Dissertationen zum Thema „Spectroscopies and electron microscopy“
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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.
Der volle Inhalt der QuelleSurface 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
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.
Der volle Inhalt der QuelleBücker, Kerstin. „Characterization of pico- and nanosecond electron pulses in ultrafast transmission electron microscopy“. Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAE014/document.
Der volle Inhalt der QuelleThis thesis presents a study of ultrashort electron pulses by using the new ultrafast transmission electron microscope (UTEM) in Strasbourg. The first part focuses on the stroboscopic operation mode which works with trains of picosecond multi-electron pulses in order to study ultrafast, reversible processes. A detailed parametric study was carried out, revealing fundamental principles of electron pulse dynamics. New mechanisms were unveiled which define the pulse characteristics. These are trajectory effects, limiting the temporal resolution, and chromatic filtering, which acts on the energy distribution and signal intensity. Guidelines can be given for optimum operation conditions adapted to different experimental requirements. The second part starts with the setup of the single-shot operation mode, based on intense nanosecond electron pulses for the investigation of irreversible processes. Having the first ns-UTEM equipped with an electron energy loss spectrometer, the influence of chromatic aberration was studied and found to be a major limitation in imaging. It has to be traded off with spherical aberration and signal intensity. For the first time, the feasibility of core-loss EELS with one unique ns-electron pulse is demonstrated. This opens a new field of time-resolved experiments
Beato, Medina Daniel. „Characterization of 2D architectures on metallic substrates by electron spectroscopy and microscopy“. Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4730/document.
Der volle Inhalt der QuelleNanosciences and surface science are key elements in the conception of a diversity of innovative materials designed to better cope with the needs of current technology. Within this context, we have resolved to characterise the properties of different two-dimensional structures grown on silver substrates with the help of several complementary techniques of surface analysis.Firstly, we have studied auto-assembled 2D films of cobalt phthalocyanine on Ag(100) substrates. In situations with coverages close to the monolayer, two phases were observed: the (5x5) and the (7x7). The electron energy loss spectroscopy has allowed us to support the existence of two inequivalent charge transfer mechanisms between the substrate and the molecules due to differences in the adsoprtion sites. Secondly, we have synthesised both monolayer and multilayer silicene by evaporating silicon atoms on Ag(111) substrates. We have decided to delve into the characteristics of multilayer silicene as it’s less well-known than its monolayer counterpart. With this aim, the system has been subjected to experiments of photoemission spectroscopy and diffraction. In this manner, several hypotheses on the very nature of this material have been tested. On another matter also related to silicene, we have studied its functionalization by adsorption of F4TCNQ molecules and atomic hydrogen
George, Andrew R. „A new spectroscopic method for the non-destructive characterization of weathering damage in plastics /“. Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1605.pdf.
Der volle Inhalt der QuelleMahfoud, Zackaria. „Nanometric spectroscopies of plasmonic structures and semi-conductors nanocrystals“. Thesis, Troyes, 2014. http://www.theses.fr/2014TROY0003/document.
Der volle Inhalt der QuelleFor 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
Sidhoum, Charles. „In-situ study of hybrid nanomaterial formation : a multiscale approach combining electron microscopy and spectroscopic techniques“. Electronic Thesis or Diss., Strasbourg, 2023. http://www.theses.fr/2023STRAE041.
Der volle Inhalt der QuelleThis thesis explores the nucleation and growth of two distinct chemical systems using in-situ Transmission Electron Microscopy (TEM) as a main tool. The first system involves hybrid perovskites, synthesized through a precipitation method using two solvents with different polarities. The second system investigates the growth of a more covalent structure, the tungsten oxide gel, using a sol-gel approach. These “Chimie-Douce” approaches often leads to metastable kinetic phases that slowly transition to a more stable thermodynamic phase. The primary goal of this thesis is to leverage in-situ techniques to monitor these processes in real-time, providing insights into the kinetics and chemical transformations.The in-situ TEM data are complemented by other techniques, such as X-ray diffraction, Small Angle X-ray Scattering, Nuclear Magnetic Resonance, and others. This combined approach seeks to fill a gap in the dynamic in-situ studies at the nanometer scale, focusing on correlative studies to obtain a comprehensive view of the formation mechanisms
Laitenberger, Peter. „Structural and spectroscopic studies of surfaces“. Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364531.
Der volle Inhalt der QuelleNataf, Guillaume F. „New approaches to understand conductive and polar domain walls by Raman spectroscopy and low energy electron microscopy“. Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS436/document.
