Global ETD Search

11	Spectroscopie de la vapeur d'eau par Transformation de Fourier. Application aux régions d'intérêt atmosphérique / Fourier Transform spectroscopy of water vapor. Application for spectral ranges of atmospheric interest Oudot, Charlotte 09 December 2011 (has links) Le travail présenté dans ce mémoire concerne le cadre global de la connaissance de notre atmosphère. L'exploitation des spectres atmosphériques requiert une bonne connaissance des paramètres de raies des molécules qui la composent. En particulier de la vapeur qui en est l'absorbant principal. Des spectres ont été enregistrés avec le spectromètre par transformation de Fourier construit au laboratoire et ceux ci ont été traités en ajustement multi-spectres avec le logiciel MultiFiT. Ce travail se focalise sur la mesure précise des intensités de raie dans deux régions spectrales. A 10 µm, région d'intérêt atmosphérique pour l'instrument IASI, deux études sur les intensités sont présentées. Pour l'isotopologue principal de 1200 à 1400 cm-1, 300 transitions ont pu être mesurées et comparées aux données de la littérature. Le but de ce travail était de déterminer la meilleure base de données pour l'exploitation des spectres IASI. De 1000 à 2300 cm-1, les isotopologues H218O et HD18O ont été étudié à partir de spectres enrichis en 18O. Ce travail a permis de mesurer et d'attribuer un ensemble de 2500 transitions. Enfin ce mémoire propose une révision complète des intensités de la région 1.25µm, qui présentent un important problème dans les bases de données. 39 spectres ont été enregistrés pour cette région avec des échantillons d'eau naturelle. Plus de 11000 transitions ont pu être mesurées et sont comparées aux données de la littérature. Une partie de ces intensités, publiées en 2010, a été exploité par L. Tallis de l'université de Reading. Enfin ce mémoire présente le début d'une exploitation des coefficients d'élargissement obtenus dans la région de 1.25µm. / The work presented in this manuscript concern the knowledge of our atmosphere. In fact, the analysis of atmospheric spectra needs a good understanding of atmospheric molecular species. In particular the water vapor plays a special role as the first absorbent of earth's atmosphere. Spectra were recorded by Fourier transform spectrometer designed in the laboratory and lines parameters fitted with multi-spectra procedure named MultiFiT. The spectroscopic studies focus on lines intensity measurements for two different spectral ranges. The first presented is 10 µm, were two studies have been done. For the H216O isotopologue in the 1200 – 1400 cm-1 range, 300 transitions were measured and compared with literature data. The aim of this work was to determine the best spectroscopic database for IASI recording analysis. In 1000 to 2300 cm-1, H218O and HD18O isotopologue were measured with enriched 18O spectra. Over 2500 transitions were measured and assigned. Also this manuscript presents a huge work done in the 1.25µm region. This range appears in database with an important discrepancy for line intensities. 39 spectra were recorded with water vapor sample in natural abundance. Over 11000 transitions were measured and assigned, comparison to literature data are also presented. A part of this work were published in 2010 and used by L.Tallis, form University of Reading, for atmospheric application. At the end of this manuscript is presented the first comparisons with calculated data done for self broadening coefficients in the 1.25µm region. Bases de données : HITRAN Geisa... Paramètre de raie : intensité Iasi Vapeur d'eau Fourier transform spectrometer Spectroscopic databases : HITRAN Geisa... Line parameters Iasi Water vapor
12	Influência da mercerização e irradiação por feixe de elétrons na aderência da fibra do ouriço da castanha do Brasil em matriz de polietileno de alta densidade / Influency of mercerization and electron beam irradiation on the adhesion between fibre from Brazil nut pod and a high density polyethilene matrix CAMPOS, REJANE D. de 10 December 2015 (has links) Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2015-12-10T17:59:26Z No. of bitstreams: 0 / Made available in DSpace on 2015-12-10T17:59:26Z (GMT). No. of bitstreams: 0 / Tese (Doutorado em Tecnologia Nuclear) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP FIBERS NUTS COMPOSITE MATERIALS REINFORCED MATERIALS POLYETHYLENE MATRIX MATERIALS ADHESION ELECTRON BEAMS IRRADIATION MECHANICAL PROPERTIES SUSTAINABLE DEVELOPMENT X-RAY DIFFRACTION THERMAL GRAVIMETRIC ANALYSIS FOURIER TRANSFORM SPECTROMETER
