Tesis sobre el tema "Spectroscopies et microscopie électronique"
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Lourenço-Martins, Hugo. "Experiment and theory of plasmon coupling physics, wave effects and their study by electron spectroscopies". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS284/document.
Texto completoSurface plasmons (SP) are electromagnetic waves propagating at the interface between two media typically a metal and a dielectric. SPs can confine electromagnetic fields in very short volumes (typically one to few nanometers), well below the light diffraction limit. This property has a tremendous number of applications ranging from fundamental physics (e.g. quantum optics) to applications (e.g. cancer therapy). However, the price to pay is that SPs suffer from huge ohmic losses in the metal which leads to very short lifetimes (typically few femtoseconds). Theoretically, this presence of dissipation dramatically hardens the theoretical description of SPs. Another consequence of the sub-wavelength confinement of light associated with SPs is that their observation requires a nanometric resolution - which excludes the use of standard optical techniques. Yet, the scanning transmission electron microscope (STEM) is a particularly suitable tool to study SPs as it employs fast electrons with typical wavelength from 1 to 10 picometers. Thus, the last decade has seen the tremendous development of electron-based spectroscopies applied to nano-optics such as electron energy loss spectroscopy (EELS), cathodoluminescence spectroscopy (CL) or STEM- Hanbury Brown and Twiss interferometry (HBT). In this thesis, I explored different open problems of plasmonics and nano-optics under the scope of electron microscopy and spectroscopies. In chapter 3, I develop a formalism taking into account both the quantum and relativistic nature of EELS experiments using elements of quantum field theory. In chapter 4, I apply the latter formalism to the case of EELS measurements of SPs using electrons with shaped phase. In chapter 5, I give several theoretical and experimental results on coupling experiments involving SPs. Particularly, I demonstrate a counterintuitive type of coupling, the so-called self- hybridization which is a consequence of the non-Hermitian nature of the LSP eigenproblem and draw analogy with open quantum system. Finally, in chapter 6, I discuss the recent result on vibrational EELS in monochromated STEM
Couture, Michelle. "Étude des interactions entre des liposomes cationiques et l'ADN par spectroscopies RMN des solides et infrarouge, dichroïsme circulaire et microscopie électronique". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0016/MQ56396.pdf.
Texto completoCerre, Nathalie. "Microscopie en réflexion par fibres optiques : théorie et réalisation". Dijon, 1992. http://www.theses.fr/1992DIJOS010.
Texto completoBadjeck, Vincent. "Etude par spectro-microscopie électronique d'aciers ODS non irradiés et implantés par hélium". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS086.
Texto completoIrradiated and non-irradiated (Y-Ti-O) oxide-dispersion-strengthened (ODS) steels are investigated by scanning transmission electron microscopy coupled with electron energy-loss spectroscopy (STEM-EELS) to study their chemical structure and the effects of radiation. Analytical methods such as multivariate statistical analysis (MVA) and EELS curve-fitting are carried out to achieve elemental quantification or study the edge fine structures (ELNES). Using MVA, the spectrum-images (SI) can be separated into independent spectral responses to gain insights into the valence state of various elements such as Ti or Cr. Investigations on post-mechanical-alloyed (MA) powders show that the nanoparticle (NP) precipitation occurs only after a further high-temperature treatment (consolidation). In non-irradiated consolidated samples, medium-sized NPs (> 3-4 nm) are found to adopt a Y2Ti2O7-d defective pyrochlore structure with a (Y-Ti-O)-Cr core-shell structure with a reduced-Ti layer also depleted in Y. Cr is also shown to segregate to the grain boundaries in non-irradiated samples. The measured O/Ti ratio of 3.2 found for medium-sized NPs and the observed non-homogeneity of the inter-reticular distance d222 through the particle is interpreted as being due to defects in the particles’ structure; it is indeed confirmed that Y2Ti2O7 medium-sized NPs in ODS steels present numerous defects and are non-stoichiometric. The Ti oxidation state is shown to vary from the centre of the NPs to their periphery from Ti4+ in distorted Oh symmetry to a valency often lower than 3+. Independent component analysis (ICA) allows us to generate bonding maps and extract a Ti-Cr interfacial response. An inter-diffusion of Ti and Cr atoms is observed at this interface. The smallest NPs present a different and ill-defined structure and interface with the Fe-Cr matrix. They either consist of a highly oxygen-deficient pyrochlore structure (Y2Ti2O6+d) or an unknown YaTibOc chemical structure. The O/Ti ratio decreases from 3-3.5 to below 1 for an NP size going from 4 to 1.8 nm. A few large particles (sized from tens to hundreds of nm) present a N-Ti-O or Ti-O chemistry but represent only a small percentage of all the NPs (< 1%). To study the neutron irradiation-induced changes, a number of ODS samples were implanted with He+ ions and irradiated with Fe+ ions. After irradiation, they display a homogeneous distribution of high-pressure He bubbles and radiation-induced Cr depletion, segregation and precipitation (RID, RIS and RIP). The He bubbles are frequently trapped at the NP-matrix interface, although bubbles can exist freely in the matrix, trapped by dislocations and at grain boundaries. The He-K line (21.218 eV for free atoms) shifts to higher energy in the bubbles (ΔE = 0.5 to 4 eV); this is shown to be correlated with the He density. He quantification is carried out with three different methods: spatial difference, curve-fitting and MVA. The density and pressure values are found to reach 100 nm-3 and 8 GPa respectively, although the pressure measurement is only semi-quantitative given that the error bars can reach 30%. The curve-fitting method allows us to map the He-K energy position and intensity, yielding the density, in individual bubbles. The spectral response of individual bubbles can be separated in an SI containing many bubbles at different densities using ICA or vertex component analysis (VCA). Bubbles larger than 4 nm are shown to be under-pressurized or at equilibrium with the Fe-Cr matrix. Below 3.5 nm, the He pressure is shown to increase markedly, passing into the over-pressurised regime
Sayah, Elie. "Etude par microscopie électronique en transmission et spectroscopies in situ des catalyseurs Ag/oxyde à porosité organisée : application en oxydation du dichlorométhane". Paris 6, 2011. http://www.theses.fr/2011PA066583.