Der volle Inhalt der QuelleWe investigate the structural and electronic properties of domain walls to achieve a better understanding of the conduction mechanisms in domain walls of lithium niobate and the polarity of domain walls in calcium titanate. In a first part, we discuss the interaction between defects and domain walls in lithium niobate. A dielectric resonance with a low activation energy is observed, which vanishes under thermal annealing in monodomain samples while it remains stable in periodically poled samples. Therefore we propose that domain walls stabilize polaronic states. We also report the evolution of Raman modes with increasing amount of magnesium in congruent lithium niobate. We identified specific frequency shifts of the modes at the domain walls. The domains walls appear then as spaces where polar defects are stabilized. In a second step, we use mirror electron microscopy (MEM) and low energy electron microscopy (LEEM) to characterize the domains and domain walls at the surface of magnesium-doped lithium niobate. We demonstrate that out of focus settings can be used to determine the domain polarization. At domain walls, a local stray, lateral electric field arising from different surface charge states is observed. In a second part, we investigate the polarity of domain walls in calcium titanate. We use resonant piezoelectric spectroscopy to detect elastic resonances induced by an electric field, which is interpreted as a piezoelectric response of the walls. A direct image of the domain walls in calcium titanate is also obtained by LEEM, showing a clear contrast in surface potential between domains and walls. This contrast is observed to change reversibly upon electron irradiation due to the screening of polarization charges at domain walls
Badjeck, 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.
Der volle Inhalt der QuelleIrradiated 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
Tournier-Colletta, Cédric. „Etude par spectroscopies d'électrons d'interfaces métalliques et semiconductrices“. Thesis, Nancy 1, 2011. http://www.theses.fr/2011NAN10109/document.
Der volle Inhalt der QuelleThis 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)
Gulina, L. B., und V. P. Tolstoy. „As2S3 Thin Films Synthesized in “Soft Chemistry” Conditions and Microtubules From Them“. Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35003.
Der volle Inhalt der QuelleBaaboura, 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.
Der volle Inhalt der QuelleA 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
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.
Der volle Inhalt der QuelleThis 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
Lepot, Kevin. „Recherche et caractérisation de traces fossiles d'activité microbienne archéenne (Pilbara Drilling Project, Australie)“. Paris, Institut de physique du globe, 2007. http://www.theses.fr/2007GLOB0007.
Der volle Inhalt der QuelleFesty, Frederic. „Structural and spectroscopic studies of surfaces on the nanometre scale“. Thesis, University of Birmingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368802.
Der volle Inhalt der QuelleUkyo, Yoshio, Kayo Horibuchi, Hiroki Kondo, Hideaki Oka, Yuji Kojima, Kazuyoshi Tatsumi und Shunsuke Muto. „Effect of Mg-doping on the degradation of LiNiO2-based cathode materials by combined spectroscopic methods“. Elsevier, 2012. http://hdl.handle.net/2237/20830.
Der volle Inhalt der QuelleNikolaievskyi, Dmytro. „Searching for spatial and chemical control of graphene modification : atomic force microscopy assisted folding and covalent functionalisation“. Electronic Thesis or Diss., Aix-Marseille, 2022. http://www.theses.fr/2022AIXM0263.
Der volle Inhalt der QuelleMany efforts are put in manipulating graphene with local and chemical control to tune its electronic properties, enabling its application in device fabrication. We have used atomic force microscopy (AFM) to investigate catalytic scanning probe lithography (cSPL) as a method to functionalise covalently a supported chemical vapour deposition graphene. We have shown that supported graphene is cut at smaller tip forces in liquid than in air. So far, the cSPL epoxidation with a manganese-based catalytic system was inefficient to functionalise graphene, but AFM scanning has opened the way for studying graphene folding by the “cut and fold” method. We have explored contact mode AFM scanning of micrometric zones of few-layer graphene (FLG), where graphene is cut and pushed at the top of scanned zones, forming wide folded stacks. Transmission electron microscopy and Raman analyses have revealed the creation of a turbostratic multilayer graphene (MLG), consisting of folded stacks of 10–20 layers, with an interlayer distance of 0.36 nm. Linear defects are introduced by folding, likely due to loops and folding edges. Thus, the cut and fold method creates a particular kind of MLG from initial FLG, sharing properties of free-standing and free-stacked graphene, and electronically different from the FLG. Finally, we have done preliminary tests of the reversible distortion of graphene by covalently grafted bridged azobenzene structures, using photoinduced E/Z isomerisation. We have confirmed functionalisation by Raman and XPS and observed UV-induced electric resistance changes
Washim, Hossain. „Surface Enhanced Raman Spectroscopic Study of Some Functional Molecules Adsorbed on Noble Metal Nano Particles“. Thesis, University of North Bengal, 2019. http://hdl.handle.net/123456789/2833.
