Literatura académica sobre el tema "Electron spectroscopie"
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Artículos de revistas sobre el tema "Electron spectroscopie"
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MIKI, Hideho, Tamio KAMIDATE, Hiroto WATANABE, Mamoru TAMURA y Isao YAMAZAKI. "Electron spin resonance spectroscopie method for the identification animal meats." Analytical Sciences 6, n.º 3 (1990): 459–60. http://dx.doi.org/10.2116/analsci.6.459.
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Reuther, H. "Conversion Electron Moessbauer Spectroscopie Studies on Ion Implanted Iron Layers". Isotopenpraxis Isotopes in Environmental and Health Studies 24, n.º 11-12 (enero de 1988): 419–22. http://dx.doi.org/10.1080/10256018808624018.
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Marmet, Paul y Hamid K. Nasrallah. "Spectroscopie d'électroionisation de HBr et DBr entre 11 et 25 eV". Canadian Journal of Physics 63, n.º 8 (1 de agosto de 1985): 1015–21. http://dx.doi.org/10.1139/p85-167.
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Electroionization spectra of HBr and DBr are measured and analyzed between the ionization threshold and 25 eV. Several negative-ion states having configurations (4pσ) (4pπ)4 5s2, 5p2, and 4d2, associated with Rydberg states converging to the 2Σ+ limit, have been identified. Other structures result from the excitation of the inner 4sσ electron. Finally, data on DBr are used to confirm the interpretation.
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Zhang, Ying, Dongdong Qi, Jianzhuang Jiang y Xuan Sun. "A novel photochromic and electrochromic europium tetraazaporphyrinato and phthalocyaninato heteroleptic double-decker for information storage". Journal of Porphyrins and Phthalocyanines 13, n.º 12 (diciembre de 2009): 1197–205. http://dx.doi.org/10.1142/s1088424609001558.
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A novel tetraazaporphyrinato and phthalocyaninato mixed heteroleptic double-decker sandwich rare-earth compound with photochromic and electrochromic features has been facilely synthesized by one-pot reaction using Eu(acac)3 ·n H2O , metal-free phthalocyanine H2Pc′ ( Pc′ = 2,3,9,10,16,17,23,24-octakis(decyloxy)phthalocyanine), and the photochromic precursor 1,2-dicyano-l,2-bis(2,3,5-trimethyl-3-thienyl)ethane as starting materials. The compound was well characterized by elemental analysis and various spectroscopic methods including UV-vis, IR, 1H NMR, and mass spectroscopies. The electrochemical behavior of this compound was studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods, which showed up to three one-electron oxidation and four one-electron reduction processes, demonstrating an electro-active compound for high-density information storage. The photochromic performance of the compound was detected by electronic absorption spectra, suggesting the compound to be a good candidate for non-destructive readout by means of UV-vis spectroscopy.
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Menningen, K. L., M. A. Childs, H. Toyoda, L. W. Anderson y J. E. Lawler. "Evaluation of a substrate pretreatment for hot filament CVD of diamond". Journal of Materials Research 9, n.º 4 (abril de 1994): 915–20. http://dx.doi.org/10.1557/jmr.1994.0915.
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The absolute concentration of methyl radicals (CH3) and the mole fraction of acetylene (C2H2) are measured in a hot filament chemical vapor deposition (CVD) system both during and after an initial pretreatment that has been used successfully in microwave plasma and oxyacetylene torch CVD systems to produce more uniform and higher density crystal nucleation. The pretreatment technique, which consists of deposition for a relatively short time with a high input concentration of hydrocarbon in the feed gas, was studied for both methane (CH4) and C2H2 as the input hydrocarbon diluted in H2. Scanning electron micrographs of diamond films deposited under the conditions studied indicate that the pretreatment using CH4 is not effective in increasing the crystal nucleation density, but is moderately effective in increasing the crystal size. The C2H2 pretreatment has no apparent effect upon either the crystal size or nucleation density. The spectroscopie measurements suggest that the surface condition of the filament is the prominent factor affecting the gas phase chemistry both during and after the pretreatment stage.
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DEY, S. C. y S. S. NATH. "SIZE-DEPENDENT PHOTOLUMINESCENCE AND ELECTROLUMINESCENCE OF COLLOIDAL CdSe QUANTUM DOTS". International Journal of Nanoscience 12, n.º 02 (abril de 2013): 1350013. http://dx.doi.org/10.1142/s0219581x13500130.
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Here we adopt a convenient green chemical route for synthesis of CdSe quantum dots, their characterization by UV/Vis absorption spectroscopy, X-ray diffraction study and transmission electron microscopy. We carry out photoluminescence and electroluminescence spectroscopy to investigate the variation in electro-optical property with size. By UV/Vis spectroscopy, blue shift is revealed and bandgap is also calculated. X-ray diffraction spectrum reveals cubic structure and transmission electron micrographs show quantum dots of different size distributions (in the range 2–8 nm). Both the luminescence spectroscopies reveal green-orange luminescence depending upon the size distribution and indicate the possibility of using CdSe quantum dots as light emitting devices with better compatibility and faster response.
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Christopher, Joshua, Masoud Taleb, Achyut Maity, Mario Hentschel, Harald Giessen y Nahid Talebi. "Electron-driven photon sources for correlative electron-photon spectroscopy with electron microscopes". Nanophotonics 9, n.º 15 (18 de septiembre de 2020): 4381–406. http://dx.doi.org/10.1515/nanoph-2020-0263.
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AbstractElectron beams in electron microscopes are efficient probes of optical near-fields, thanks to spectroscopy tools like electron energy-loss spectroscopy and cathodoluminescence spectroscopy. Nowadays, we can acquire multitudes of information about nanophotonic systems by applying space-resolved diffraction and time-resolved spectroscopy techniques. In addition, moving electrons interacting with metallic materials and optical gratings appear as coherent sources of radiation. A swift electron traversing metallic nanostructures induces polarization density waves in the form of electronic collective excitations, i.e., the so-called plasmon polariton. Propagating plasmon polariton waves normally do not contribute to the radiation; nevertheless, they diffract from natural and engineered defects and cause radiation. Additionally, electrons can emit coherent light waves due to transition radiation, diffraction radiation, and Smith-Purcell radiation. Some of the mechanisms of radiation from electron beams have so far been employed for designing tunable radiation sources, particularly in those energy ranges not easily accessible by the state-of-the-art laser technology, such as the THz regime. Here, we review various approaches for the design of coherent electron-driven photon sources. In particular, we introduce the theory and nanofabrication techniques and discuss the possibilities for designing and realizing electron-driven photon sources for on-demand radiation beam shaping in an ultrabroadband spectral range to be able to realize ultrafast few-photon sources. We also discuss our recent attempts for generating structured light from precisely fabricated nanostructures. Our outlook for the realization of a correlative electron-photon microscope/spectroscope, which utilizes the above-mentioned radiation sources, is also described.
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SCHEIPERS, A. y H. MERZ. "CORRELATION EFFECTS IN NiO: COMPARISON OF NEAR THRESHOLD EXCITATION SPECTROSCOPIES". International Journal of Modern Physics B 07, n.º 01n03 (enero de 1993): 337–40. http://dx.doi.org/10.1142/s0217979293000706.
