Teses / dissertações sobre o tema "Electronic spectroscopies"
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Li, Xin. "Theoretical studies on electronic structure and x-ray spectroscopies of 2D materials". Doctoral thesis, KTH, Teoretisk kemi och biologi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-185683.
Texto completo da fonteQC 20160425
Lindblad, Andreas. "A Treatise on the Geometric and Electronic Structure of Clusters : Investigated by Synchrotron Radiation Based Electron Spectroscopies". Doctoral thesis, Uppsala University, Department of Physics and Materials Science, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8463.
Texto completo da fonteClusters are finite ensembles of atoms or molecules with sizes in the nanometer regime (i.e. nanoparticles). This thesis present results on the geometric and electronic structure of homogeneous and heterogeneous combinations of atoms and molecules. The systems have been studied with synchrotron radiation and valence, core and Auger electron spectroscopic techniques.
The first theme of the thesis is that of mixed clusters. It is shown that by varying the cluster production technique both structures that are close to that predicted by equilibrium considerations can be attained as well as far from equilibrium structures.
Electronic processes following ionization constitute the second theme. The post-collision interaction phenomenon, energy exchange between the photo- and the Auger electrons, is shown to be different in clusters of argon, krypton and xenon. A model is proposed that takes polarization screening in the final state into account. This result is of general character and should be applicable to the analysis of core level photoelectron and Auger electron spectra of insulating and semi-conducting bulk materials as well.
Interatomic Coloumbic Decay is a process that can occur in the condensed phases of weakly bonded systems. Results on the time-scale of the process in Ne clusters and mixed Ar/Ne clusters are herein discussed, as well observations of resonant contributions to the process. In analogy to Auger vis-à-vis Resonant Auger it is found that to the ICD process there is a corresponding Resonant ICD process possible. This has later been observed in other systems and by theoretical calculations as well in subsequent works by other groups.
Delocalization of dicationic valence final states in the hydrogen bonded ammonia clusters and aqueous ammonia has also been investigated by Auger electron spectroscopy. With those results it was possible to assign a previously observed feature in the Auger electron spectrum of solid ammonia.
Lee, Min-I. "Atomic structure, electronic states and relaxation dynamics in photovoltaic materials and interfaces from photoemission-related spectroscopies". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS220/document.
Texto completo da fonteThe efficiency of the photovoltaic process depends on the electronic band structure of the active material and the charge carrier dynamics. In this thesis, we have studied how these issues are related to the atomic structure in materials for two different technologies of solar cells, namely silicon heterostructure solar cells, and hybrid organic-inorganic perovskite solar cells. In silicon heterostructure solar cells, we have analyzed the impact of defects on the electronic properties of amorphous silicon heterostructures (a-Si:H/a-SIC:H/c-Si) by core level and valence band spectroscopies. In particular, we have quantified the number of dangling bonds inside a-Si:H layer upon irradiation, we have identified the electronic states associated to them, and we have understood the transitions previously observed by photoluminescence. In perovskite solar cells, we have correlated the atomic structure, the electronic structure and the electronic dynamics for two- and three-dimensional hybrid organic-inorganic perovskites. We have used with this goal a whole panel of complementary techniques: X-ray diffraction, angle-resolved photoemission spectroscopy, inverse photoemission spectroscopy, and time-resolved two-photon photoemission. In the two-dimensional perovskite (C₆H₅C₂H₄NH₃)₂PbI₄, the valence and conduction bands have been determined experimentally and compared to spectral function simulations. In the three-dimensional perovskite CH₃NH₃PbI₃, we have again determined the band structure and simulated it. Very broad spectral features have been experimentally observed, which relax the optical transition conditions impacting in the solarcell efficiencies. In both experiments and calculations, we observe that the spectral weight follows a cubic periodicity while the system is structurally in the tetragonal phase. This apparent contradiction is explained by the band broadness, which hides the band folding of the tetragonal distortion. As for the relaxation dynamics, we have observed that the photoexcited carriers thermalize in a subpicosecond time scale through the coupling to organic cation vibrations. At longer timescales (10~100 picoseconds), the electron diffusion controls the dynamics. This dynamics is affected by the annealing-induced defects, which localize the photoexcited electrons for more than 300 picoseconds
Carleschi, Emanuela. "Electronic structure of transition metal and rare earth ions in complex materials by resonant core-level spectroscopies". Doctoral thesis, Università degli studi di Trieste, 2009. http://hdl.handle.net/10077/3061.