Der volle Inhalt der QuelleMaigné, Alan. „Caractérisation et modélisation par microscopie électronique en transmission à balayage (STEM) et spectroscopie de perte d’énergie d’électrons (EELS) de « nanohorns » de carbone monofeuillet fonctionnalisés pour des applications pharmaceutiques Review of recent advances in spectrum imaging and its extension to reciprocal space Revealing the Secret of Water-Assisted Carbon Nanotube Synthesis by Microscopic Observation of the Interaction of Water on the Catalysts Role of Subsurface Diffusion and Ostwald Ripening in Catalyst Formation for Single-Walled Carbon Nanotube Forest Growth Effect of hole size on the incorporation of C60 molecules inside single-wall carbon nanohorns and their release Adsorption Phenomena of Tetracyano-p-quinodimethane on Single-Wall Carbon Nanohorns Carbon Nanohorns as Anticancer Drug Carriers Effect of Functional Groups at Hole Edges on Cisplatin Release from Inside Single-Wall Carbon Nanohorns Optimum Hole-Opening Condition for Cisplatin Incorporation in Single-Wall Carbon Nanohorns and Its Release Functionalization of Carbon Nanohorns with Azomethine Ylides: Towards Solubility Enhancement and Electron-Transfer Processes Aqueous carbon nanohorn–pyrene–porphyrin nanoensembles: Controlling charge-transfer interactions Photoinduced Electron Transfer on Aqueous Carbon Nanohorn–Pyrene– Tetrathiafulvalene Architectures Soluble Functionalized Carbon Nanohorns“. Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS600.
Der volle Inhalt der QuelleIn this manuscript, we will expose the characterization and modelling of Single Wall Nanohorns (SWNH) and Nanotube Forests by analytical microscopy and the functionalization of SWNH for drug delivery applications. Firstly, we will introduce the microscopy and spectroscopy methods used for our experiments. We will then study the growth process of Single Wall Carbon Nanotubes (SWCNT) forests (within the framework of a collaboration with AIST, Japan). SWCH, their structure, modifications and filling properties will be analysed in details. An original method will be presented to study the porosity of inorganic material with EELS. Ab initio calculation will also be used to explore the effect of the defects present in the SWNH wall on the oxidation and filling process. We will study the potentialities of Single Wall Carbon nanohorns as Drug Delivery Systems and particularly as anticancer drug carriers
Colboc, Hester. „Caractéristiques physico-chimiques, genèse et conséquences tissulaires des dépôts cutanés calciques“. Electronic Thesis or Diss., Sorbonne université, 2022. http://www.theses.fr/2022SORUS081.
Der volle Inhalt der QuelleAlthough 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
Goodall, Rosemary Anne. „Spectroscopic studies of Maya pigments“. Thesis, Queensland University of Technology, 2007. https://eprints.qut.edu.au/16958/1/Rosemary_Goodall_Thesis.pdf.
Der volle Inhalt der QuelleGoodall, Rosemary Anne. „Spectroscopic studies of Maya pigments“. Queensland University of Technology, 2007. http://eprints.qut.edu.au/16958/.
Der volle Inhalt der QuelleCardwell, Drew. „Investigation of electrically-active defects in AlGaN/GaN high electron mobility transistors by spatially-resolved spectroscopic scanned probe techniques“. The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1373894407.
Der volle Inhalt der QuelleChan, Alan Jenkin. „3D Time-Resolved Hetero-Coagulation of Soft Latex and Hard Colloidal Particles and the Structuration of the Resulting Gel Network“. Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS026.