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At UHV-cleaved single-crystal NiO(100) surfaces core electron energy loss spectra (CEELS) at low primary energy and soft x-ray appearance potential spectra (SXAPS) have been measured at the oxygen K-threshold: the near-edge fine-structures have been investigated up to 40 eV above the threshold. Both spectroscopic methods probe in different ways the structure of the lowest empty states. CEELS is closely related to x-ray absorption spectroscopy (XAS), in both cases the excited final configuration consists of one core hole and one additional electron near the Fermi level E F. In APS we can study correlation effects very directly because the excited system consists of one core hole and two additional interacting electrons in localized resp. delocalized states near E F. The interpretation of the CEELS and SXAPS spectra at the oxygen K-edge is in agreement with a description of NiO as an intermediate valence system, where the charge-transfer gap is smaller than the Hubbard correlation energy. The comparison of our measured spectra with the experimental XAS of NiO shows the dominance of optically allowed channels in both spectroscopies.
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Shimizu, Ryuichi y Hideki Yoshikawa. "Monte Carlo Simulation of Background in electron spectroscopies". Proceedings, annual meeting, Electron Microscopy Society of America 50, n.º 2 (agosto de 1992): 1664–65. http://dx.doi.org/10.1017/s0424820100132959.
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Recent progress in getting precise knowledge on inelastic scattering, particularly, on dielectric functions for various types of material has been enabling the electron spectroscopic spectra obtained by Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and reflection electron energy loss spectroscopy (REELS) to be reproduced theoretically with considerable success. For this Monte Carlo simulation is probably most powerful tool, leading to more comprehensive understanding of not only the signal generation but also the background formation.In this paper we present a Monte Carlo simulation approach based on the uses of Mott-scattering cross section and appropriate dielectric function for describing elastic scattering and inelastic scatterings, respectively. With respect to the dielectric function one can use, to good approximation in general, the optical dielectric constants from the data base provided by synchrotron radiation facilities.As typical examples of the Monte Carlo simulation the applications to the AES, XPS, and REELS are shown in Figs. 1, 2, and 3, respectively. The N(E)-spectrum in Fig.l demonstrates how the Monte Carlo simulation describes the energy loss spectrum due to plasmon excitation near at primary energy, general shape of energy distributions of backscattered electrons and secondary electrons.
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Orosz, Gábor Tamás, György Gergely, Sándor Gurbán, Miklós Menyhard y Aleksander Jablonski. "Inelastic Mean Free Path Data for Si Corrected for Surface Excitation". Microscopy and Microanalysis 11, n.º 6 (15 de noviembre de 2005): 581–85. http://dx.doi.org/10.1017/s1431927605050713.
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Surface-sensitive electron spectroscopies, like Auger electron spectroscopy, X-ray photoelectron spectroscopy and elastic peak electron spectroscopy (EPES) are suitable techniques to investigate surfaces and thin layers. A theoretical model for electron transport is needed to process the observed electron spectra. Electron transport descriptions are based on the differential elastic cross sections for the sample atoms and the inelastic mean free path (IMFP) of backscattered electrons. An electron impinging on the sample can lose energy either due to surface or volume excitations. In the present work a Monte Carlo (MC) simulation of the elastic peak of Si, Ag, Ni, Cu, and Au for surface analysis is presented. The IMFP of Si was determined applying the EPES method. The integrated elastic peak ratio of Si with the standard metal reference samples corrected for surface excitation provided IMFP values of Si in the energy range E = 0.2–2.0 keV. Experiments were made with the ESA 31 HSA (ATOMKI) and with the DESA-100 (Staib) spectrometers. Surface correction was based on the application of Chen's model and material parameters. The Monte Carlo simulations of elastically backscattered electron trajectories were made using new EPESWIN software of Jablonski. An improvement of IMFP experimental results was achieved applying the presented procedure.
Tesis sobre el tema "Electron spectroscopie"
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Vanzini, Marco. "Auxiliary systems for observables : dynamical local connector approximation for electron addition and removal spectra". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLX012/document.
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Cette thèse propose une méthode théorique innovante pour l'étude des spectres d'excitation à un électron, mesurée par spectroscopie de photoémission directe et inverse.La plupart des calculs actuels au niveau de l’état de l’art reposent sur des fonctions de Green à plusieurs corps et des self-énergies complexes et non locales, évaluées spécifiquement pour chaque matériau. Même lorsque les spectres calculés sont en très bon accord avec les expériences, le coût de calcul est très important. La raison est que la méthode elle-même n'est pas efficace, car elle fournit beaucoup d'informations superflues qui ne sont pas nécessaires pour l'interprétation des données expérimentales.Dans cette thèse, nous proposons deux raccourcis par rapport à la méthode standard. Le premier est l'introduction d'un système auxiliaire qui cible, en principe, le spectre d'excitation du système réel. L'exemple type est la théorie de la fonctionnelle de la densité, pour lequel le système auxiliaire est le système de Kohn-Sham : elle reproduit exactement la densité du système réel par l'intermédiaire d'un potentiel réel et statique, le potentiel de Kohn-Sham. La théorie de la fonctionnelle de la densité est, cependant, une théorie de l'état fondamental, qui ne fournit que rarement des propriétés d'état excités : un exemple est le fameux problème de la sous-estimation de la bande interdite. Le potentiel que nous proposons (le potentiel spectral), local et dépendant de la fréquence, mais réelle, peut être considéré comme une généralisation dynamique du potentiel de Kohn-Sham qui donne en principe le spectre exact.Le deuxième raccourci est l'idée de calculer ce potentiel une fois pour toute dans un système modèle, le gaz d'électrons homogène, et de le tabuler. Pour étudier des matériaux réels, nous concevons un connecteur qui prescrit l'utilisation des résultats du gaz pour calculer les spectres électroniques.La première partie de la thèse traite de l'idée de systèmes auxiliaires, montrant le cadre général dans lequel ils peuvent être introduits et les équations qu'ils doivent satisfaire. Nous utilisons des modèles de Hubbard solubles exactement pour mieux comprendre le rôle du potentiel spectral ; en particulier, il est démontré que le potentiel peut être défini uniquement chaque fois que le spectre est non nul, et donne toujours les spectres attendus, même lorsque la partie imaginaire ou les contributions non locales de la self-énergie jouent un rôle de premier plan.Dans la deuxième partie de la thèse, nous nous concentrons sur les calculs pour les systèmes réels. Nous évaluons d'abord le potentiel spectral dans le gaz d'électrons homogène, puis l'importons dans le système auxiliaire pour évaluer le spectre d'excitation. Toute l’interdependence non triviale entre l'interaction électronique et l'inhomogénéité du système réel entre dans la forme du connecteur. Trouver une expression pour cela est le véritable défi de la procédure. Nous proposons une approximation raisonnable basée sur les propriétés locales du système, que nous appelons approximation du connecteur dynamique local.Nous mettons en œuvre cette procédure pour quatre prototypes de matériaux différents : le sodium, un métal presque homogène ; l'aluminium, encore un métal mais moins homogène ; le silicium, un semi-conducteur ; l'argon, un isolant inhomogène. Les spectres que nous obtenons avec cette approche concordent de manière impressionnante avec ceux qui sont évalués via la self-énergie, très coûteuse en temps de calcul, démontrant ainsi le potentiel de cette théorieThis thesis proposes an innovative theoretical method for studying one-electron excitation spectra, as measured in photoemission and inverse photoemission spectroscopy.The current state-of-the-art realistic calculations rely usually on many-body Green’s functions and complex, non-local self energies, evaluated specifically for each material. Even when the calculated spectra are in very good agreement with experiments, the computational cost is very large. The reason is that the method itself is not efficient, as it yields much superfluous information that is not needed for the interpretation of experimental data.In this thesis we propose two shortcuts to the standard method. The first one is the introduction of an auxiliary system that exactly targets, in principle, the excitation spectrum of the real system. The prototypical example is density functional theory, in which the auxiliary system is the Kohn-Sham system: it exactly reproduces the density of the real system via a real and static potential, the Kohn-Sham potential. Density functional theory is, however, a ground state theory, which hardly yields excited state properties: an example is the famous band-gap problem. The potential we propose (the spectral potential), local and frequency-dependent, yet real, can be viewed as a dynamical generalisation of the Kohn-Sham potential which yields in principle the exact spectrum.The second shortcut is the idea of calculating this potential just once and forever in a model system, the homogeneous electron gas, and tabulating it. To study real materials, we design a connector which prescribes the use of the gas results for calculating electronic spectra.The first part of the thesis deals with the idea of auxiliary systems, showing the general framework in which they can be introduced and the equations they have to fulfill. We then use exactly-solvable Hubbard models to gain insight into the role of the spectral potential; in particular, it is shown that a meaningful potential can be defined wherever the spectrum is non-zero, and that it always yields the expected spectra, even when the imaginary or the non-local parts of the self energy play a prominent role.In the second part of the thesis, we focus on calculations for real systems. We first evaluate the spectral potential in the homogeneous electron gas, and then import it in the auxiliary system to evaluate the excitation spectrum. All the non-trivial interplay between electron interaction and inhomogeneity of the real system enters the form of the connector. Finding an expression for it is the real challenge of the procedure. We propose a reasonable approximation for it, based on local properties of the system, which we call dynamical local connector approximation.We implement this procedure for four different prototypical materials: sodium, an almost homogeneous metal; aluminum, still a metal but less homogeneous; silicon, a semiconductor; argon, an inhomogeneous insulator. The spectra we obtain with our approach agree to an impressive extent with the ones evaluated via the computationally expensive self energy, demonstrating the potential of this theory
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Abbas, Chahine. "Optical spectroscopy of indirect excitons and electron spins in semiconductor nanostructures". Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTS049.