Texto completoNunez, Eroles Marc. "Nanogravure et caractérisation structurale et électronique de rubans de graphène cristallins". Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30201/document.
Texto completoThe main objectives of this thesis are the fabrication and high-resolution structural characterisation of graphene nanoribbons with atomically smooth edges as well as their device integration and electronic transport study. In first place, we show that crystalline graphene nanoribbons with width under 100 nm and structural properties better than the state of the art can be patterned by a focused electron beam in presence of oxygen. The structural characteristics of the ribbons are also better than the old process using water vapour. Secondly, nanoribbons structure is characterized down to the atomic scale by spherical aberration corrected transmission electron microscopy. We show that the nanoribbons crystallinity, of the centre as well as along the cut edges, is preserved. The performance of our process reaches the state of the art and its reproducibility allows to produce ribbons with length of hundreds of nanometer but as narrow as 16 nm. After that, we have transposed the suspended nanoribbon etching to a partially suspended configuration on a SiO2/Si substrate allowing the integration in devices suitable for electronic transport measurements at low temperature and under magnetic field. The electronic transport in contacted ribbons of 60x300 nm shows a gap and oscillations on backgate scanning measurements that are in agreement with a Coulomb blockade mechanism with dot sizes in the range of the ribbon surface. Even though those results show the persistence of tunnel barriers, the edges quality look good enough to avoid additional confinement. Other than mesoscopic devices, our ribbon fabrication process by electronic beam under oxygen atmosphere opens perspectives in two emergent fields. The process is ultra high vacuum compatible and perfectly adapted to the development of an atomic graphene based technology. A characterisation of contaminants of graphene samples as well as electrical characterisation of graphene devices has been performed in a multiprobe scanning tunnelling microscope in ultra high vacuum. Finally, our graphene nanoribbons have the right dimensions and structural qualities required for the observation of plasmonic behaviour of graphene in visible light and so interact with metallic plasmonic structures. This coupling has been analysed by studying the Raman signal of graphene at the close environment of gold colloids
Mahfoud, Zackaria. "Nanometric spectroscopies of plasmonic structures and semi-conductors nanocrystals". Thesis, Troyes, 2014. http://www.theses.fr/2014TROY0003/document.
Texto completoFor this thesis, I have realised some experimental works using electron microscopy and electron spectroscopies for the study of plasmonic nanostructures and semiconductor nanocrystals . The aim being to study their optical properties with spatial resolutions of the order of a few nm. At this level it is possible to observe the electric near-field associated to the localised surface plasmon resonances supported by metallic nanostructures . So I was able to study the effect due to the presence of roughness on single gold nanorods and I have found that their presence locally alterate the structure of the electric near-field . Combined measurement of electron energy loss spectroscopy (EELS ) and cathodoluminescence spectroscopy were used to compare the near-field and far-field responses respectively. A study by EELS on the coupling between two metal nanorods positioned end to end and separated by a disance of tens of nanometers was used to map the localisation of hybridised modes separately on each branch of the dimers. Finally, comparative studies of cathodoluminescence and photoluminescence on single quantum dots have shown the equivalence of the information collected by these two techniques for such light emitters
Mahjoub, Mohamed Aymen. "Contributions aux études quantitatives par spectroscopies électroniques (EPES et XPS) : Applications aux surfaces nanostructurées". Thesis, Clermont-Ferrand 2, 2016. http://www.theses.fr/2016CLF22666/document.
Texto completoThis thesis focuses on the development of new in-situ methods of characterization based on the electron spectroscopies (XPS and EPES) coupled with theoretical calculations obtained through Monte-Carlo simulations in order to perform very precise quantitative studies. The first part of this thesis was devoted to quantitative studies of XPS and MM-EPES measurements. Firstly, the correction function of a hemispherical analyzer (HSA) which is a combination of the analysis area (A) and the transmission (T) was determined using a new method based on the elastic images. For the first time, the dependence of A on the kinetic energy of electrons was highlighted. Using this function, an in-situ method based on the combination of XPS and MM-EPES modeling was setting up. This method was used to determine the organization of gold film deposed on oxidized silicon substrate. Measurements show that this method is able to determine surface parameters when the microscopy techniques do not give any information in the case of a small quantity of gold deposit (less than 2 nm). The second part of this work was directed towards developing a new generation of microscopy called MM-EPEM which is based on the detection of elastic electrons. The stages required to obtain these images are well described and optimized here. The MM-EPEM images processing was used to study gold growth on different substrates. This technique is a non-destructive method and allows the operator to construct chemical tomography and to determine the nano-organization of the surface
Ramade, Julien. "Spectroscopie optique et microscopie électronique environnementale de nanoparticules Ag-In et Ag-Fe en présence de gaz réactifs". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1221/document.
Texto completoBimetallic nanoparticles (NPs) are known to present interesting catalytic properties justifying their use in several industrial processes in the domain of heterogeneous catalysis. However, their (chemical, geometrical, electronical) structure may evolve under realistic reactive atmosphere, involving a modification of their properties. In this multidisciplinary work, the aim is focused on the surface reactivity monitoring of these NPs under controlled gaseous environment. For this purpose, we developed an in situ spectrophotometer based on spatial modulation to monitor the structure evolution of a large assembly of NPs through the study of their localized surface plasmon resonance (LSPR). This global approach has been coupled with a more local approach by environmental transmission electronic microscopy (E-TEM). E-TEM observations have shown both composition and environmental effects on the chemical structure of Ag-In NPs. This structure evolves from a stable low-enriched indium alloy to a core@shell configuration with a shell composed of indium oxide as the indium atomic concentration increases. Furthermore, stable structure (core@shell, Janus, reduced system) domains were evidenced under reducing atmosphere, depending on the temperature and hydrogen pressure. Lastly, Ag-Fe NP oxido-reduction was monitored on the new setup through LSPR modifications. MET observations, environmental plasmonics and simulations (optical response, Monte-Carlo simulations) suggest that these metals are initially segregated, with an enriched-silver surface. The exposure to an oxidative atmosphere seems to induce the diffusion of iron onto the surface, followed by the formation of magnetite (Fe3O4)
Losquin, Arthur. "Surface Plasmon modes revealed by fast electron based spectroscopies : from simple model to complex". Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00919765.