Der volle Inhalt der QuelleNatural rubber (NR) is an indispensable raw material used in the manufacturing of more than 40,000 products primarily due to its excellent intrinsic physical properties. However, NR is seldom used in its raw state. Often, it needs to be reinforced with particulate fillers (nanoparticles) to further improve its physical strength required for most applications. The precise origin of this mechanical reinforcement effect remains unclear, however, optimal reinforcements appears to depend on the dispersion of filler in the NR matrix and the interaction of NR and filler.It was found that the conventional method of pouring fine powders in a solid block of rubber/melt is not the most efficient way to disperse the fillers. The new alternative approach in which the two components are first dispersed in liquid has shown promising results but available literature is still very limited. Furthermore, the microscopic mechanism involved in the interaction of NR and filler in liquid is still unknown. In this context, we (i) described the physico-chemical surface properties of NR particles in liquid, (ii) identified key filler (size, composition, surface activity, concentration) and solution (ion valence) related parameters to comprehend the structural, morphological, and dynamical evolution of the NR-filler interaction, and (iii) quantified the mechanical properties of the NR particles. With this approach we were able to provide the first reports on the physical processes involved in the interaction of NR and filler. More importantly, a recipe for the basic yet crucial parameters that controls and modulates NR-filler heteroaggregation was established. This could open the way to further understand the reinforcement effect
Burema, Shiri. „Inelastic Electron Tunneling Spectroscopy with the Scanning Tunneling Microscope : a combined theory-experiment approach“. Thesis, Lyon, École normale supérieure, 2013. http://www.theses.fr/2013ENSL0821.
Der volle Inhalt der QuelleInelastic Electron Tunneling Spectroscopy (IETS) with the Scanning Tunneling Microscope (STM) is a novel vibrational spectroscopy technique that permits to characterize very subtle properties of molecules adsorbed on metallic surfaces. Its proposed symmetry-based propensity selection rules, however, fail to fully capture its exact mechanism and influencing factors; are not directly retraceable to an adsorbate property and are cumbersome. In this thesis, a theoretical approach was taken to improve them. An IETS simulation protocol has been developed, parameterized and benchmarked, and consequently used to calculate IETS spectra for a set of systematically related small molecules on copper surfaces. Extending IETS principles were deduced that refer to the tunneling state’s vacuum extension, the selective activating/quenching of certain types of modes due to the moieties’ electronic properties, and the applicability of a sum rule of IETS signals. Also, fingerprinting IETS-signals that enable discrimination between adsorbate orientations, the chemical nature of atoms and structural isomers were determined and a strategy using straightforward electronic density distribution properties of the isolated molecule to predict IETS activity without (large) computational cost was developed. This expertise was used to rationalize and interpret experimentally measured IETS spectra for adsorbed metalloporphyrins and metallophthalocyanines, being the first IETS studies of this large size. This experimental approach permitted to determine the current limitations of IETS-simulations. The associated identification shortcomings were resolved by conducting complementary STM-image simulations
Fernández, del Río Lía. „An Investigation of the Polarizing Properties and Structural Characteristics in theCuticles of the Scarab Beetles Chrysina gloriosa and Cetonia aurata“. Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-86339.
Der volle Inhalt der QuelleMonnier, Laurine. „Analyses structurales par microscopie électronique d'hexaferrites magnétiques Ca2+xFe16-xO26-(x/2)“. Thesis, Normandie, 2018. http://www.theses.fr/2018NORMC224/document.
Der volle Inhalt der QuelleThis thesis reports on the synthesis and the characterization of hexaferrite compounds in the Ca-Fe-O system. This work has allowed to isolate four polycrystalline compounds presenting the chemical formula (Ca4Fe5O13)1-x(Fe9O12)1+x (x= 0.334; 0.301 and 0.128) and (Ca4Fe5O13)(Fe4O4). Their crystalline structure has been determined using the precession electron diffraction tomography and has been validated through high resolution imaging microscopy (HREM/HAADF). X-ray diffraction and neutron diffraction studies on polycrystalline samples have confirmed the different structural models. Fine analysis of intergrowth defects in HAADF imaging revealed significant deviations in composition with respect to the ideal composition (Ca4Fe5O13)(Fe9O12) at the origin of the three observed polymorphs. In addition to the studies on micron-sized crystals in the 80s, obtaining polycrystralline samples allowed the measurement of their physical properties. Despite the complexity of these structures and the presence of extensive defects, the Mössbauer spectroscopy has highlighted a unique oxidation degree of iron (+3) and confirmed as well the various magnetic transitions initially detected by magnetization measurements, as well as their evolution versus the x deviation value. Electrical resistivity and Seebeck coefficient measurements were performed on the samples
Gonano, Bruno. „Influence des ions sulfates sur la physico-chimie d'oxydes de fer type perovskite“. Thesis, Normandie, 2017. http://www.theses.fr/2017NORMC222/document.