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Ce travail porte sur l’étude optique de la dynamique de spin de deux systèmes: un gaz d’électrons dans des couches minces de CdTe d’une part et des excitons indirects dans un double puits quantique asymétrique en GaAs d’autre part. Des mesures de photoluminescence résolue en temps et en polarisation, et des mesures de spectroscopie pompe-sonde ont permis la détermination des temps de vie et des temps de relaxation de spin des excitons indirects. Le comportement général de la structure a été décrit, les contraintes techniques ont été mise en évidence et les meilleures conditions expérimentales ont été identifiées. En photoluminescence, nous avons mesuré des temps de vie de l’ordre de la quinzaine de ns et des temps de relaxation de spin de 5 ns dans le meilleur cas. L’utilisation d’un setup de spectroscopie pompe-sonde permettant d’étudier des délais très longs a démontré que des temps plus longs encore peuvent être atteints en séparant d’avantage deux impulsions lasers successives.Pour les électrons dans CdTe nous avons utilisé une autre méthode optique: la spectroscopie de bruit de spin qui s’est récemment imposée comme un outil de choix pour étudier la dynamique de spin dans les semi-conducteurs. Son principe consiste à sonder la dynamique d’un système de spins à travers ses fluctuations spontanées. Pour ce faire, ces fluctuations sont encodées dans le plan de polarisation d’un laser hors résonnant par l’intermédiaire de la rotation Faraday.Alors que les réalisations concrètes de cette technique se limitaient jusqu’à présent aux corrélations temporelles, nous proposons ici la première implémentation permettant d’accéder également aux corrélations spatiales du systèmes de spin. Cet accès à la dynamique spatiale est autorisé par une sélectivité en vecteur d’onde de la lumière diffusée venant de l’échantillon et nous offre l’opportunité de mesurer simultanément le temps de relaxation de spin et le coefficient de diffusion de spin. Ayant ainsi une vision complète de la dynamique de spin dans CdTe, nous avons pu confronter la physique du spin bien connue dans GaAs à nos observations dans CdTe. Contre toutes attentes, il semblerait que nos connaissances de GaAs ne soient pas directement transposables à CdTeThis work provides an optical study of spin dynamics in two different systems: electrons gas in n-doped CdTe thin layers, and indirect excitons in asymmetric GaAs coupled quantum wells. Time and polar resolved photoluminescence and pump-probe spectroscopy allowed the determination of both the lifetime and the relaxation time of indirect excitons.The global behaviour of the dedicated biased sample has been described, major technical constraints have been pointed out and optimal working conditions have been identified. In photoluminescence, we obtained a lifetime of 15 ns and a spin relaxation time of 5 ns. Pump-probe spectroscopy with an exceptional delay range shown that longer characteristic times could be obtained increasing the delay between two laser pulses.An other optical method has been used to study electrons in CdTe thin layers. Spin noise spectroscopy has recently emerged as an ideal tool to study dynamics of spin systems through their spontaneous fluctuations which are encoded in the polarisation state of a laser beam by means of Faraday rotation. Common spin noise setups provide only temporal fluctuations, spatial information being lost averaging the signal on the laser spot. Here, we demonstrate the first implementation of a spin noise setup providing both spatial and temporal spin correlations thanks to a wave vector selectivity of the scattered light. This gave us the opportunity to measure both the spin relaxation time and the spin diffusion coefficient. This complete vision of the spin dynamics in CdTe has been compared to our understanding of spin physics in GaAs. Against all odds, this knowledge seems not to be directly transposable from GaAs to CdTe
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Nilforoushan, Niloufar. "Out-of-equilibrium electron dynamics of Dirac semimetals and strongly correlated materials". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS573/document.