Texto completoBoulogne, Bruno. "Etude par microscopie électronique en transmission et spectroscopie infrarouge des défauts de réseau dans la berlinite AlPO4". Lille 1, 1987. http://www.theses.fr/1987LIL10221.
Texto completoPoulain, Clément. "Nanostructuration de la surface O/Cu(110) et rôle sur la réactivité". Paris 6, 2013. http://www.theses.fr/2013PA066153.
Texto completoMiniaturisation of structures at surfaces used for devices elaboration with varied applications is a key issue for performance upgrades and the discovery of new properties. Along with potential methods for the conception of new nanostructures, self-organisation attracts much interest as an alternative for lithography techniques due to its low cost and simplicity. In this thesis, we used scanning tunnelling microscopy (STM) and Auger electron spectroscopy (AES) to study the O/Cu(110) surface nanostructuration and its role on reactivity. The one dimensional periodic pattern formed by the surface consists of alternating clean metallic and (2x1) reconstructed oxidized stripes. The adjustment of nanostructural parameters, namely the periodicity and the stripes width, is done by the oxygen coverage rate. This outstanding feature makes the system an ideal playground to study the structure role on reactivity. The sample behaviour as a function of its characteristics should indeed allow a better understanding of its formation in order to control the properties coming with its configuration. However, the classical preparation method implies a limited variation of the nanostructural parameters. In this thesis, we have elaborated an alternative method, based on sulphur pre-adsorption, which considerably widens the domains that the parameters are able to reach. We have developed a model, based on classical elasticity, which successfully describes the results obtained by our new nanostructuration method. We have then exposed radically different nanostructures to O2 and H2S. We were able to witness that the reaction mechanisms were modified and depended on the nanostructural parameters. Oxidation leads to monoatomic troughs formation on the clean stripes, whereas H2S exposure induces an attack of the stripes edges and the formation of S-c(2x2) islands on the oxidized stripes
Sennour, Mohamed. "Apport de la microscopie électronique en transmission et de la spectroscopie EELS à la caractérisation de nitrures (AIN, CrN) dans le fer et l'alliage Fe-Cr". Lyon, INSA, 2002. http://theses.insa-lyon.fr/publication/2002ISAL0020/these.pdf.
Texto completoDupont-Ferrier, Eva. "Interactions et transport électronique dans le système ErSi2/Si (111) : une étude par microscopie et spectroscopie tunnel à basse température". Université Joseph Fourier (Grenoble), 2006. http://www.theses.fr/2006GRE10245.
Texto completoThis PhD relates sorne physical phenomenon occuring in the 2D electron gas (2DEG) formed by a monolayer of erbium silicide (ErSb) epitaxially grown on silicon. The true 2D metal character of the ErSb/Si( Ill) material is well established. For this study, we have used low temperature scanning tunneling microscopy (STM) and spectroscopy (STS). Firstly, we examined local interactions between impurities and the 2DEG (formed by a continuous layer of silicide). STS has been used to characterize the spectroscopic signature of adsorbates and intrinsic defects of the silicide layer. Bound states have been reported on sorne of these impurities. Good qualitative agreement is fond with theoretical results derived from a chimisorption model (Grimley-Newns-Anderson) and a Friedellike model. Secondly, related to the question of electronic properties of semiconductor surfaces, we have studied the transport of charges injected by the STM tip in a 2D silicide island grown on Si(111). The change ofvarious parameters such as the chemical state of the inter-island surface, the type and doping level of silicon, the substrate temperature, selectively activate conductions paths either parallel or perpendicular to the surface. By means of conductance spectra, recorded over a wide range of conductance, we have analyzed the various mechanisms potentially involved in the charge evacuation from nanometric island
Ismeurt, Michel. "Gravure du silicium face (100) sous SF6 stimulée par faisceau au laser CO2 et thermiquement activée". Aix-Marseille 2, 1986. http://www.theses.fr/1986AIX22053.
Texto completoTournier-Colletta, Cédric. "Etude par spectroscopies d'électrons d'interfaces métalliques et semiconductrices". Thesis, Nancy 1, 2011. http://www.theses.fr/2011NAN10109/document.
Texto completoThis thesis is devoted to the electronic properties of low-dimensional systems based on metal and semiconducting materials. The first part deals with the Shockley state confinement in Ag(111) nanostructures, by means of very-low temperature (5 K) STM/STS measurements. We study the electronic structure and spatial distribution of the confined modes. Then the discrete nature of the electronic spectrum allows one to yield the quasiparticule lifetime. A Fermi-liquid behaviour is evidenced and we show that the dominant decay mechanism is attributed to the electron-phonon coupling. The extrinsic contribution arising from the partial confinement of the electronic wave is obtained as well. A scaling law with the nanostructure width is demonstrated, from which we deduce a higher reflection amplitude than in monoatomic islands. In the second part of the thesis, we study semiconducting ultra-thin films produced by alkali (K, Rb, Cs) deposition on the Si(111):B-[root of]3 surface. This work solves the controversy concerning the ground state of this system, and especially the nature of the 2[root of]3 surface recontruction obtained at saturation coverage. Prior understanding of the crystallographic structure allows to elucidate the electronic properties. We show that a one-electron picture, leading to a band insulator scenario, gives a good description of the system, in spite of strong polaronic effects. This conclusion results from an in-depth, combined study of complementary techniques (LEED, ARPES, XPS, STM/STS and DFT calculations)
Dollé, Mickael. "Etude par spectroscopie d'impédance électrochimique, couplée à la microscopie électronique, d'interfaces de batteries au lithium et à ions lithium". Amiens, 2002. http://www.theses.fr/2002AMIE0207.