Der volle Inhalt der QuelleIn this study, we have shown that in perovskite-type iron oxides, sulfate ions (SO42-) can be used to bring structural and electronic anisotropy, or on the contrary to break long distance ordering and cause the isotropy of the material.Thus, this work made it possible to isolate the two-dimensional compounds: Sr4Fe2.5-x□x07.25-(3x/2)(SO4)0.5 (with x = 0.25 and 0.5). They can be described as an intergrowth SrO/SrFeO2,5/SrFe0,5-x□xO1,25-(3x/2)(SO4)0.5/SrFeO2,5 and crystallize in a quadratic mean cell I4/mmm (a=ap et c≈29 Å). The unbridged sulfates tetrahedra are oriented transversely with respect to c ⃗ for x=0.5 and longitudinal for x=0 and 0.25 because bridged to the iron pyramids of the shared layer. The iron atoms of the non-mixed layers SrFeO2,5 are in pyramidal coordination for x=0 and pyramidal and octahedral coordination for x=0.5 and x=0.25, in order to respect the trivalence of iron. However, for x=0.5, two magnetic configurations are observed whereas the compounds x=0 and x=0.25 show only one. In the compound Sr4Fe2.5□xO7.25(SO4)0.25(CO3)0.25, the influence of the carbonates (CO32-) is directly felt on the stacking parameter, which is smaller. The compounds are semiconductors with high electronic resistivity values (of the order of 106Ω.cm) and are not ionic conductors.The ordered phase "15R" SrFe0.6Cr0.4O2.8 becomes disordered when 10% of the iron is substituted with sulfates (SrFe0.5Cr0.4O2.1(SO4)0.1) and adopts a pseudo-cubic structure. Its physical properties are then modified because we switch from a ferromagnetic to an antiferromagnetic behavior (TN=800K). This oxygen-deficient compound shows more or less large structural defects and a semiconductor behavior. No ionic conduction phenomenon is observed
Servanton, 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.
Der volle Inhalt der QuelleNowadays, 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
Antunez, de Mayolo Eduardo. „Study of the Optical Properties of sp2-Hybridized Boron Nitride“. Thesis, Linköpings universitet, Tillämpad optik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-125738.
Der volle Inhalt der QuelleShreepathi, Subrahmanya, Hung Van Hoang und Rudolf Holze. „Corrosion Protection Performance and Spectroscopic Investigations of Soluble Conducting Polyaniline-Dodecylbenzenesulfonate Synthesized via Inverse Emulsion Procedure“. Universitätsbibliothek Chemnitz, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-200900775.
Der volle Inhalt der QuelleNunez, Eroles Marc. „Nanogravure et caractérisation structurale et électronique de rubans de graphène cristallins“. Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30201/document.
Der volle Inhalt der QuelleThe 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
Colaço, Élodie. „Design and characterization of biomimetic biomineralized nanomaterials“. Thesis, Compiègne, 2019. http://www.theses.fr/2019COMP2529.
Der volle Inhalt der QuelleThe design of a composite based on collagen and hydroxyapatite crystals attractes a great interest in materials science and biomedical research particularly for bone tissue applications. The objective is to synthesize, at the nanoscale, a biomaterial from these two components in a controlled conditions in order to modulate its physicochemical, structural and mechanical properties. This thesis project highlights the role of collagen in the mineralization mechanism with the aim of developing a biomimetic biomineralized nanomaterial. To this end, several strategies have been suggested: (i) assembly of collagen with preformed hydroxyapatite crystals, (ii) mineralization of hydroxyapatite by enzymatic catalysis (iii) elaboration of mineralized enzyme-based multilayers by the "layer-by-layer" strategy to form a nanofilm or nanotube in the presence of collagen or not. The characterization of the various mineralized nanostructured materials obtained is performed by several physicochemical techniques including transmission electron microscopy (TEM) and scanning electron microscopy (SEM), atomic force microscopy (AFM), vibrational spectroscopy (IR and Raman), turbiscan, quartz crystal microbalance (QCM-D) and light scattering measurement (DLS)
Chervy, Pierre. „Caractérisation biophysique des interactions entre le Lanréotide et des membranes lipidiques“. Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS306.