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Les matériaux quantiques ont récemment introduit en physique de la matière condensée pour unifier tous les matériaux dans lesquels les fortes corrélations électroniques gouvernent les propriétés physiques du système (e.g. les isolants de Mott) et les matériaux dont les propriétés électroniques sont déterminées par la géométrie de la fonction d’onde (e.g. matériaux de Dirac). Ces matériaux montrent des propriétés émergentes résultantes de l’intrication de différents degrés de libertés : la charge, le spin et le moment orbital, donnant lieu aux propriétés topologiques des électrons. L’étude de ces interactions et des compétitions entre les degrés de liberté pertinents nécessite l’utilisation de techniques pompe-sonde ultra-rapides. Particulièrement, les pulses laser femtosecondes interagissent uniquement avec les électrons pour les placer dans un état hors-équilibre décrit par des distributions de type non Fermi-Dirac. La dynamique subséquente implique de nombreux processus, avec un temps de relaxation relié aux constantes de couplage. De plus, dans les techniques résolues en temps, la lumière peut agir comme un paramètre externe, différent des paramètres thermodynamiques, pour explorer le diagramme de phase. Cela nous donne l’opportunité de stabiliser de nouveaux états inaccessibles par des chemins thermiques quasi-adiabatiques ou de manipuler les propriétés physiques des systèmes.Dans cette thèse, nous avons réalisé différentes expériences dans le but d’étudier les propriétés à l’équilibre et hors équilibre de deux matériaux corrélés: BaCo₁₋ₓNiₓS₂ et (V₁₋ₓMₓ)₂O₃.La première partie de ce projet a été dédiée principalement à l’étude de BaNiS₂, le précurseur métallique de la transition de Mott dans BaCo₁₋ₓNiₓS₂ . En utilisant l’ARPES, nous avons étudié la structure de bandes électroniques de BaNiS₂ dans toute la zone de Brillouin. L’expérience, combinée avec des calculs théoriques, révèle un nouveau type de cône de Dirac bidimensionel à caractère orbitalaire d et induit par les corrélations. Le croisement des bandes est protégé par les symétries particulières de la structure cristalline. Nous avons aussi mesuré la structure de bandes de l’isolant de Mott BaCoS₂ dans ses phases magnétique et non magnétiques.Dans la seconde partie, nous avons étudié la dynamique électronique hors équilibre de BaNiS₂ et (V₁₋ₓMx)₂O₃. Grâce à des mesures tr-ARPES et tr-Réflectivité, nous avons observé une renormalisation non thermique et ultra-rapide du cône de Dirac dans BaNiS₂. Ce phénomène est purement provoqué par les excitations électroniques et est stabilisé par l’intéraction entre les électrons et les phonons. De plus, en utilisant différentes techniques pompe-sonde (tr-XRD basé sur XFEL et tr-Réflectivité) nous avons aussi exploré des phases hors-équilibre du matériau prototype de Mott-Hubbard (V₁₋ₓMx)₂O₃ appartenant à différentes parties de son diagramme de phase. Nos résultats montrent une phase transitoire non thermique se développant immédiatement après la photoexcitation ultra-rapide et durant quelques picosecondes dans les phases métallique et isolantes. Cette phase transitoire est accompagné par une distorsion structural qui correspond à un durcissement du réseau et est marqué par un “blue shift” du mode phononique A₁g. Nos résultats soulignent l’importance du remplissage des orbitales aussi bien que des effets important des forts couplages électron-réseau sélectifs dans les matériaux fortement corrélésQuantum materials is a new term in condensed matter physics that unifies all materials in which strong electronic correlation governs physical properties of the system (e.g. Mott insulators) and materials whose electronic properties are determined by the geometry of the electronic wave function (e.g. Dirac materials). These materials show emergent properties– that is, properties that only appear by intricate interactions among many degrees of freedom, such as charge, spin and orbital, giving rise to topological properties of electrons. The study of these interactions and competitions between the relevant degrees of freedom demands applying ultrafast pump-probe techniques. Particularly, femtosecond laser pulses act only on the electrons and set them to an out-of-equilibrium state inexplicable by the Fermi-Dirac distribution. The ensuing dynamics involves various processes and the rate at which the relaxation occurs is related to the coupling constants. Moreover, in time-resolved pump-probe techniques light can act as an additional external parameter to change of the phase diagram – different from thermodynamic parameters. It gives us the opportunity of stabilizing new states inaccessible by quasi-adiabatic thermal pathways or eventually manipulating the physical properties of the systems.In this thesis, we performed different experiments in order to study the equilibrium and out-of-equilibrium properties of two correlated compounds: BaCo₁₋ₓNiₓS₂ and (V₁₋ₓMₓ)₂O₃.The first part of the project was mainly devoted to the study of BaNiS₂ that is the metallic precursor of the Mott transition in BaCo₁₋ₓNiₓS₂. By applying ARPES, we studied the electronic band structure of BaNiS₂ in its entire Brillouin zone. These results combined with some theoretical calculations give evidence of a novel correlation-induced and two-dimensional Dirac cone with d-orbital character. The band crossing is protected by the specific symmetries of the crystal structure. We also investigated the electronic band structure of the Mott insulator BaCoS₂ in its magnetic and nonmagnetic phases.In the second part, we studied the out-of-equilibrium electron dynamics of BaNiS₂ and (V₁₋ₓMx)₂O₃. By means of tr-ARPES and tr-reflectivity measurements, we observed an ultrafast and non-thermal renormalization of the Dirac cone in BaNiS₂ . This phenomenon is purely provoked by the electronic excitation and is stabilized by the interplay between the electrons and phonons. Moreover, by applying various pump-probe techniques (XFEL-based tr-XRD and tr-Reflectivity) we also explored the out-of-equilibrium phases of the prototype Mott-Hubbard material (V₁₋ₓMx)₂O₃ in different parts of its phase diagram. Our results show a transient non-thermal phase developing immediately after ultrafast photoexcitation and lasting few picoseconds in both metallic and insulating phases. This transient phase is followed by a structural distortion that corresponds to a lattice hardening and is marked by a “blue shift” of the A₁g phonon mode. These results underline the importance of the orbital filling as well as the strong effect of the selective electron-lattice coupling in the strongly correlated materials
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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.
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La physique des surfaces et nanosciences est une discipline qui permet la conception d’une diversité de matériaux innovants pour mieux répondre aux besoins de la technologie actuelle. Dans ce contexte, nous nous sommes intéressés à caractériser les propriétés de différentes structures 2D élaborées sur des substrats d’argent en combinant différentes techniques d'analyses de surface.D'une part nous avons étudié des films 2D auto-assemblés à base de phtalocyanine de cobalt adsorbées sur Ag(100). Au régime de la monocouche, deux phases ont été essentiellement observées : la (5x5) et la (7x7). La spectroscopie de pertes d'énergie nous a permis de mettre en évidence deux mécanismes de transfert de charge métal/molécule différents en raison des sites d'adsorption différents.D'autre part, nous avons synthétisé, par évaporation d'atomes de silicium sur de l'Ag(111), du silicene en monocouche et multicouche. Ainsi nous avons entrepris des mesures dans le but de comprendre les propriétés structurales du silicene en multicouche. Pour cela nous avons engagé des mesures par spectroscopie de photoémission et diffraction de photoélectrons, et comparé nos données avec des simulations réalisées dans le cadre la diffusion multiple. Plusieurs hypothèses concernant la nature de ce matériau ont pu être testées. Par ailleurs nous avons étudié la fonctionnalisation du silicene par hydrogénation et adsorption de molécules de F4TCNQNanosciences 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
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Marie, Xavier. "Spectroscopie optique dans les puits quantiques. Couplage electron-reseau : aspect statique et dynamique". Toulouse, INSA, 1991. http://www.theses.fr/1991ISAT0007.
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Deux aspects de la spectroscopie optique dans les puits quantiques sont abordes dans ce memoire. D'une part, on traite theoriquement et experimentalement des proprietes electroniques de puits quantiques contraints (in,ga)as/gaas. Un modele base sur la theorie elastique est formule afin d'interpreter les positions des raies spectrales observees. Nous avons applique cette etude physique au choix des caracteristiques des puits permettant l'optimisation des structures lasers. D'autre part, nous avons etudie experimentalement par spectroscopie de photoluminescence stationnaire et resolue en temps de refroidissement et la localisation sur les rugosites d'interface d'excitons dans des multi-puits quantiques gaas/algaas non couples. La modelisation de l'interaction exciton-phonon dans ces structures a puits quantiques met en evidence un renforcement du taux de perte d'energie des excitons du fait de l'interaction par potentiel de deformation acoustique par rapport au cas du massif. Un modele de localisation dependant de la temperature excitonique permettant de rendre compte des dynamiques experimentales d'excitons a basse temperature est formule
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Nataf, 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.