Texto completo da fonteIn the course of this thesis I present an experimental investigation into various strongly correlated transition metal and rare earth compounds using core-level spectroscopic techniques, which have augmented the understanding of the electronic properties of these different systems. I will discuss the orbital occupation and the symmetry of the states near the Fermi level, responsible for the variety of ground states shown by a variety of strongly correlated systems such as misfit cobaltates, strontium ruthenates, metallic manganese and rare earth compounds.
XXI Ciclo
1978
Tournier-Colletta, Cédric. "Etude par spectroscopies d'électrons d'interfaces métalliques et semiconductrices". Thesis, Nancy 1, 2011. http://www.theses.fr/2011NAN10109/document.
Texto completo da fonteThis 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)
Capogrosso, Valentina. "Dimensionality and ordering effects on the electronic structure of low dimensional strongly correlated electron transition metal oxides". Doctoral thesis, Università degli studi di Trieste, 2013. http://hdl.handle.net/10077/8587.
Texto completo da fonteNel vasto scenario dei materiali fortemente correlati gli ossidi dei metalli di transizione hanno attratto enorme interesse a causa delle loro interessanti proprietà fisiche, come ad esempio, la superconduttività nei cuprati e la magnetoresistenza gigante nelle manganiti. In particolare, il mio interesse è stato rivolto ad una specifica classe di materiali, per i quali la dimensionalità è il parametro più importante. Le attività sperimentali sono state focalizzate verso due sistemi: la manganite Pr0.5Ca1.5MnO4 dopata a metà e a strato singolo (hd-PCMO) e la famiglia dei rutenati Srn+1RunO3n+1 (n=1,2,3). Entrambi questi sistemi esibiscono fenomeni affascinanti strettamente legati ad una complicata interazione tra i gradi di libertà del reticolo cristallino, di spin, di carica, ed orbitale, dove la dimensionalità cristallina gioca un ruolo cruciale. Con il mio progetto di dottorato ho studiato alcune proprietà dei materiali sopracitati per mezzo di spettroscopie con raggi X, come l’emissione risonante di raggi X (RXES) e l’assorbimento di raggi X (XAS) statico e risolto in tempo. Tutte le misure sono state condotte utilizzando la linea di luce BACH (linea di luce per dicroismo avanzato) dell’anello di accumulazione Elettra della Elettra-Sincrotrone Trieste. Il sistema hd-PCMO presenta una transizione di ordinamento di carica ed orbitale (CO-O) ad una temperatura TCO relativamente elevate, i.e. 340 K, accompagnata da una distorsione strutturale ortorombica, dove i portatori di carica fortemente correlati eg del Mn si ordinano in sotto-reticoli cristallografici separati (stato di carica ordinato) con un carattere orbitale specifico (stato di ordinamento orbitale). Inoltre, hd-PCMO presenta anche una risposta reticolare anomala ad una temperatura 20 K sopra la temperatura di Neél TN, che è associata ad un inatteso accoppiamento spin-reticolo. Poiché mancava uno studio degli stati elettronici non occupati del PCMO, misure dipendenti dalla temperatura per mezzo del dicroismo lineare (XLD) sono state realizzate alle soglie K dell’ossigeno e L3 del Mn al fine di spiegare il ruolo della topologia orbitale dei Mn 3d – O 2p. I dati sperimentali, supportati da calcoli ab-initio LDA+U, ci danno informazioni sulla ridistribuzione di carica e sui cambiamenti delle p-DOS alla transizione CO-O e a quella antiferromagnetica (AFM). I risultati ottenuti mostrano che l’interazione competitiva tra la distorsione locale atomica, necessaria per permettere l’ordinamento CO, e le dinamiche di carica