Der volle Inhalt der QuelleThe aim of this work is to characterize the interaction between the Lanreotide – a dicationic octapeptide – and membranes composed of lipids. Even if the peptide is very soluble, it has self-assembling properties. Above the critical concentration – which is sensitive to both temperature and ionic strength – the peptide self-assembles into nanotubes whose structure has been solved by the team. The present work is divided into two parts: on one side the study of the interaction of the Lanreotide with anionic membranes, on the other one the study of the interaction of the Lanreotide with neutral membranes.We adopted a structural approach to characterize the membrane-peptide mixture: X-ray scattering, vibrational spectroscopy (ATR-FTIR), electron microscopy (negative staining and freeze-fracture) ; we also used a quantitative approach (ultrafiltration and peptide quantification) in order to determine the stoichiometry of the interaction. In the presence of anionic lipids, the peptide interacts with membranes until its saturation. This interaction, which is not abolished at high ionic strength (2M NaCl or phosphate), induces the self-assembly of the peptide at the surface of the membrane. This phenomenon generates mixed self-assemblies composed of a stack of peptide bilayers sandwiched by lipids bilayers. These stacks wrap into an Archimedian spiral which is a regular spiral with a constant step. In these mixed assemblies, the peptide is organized in a new architecture compared to the self-assemble nanotubes. This new structure has been characterized and solved in this study.In the case of neutral membrane-Lanreotide mixture, the peptide partitions between water and lipids. This observation suggests that in this condition the peptide is able to cross the membranes. The peptide-membrane interaction also decreases the critical concentration of the peptide
Habib, Lamice. „Étude des propriétés membranaires des vésicules lipidiques incorporant des triterpènes oxygénés bioactifs d'origine végétale : application à la cucurbitacine E et à l'érythrodiol“. Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10022/document.
Der volle Inhalt der QuelleCucurbitacin E and erythrodiol are natural oxygenated triterpenes having respectively, a tetra and pentacyclic skeleton. They are known for their numerous biological properties. In this thesis, we studied their interaction with the membranes of lipid vesicles to better understand their pharmacodynamics. We have prepared liposomes in the absence and presence of cucurbitacin E and erythrodiol using the reverse phase evaporation technique followed by extrusion, the hydration of lipid film and the ethanol injection techniques. The physicochemical characteristics of lipid vesicles incorporating or not the triterpenic molecules were investigated by appropriate techniques. The determination of cucurbitacin E and erythrodiol in the vesicles by high performance liquid chromatography showed high incorporation efficiencies of both triterpenes. Size measurements obtained by dynamic light scattering showed that liposomes incorporating triterpenes were smaller than empty liposomes. The images obtained by transmission electron microscopy confirmed the formation of spherical vesicles. Measurements of vesicles dimensions by atomic force microscopy (AFM) demonstrated that liposomes incorporating cucurbitacin E were higher and more resistant to the force exerted by the AFM tip than the blank liposomes. Liposomes incorporating erythrodiol were more fragile and tend to break up into lipid bilayers on the mica surface. Results obtained by differential scanning calorimetry suggested that cucurbitacin E is localized at the polar-apolar interface of the liposomal membrane while erythrodiol is inserted between the acyl chains of the phospholipids leading to the formation of heterogeneous lipid domains. The release kinetics of the sulforhodamin B encapsulated into the aqueous phase and measured by fluorescence spectroscopy revealed that the liposomal membrane becomes in the presence of cucurbitacin E, more permeable to this probe. The overall results suggest that cucurbitacin E and erythrodiol affect differently
Jin, Liang. „Direct electron detection in transmission electron microscopy“. Diss., [La Jolla, Calif.] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p3344737.
Der volle Inhalt der QuelleTitle from first page of PDF file (viewed April 3, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 148-151).
Davies, D. G. „Scanning electron acoustic microscopy“. Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304042.
Der volle Inhalt der QuelleDuncan, James Lyon. „Electron microscopy of photosystems“. Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412477.
Der volle Inhalt der QuelleAllenspach, Rolf Allenspach Rolf Allenspach Rolf Allenspach Rolf. „Magnetic characterization at surfaces by spin polarized electron spectroscopies /“. [S.l.] : [s.n.], 1985. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=7952.
Der volle Inhalt der QuelleMai, Van Huy. „Étude de phénomènes de commutation de résistance de films minces de LixCoO2“. Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112115/document.