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Ce travail de thèse porte sur les propriétés structurales et électroniques des parois de domaines ferroïques ; il a pour objectif une meilleure compréhension des mécanismes de conduction dans les parois de domaines du niobate de lithium d’une part, et de la polarité des parois de domaine dans le titanate de calcium d’autre part. La première partie est consacrée aux interactions entre les défauts et les parois de domaine dans le niobate de lithium. L’observation d’une relaxation diélectrique de faible énergie d’activation et l’analyse de son comportement sous l’effet d’un recuit dans des échantillons avec et sans parois nous conduisent à proposer que les parois de domaines stabilisent des états polaroniques. Nous rapportons aussi l'évolution de modes Raman dans des échantillons congruents de niobate de lithium dopés de manière croissante en magnésium. Nous identifions des décalages en fréquence spécifiques aux parois de domaines. Les parois de domaines apparaissent alors comme des lieux de stabilisation des défauts polaires. Nous utilisons la microscopie électronique miroir (MEM) et la microscopie électronique de faible énergie (LEEM) pour caractériser les domaines et parois de domaines à la surface du niobate de lithium dopé magnésium. Nous démontrons que les réglages de la distance focale peuvent être utilisés pour déterminer la polarisation du domaine. Aux parois de domaines, un champ électrique latéral, provenant de différents états de charge de surface, est mis en évidence. Dans une seconde partie, nous étudions la polarité des parois de domaine dans le titanate de calcium. Nous utilisons la spectroscopie de résonance piézo-électrique pour mettre en évidence l’excitation de résonances élastiques par un signal électrique, ce qui est interprété comme une réponse piézoélectrique des parois de domaines. Une image directe des parois de domaine du titanate de calcium est obtenue par LEEM, et montre une différence de potentiel de surface entre domaines et parois. Ce contraste peut être modifié sous l’effet d’injection d’électrons, par un effet d’écrantage des charges de polarisation aux paroisWe 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
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Pommeret, Stanislas. "Mecanismes primaires du couplage electron-especes protiques en phase aqueuse pure : etude par spectroscopie laser femtoseconde; approche quantique de l'interaction electron-eau". Paris 11, 1991. http://www.theses.fr/1991PA112050.
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Les travaux de cette these traitent des mecanismes de couplage entre un electron, des molecules d'eau ou des especes protiques (ion hydronium, radical hydroxyle). Deux etudes complementaires ont ete menees dans des phases aqueuses pures. La premiere etude, a caractere structural, correspond a une approche semi-quantique d'un etat totalement hydrate de l'electron. Les resultats obtenus montrent l'importance de la seconde sphere d'hydratation dans la localisation de cet electron a 77 et 300 kelvin. La seconde partie de ce travail se refere a l'etude de la dynamique des mecanismes reactionnels primaires dans l'eau et l'eau lourde a temperature ambiante: la reaction ion-molecule, la formation de paires radicalaires, la recombinaison geminee de l'electron avec le proton hydrate et de radical hydroxyle. La dynamique de ces reactions est etudiee par spectroscopie d'absorption, du proche ultra-violet au proche infra-rouge, resolue en temps a l'echelle de quelques dizaines de femtosecondes. L'analyse de ces processus primaires integre le caractere protique des molecules d'eau
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Piccardo, Marco. "Spectroscopie des processus photoélectriques dans les structures et dispositifs III-N". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX056/document.
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Malgré les rapides progrès technologiques dans les nitrures, les propriétés intrinsèques des alliages de nitrures et les processus physiques qui gouvernent la physique de ces dispositifs sont encore mal connus. Au cours de mon travail de thèse, de nouvelles approches expérimentales et théoriques ont été développées pour aborder l’étude des mécanismes microscopiques qui gouvernent les propriétés électroniques des dispositifs à base de nitrures semi-conducteurs. Une nouvelle technique expérimentale permettant de mesurer directement la distribution en énergie des électrons de conduction d’une LED en fonctionnement est explorée. Cette approche permet l’observation directe de populations d’électrons chauds excités dans le dispositif optoélectronique sous injection électrique et émis dans l’ultravide. Une théorie récente de la localisation dans les systèmes désordonnés est appliquée aux matériaux et dispositifs optoélectroniques à base de nitrures. Cette méthode permet pour la première fois la détermination du paysage de localisation induit par le désordre d’alliage sans résoudre l’équation de Schrödinger. Expérimentalement, une signature claire du désordre d’alliage est observée par des mesures de spectroscopie de photocourant dans des puits quantiques d’InGaN sous forme d’une queue d’Urbach pour des excitations d’énergie inférieure à la largeur de la bande interdite. Ceci permet de définir une énergie caractéristique du désordre qui est en excellent accord avec les prédictions fournies par la nouvelle théorie de la localisationIn spite of the rapid technological progress in nitrides, the intrinsic properties of nitride alloys and the physics of III-N devices are still not well understood. In the course of my thesis work, novel experimental and theoretical approaches to tackle the study of the microscopic mechanisms governing the electronic properties of nitride semiconductors have been developed. A new experimental technique allowing to directly measure the energy distribution of conduction electrons of an operating LED is explored. This approach allows the direct observation of hot electron populations excited in the optoelectronic device under electrical operation and emitted in ultra-high vacuum. A recent theory of localization in disordered systems is applied to nitride materials and optoelectronic devices. This method allows for the first time the determination of the localization landscape induced by alloy disorder without resorting to the Schrödinger equation. Experimentally, a clear signature of alloy disorder is observed by biased photocurrent spectroscopy of InGaN quantum wells in the form of an Urbach tail for below-gap excitation and is found to be in excellent agreement with the predictions given by the novel localization theory
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Zhou, Jianqiang. "Theory of electron spectroscopy : beyond the state-of-the-art". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX017/document.
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Le sujet de cette thèse se place dans le cadre de la spectroscopie théorique. En particulier, je propose une nouvelle dérivation ab-initio pour trouver des approximations pour la fonction de Green (GF) à un corps. Cette approche conduit à une meilleure description du couplage fermion-plasmon dans le cadre de la théorie des perturbations à plusieurs corps (MBPT), qui peut être utilisée pour étudier la spectroscopie de photoémission directe et inverse.En spectroscopie de photoémission, un échantillon est irradié par des photons et des électrons sont émis. A partir de la différence d'énergie du photon incident et des d'électrons sortant, un grand nombre d'informations sur les propriétés de l'échantillon peut être obtenu, par exemple les structures de bandes ou la durée de vie des excitations. Dans une cadre de particules indépendantes, cette différence d'énergie correspond au niveau d'énergie d'une particule que l'électron émis occupait avant la mesure. Cela conduit à un pic très intense dans le spectre, avec un poids normalisé à un. En réalité, la photoémission n'est pas juste des photons entrants et des électrons indépendants sortants, car l'échantillon est un système à plusieurs corps en interaction. L'interaction de Coulomb et la nature anti-symétrique des fermions donnent lieu aux effets d'échange-corrélation, ce qui rend le problème fondamentalement difficile à résoudre. La description, la compréhension et la prédiction des effets de l'interaction de Coulomb sur les propriétés des matériaux a été, pendant des années, l'un des grands défis de la physique théorique de la matière condensée. Dans le cadre de cette thèse, on peut imaginer que, premièrement, la photoémission crée un trou (à savoir, un électron manquant) dans l'échantillon, ce qui provoque la relaxation de tous les électrons restants. En raison de l'interaction attractive entre les trous chargés positivement et les électrons chargés négativement, les électrons se déplacent vers les trous et créent des ''quasi-particules''. L'interaction effective entre les quasi-particules est l'interaction de Coulomb écrantée dynamiquement. Elle est en général plus faible que l'interaction de Coulomb nue. Par conséquent, la structure de bandes observée est celle de quasi-particules, qui diffère du résultat en particules indépendantes. Deuxièmement, lorsque le trou se propage dans l'échantillon les électrons restants peuvent présenter des oscillations collectives : réponse de la densité à la perturbation. Ce sont des excitations neutres avec une nature approximativement bosonique, parce qu'elles sont constituées par des paires de fermions.Le couplage du trou avec les excitations neutres conduit à des structures supplémentaires dans le spectre de photoémission, appelées satellites. Cela réduit le poids des quasi-particules qui est maintenant fractionnée. Le plus souvent, les satellites dominants sont dus à des plasmons, des oscillations collectives à longue portée, mais on peut aussi observer des transitions ou excitons interbandes ou d'autres satellites qui sont dus à des couplages plus