13	Inverse Problems of Deconvolution Applied in the Fields of Geosciences and Planetology / Problèmes inverses de déconvolution appliqués aux Géosciences et à la Planétologie Meresescu, Alina-Georgiana 25 September 2018 (has links) Le domaine des problèmes inverses est une discipline qui se trouve à la frontière des mathématiques appliquées et de la physique et qui réunit les différentes solutions pour résoudre les problèmes d'optimisation mathématique. Dans le cas de la déconvolution 1D, ce domaine apporte un formalisme pour proposer des solutions avec deux grands types d'approche: les problèmes inverses avec régularisation et les problèmes inverses bayésiens. Sous l'effet du déluge de données, les géosciences et la planétologie nécessitent des algorithmes de plus en plus plus complexe pour obtenir des informations pertinentes. Dans le cadre de cette thèse, nous proposons d'apporter des connaissances dans trois problèmes de déconvolution 1D sous contrainte avec régularisation dans le domaine de l'hydrologie, la sismologie et de la spectroscopie. Pour chaque problème nous posons le modèle direct, le modèle inverse, et nous proposons un algorithme spécifique pour atteindre la solution. Les algorithmes sont définis ainsi que les différentes stratégies pour déterminer les hyper-paramètres. Aussi, des tests sur des données synthétiques et sur des données réelles sont exposés et discuté du point de vue de l'optimisation mathématique et du point de vue du domaine de l'application choisi. Finalement, les algorithmes proposés ont l'objectif de mettre à portée de main l'utilisation des méthodes des problèmes inverses pour la communauté des Géosciences. / The inverse problem field is a domain at the border between applied mathematics and physics that encompasses the solutions for solving mathematical optimization problems. In the case of 1D deconvolution, the discipline provides a formalism to designing solutions in the frames of its two main approaches: regularization based inverse problems and bayesian based inverse problems. Under the data deluge, geosciences and planetary sciences require more and more complex algorithms for obtaining pertinent information. In this thesis, we solve three 1D deconvolution problems under constraints with regularization based inverse problem methodology: in hydrology, in seismology and in spectroscopy. For every of the three problems, we pose the direct problem, the inverse problem, and we propose a specific algorithm to reach the solution. Algorithms are defined but also the different strategies to determine the hyper-parameters. Furthermore, tests on synthetic data and on real data are presented and commented from the point of view of the inverse problem formulation and that of the application field. Finally, the proposed algorithms aim at making approachable the use of inverse problem methodology for the Geoscience community. Parcimonie Régularisation Déconvolution 1 D Hydrologie Sismologie Douceur Positivité Causalité Spectromètre à tranformée de Fourier Sparsity Regularization 1 D deconvolution Hydrology Seismology Smoothness Positivity Causality Fourier transform spectrometer
14	Echantillonnage direct de franges lumineuses avec des nanodétecteurs supraconducteurs dans un interféromètre en optique intégrée : application à la conception et la réalisation d'un micro-spectromètre SWIFTS / Direct sampling of light interferences with superconducting nanodetectors for the realization of a SWIFTS microspectrometer. Cavalier, Paul 18 May 2011 (has links) Ce travail porte sur la réalisation d'un microspectromètre SWIFTS (Stationary Wave Integrated Fourier Transform Spectrometer) incluant des compteurs de photons SNSPD (Superconducting Nanowire Single Photon Detector). Il met en œuvre un interféromètre intégré à guide d'onde en arête bouclé, en SiN, sous lequel sont disposés 24 nanofils supraconducteurs SNSPD en NbN échantillonnant les interférences au pas de 160nm, à une longueur d'onde centrée sur 1.55µm. La conception, l'étude des composantes optique et électronique, la fabrication et la caractérisation à 4.2K sont décrites, jusqu'à la mise en évidence d'une modulation de puissance lumineuse dans le guide conformément à la formation attendue d'interférences. Le SWIFTS-SNSPD constitue le premier dispositif optoélectronique supraconducteur à part entière, doublement intégré. Sa capacité unique d'échantillonnage direct de franges d'interférences ouvre de nombreuses perspectives, pour des applications allant de l'astrophysique aux télécoms. / This work presents the realization of a SWIFTS (Stationary Wave Integrated Fourier Transform Spectrometer) micro-spectrometer with SNSPD (Superconducting Nanowire Single Photon Detector) photon counters. The device features an integrated interferometer made of a SiN loop ridge-waveguide, with an array of 24 NbN-nanowire SNSPD underneath that samples at a 160nm period the interferogram of a laser light, at a wavelength centred on 1.55µm. The conception, preliminary studies of integrated optics and electronics, fabrication and characterization at 4.2K of the final device are described, in particular the observation of the detected signal modulation in the waveguide in agreement with the expected interference formation. The SWIFTS-SNSPD constitutes the first stand-alone, fully integrated superconducting optoelectronic device. Its unique capability of direct sampling of light interferogram opens numerous perspectives, with possible applications ranging from astrophysics to telecommunications. SWIFTS Spectromètre à transformée de Fourier Dispositif Intégré Supraconducteur Optoélectronique Intégrée Refroidie SNSPD NbN Compteur de Photons Supraconducteur SWIFTS Fourier Transform Spectrometer Superconducting Integrated Devices Cooled Integrated Optoelectronics NbN SNSPD Superconducting Photon Counter