Der volle Inhalt der QuelleFlash memory has been famous in the field of non-volatile memory; currently it is extremely used for digital data storage in almost type of mobile electronic device (laptop, mobile phone, tablet ...). To overcome its current limitations (information density, access speed, endurance), a large number of research develop, especially exploring the concept of resistive memory (Re- RAM), which is based on switching between two resistance states (or more) via the application of a voltage.The Re-RAM whose resistance change depends on electrochemical reactions are potentially good candidates; the involved redox mechanisms are often, with particular cations migration of metal elements (between the electrodes), or oxygen deficiencies. This filamentary nature makes difficult to achieve extreme miniaturization at the nanoscale.For this purpose, a completely different class of materials - used in the field of energy storage - is explored. The objective of this thesis is thus to deepen the study of resistance switching phenomena observed in films LixCoO2. We first characterize the structural and electrical properties at the nanoscale, such films deposited on various types of substrates. We then seek to determine the electrochemical mechanisms underlying modification: they are in effect in reverse for the same sign of potential, as it is in the configuration of a contact nanoscale AFM tip / film, or in the configuration of a micrometer contact electrode / film / electrode. In the first configuration we determine the electrochemical reactions involved. In the second, we propose a radically different mechanism, supported by several converging results. Finally, we present promising first results regarding the potential applicability of these films to Re - RAM, and beyond, the neuromorphic circuits (multiple resistance states - additivity phenomena)
Chaaban, Abdul Amir. „Etude de l'organisation structurale des nanocolloïdes humiques“. Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30062/document.
Der volle Inhalt der QuelleThe structural organization of humic nanocolloids remains a matter of harsh debate, and surprisingly, it is yet not possible to decide between an arrangement of the humic matter in the form of randomly coiled macromolecules more or less connected, and a supramolecular organization of small heterogeneous molecules linked by hydrogen bonds and hydrophobic interactions. In this study, we investigate the reconformation induced by the addition of cationic surfactants (C n-trimethylammonium chloride) of varying alkyl chain length with a series of humic substances (HS) and Dissolved Organic matter (DOM) from two blackwater rivers of the Central Amazon. Turbidity measurements, Dynamic light scattering, electrophoretic mobility, surface tension, fluorescence spectroscopy, small angle neutron scattering and cryo-transmission electron microscopy (cryo-TEM), are combined to describe the Humic Substance/Surfactant complexes obtained. The association between the oppositely charged HS and cationic surfactant is driven by both electrostatic and hydrophobic interactions. A variety of molecular structures, unilamellar vesicles, disks, globules, spheroidal micelles, are visualized by cryo-TEM depending on surfactant concentration. Such sequence, consistent with those displayed by catanionic systems, provides an independent confirmation of both the amphiphilic nature of HS and of its supramolecular organization. In addition, the molecular rearrangement was investigated using single-scan fluorescence emission spectra spectroscopy, thus identifying the chemical groups responsible for the fluorescence properties in HS and DOM. The addition of cationic surfactant to HS/DOM unveils an unexpected fine structure of humic-like fluorescence through new emission peaks that are not evidenced in the references HS/DOM. An enhanced protein-like fluorescence indicating major restructuration and structural stacking/de-stacking is observed. All our results support a supramolecular organization of humic substances and DOM
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.
Der volle Inhalt der QuelleSemiconductor 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
Duchesne, Isabelle. „Electron microscopic and spectroscopic studies on the surface ultrastructure of kraft pulp fibres /“. Umeå : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2001. http://epsilon.slu.se/avh/2001/91-576-6089-1.pdf.
Der volle Inhalt der QuelleLepinay, Kevin. „Développement et applications de la tomographie chimique par spectroscopie EDX“. Thesis, Lyon, INSA, 2013. http://www.theses.fr/2013ISAL0124/document.