Texto completoCastignolles, Marie. "Etudes de la synthèse et de la structure par microscopie et spectroscopie électroniques de nanotubes de carbone purs et dopés à l'azote". Montpellier 2, 2004. http://www.theses.fr/2004MON20136.
Texto completoColboc, Hester. "Caractéristiques physico-chimiques, genèse et conséquences tissulaires des dépôts cutanés calciques". Electronic Thesis or Diss., Sorbonne université, 2022. http://www.theses.fr/2022SORUS081.
Texto completoAlthough many dermatological pathologies are associated with pathological skin deposits, endogenous or exogenous, these remain poorly described. Their sub-micrometric size as well as their diversity of chemical composition require the use of various physico-chemical tools to allow a complete characterization. Our objective is to provide a multi-scale physico-chemical characterisation from micrometer to nanometer, but also to explore the genesis and tissue consequences of these deposits using different techniques in order to extract a clinical message. After presenting the current knowledge on these calcifying dermatoses and describing the principles of scanning electron microscopy coupled with energy dispersive X-ray spectroscopy and vibrational spectroscopies, we present the application of these tools to four different dermatoses: calciphylaxis, calcified leg ulcers, calcinosis cutis on epidermal necrolysis and sarcoidosis. Our results show that endogenous skin deposits are mainly composed of carbapatite, whose ultrastructural appearance corresponds to phosphocalcium nanospherules aggregating to form micron-sized plaques. These deposits show a tropism towards the elastic fibres that complementary studies by multiphoton microscopy will allow to explore. These original results provide a better understanding of the physio-genesis of cutaneous calcifications, but also allow us to envisage diagnostic methods and therapeutic approaches
Lambert, Jean-Marc. "Synthèses et caractérisations de nouvelles formes moléculaires du carbone : fulllerènes, dérivés et nanotubes". Montpellier 2, 1995. http://www.theses.fr/1995MON20079.
Texto completoVan, de Moortèle Bertrand. "Etude par spectroscopie mécanique et microscopie électronique en transmission de la stabilité thermique de verres métalliques massifs : effets de la décomposition et de la nanocristallisation". Lyon, INSA, 2002. http://theses.insa-lyon.fr/publication/2002ISAL0078/these.pdf.
Texto completoCordier, Catherine. "Influence des élèments substitutionnels sur les distributions d'interstitiels et la précipitation de nitrures dans les solutions solides et les composés du fer et de l'azote". Lille 1, 1989. http://www.theses.fr/1989LIL10104.
Texto completoBaaboura, Jassem. "Effets de confinement quantique dans les matériaux de faible dimension dévoilés par des spectroscopies électroniques corrélées dans le temps". Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASP025.
Texto completoA profound understanding of interactions within luminescent materials under excitation is imperative for advancing optoelectronic devices. Materials with small dimensions exhibit unique optoelectronic properties resulting from quantum effects and spatial confinement.Our approach to analyzing the optoelectronic properties of nanomaterials is marked by a versatile methodology, employing various techniques integrated into the scanning transmission electron microscope (STEM). Utilizing an accelerated electron source at 60 keV, our study successfully overcame diffraction limitations. The STEM microscope, with nanometric resolution capabilities in measuring energy absorption through transmitted electron energy loss spectroscopy (EELS), formed the central aspect of our exploration. Enhanced by an integrated spectroscopic system into the microscope, we performed an in-depth analysis of the luminescence spectrum (cathodoluminescence) of nanostructures.The integration of these techniques facilitates the exploration of optoelectronic effects induced by excitons in low-dimensional materials, particularly in monolayer TMD-based heterostructures (WS2 et MoSe2) that were carefully prepared in a cleanroom. Luminescence mappings revealed correlations between the emission intensity of exciton XA and the trion, depending on the spatial displacements of the probe across the sample surface. These observations enabled deductions about the dependence of trion or exciton generation on the deformations of the layers within the heterostructure.Excitation by an electron source induces multiple electronic transitions, presenting a challenge compared to optical excitation. To tackle this challenge, the STEM team at LPS developed an experimental technique, the cathodoluminescence excitation spectroscopy (CLE), to identify the electron responsible for the emission of each photon. This identification, coupled with the magnetic spectrometer providing information on the energy absorbed by the sample, facilitates identifying the type of excitation leading to photon emission. The identification of the electron responsible for photon emission was achieved through temporal coincidence, utilizing a photomultiplier and a temporally resolved electron detector, Timepix3.A thorough investigation of the Timepix3 detector during this thesis unveiled the underlying mechanisms, spanning from the initial impact of the electron on the detector surface to its subsequent detection within the readout layer. This study, incorporating various experimental approaches, significantly contributed to the precise characterization of the detector, ultimately optimizing its temporal resolution.The temporal coincidence technique was applied to other low-dimensional materials, such as AlN nanowires with GaN/AlN quantum wells. This approach provided insights into the lifetime of excitations, uncovering a close dependence on the screening of the electric field within these nanowires. Simulations and experimental results demonstrated notable variations based on the current and spatial excitation position within the nanowire. While these dependencies are distinct, they are closely interlinked, influencing the migration of charges from barriers to wells and thus exerting a significant impact on the lifetime and emission energy of excitons.Finally, an energy-dependent study of electrons coinciding with photons unveiled the emission efficiency for each energy absorption, highlighting specific de-excitation processes leading to exciton generation, resulting in photon emission.These results not only enhance our comprehension of low-dimensional materials but also forge new pathways for the development of optoelectronic devices, particularly LEDs
Lelias, Marc-Antoine. "Influence d'agents chélatants et du mode de sulfuration sur la structure et l'activité de catalyseurs d'hydrotraitement". Caen, 2008. http://www.theses.fr/2008CAEN2050.