complexes.Cela montre que pour avoir une bonne description de la spectroscopie de photoémission, nous devrions étudier la propagation de particules, ainsi que l'interaction entre les particules et les plasmons ou d'autres excitations. La fonction de Green donne l'amplitude de probabilité de particules se propageant d'un point à un autre. Sa partie imaginaire donne la funtion spectrale qui a un lien direct vers le spectre mesuré dans une expérience de photoémission. Les dérivations et approximations proposées dans cette thèse donnent une nouvelle façon de calculer la fonction de Green, ce qui améliore la description de la spectroscopie de photoémission. En outre, cela permet d'accéder à d'autres grandeurs qui peuvent être obtenues à partir de la fonction de Green à un corps, en particulier les énergies totalesThe topic of this thesis is situated in the framework of theoretical spectroscopy. In particular, I propose a new ab-initio derivation to find approximations for the one-body Green's function (GF) . This approach leads to an improved description of fermion-plasmon coupling in the framework of many-body perturbation theory (MBPT), which can be used to study direct and inverse photoemission spectroscopy. Although the observed phenomena have been well known before, my formulation yields a better description than previous state-of-the-art approaches. It answers several open questions, cures some fundamental shortcomings and suggests a way for systematic improvement.In photoemission spectroscopy, a sample is irradiated by photons and electrons are emitted. From the energy difference of the incoming photon and outgoing electron, a great deal of information on the properties of the sample can be obtained, e.g. the band structures or lifetimes of excitations. In an independent-particle picture, this energy difference corresponds to the one-particle energy level that the emitted electron was occupying before the measurement. This leads to a sharp peak in the spectrum, with weight normalized to one. In reality, photoemission is not just photons in and independent electrons out, because the sample is an interacting many-body system. The Coulomb interaction and the anti-symmetric nature of fermions give rise to the so-called exchange-correlation effects, which makes the problem fundamentally difficult to solve. The description, understanding and prediction of the effects of the Coulomb interaction on the properties of materials has been one of the big challenges of theoretical condensed matter physics for ages. In the framework of this thesis one can imagine that first, the photoemission creates a hole (i.e., a missing electron) in the sample, which causes all remaining electrons to relax. Due to the attractive interaction between positively charged holes and negatively charged electrons, the electrons move towards to the holes and dress them to create ''quasi-particles''. The effective interaction between quasi-particles is the dynamically screened Coulomb interaction. It is in general weaker than the bare Coulomb interaction. Consequently, the observed band structure is a quasi-particle band structure, which differs from the result of an independent-particles band structure calculation. Second, when the hole propagates in the sample the remaining electrons can show collective oscillations, the density response to the perturbation. These are neutral excitations with approximately bosonic nature, because they are constituted by pairs of fermions.The coupling of the hole to the neutral excitations leads to additional structures in the photoemission spectrum, called satellites. This reduces the quasi-particle weight that is now fractional. Most often, the dominant satellites are due to plasmons, collective long-range oscillations, but one can also observe interband transitions or excitons, or other satellites that are due to more complicated couplings.This overview shows that in order to have a good description of photoemission spectroscopy, we should study the propagation of particles, as well as the interaction between particles and plasmons or other excitations. The Green's function gives the probability amplitude of particles propagating from one point to another. Its imaginary part yields the spectral function that has a direct link to the spectrum measured in a photoemission experiment. The derivations and approximations proposed in this thesis give a new way to calculate the Green's function, which improves the description of photoemission spectroscopy. Moreover, it gives access to other quantities that can be obtained from the one-body Green's function, in particular total energies
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Wopperer, Philipp. "Electron photoemission from sodium and carbon clusters". Phd thesis, Université Paul Sabatier - Toulouse III, 2013. http://tel.archives-ouvertes.fr/tel-00860445.
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Des distributions angulaires (PAD) et des spectres (PES) de photoélectrons émis par des agrégats sous l'action des lasers à impulsions femtosecondes linéairement polarisées ou d'une impulsion instantanée sont calculés théoriquement dans un modèle basé sur la théorie de la fonctionnelle de la densité dépendante du temps (TDDFT). Les systèmes finis étudiés sont de petits agrégats de sodium, des chaînes de carbone C_N (N = 3, 5, 7), et le célèbre buckminsterfullerène C_60. Le comportement de l'émission éléctronique est exploré en fonction de la taille, la forme, la structure électronique et ionique ainsi qu'en fonction des paramètres du laser. En outre, des procédures de détermination de la PAD d'un ensemble de molécules ou d'agrégats orientés de façon aléatoire, sont élaborées. Les résultats de la TDDFT sont de plus comparés aux modèles stationnaires et aux données expérimentales. Les méchanismes d'ionisation sont étudiés dans le régime à un photon et à multiphoton.
Libros sobre el tema "Electron spectroscopie"
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1942-, Thompson Michael, ed. Auger electron spectroscopy. New York: Wiley, 1985.
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Hagen, Wilfred Raymond. Biomolecular EPR spectroscopy. Boca Raton: Taylor & Francis, 2008.
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Scottish, Universities Summer School in Physics (40th 1992 Dundee Scotland). Quantitative microbeam analysis: Proceedings of the Fortieth Scottish Universities Summer School in Physics, Dundee, August 1992. Bristol: The School, 1993.
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1941-, Menze D., Pfeil W, Schwille W. J. 1938- y Universität Bonn Physikalisches Institut, eds. Electron and photon interactions at intermediate energies: Proceedings of the 1984 workshop held at Bad Honnef, Germany, October 29-31, 1984. Berlin: Springer-Verlag, 1985.
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B, Williams David. Transmission electron microscopy: A textbook for materials science. New York: Plenum, 1996.
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Barry, Carter C., ed. Transmission electron microscopy: A textbook for materials science. New York: Plenum Press, 1996.
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Weigold, Erich y Ian E. McCarthy. Electron Momentum Spectroscopy. Boston, MA: Springer US, 1999. http://dx.doi.org/10.1007/978-1-4615-4779-2.
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Balcar, E. Neutron-electron spectroscopy. Chilton: Rutherford Appleton Laboratory, 2000.
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Weigold, Erich. Electron Momentum Spectroscopy. Boston, MA: Springer US, 1999.
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Weigold, Erich. Electron momentum spectroscopy. New York: Kluwer Academic/Plenum Publishers, 1999.
Buscar texto completoCapítulos de libros sobre el tema "Electron spectroscopie"
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Dresselhaus, G. y M. Laguës. "Electron Spectroscopies". En Intercalation in Layered Materials, 271–90. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4757-5556-5_21.
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Pesin, L. A. "Electron Spectroscopy". En Physics and Chemistry of Materials with Low-Dimensional Structures, 371–94. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4742-2_25.
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Gooch, Jan W. "Electron Spectroscopy". En Encyclopedic Dictionary of Polymers, 262. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_4320.
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Horiuchi, Shin. "Electron Microscopy for Visualization of Interfaces in Adhesion and Adhesive Bonding". En Interfacial Phenomena in Adhesion and Adhesive Bonding, 17–112. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-4456-9_2.
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AbstractThis chapter provides an overview of electron microscopy techniques to investigate interfaces in polymeric materials and adhesive bonds. First, how the instruments of energy-filtering transmission electron microscopy (EFTEM), scanning transmission electron microscopy (STEM), and scanning electron microscopy (SEM) work and are operated is briefly described. The principles of electron energy-loss spectroscopy (EELS) and energy-dispersive X-ray spectrometry (EDX), which are spectroscopic techniques associated with these instruments, are described. Next, the specimen preparation techniques, such as ultramicrotomy, heavy metal staining, focused ion beam (FIB) fabrications, and replica method, which are essential for these electron microscopy tasks, are introduced. This chapter also reviews advanced electron microscopy techniques, such as STEM-EDX-tomography, chemical phase mapping using electron energy-loss near-edge structure (ELNES), and in situ tensile TEM. Numerous examples of the application of these techniques to various surfaces and interfaces present in polymer alloys and composites, crystalline polymers, adhesive bonds, and metal substrate surfaces are presented.