15	Studies of crystalline organic molecular materials under extreme conditions Biggs, Timothy James January 2006 (has links) This thesis describes investigations into the properties of -phase BEDT-TTF charge transfer salts. Charge transfer salts are mainly studied as they are very useful test beds for fundamental physics due to the tuneability of their proper- ties and ground states. The effects of temperature and pressure on such systems have been studied, as these allow access to a wide range of different states and properties. Transport properties of these systems have been studied to obtain information about the Fermi surface and effective mass, and the effect of deuter- ation and also change of pressure media will be discussed. The interaction of infrared radiation with these systems has also been investigated and simultaneous pressure and temperature measurements will be presented, something not greatly studied due to the large technical challenges. The techniques and approaches for overcoming these are also discussed. Chapter 1 provides an introduction to the organic materials themselves with particular emphasis on the actual compounds studied. Chapter 2 provides the necessary theoretical background for studying organic charge transfer salts using magnetic quantum oscillations and their infrared re- ectivity. Chapter 3 covers the experimental techniques and also discusses some of the challenges encountered and their solutions to aid others working in this area. Chapter 4 describes an investigation into the transport properties of - (ET)2Cu(SCN)2 by studying Shubnikov-de Haas oscillations using both deuter- ated and normal samples and using two different pressure media, and comparing it to work done using a third. Chapter 5 presents an investigation into the pressure dependence of selected phonon modes in -(ET)2Cu(SCN)2 using infrared radiation on a deuterated sam- ple. Chapter 6 presents what is believed to be the first pressure and temperature dependent infrared study of an organic molecular material. In this case the or- ganic molecular material is d8--(ET)2Cu[N(CN)2]Br, but the techniques should be readily transferable to other materials. 547.137
16	Constructing and Commissioning HELIOS – A High Harmonic Generation Source for Pump-Probe Measurements with sub 50 fs Temporal Resolution : The Development of Experimental Equipment for Extreme Ultraviolet Spectroscopy Terschlüsen, Joachim A. January 2016 (has links) This thesis presents HELIOS, an in-house laboratory for time-resolved pump-probe spectroscopy with extreme-ultraviolet (XUV) probe radiation. A wide span of pump wavelengths can be generated using commercial laser equipment while XUV probe radiation is generated via a high harmonic generation process in a noble gas delivering probe photons with energies between 20 eV and 72 eV. The XUV beam path features a time-preserving monochromator and was constructed and built in-house. HELIOS features an overall time resolution of about 50 fs when using 800 nm pump and 41 eV probe photons. An energy resolution of 110 meV at 41 eV photon energy can be achieved. HELIOS features two beamlines. One µ-focus beamline with an XUV focal size of about 20 µm can be used with experiments that require such a small XUV focal size as well as with different end stations. The other beamline features a semi-permanently mounted end station for angle-resolved photoelectron spectroscopy under ultra-high vacuum conditions. Experiments demonstrating the usability of HELIOS and the two beamlines are presented. A pump-probe measurement on graphene demonstrates the capability of determining a large part of the k-space in only one measurement due to the use of an ARTOF angle-resolved time-of-flight electron spectrometer. A non-angle-resolved pump-probe measurement on the conducting polymer PCPDTBT demonstrates the high signal-to-noise ratio achievable at this beamline in non-angle-resolved photoelectron-spectroscopy pump-probe measurements. The usability of the µ-focus beamline is demonstrated with time-resolved measurements on magnetic samples employing an in-house-designed spectrometer. These experiments allow the retrieval of element-specific information on the magnetization within a sample employing the transversal magneto-optical Kerr effect (T-MOKE). Additionally, a Fourier transform spectrometer for the XUV is presented, the concept was tested at a synchrotron and it was used to determine the longitudinal coherence of the XUV radiation at HELIOS. Angle-resolved time-of-flight Angle resolved time of flight ARTOF ARPES tr-ARPES fs fs resolution Fourier transform spectrometer Fourier-transform spectrometer Fourier transform spectroscopy Fourier-transform spectroscopy FTS gas cell high harmonic generation laser liquid jet monochromator HELIOS HHG off-plane mount off plane mount OPA optical parametric amplifier PCPDTBT pulse shaping pump probe pump-probe measurements pump-probe measurements pump-probe spectroscopy pump-probe spectroscopy Rowland spectrometer time-of-flight spectrometer time of flight spectrometer TOF time-resolved spectroscopy time resolved spectroscopy time-resolved experiments time resolved experiments T-MOKE tr-PES PES photoelectron spectroscopy transverse magneto optical Kerr effect transverse magneto-optical Kerr effect ultrafast ultra-high vacuum ultra high vacuum UHV XUV VUV X-rays Permalloy magnetization dynamic

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