Texto completoThe aim of this study was to determine the influence of chelating agents and sulfidation procedure on the structure and activity of hydrotreating catalysts. Addition of chelating agent like Nitrilo Triacetic Acid (NTA) and Ethylene Diamine Tetra-acetic Acid (EDTA) leads to a large increase of thiophene hydrodesulfidation and 2,6-dimethyl aniline hydrogenation activities, that can be related to a higher amount of CoMoS sites. The study of the genesis of the sulfide phase by IR spectroscopy reveals that NTA changes the rate of Co promotion of the sulfide slab and the accessibility of the support. This shows that chelating agents improve the amount of active cobalt in the CoMo catalysts. Parallel between spectroscopic and catalytic data also suggests some changes in the structure of sulfide slabs. The sulfidation under high pressure improves the promotion degree of CoMo(P)/Al2O3 catalysts. The characterization of adsorbed n(CO) in the high-pressure IR CellEx cell reveal the appearance of new CO bands at 2094 and 2084 cm-1 that could respectively characterized “type II” CoMoS sites and “CoMoPS” sites. Finally, study of « industrial » catalysts by characterization techniques as HREM, Mossbauer, IR spectroscopy and catalytic tests leads to a more accurate knowledge of complex systems, and to the definition of the strengths and weaknesses of theses analytical tools
RANGAN, Sylvie. "Réactivité des nitriles sur la surface Si(001)-2x1, étudiée par spectroscopies de photoémission, d'absorption X et microscopie tunnel". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2004. http://tel.archives-ouvertes.fr/tel-00010268.
Texto completoSerra, Raphaël. "Moments magnétiques et structure électronique au voisinage des interfaces : étude par spectroscopie de pertes d'énergie d'électrons et calculs ab-initio". Toulouse 3, 2009. http://thesesups.ups-tlse.fr/607/.
Texto completoThe magnetic moment of iron atoms is considerably modified close to the interfaces. The electron energy lost spectroscopy (EELS) allows the study of the electronic structure with a spacial resolution at the nanometer scale. Particularly the threshold L2,3 of transition metal can bring information concerning local variations of the magnetic moment. In fact, there is a relationship between the intensity ratio I(L3)/I(L2) measured at the threshold of iron and the magnetic moment of this atom. However the relation that bring together these two quantities is not obvious but the studies carried on compounds and alloys containing iron showed empiric evidences that the intensity ratio I(L3)/I(L2) varies in a monotone way with the magnetic moment of iron atom. In this work, we were interested in the variation of the intensity ratio I(L3)/I(L2) induced by the interfaces in three different epitaxial systems containing tin iron layers. Those systems are different, one from each other, by the atomic and/or chemical structure at the interface in close proximity to the iron layer. In addition, for each of these systems we studied the influence of the thickness of the iron layer on the electronic and magnetic structure using ab-initio methods. The variations of the intensity ratio of the threshold L2,3 induced by the interfaces are correlated to the magnetic moment variations of the iron atoms which are calculated for each systems by ab-initio methods
Gavillet, Julie. "Etude par microscopie électronique en transmission de la nucléation et de la croissance des nanotubes de carbone monofeuillets". Paris 6, 2001. http://www.theses.fr/2001PA066427.
Texto completoBecquart-Gallissian, Alice. "Etude par microscopie électronique et diffraction de rayons X des mécanismes de formation de l'oxyde dans les alliages argent-magnésium". Aix-Marseille 3, 2000. http://www.theses.fr/2000AIX30020.
Texto completoInternal oxidation is ideal for following a precipitation reaction from its initial stages up to oxide formation. In this work, the mechanism of oxide formation and its different morphologies, MgO precipitates or inner bands parallel to the surface, have been studied in silver-magnesium binary alloys. The principle techniques of investigation used were conventional and high resolution transmission electron microscopy (CTEM HRTEM), electron energy loss spectroscopy (EELS), X ray diffraction, scanning électron microscopy (SEM) and energy dispersive spectroscopy (EDS). It has been shown for the first time in these alloys that there exists two types of precipitation : inter and intragranular. Moreover, it was pointed out that the formation of coherent precipitate and their growth is the best way to obtain well-defined metal-oxide interface. .
Abdellani, Fatima. "Reconstruction de profils de surfaces rugueuses à partir de l'analyse de leur micrographie électronique et leur caractérisation à l'aide de nouveaux paramètres statistiques". Aix-Marseille 3, 1994. http://www.theses.fr/1994AIX30068.
Texto completoMagné, Damien. "Synthèse et structure électronique de phases MAX et MXènes". Thesis, Poitiers, 2016. http://www.theses.fr/2016POIT2284/document.
Texto completoThe aim of this work is at first to study the electronic structure of bidimensional titanium carbide systems, belonging to the MXene family and also to synthesize thin films of such new materials to characterize their properties. The study of the electronic structure has been performed for the Ti3C2T2 MXene with a special attention to the T surface groups by using a combination of electron energy loss spectroscopy and ab initio calculations. This study, focused on both valence and core electrons excitations, enabled the identification of the surface group localization, their influence on the MXene electronic structure as well as their chemical nature. The limits of our TEM-based study is also discussed in view of irradiation phenomena which induce the loss of hydrogen atoms. The synthesis of a MXene thin film requires, beforehand, that of a MAX phase thin film: we opted for Ti2AlC, the precursor for the Ti2C MXene. The MAX phase thin film synthesis was carried out by ex-situ annealing of a multilayer layers. X-ray diffraction experiments and cross-sectional transmission electron microscopy observations show that a highly textured Ti2AlC thin film is obtained above 600°C after the formation, at 400°C, of a metastable solid solution. Finally, by using the same process for V2AlC, we demonstrate that the initial phase orientation plays a key role for the texture of the thin film so obtained
Pouch, Sylvain. "Nano caractérisation de matériaux pour le photovoltaïque par microscopie en champ proche et spectroscopie électronique : mesures de travail de sortie et de temps de vie de porteurs". Thesis, Lille 1, 2015. http://www.theses.fr/2015LIL10197/document.