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Hüfner, Stefan. "Photoemission of Valence Electrons from Metallic Solids in the One-Electron Approximation". En Photoelectron Spectroscopy, 347–409. Berlin, Heidelberg: Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-662-09280-4_6.
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Gupta, Preeti, S. S. Das y N. B. Singh. "Electron Spin Resonance Spectroscopy". En Spectroscopy, 123–49. New York: Jenny Stanford Publishing, 2023. http://dx.doi.org/10.1201/9781003412588-4.
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Mayer, Joachim, Christine Deininger y Ludwig Reimer. "Electron Spectroscopic Diffraction". En Springer Series in Optical Sciences, 291–345. Berlin, Heidelberg: Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/978-3-540-48995-5_6.
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Reimer, Ludwig. "Electron Spectroscopic Imaging". En Springer Series in Optical Sciences, 347–400. Berlin, Heidelberg: Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/978-3-540-48995-5_7.
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Samarin, Sergey, Oleg Artamonov y Jim Williams. "New Experimental Technique for Studying Electron-Electron Interaction, Electron Correlation, Mechanism of Electron Emission and Electronic Properties of Surfaces". En Spin-Polarized Two-Electron Spectroscopy of Surfaces, 5–86. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-00657-0_2.
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Zhang, Y., Z. R. Ye y D. L. Feng. "Electron Spectroscopy: ARPES". En Iron-Based Superconductivity, 115–49. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-11254-1_4.
Texto completoActas de conferencias sobre el tema "Electron spectroscopie"
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Schwartz, Benjamin J. y Peter J. Rossky. "Polarized Ultrafast Transient Spectroscopy of the Hydrated Electron: Quantum Non-Adiabatic Molecular Dynamics Simulation". En International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/up.1994.thd.9.
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The transient spectroscopy of the aqueous solvated electron has been the subject of intense experimental1-3 and theoretical4-8 interest recently. Hydrated electrons play an important role as intermediaries in the radiation chemistry of water, as well as in solution photochemistry and electron transfer reactions. Furthermore, the coupling of solvent fluctuations to the electronic absorption spectrum makes the hydrated electron an outstanding probe of electronic solvation dynamics in the aqueous environment. The optical absorption spectrum of the hydrated electron is comprised of three s->p like transitions which are highly broadened and split by coupling to solvent fluctuations.6
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Capasso, F., S. Sen, A. Y. Cho y A. L. Hutchinson. "Resonant Tunneling Electron Spectroscopy". En Picosecond Electronics and Optoelectronics. Washington, D.C.: Optica Publishing Group, 1987. http://dx.doi.org/10.1364/peo.1987.thc4.
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In this paper we demonstrate a new electron spectroscopy technique based on resonant tunneling. The key difference compared to conventional hot electron spectroscopy1 is the use of a resonant tunneling double barrier in the collector of the structure (Fig. 1). The advantage of this new feature is that it allows one to obtain information on the electron momentum distribution n(p⊥) (or energy distribution n(E⊥)) perpendicular to the layers directly from the measured resonant tunneling collector current, without requiring the use of derivative techniques. Figure 1 illustrates the band diagrams of two structures for resonant tunneling electron spectroscopy. The first one (Fig. 1a), realized by us in the present experiment, consists of a reverse biased pn heterojunction and can be used to investigate hot minority carrier transport. Incident light is strongly absorbed in the wide-gap p+ layer. Photo-generated minority carrier electrons diffuse to an adjacent low-gap layer. Upon entering this region electrons are ballistically accelerated by the abrupt potential step and gain a kinetic energy ≅ ΔEc. Collisions in the low gap layer tend to randomize the injected, nearly mono-energetic distribution, making it "hot".
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Policht, Veronica R., Mattia Russo, Fang Liu, Chiara Trovatello, Margherita Maiuri, Yusong Bai, Xiaoyang Zhu, Stefano Dal Conte y Giulio Cerullo. "Time-Resolved Electron and Hole Transfer Dynamics in a TMD Heterostructure by Two-Dimensional Electronic Spectroscopy". En International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/up.2022.th4a.8.
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Photoexcited electrons and holes rapidly undergo spatial separation in transition metal dichalcogenide Heterostructures (HS) with Type II band alignment. Using Two-dimensional Electronic Spectroscopy, we simultaneously detect interlayer hole and electron transfer in a WS2/MoS2 HS with sub-100 fs timescales.
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Myers, Anne B. y Alan E. Johnson. "Electronic and Vibrational Dephasing in Solution by Dynamic Symmetry Breaking". En International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1996. http://dx.doi.org/10.1364/up.1996.fe.25.
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All spectroscopies, whether explicitly time-resolved or steady-state, are sensitive to fluctuations in the spectroscopic environment of the chromophore on the time scale of the radiation-matter interaction(s). Simple "two-state jump" models that assume random hopping between just two spectroscopically distinct environments have been well studied. Such models can provide some qualitative insight into the influence of fluctuations on a particular spectroscopy even if the actual system accesses a continuous distribution of states, as is usually the case for chromophores in liquids. The usual two-state models assume that the states differ in their transition frequencies to one or more accessible excited states. In linear spectroscopies, such models predict the well-known coalescence from two discrete resonances to a single broad one which then motionally narrows as the fluctuation rate increases. For multiphoton spectroscopies the effects are more complicated; in particular, for monochromatically excited spontaneous emission, increasing the fluctuation rate causes evolution from a sharp, "resonance Raman-like" spectrum to one having increasing contributions from broad emission.1 The transition frequency fluctuations constitute a source of electronic pure dephasing at the level of the chromophore's density matrix, generating a "fluorescence" component to the emission.
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Monot, P., T. Auguste, P. Gibbon, F. Jakober, G. Mainfray, J. L. Miquel y M. Louis-Jacquet. "Propagation of intense laser pulses in an underdense plasma". En High Resolution Fourier Transform Spectroscopy. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/hrfts.1994.wa5.
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The new generation of short duration lasers provides pulses in excess of the terawatt level, that can be focused up to 1018 W/cm2 [1]. For such an intensity, the quiver motion of a free electron becomes relativistic and numerous new physical effects are expected, such as harmonic generation [2], particle acceleration [3] and relativistic self-focusing [4,5]. In order to observe these effects resulting from laser-electron interaction, a high electron density (Ne) is required. In fact, with regard to the small laser-electron interaction cross-section, a large number of electrons is needed for any significant field emission. Furthermore, using a high density, a collective response of electrons is driven that induces intense longitudinal fields required to accelerate particles. A significant change of the refractive index should also occur that will influence beam propagation if the electron density is large enough.
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Kim, S. Y. y K. Vedam. "Characterization of gold/electrolyte interface by spectroscopic ellipsometry". En OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1987. http://dx.doi.org/10.1364/oam.1987.tho6.
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In situ spectroscopic ellipsometric measurements have been carried out on a gold electrode in an electrolyte under a dc electric field. An intermediate layer which begins to form just above the threshold potential of the oxidation of gold has been detected and characterized in terms of its optical properties and thickness. It is confirmed with the aid of computer simulation that the effect of the redistribution of the ions in liquid and the electrons in gold electrode on the ellipsometric parameters Δ and ψ has a minimal effect compared with the experimental results. Even though the intermediate layer at the S/L interface revealed some properties which are characteristics of metals, a simple model based on the modulation of gold under a dc electric field turned out to be unable to explain quantitatively the experimentally observed changes of δΔ and δψ.