del meccanismo di hopping regolano lo stato orbitale dei portatori di carica. Inoltre, sulla base di studi teorici che predicono la formazione di fasi orbitali e strutturali transienti “nascoste” per mezzo della stimolazione ottica, abbiamo studiato le DOS non occupate dello stato metastabile indotto otticamente nel PCMO per mezzo della XAS risolta in tempo, che offre uno strumento unico per misurare le DOS proiettate in sito ed in simmetria degli stati metastabili della materia. Le misure XAS risolte in tempo alla soglia K dell’ossigeno sono state realizzate per mezzo di un nuovo apparato sperimentale disponibile a BACH, che si basa su un laser Ti:zaffiro (impulsi di pompa) con tasso di ripetizione variabile sincronizzato con gli impulsi a 500 MHz dei raggi X (impulsi di sonda). L’evoluzione temporale degli spettri XAS attraverso la transizione CO-O fotoindotta otticamente risulta differente rispetto alle misure XAS adiabatiche, dimostrando l’esistenza di una “fase nascosta” fotoindotta nel PCMO, la cui natura è ancora sconosciuta. I rutenati Srn+1RunO3n+1 (n=1,2,3) sono emersi come una famiglia importante di peroschiti a causa dell’evoluzione inattesa e senza precedenti dal comportamento anisotropico ferro- o metamagnetico del Sr4Ru3O10 (n=3) dipendente dalla direzione del campo magnetico, all’ aumentato paramagnetismo di Pauli vicino all’ordinamento magnetico del Sr3Ru2O7 (n=2) e, infine, alla superconduttività a bassa temperature in Sr2RuO4 (n=1). Nonostante vengano riportati numerosi studi sulle proprietà strutturali e magnetiche di questi composti, l’evoluzione delle strutture elettroniche occupate e non occupate non è stata investigata in dettaglio. Quindi, la dipendenza delle strutture elettroniche e l’ibridizzazione degli stati 2p dell’ossigeno sono state investigate combinando la spettroscopia XAS alla soglia K dell’ossigeno (transizione 2p-1s) dipendente dalla polarizzazione e la spettroscopia RXES. Una sezione del capitolo 3 è dedicata ad illustrare un setup sperimentale sviluppato recentemente per esperimenti XAS risolti in tempo sfruttando la struttura temporale “multibunch” dell’anello di accumulazione del sincrotrone. Sfruttando le potenzialità di questo setup, la transizione di superficie semiconduttore-metallo nel germanio cristallino è stata fotoindotta ed il set completo di dati viene discusso. Lo schema della mia tesi di dottorato è il seguente. Il primo capitolo presenta una panoramica dell’intero lavoro. Il secondo capitolo è diviso in due sezioni. La prima sezione introduce il lettore alla fisica orbitale ed alle transizioni di fase elettroniche nei metalli di transizione a ridotta dimensionalità, con un excursus sullo stato dell’arte dei composti 3d del manganese e la famiglia 4d dei rutenati. L’intento della seconda sezione è quello di spiegare l’importanza delle tecniche spettroscopiche nei raggi X molli come strumenti per investigare le proprietà elettroniche dei solidi. La descrizione delle spettroscopie XAS e RXES vengono riviste più in dettaglio nel capitolo 3, che include anche la descrizione dell’apparato sperimentale della beamline BACH e del laboratorio T-ReX al Sincrotrone Elettra. Il capitolo 4 è dedicato alla teoria funzionale di densità (DFT) ed alla approssimazione locale di densità più U (LDA+U) ed ai dettagli del modello del sistema hd-PCMO. Il capitolo 5, che presenta i casi studiati, è diviso in due sezioni: il caso del PCMO, che include le misure XAS statiche e risolte in tempo, ed il caso della serie Ruddlesden-Popper dei rutenati di Sr investigate per mezzo della RXES. Nel capitolo finale vengono presentati i commenti finali su questo lavoro.