Texto completoPhotovoltaic technologies represent a great hope for actual energetic issues. We are now working with the third generation of solar cells, composed of nano structured devices. At these levels, the performances measured by conventional techniques are averaged. In order to access local physical quantities, advanced characterization technics have to be developed. The goal of this thesis is the local measurement of work function and carrier lifetime by atomic force microscopy and electron spectroscopy. After a historical overview on photovoltaic technologies and a detailed explanation of the operating principle of the characterization techniques, we present three studies:1) A work function measurement on silicon-germanium heterostructures by XPEEM and KFM, to demonstrate the complementarity of these techniques. We saw that both are able of imaging small (10 meV) work function variations, and have revealed a contrast inversion effect due to a surface state.2) A work function measurement by KFM on III-V materials. We saw that the maximum spatial resolution is dependent on a bend bending covering effect, highlighted with a self-consistent simulation of the surface potential.3) A technique giving access to carrier lifetime mappings, through the acquisition of several KFM images as a function of frequency modulated illumination. This technique has been successfully applied to an PBTFB-PCBM organic solar cell
Maillet, Tony. "Oxydation d'hydrocarbures sur Pd et PdRh déposés sur Al2O3 et ZrO2 - caractérisation par échange 18 O2/16 O2 et par spectroscopie infrarouge de CO et de NO". Poitiers, 1998. http://www.theses.fr/1998POIT2261.
Texto completoDalle, Caroline. "Contribution à l'étude des mécanismes liés à la photosensibilité de type I et de type IIA des verres de silice par spectroscopie infrarouge et microscopie électronique en transmission". Lille 1, 2000. http://www.theses.fr/2000LIL10183.
Texto completoLa photosensibilite des verres est exacerbee par le chargement en hydrogene gazeux avant l'insolation. Afin de mieux comprendre les origines microscopiques de ce phenomene, nous avons etudie par spectroscopie infrarouge les especes formees lors de l'insolation a 244 nm de verres de silice hydrogenes. Parmi les trois especes detectees (hydroxyles, hydrures et eau moleculaire), seule l'espece hydroxyle a des proprietes analogues d'un point de vue cinetique de croissance et stabilite thermique a celles de la variation d'indice de refraction. Enfin nous avons observe a l'aide de la microscope electronique en transmission un reseau de type iia dans une fibre germanosilicate. L'analyse des donnees (analyse chimique et contraste des cliches) semble reveler une dilatation du verre dans les parties insolees
Rousseau, Marthe. "Structure, croissance et biologie de la nacre". Paris, Muséum national d'histoire naturelle, 2004. http://www.theses.fr/2004MNHN0008.
Texto completoSheet nacre is the internal lustrous 'mother of pearl' layer of many molluscan shells e. G. Pinctada margaritifera, the black-lip oyster of French Polynesia, our model. The aim of this work is to study the 'brick and mortar' organization of the flat polygonal tablets of nacre and to understand its growth mechanism in relation with the biochemical parameters involved in the biomineralization. The structural study of nacre was conducted at different scales. At nanoscale, atomic force microscopy (AFM) reveals the intimate structure of the bio-crystal : a continuous organic framework composes the tablet and contains innumerable small aragonite crystallites with a mean size of 45nm. Transmission electron microscopy (TEM) shows that this intracrystalline organic matrix is crystallized and behaves as a single crystal at the scale of the tablet, exactly as the mineral phase aragonite. X-ray diffraction shows, thanks to the pole figure technique, that the crystallographic orientation of the tablets are all aligned parallel to each other with their c axis perpendicular to the polygonal base and their b axis radial (i. E. The direction of extension of each layer). The growth mechanism was studied with a particular attention to elucidate the "mineral-bridge" model, recently proposed for nacre of Haliotis or Mytilus. Our observations invalidate this model : the organic matrix is the continuous phase within the tablet whereas the mineral phase is discontinuous. In Pinctada from one row to the next, bridges exist but they are completely organic. Our conclusions point out that the intracrystalline organic matrix behaves as a template for crystal formation by a heteroepitaxial mechanism. In sheet nacre, biomineralization takes place in 5 main steps : (i) the discharge of the extra-pallial fluid, (ii) the shaping of this fluid as a film (compartment), (iii) nucleation, (iv) growth of the tablets, and finally (v) the complete mineralization of the compartment. Growth and development of the platelets can be modeled as a Voronoi diagram. This growth is deduced to occur following a self-ordering process within the film (theory of the open compartment). Our experimental evidences provide a dynamic morphogenetic model of the growth front. It is characterized by its 'stairs-like' structure. The mineralization front involves the whole surface of the shell, simultaneously. This model helps to understand for example, how the signal for nucleation occurs or how the extension in the front of the shell and the thickening at the back occur together. The important issue of calcium and carbonate transport during crystal formation was studied in pearl oysters during the phase of active growth. The carbonic anhydrase activity and the various levels of calciotropic hormones in hemolymph and tissues could be measured. The circulating concentration of calcium could be characterized in the three main organs : gill, hemolymph and mantle. Furthermore are emphasized the relationships between the laminar structure of nacre with its optical properties. When the layers are parallel to the surface and their thickness is comparable to the wavelength of visible light, interference phenomena occur producing colors which vary with the in French the 'orient' of the mother of pearl. Incidence. This iridescence phenomenon is at the origin of what is called
Fiawoo, Marie-Faith. "Etude par microscopie électronique en transmission de la germination et de la croissance des nanotubes de carbone synthétisés à moyenne température". Phd thesis, Université Paris Sud - Paris XI, 2009. http://tel.archives-ouvertes.fr/tel-00439903.
Texto completoFiawoo, Marie-Faith. "Etude par microscopie électronique en transmission de la germination et la croissance des nanotubes de carbone synthétisés par dépôt chimique en phase vapeur". Paris 11, 2009. http://www.theses.fr/2009PA112131.