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Scherer, N. F., L. W. Ungar, D. C. Arnett, L. D. Book, H. Hu y G. A. Voth. "Charge-Transfer Dynamics in Blue Copper Proteins: Experiment and Simulation". En International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1996. http://dx.doi.org/10.1364/up.1996.fc.4.
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Blue copper proteins function as mobile electron carriers in biological systems by transfering electrons to and from their "type I" copper active sites liganded to the protein matrix.1 In reduced form, these active sites have a strong ligand-to-metal charge transfer transition between the copper atom and a cysteine sulfur ligand in the region of 595-630 nm, which gives the proteins their characterisitic blue color.2 This strong absorption makes blue copper proteins suitable for ultrafast spectroscopic studies of protein electron transfer. Elucidation of electronic and nuclear dynamics of these systems requires classical and quantum simulations in conjunction with experiment. The resultant spectral density describing the optically induced charge transfer process may be useful in understanding the long range electron transfer of physiological function.
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Shao, Hua-Chieh y Anthony F. Starace. "Imaging electronic motions by ultrafast electron diffraction". En Ultrafast Nonlinear Imaging and Spectroscopy V, editado por Zhiwen Liu. SPIE, 2017. http://dx.doi.org/10.1117/12.2273560.
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Isler, R. C. "Spectroscopic techniques for studying magnetic fusion plasmas". En OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1989. http://dx.doi.org/10.1364/oam.1989.wy3.
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Magnetic fusion plasmas have temperatures ranging from several tens of electron volts at the edge up to several kiloelectron volts at the center. Electron densities typically vary from 1 to 10 × 1013/cm3. Spectroscopic techniques using wavelengths from the x-ray through the visible regions are employed to measure a number of parameters.1 These quantities include, but are not restricted to, plasma temperatures, radiated power, impurity content and transport, radial electric fields as inferred from plasma rotation, neutral hydrogen densities, and rotational transforms of magnetic fields. In addition to passive spectroscopy, active techniques are used for enhancing spectroscopic capabilities. Introduction of trace amounts of nonintrinsic impurities by laser ablation, excitation by charge exchange between energetic hydrogen beams incident on highly ionized impurities, laser-induced fluorescence, and excitation of lithium introduced in a beam or as a pellet have all been employed for making one or more types of measurement. In particular, charge exchange from hydrogen beams has become widely adopted as the standard method of measuring ion temperatures, plasma rotation, and concentrations of fully ionized low-Z impurities.2
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Cha, Myoungsik, Akira Otomo, William E. Torruellas, George I. Stegeman, David Beljonne, Jean Luc Brédas, Winfried H. G. Horsthuis y Guus R. Möhlmann. "Nonlinear Spectroscopy of DANS Side Chain Polymers". En Organic Thin Films for Photonic Applications. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/otfa.1995.ma.5.
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Molecular systems, in particular polymers, with π-electron donor-acceptor groups are becoming potential candidates in applications where large bandwidth and low costs are desired for electro-optical modulation of optical information. Di-Phenyl molecules including Disperse-Red-1 and Di-Amino-Nitro-Stilbene (DANS) embody most of the requirements in stability, high loading, processability and very large electro-optical figures of merit1. However little is known about their electronic structure represented by their excited state spectrum and responsible for their nonlinear optical response, for both second and third order. We present a complete spectroscopic study of the DANS molecular system and compare our theoretical predictions to the second order nonlinear spectrum and four third order nonlinear optical spectra of amorphous DANS side-chain polymers. In particular we can successfully explain shifts of the nonlinear spectrum compared to the linear absorption one by properly accounting for Frank-Condon type displacements2.
Informes sobre el tema "Electron spectroscopie"
1
Gallagher, A. Spectroscopic diagnostics of electron-atom collisions. Office of Scientific and Technical Information (OSTI), enero de 1991. http://dx.doi.org/10.2172/5957609.
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2
Benn, D., R. Linnen y T. Martins. Evaluating white mica as an indicator mineral for lithium bearing pegmatites, Wekusko Lake pegmatite field, Manitoba, Canada. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/328982.
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This project investigates the potential use of white micas as an indicator mineral within Li-bearing pegmatites and the potential of field portable techniques, such as Raman spectroscopy and Laser Induced Breakdown Spectroscopy (LIBS) as real-time techniques in exploration. The pegmatites in the Wekusko Lake field, Manitoba, Canada, display five zones of varying mineralization. White micas display two textures in the field (primary igneous and secondary) and four textures were identified by backscattered electron imaging (poor zonation, rimmed, patchy and exsolution). The white micas were analysed by Electron Probe Micro-Analysis (EPMA) and Laser Ablation Induction-Coupled Plasma Mass Spectroscopy (LA-ICP-MS) and the results show a strong correlation in the Li content of the white mica and the whole rock Li2O obtained from the assays of drill core. The K/Rb vs. Cs contents of the white mica indicate that the most prospective dikes contain moderate to highly evolved grains. The use of portable Raman Spectrometer, while useful for mineral identification, was not able to detect a significant Li signature at the concentrations tested (1500-6000 ppm).
3
Bozek, J. D. y A. S. Schlachter. Electron spectrometer for gas-phase spectroscopy. Office of Scientific and Technical Information (OSTI), abril de 1997. http://dx.doi.org/10.2172/603596.
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Michael Holman, Ling Zang, Ruchuan Liu y David M. Adams. Single Molecule Spectroscopy of Electron Transfer. Office of Scientific and Technical Information (OSTI), octubre de 2009. http://dx.doi.org/10.2172/966129.
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Cooke, Stephen, A. Experimentally characterizing the electronic structures of f-electron systems using advanced high resolution Fourier transform microwave spectroscopies. Office of Scientific and Technical Information (OSTI), febrero de 2013. http://dx.doi.org/10.2172/1061478.
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Mark Maroncelli, Nancy Ryan Gray. Electronic Spectroscopy & Dynamics. Office of Scientific and Technical Information (OSTI), junio de 2010. http://dx.doi.org/10.2172/981408.
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Schumacher, Andreas B. Optical spectroscopy of strongly correlated electron systems. Office of Scientific and Technical Information (OSTI), febrero de 2001. http://dx.doi.org/10.2172/776655.
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Pe-Piper, G., D. J W Piper, J. Nagle y P. Opra. Petrography of bedrock and ice-rafted granules: Flemish Cap, offshore Newfoundland and Labrador. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/331224.
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This Open File report provides petrographic information from a scanning electron microscope study of granules and small pebbles in four selected trawl samples from Flemish Cap. The mineral composition of the granules was determined by energy dispersive spectroscopy (EDS) and textures are shown in backscattered electron images (BSE). It complements Open File 8359 on the heavy mineral assemblage on Flemish Cap. Granules on the central shoals appear to be derived from outcropping Avalonian basement; those to the east and west are predominantly ice-rafted in origin. These data improve our understanding of the source of the voluminous sands on Flemish Cap and the characteristics of the Avalonian basement rocks on southern Flemish Cap.
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Ukraintsev, Vladimir A. New Data Evaluation Technique for Electron Tunneling Spectroscopy. Fort Belvoir, VA: Defense Technical Information Center, julio de 1995. http://dx.doi.org/10.21236/ada296960.
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Gardner, J. A., Ruiping Wang, R. Schwenker, W. E. Evenson, R. L. Rasera y J. A. Sommers. PAC spectroscopy of electronic ceramics. Office of Scientific and Technical Information (OSTI), diciembre de 1991. http://dx.doi.org/10.2172/10147074.
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