In the vast scenario of strongly correlated-electron materials transition-metal oxides have attracted enormous interest because of their interesting physical properties, including for example, superconductivity in cuprates and colossal magnetoresistance in manganites. In particular, my interest was directed to a particular class of materials, whose dimensionality is the most defining material parameter. With my Ph.D. project I deepened into some physical properties of these materials by means of core-levels spectroscopies such as resonant x ray emission (RXES) and static and time-resolved x ray absorption (XAS). All the measurements have been carried out at the beamline BACH (Beamline for Advanced diCHroism) at the Elettra light source facility in Trieste. The experimental activities focused on two case-study systems: the single layered half-doped Pr0.5Ca1.5MnO4 (hd-PCMO) and the layered Srn+1RunO3n+1 (n=1,2,3) family. Both these systems exhibit fascinating phenomena intimately related to a complicated interplay between the crystal lattice, spin, charge, and orbital degrees of freedom, where crystal dimensionality plays a crucial role. hd-PCMO exhibits a charge-orbital ordering (CO-O) transition at a remarkably high TCO, slightly above room temperature, accompanied by an orthorhombic structural distortion, where the strongly correlated Mn eg charge carriers order onto separate crystallographic sub-lattices (charge-ordered state) with a specific orbital character (orbital ordered state). Furthermore, hd-PCMO also displays an anomalous lattice response at temperatures 20K above the Neél temperature TN, which is associated to an unexpected spin-lattice coupling. Since a study of the PCMO unoccupied electronic states was lacking, temperature dependence measurements by XAS linear dichroism (XLD) have been performed at the O-K and Mn-L3 thresholds in order to elucidate the role of Mn 3d - O 2p orbital topology. The experimental data, supported by ab-initio LDA+U, shed light on the charge redistribution and p-DOS changes at the CO-O and antiferromagnetic (AFM) transitions. The results obtained show that the competitive interplay between the local atomic distortion, necessary for accomodating the CO-ordering, and the charge dynamics of the hopping mechanism regulates the orbital state of the charge carriers. Furthermore, on the basis of theoretical studies that predict the formation of transient “hidden” orbital and structural phases by optical stimulation, we have studied the unoccupied DOS of the optically induced metastable state in PCMO by means of time resolved XAS, which offers a unique tool to measure site and symmetry projected DOS of metastable states in matter. Tr-XAS measurements at the O-K edge have been carried out by means of a novel experimental apparatus available at BACH, which is based on a variable repetition rate Ti:sapphire laser (pump pulse) synchronized with the ∼ 500 MHz X-ray photon pulses (probe pulses). The time evolution of the XAS lineshapes across the optically photoinduced CO-O transition results different respect to the adiabatic XAS measurements, demonstrating the existence of a photoinduced “hidden phase” in PCMO, whose nature is still unknown. The layered Srn+1RunO3n+1 (n=1,2,3) have emerged as an important family of perovskites because of the unexpected and unprecedented evolution from anisotropic ferro- or metamagnetic behavior of Sr4Ru3O10 (n=3) dependent on the direction of the magnetic field, enhanced Pauli paramagnetism close to magnetic order of Sr3Ru2O7 (n=2) and, finally, to low-temperature superconductivity in Sr2RuO4 (n=1). Although numerous studies have been reported on the structural and magnetic properties of these compounds, the evolution of the occupied and unoccupied electronic structures were not investigated in detail. Thus, the dependence of electronic structures and the hybridization of O 2p states have been investigated by combining polarization dependent O K (2p-1s transition) XAS and RXES spectroscopies. A section of the chapter 3 is dedicated to illustrate a newly developed experimental setup for time-resolved XAS experiments by exploiting the multibunch time structure of a synchrotron storage ring. By exploiting the capabilities of this setup, the surface semiconductor-metal transition in crystalline germanium has been photoinduced and the complete set of data discussed. The outline of my Ph.D. thesis is the following. The first chapter presents an overview of the entire work. The second chapter is divided into two sections. The first section introduces the reader into the orbital physics and the electronic phase transitions in low dimensional transition metal oxides, with an excursus on the state of the art of 3d manganese compounds and the family of 4d Ruthenates. The second section is aimed to explain the importance of soft x-ray spectroscopic techniques as tools to investigate the electronic properties of solids. The description of XAS and RXES are reviewed in more details in chapter 3, which includes also the description of the experimental apparatus of BACH beamline and T-ReX lab at the Elettra synchrotron light source. Chapter 4 is dedicated to the Density Functional Theory (DFT) and Local Density Approximation plus U (LDA+U) theories and to the details of the modelling of the hd-PCMO system. Chapter 5, which presents the cases studied, is divided into two sections: the case of PCMO, including static and time resolved XAS measurements, and the case of Ruddlesden-Popper series of Sr Ruthenates investigated by means of RXES. In the final chapter the concluding remarks on this work are presented.