Texto completoSingle-wall carbon nanotubes can grow from nanoparticles either by high temperature processes (> 3000°), or low temperature processes (< 1200°C). In this thesis we tried to answer a few questions about the growth mechanism of carbon nanotubes synthetized by chemical vapour deposition. We tented to understand the link between some parameters’synthesis and the change in the yield of few walls carbon nanotubes using a transmission electron microscope and its analysing tools. We have been studying the different stages of growth and identified indirectly the growth but also the destruction phenomena. Trough this study we deduce as well the role of hydrogen, already known by nanotubes’ growth community, but also the role of an underlay of titanium. Besides, for the first time, this work shows that tangential and parallel nucleation and growth on nanoparticles smaller than 5 nm are often possible
Thomas, Cédric. "Etude aux échelles atomique et nanométrique de la structure électronique du graphite exposé à l'hydrogène (atomes, ions, plasma) modèle des premières étapes de l'érosion chimique dans les tokamaks". Aix-Marseille 1, 2008. http://theses.univ-amu.fr.lama.univ-amu.fr/2008AIX11029.pdf.
Texto completoIn this report, we present a study of the physical properties (vibrational and electronic structures, surface morphology) of graphite surfaces subjected to hydrogen (or deuterium) flux considering atoms, ions or plasmas. We have used the following surface analysis techniques : scanning tunnelling microscopy (STM), high-resolution electron energy loss spectroscopy (HREELS) and low-energy electron diffraction (LEED). When graphite surfaces are exposed to atomic hydrogen, STM and HREELS data show a perturbation of the local density of states (LDOS) directly related to a surface perturbation. Thanks to DFT calculations performed in the laboratory, a model of hydrogen adsorption on a graphite surface has been developped. When graphite surfaces are previously bombarded, hydrogen-graphite ineraction seems stronger. Plasma experiments reveal a similitude concerning interaction mechanisms in comparison with atomic and ion bombardment experiments. A synergetic effect is also pointed out
Fares, Lahouari. "Etude par microscopie électronique en transmission et diffraction des rayons X des phénomènes de décollement aux interfaces barrière de diffusion TiN/Ti- diélectrique". Aix-Marseille 3, 2000. http://www.theses.fr/2000AIX30021.
Texto completoMeerson, Olivier. "Etude de l'oxydation du CO par des agrégats d'or supportés sur MgO(100) et TiO2(110) sous ultra-vide en utilisant la technique du jet moléculaire pulsé". Aix-Marseille 2, 2004. http://www.theses.fr/2004AIX22150.
Texto completoTattevin, Hélène. "Déformation et transformation de phase induites par ondes de choc dans les silicates. Caractérisation par la microscopie électronique en transmission". Phd thesis, Université Rennes 1, 1987. http://tel.archives-ouvertes.fr/tel-00675863.
Texto completoServanton, Germain. "Analyse quantitative de la distribution de l’arsenic dans les composants silicium nanométriques par spectroscopie de perte d’énergie des électrons, et contribution à l’étude de son incorporation par différentes techniques résolues à l’échelle atomique". Grenoble, 2010. http://www.theses.fr/2010GRENY048.
Texto completoNowadays, the developments of new technological nodes (CMOS 40-45 nm) require to improve physical characterization techniques in order to quantitatively map silicon dopant distribution, such as arsenic. Moreover, the dopant electrical deactivation process needs to be understood to optimize semiconductor component performances. We used Scanning Transmission Electron Microscopy (STEM) in Electron Energy Loss Spectroscopy (EELS) and Energy Dispersive X-ray (EDX) modes in order to quantitatively map at the nanometric scale the arsenic dopant distribution. We showed the necessity the lowered the primary beam energy down to 120 keV in order to significantly reduce the silicon radiation damages. The comparison between the two spectroscopic modes demonstrates that the EDX detector shows a fast saturation, while it is possible using EELS technique to map the As distribution in semiconductor components. Several applications from STMicroelectronics devices (CMOS, BiCMOS) are shown. Results demonstrate sensitivity down to 1. 10! cm° (0. 02%) with a spatial resolution close to 2 nm. In a second part of the thesis, we focused on the arsenic dopant deactivation process from epitaxially grown samples (As:Si and Ge:Si). It is known that As,;V, (V, vacancy) clusters tend to inactivate arsenic. Using Extended X-ray Absorption Fine Structure (EXAFS), we show the progressive arsenic clustering tendancy when the As concentrations increase. Atom Probe Tomography (APT) experiments performed at the Groupe de Physique des Matériaux (GPM) from the University of Rouen evidenced on the same layers a difference between the As-As and the Ge-Ge inter atomic distances. To conclude, on the contrary to the germanium, the arsenic atoms incorporates frequently in complex sites (not substitutional), which explains the low electrical activity from the studied layers
Rémy, Corinne. "Le polymorphisme du silicate bicalcique Ca₂SiO₄ : implications géophysique et industrielle". Paris 6, 1995. http://www.theses.fr/1995PA066446.
Texto completoLleres, David. "Nouvelles stratégies de vectorisation non virale impliquant des détergents cationiques : Caractérisation physicochimique et devenir intracellulaire des complexes vecteurs/ADN". Université Louis Pasteur (Strasbourg) (1971-2008), 2003. http://www.theses.fr/2003STR13184.