Der volle Inhalt der QuelleThis thesis focuses on the evaluation of the STEM EDX chemical tomography technique: development of experimental procedures, data processing and volumes reconstruction, quality analysis of the results and evaluation of the overall complexity. Until now, STEM EDX analysis performances were very limited, so only few studies about this technique have been realized. However, very significant progress procured by the new SDD detectors as well as by the high brightness electronic sources (X-FEG), making the STEM EDX 2D analysis very fast, have revived the possibility of the chemical tomography, although the technique has to be developed and evaluated (performance and complexity). We have worked on a Tecnai Osiris which acquires EDX chemical mapping of hundreds of thousands of pixels with resolution of one nanometer and in a few minutes. We chose to prepare the rod-shaped samples by FIB and use a sample holder allowing an angle of exploration of 180° without shadowing effects. Then, using model samples (SiO2 balls in resin), we evaluated the sample deformation due to the electron beam irradiation. This allowed us to propose a method to reduce this effect by depositing a 20 nm chromium layer. Images simulations were used to evaluate the software and the reconstruction methods. The methodology of each step of the STEM EDX tomography analysis is then explained and the technique interest is demonstrated by comparing the 2D and the 3D analysis of a transistor 28 nm FDSOI. The quality of the reconstructions (signal-to-noise ratio, spatial resolution) was evaluated, in function of experimental parameters, using simulations and experiments. A resolution of 4 nm is demonstrated through the analysis of a test pattern and a "gate all around” transistor. For the same transistor, the possibility and the interest of a failure analysis at the nanoscale is proven. Analyses of a SRAM gate fail or of the holes in a copper pillar explain the benefits of a combination between a HAADF volume (morphology and resolution < 4 nm) and an EDX volume (chemical information). To conclude, this technique, which still needs to be improved in terms of simplicity, is already showing its usefulness for the analysis and the development of advanced technologies (20nm node and beyond)
Alajtal, Adel Imhemed. „Raman spectroscopic application for the analysis of organic compounds and minerals of astrobiological significance : the detection and discrimination of organic compounds and mineral analogues in pure and mixed samples of astrobiological significance using raman spectroscopy, XRD and scanning electron microscopy“. Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/4425.
Der volle Inhalt der QuelleAlajtal, Adel I. „Raman spectroscopic application for the analysis of organic compounds and minerals of astrobiological significance. The detection and discrimination of organic compounds and mineral analogues in pure and mixed samples of astrobiological significance using raman spectroscopy, XRD and scanning electron microscopy“. Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/4425.
Der volle Inhalt der QuelleGeronimi-Jourdain, Théo. „New breakthrough in plasmon-mediated surface functionalization“. Electronic Thesis or Diss., Université Paris Cité, 2023. http://www.theses.fr/2023UNIP7076.
Der volle Inhalt der QuelleThe assembly of coupled nanoparticles (NPs) has aroused great interest in recent years, with a view to applications in the detection of chemical compounds (molecules, explosives, drugs,...) belonging to the field of surface exalted Raman spectroscopy (SERS) for example. Recently, the coupling of periodic structures of metallic nanoparticles NPs has allowed to highlight resonances called surface collective resonances (SLR) resulting from the coupling between localized surface plasmon modes and diffraction modes. These resonances are characterized by a very fine spectral width implying a strong exaltation of the electric field in the vicinity of the nanoparticles. In this thesis, we propose an experimental study verified by means of Finite Difference Time Domain (FDTD) modeling, of individual and collective plasmonic resonances of surfaces supported by periodic arrays of metallic NPs elaborated by the electron lithography technique. The first part of this thesis, highlights the main optical characteristics, from the single NP to the assembly of NPs in periodic array. This chapter is illustrated with some examples from the literature on the excitation of these surface plasmons, to generate a localized surface functionalization. In a second step, an in-depth study on the improvement of the morphology conditions of the plasmonic substrates, in order to improve the molecular grafting at the level of the NPs, is presented. Then, we present the results obtained for a chemical grafting method, implemented in the laboratory, which allows the direct visualization of lattice modes, by grafting organic molecular films derived from diazonium salts, by exciting SLRs modes. Finally, the last part deals with the study of binary arrays of nanoparticles which revealed the emergence of two hybrid plasmonic modes, originating from the asymmetry of the elementary pattern. We then carried out, with the help of our grafting strategy, a study on the attachment of molecules only in the regions of maximum exaltions of the electric fields by exciting sometimes in the symmetric mode, sometimes in the anti-symmetric mode. During this PhD, these research works have allowed a clear improvement of the understanding and control of the deposition localization at the nanoparticle scale. It is on this solid basis that it is possible to associate materials already known for their remarkable optical properties (metallic NPs, quantum dots -QDs), with a thermosensitive polymer (pNIPAM), allowing an active and reversible control of the exaltation (or inhibition) of light emission by QDs, at the scale of the metallic NP. Such a control would allow a major advance in the optical performances of QDs incorporated in optical components
Goode, Angela Erin. „Correlation of electron and X-ray spectroscopies in nanoscale systems“. Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/14421.
Der volle Inhalt der QuelleBruley, John. „Analytical electron microscopy of diamond“. Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.237560.
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