XXV Ciclo
1983
Gallo, Erik. "Modification of the electronic structure of catalytic active transition-metal centers upon molecular adsorption : an XAS/XES study". Thesis, Rennes 1, 2013. http://www.theses.fr/2013REN1S054/document.
Texto completo da fonteThe purpose of this research project was to apply advanced X-ray based spectroscopic techniques for investigating the electronic structure of transition metals within catalysts and molecular sieves under in-situ conditions. Thus, the first chapter of the thesis, "X-Ray Spectroscopy: an Overview " briefly presents the spectroscopic techniques available at ID26, beamline of the European Synchrotron Radiation Facility (Grenoble) where all the measurements reported in this work have been obtained. In the second chapter, "Study of the Electronic structure of the Ti-sites in TS-1 using hard X-ray spectroscopy", it is reported the electronic characterization of the Ti centres in titanium silicalite-1 (TS-1), that is a relevant catalyst employed in industrial plants worldwide. The chapter shows that the combination of X-ray absorption and X-ray emission spectroscopy with quantum mechanical calculations is effective to obtain important insights on the electronic structure of the Ti-centres under in-situ conditions. The third chapter entitled “Identification of the Ti-Ligands in Silica Supported Ziegler-Natta Catalyst by X- Ray Emission Spectroscopy" presents the study of a variant of the Ziegler-Natta catalyst. The chapter discusses the interpretation of the valence emission lines within the theoretical framework provided by the density functional theory (DFT) and proposes possible models for the Ti-ligand-environment. The fourth chapter, entitled "Observing the dd-Excitations in CPO-27-Ni using Resonant Inelastic X-ray Scattering", concludes the main part of the thesis. It presents the application of resonant inelastic X-ray scattering (RIXS) for obtaining the crystal field excitations of the Ni ions within nickel oxide and within a Ni- metal-organic-framework (CPO-27-Ni). The chapter briefly describes the different theoretical approaches that can be used for the interpretation of the spectral features and discusses the adsorption of probe molecules like H2O, CO and H2S on the Ni centres of CPO-27-Ni. The last chapter (Chapter five) drawn a series of conclusions concerning the performed investigations and indicates possible future research directions. In Appendix A entitled "Pump and Probe Time Resolved Experiments at ID26" it is reported the description of the experimental setup co-developed and co-realized by the candidate for time resolved experiments. The appendix also accounts for the scientific outcome of the performed pump and probe measurements. The curriculum vitae and the publications list of the candidate are respectively reported in Appendix B and C
Mahjoub, Mohamed Aymen. "Contributions aux études quantitatives par spectroscopies électroniques (EPES et XPS) : Applications aux surfaces nanostructurées". Thesis, Clermont-Ferrand 2, 2016. http://www.theses.fr/2016CLF22666/document.
Texto completo da fonteThis 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
Darsey, Gary Paul. "The electronic structure of methyl-substituted ferrocenes and early transition metal bent metallocenes by gas phase ultraviolet and X-ray photoelectron spectroscopies". Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184473.
Texto completo da fonteKELLOGG, GLEN EUGENE. "ELECTRONIC FACTORS OF CARBON - HYDROGEN AND DOUBLE-BONDED CARBON BOND ACTIVATION: EXPERIMENTAL INFORMATION FROM ULTRAVIOLET AND X-RAY PHOTOELECTRON SPECTROSCOPIES (CORE, VALENCE, OLEFIN)". Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/188067.
Texto completo da fonteHuang, Meng-Jie [Verfasser], e H. von [Akademischer Betreuer] Löhneysen. "The electronic structure and magnetic interactions in the mixed transition-metal oxide La(Co,Ni)O3 studied by x-ray absorption spectroscopies / Meng-Jie Huang ; Betreuer: H. von Löhneysen". Karlsruhe : KIT-Bibliothek, 2016. http://d-nb.info/1126036668/34.