Texto completoThe success of gene therapy depends on the development of vectors able to efficiency deliver therapeutic gene into target cells. For in vivo applications, the size and the stability of vector/DNA complexes are key determinants for an efficient blood diffusion and intracellular trafficking. Within this framework, new synthetic vectors combining properties of cationic detergents and lipids were synthesized in the laboratory of J. P Behr. In spite of their favourable monomolecular DNA condensing properties, the transfection efficiency of these vectors was limited. In this context, in order to study the structure-activity relationship of these vectors, we have characterized the physicochemical properties of DNA complexed with dimerizable cationic detergents. By fluorescence spectroscopy, we have investigated their ability to condense DNA, the molecular order of the hydrophobic domains, and the stability of these complexes. Indeed, a minimal hydrocarbon tail length is required to stabilize the complexes. Moreover, a tight relationship between the stability of these complexes and their transfection efficiency was established. Based on these results, we have prepared new ternary complexes combining cationic liposomes and cationic detergents to DNA. By this strategy, we have formed small and stable ternary complexes. In the presence of serum, their transfection efficiency was higher than lipoplexes. Confocal microscopy observations suggested that ternary complexes were only marginally destabilized by serum and efficiently internalized into cells by endocytosis. Structural studies by electron microscopy and fluorescence spectroscopy associated with the monitoring of intracellular trafficking revealed that the internal lamellar organization of the complexes was strongly correlated with their colloidal stability and their high transfection efficiency in the presence of serum
Rault, Julien. "Structure chimique et électronique des interfaces métal/ferroélectrique en fonction de la polarisation ferroélectrique". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2013. http://tel.archives-ouvertes.fr/tel-00840865.
Texto completoMiro, Sandrine. "Etude de l'endommagement et de la diffusion de l'hélium dans des fluoroapatites". Caen, 2004. http://www.theses.fr/2004CAEN2049.
Texto completoMenecier, Sébastien. "Réactivité entre le cuivre et l'alumine sous irradiation laser". Limoges, 2006. http://aurore.unilim.fr/theses/nxfile/default/960c01d8-a6a0-4dd3-8403-d000392f04bf/blobholder:0/2006LIMO0060.pdf.
Texto completoA laser process was used to elaborate copper tracks on alumina substrates in air. Relevant parameters were found using a Plackett and Burman design of experiments to achieve a copper track with good bonding and good electrical conductivity. This statistical method allowed determining reference parameters and pointing of the process. Copper, partially oxided during laser treatment, with important consequences on the bonding with alumina, so the wetting properties of oxidized copper on alumina have been studied, showing that CuO and Cu2O favored wetting and, simultaneously led to the formation of CuAlO2 and CuAl2O4 interphases which were responsible of the bonding alumina/copper with a physical and chemical continuity in the interfacial zone. Others analyses with Castaing microprobe and TEM and spectroscopy allowed advancing a reactional mechanism, specific to the copper-alumina-oxygen system undergoing a laser irradiation
Luong, Minh Anh. "Etude de la diffusion thermique de l'Aluminium dans des nanofils de Germanium et en alliages de SixGe1-x en utilisant la microscopie électronique en transmission in situ". Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAY050.
Texto completoSemiconductor nanowires are receiving widespread interests for their novel applications in field-effect transistors, photodetectors and biosensors. The nanowire geometry provides an interesting possibility to fabricate axial heterostructures that can be easily accessed electrically by contacting the NW edges. Depending on the size, material and composition of the heterostructure, carriers can experience quantum confinement effects, allowing to fabricate quantum dots or quantum disks inside the NW. Recently, the formation of Silicide or Germanide contacts via a thermally activated solid state reaction between the metal and Si or Ge NW has drawn significant attention because of its great advantages for fabricating short channel devices from bottom up grown NWs rather than complex and high-cost photolithography top-down approaches. The advantage of this approach is that upon heating a metal enters a semiconducting NW at both ends, creating an (inter)metallic region in the NW. If the process is well controlled and stopped at the right moment, only a thin section of semiconductor is left between metallic contacts, allowing to fabricate electrically contacted quantum-dot in a wire structures in a single fabrication step. Al/Ge NW thermal induced solid-state diffusion is a promising system since, in contrast to other metal-semiconductor combinations, no intermetallic phase is formed and a pure monocrystalline Al NW is created with a very sharp interface with the remaining Ge NW. Moreover, the combination of the intrinsically strong spin−orbit coupling in Ge and the superconducting properties of Al, make this system a promising platform to study hybrid superconductor-semiconductor devices that could be potential building blocks for superconducting quantum interference devices (SQUIDs). The challenge addressed in this PhD is to study the thermally induced exchange reaction of Al in both pure Ge as well as SixGe1-x alloy NWs using in-situ observations in a transmission electron microscope (TEM), to allow better understanding and control of the mechanisms involved in the reaction
Lambert, Jean-François. "Cristallogenèse et caractérisations physico-chimiques et optiques des matériaux semiconducteurs AIn₂Te₄ (A=Cd, Zn et Mn) : leurs potentialités comme modulateur dans la bande spectrale 1,06-10,6 micromètres". Bordeaux 1, 1993. https://tel.archives-ouvertes.fr/tel-00136625.
Texto completoBenkaddour, Mourad. "Céramiques conductrices oxydes à base de bismuth, terre rare et vanadium : élaboration, microstructure et propriétés électriques". Lille 1, 2000. https://pepite-depot.univ-lille.fr/RESTREINT/Th_Num/2000/50376-2000-408.pdf.
Texto completoDubois, Mathieu. "Simulations de microscopie à effet tunnel : application à la surface (100) du silicium et aux molécules physisorbées". Lille 1, 2004. https://pepite-depot.univ-lille.fr/RESTREINT/Th_Num/2004/50376-2004-159.pdf.
Texto completoDans un premier temps, ce modèle sera mis en application à l'étude des différentes reconstructions de la surface (100) du silicium. Les résultats théoriques reproduisent relativement bien les données expérimentales obtenues à 5\,K et permettent de comprendre la dépendance en tensions des images et de conclure que la surface est toujours semi-conductrice à basse température. Ces résultats mettent également en avant l'importance des interactions pointe-surface. Dans un deuxième temps, le modèle est utilisé pour étudier une classe de molécules, les thiénylènevinylènes, physisorbées sur la surface (100) du silicium. Nous proposons alors l'origine suivante pour la contribution principale au courant tunnel: cette contribution ne proviendrait pas de la mise en résonance de l'état HOMO de la molécule avec le niveau de Fermi de la pointe mais plutôt de l'abaissement, par la présence de la molécule, de la barrière tunnel entre la pointe et la surface, faisant ainsi ressortir, là où elle repose, les caractéristiques du silicium