. Numerical simulations made from a finite element model (using COMSOL) of our experimental setup, allow the computation of static and optical field enhancement coefficients linked to the tip geometry. Results are compared with the spatial profile of electron emission, which links the field enhancement area at the tip apex and the electron detection area. In the second part, we study DC emission and photoemission from diamond nanotips. Electron energy measurements highlight the presence of a voltage drop along the diamond tip, due to the low conductivity of this material. Electron emission current inside the tip and at the apex obeys Poole-Frenkel conduction, coupled with Fowler-Nordheim field emission observed commonly for metallic surfaces. We propose a macroscopic model to combine conduction and emission mechanisms for DC emission. Under laser illumination, emission measurements are very different from the metallic case. Electron emission saturates under intense laser illumination. In this regime, we show that the DC current cannot reach its DC value between pulses. By lowering laser repetition rate, we are able to measure the dynamics of the DC current in between laser pulses. We adapt the DC macroscopic model for laser induced photoemission using an effective capacitance, and we show very good quantitative agreement with experimental measurement obtained on diamond nanotips. The last part is an introduction to electron time-of-flight measurements to measure the temporal statistics of electron arrival times. We present the modifications made on the experimental setup to be able to make these kinds of measurements, as well as preliminary results obtained on DC and laser-induced emission from tungsten nanotip
Paré-Labrosse, Olivier. « Spectroscopie ultrarapide cohérente et non linéaire dans les semiconducteurs organiques ». Thèse, 2013. http://hdl.handle.net/1866/11027.
Texte intégralWe have studied the excitonic coherences in poly[N- 9’-heptadecanyl-2,7-carbazole-alt-5,5-(4,7-di-2-thienyl-2’,1’,3’-benzothiadiazole] (PCDTBT). Using a spacial light modulator, we shaped ultrafast laser pulses allowing us to probe the system’s coherences. We focused our strength on studying coherences of excitonic states : the singlet and the charge transfer state. We have observed that that 35 fs after excitation, these states are still coherent. This coherence is measured via the visibility that is of abot 10% and 30% respectively. Furthermore, we have shown that the coherence in states generating photocurrent has already vanished after 35 fs. Our data reveals a visibility smaller than 3%, which is lower our instruments resolution. We therefore conclude that the charge transfer states are not precursor states to photocurrent generation, because of their different visibility behavior.
HELFENSTEIN, Clémentine. « Étude du comportement interne de l’abdomen lors d’un impact : observations par échographie ultrarapide ». Phd thesis, 2013. http://tel.archives-ouvertes.fr/tel-00926939.
Texte intégralGrégoire, Pascal. « Étude de semi-conducteurs par spectroscopie d'excitation cohérente multidimensionnelle ». Thèse, 2017. http://hdl.handle.net/1866/20602.
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