Texto completo da fonteTegomo, Chiogo Bodry. "Spectroscopic studies of cerium and Ytterbium-based Kondo systems". Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0193.
Texto completo da fonteCerium and ytterbium compounds are systems that exhibit outstanding magnetic, electronic, and thermodynamic properties at low temperatures, such as the Kondo effect, heavy fermions, intermediate valence, and charge density waves. These properties are due to the very strong electron-electron interactions of the f states and the hybridization of the f states with the conduction electrons. In the first part of this thesis work, we investigate the temperature-dependent electronic structure of YbPd, a Kondo mixed-valent cubic compound at high temperature, which exhibits incommensurate and commensurate charge-density-wave (CDW) ordering below T_1 = 130 K and T_2 = 105 K, respectively. Below 105 K, magnetic Yb^{3+} and nonmagnetic Yb^{2.6+} are arranged alternatively along the c axis, in a tetragonal structure exhibiting valence order. Hard x-ray photoemission spectroscopy of Yb 3d states show temperature-independent Yb^{2+} and Yb^{3+} features indicating single-Yb site dynamic valence fluctuations above T_1, and a clear temperature dependent valence change of the two crystallographic Yb sites in the CDW phase. Simplified single-impurity Anderson model calculations of the Yb 3d states show good agreement with the temperature-dependent valency change and provide site-dependent Kondo temperatures. The results indicate an evolution from dynamic mixed-valence in the cubic phase to long-range static CDW order in the tetragonal phase, which is driven by the difference in Kondo energies of the two phases. Resonant inelastic x-ray scattering (RIXS) is a very efficient technique to study elementary excitations in a large variety of systems, such as charge transfer excitations, the crystal field, and spin-orbit excitations. In the second part of this work, we investigated cerium compounds with different Kondo temperatures using RIXS at Ce M_5-edge combined with simulation using the full multiplet theory and the single impurity Anderson model. We demonstrated that all the charge excitations observed in combined photoemission and inverse photoemission can be evidenced by RIXS spectroscopy just by varying the incident photon energy around the Ce M_5-edge. We also discuss the drastic polarization dependence of the f^0 structure in RIXS spectra and the strong temperature dependence of the fluorescence-like structure, which is reminiscent of the temperature dependence of the Kondo resonance
Pullen, Aletha Marie. "Spectroscopic characterization of carbon based molecular electronic junctions". Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1099671322.
Texto completo da fonteTitle from first page of PDF file. Document formatted into pages; contains xvii, 208 p.; also includes graphics (some col.). Includes bibliographical references (p. 189-208).
Buck, Jens [Verfasser]. "Electron spectroscopic study of electronic and morphological modifications of the WSe2 surface induced by Rb adsorption / Jens Buck". Kiel : Universitätsbibliothek Kiel, 2012. http://d-nb.info/1024692035/34.
Texto completo da fontePanten, Dietmar. "Spectroscopic properties of degenerate electronic states in negative ions". Université de Marne-la-Vallée, 2003. http://www.theses.fr/2003MARN0148.
Texto completo da fonteWhite, R. P. "Spectroscopic probes for electron transfer phenomena". Thesis, University of East Anglia, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382862.
Texto completo da fonteNdoye, Chérif A. A. Daniel Chantal Strich Alain. "Electronic spectroscopy of small organic and organometallic molecules : electronic correlation, vibronic and spin-orbit couplings". Strasbourg : Université de Strasbourg, 2009. http://eprints-scd-ulp.u-strasbg.fr:8080/1149/01/NDOYE_Cherif_2008.pdf.
Texto completo da fonteLaitenberger, Peter. "Structural and spectroscopic studies of surfaces". Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364531.
Texto completo da fonteAllenspach, 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.
Texto completo da fonteYeung, C. "Spectroscopic analysis of nanodielectric interfaces". Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/358897/.
Texto completo da fonteMulley, James Stephen. "Electronic, spectroscopic and interface properties of two transition metal oxides". Thesis, University of Reading, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.533743.
Texto completo da fonteGuo, Meiyuan. "Electronic structures of transition metal complexes-core level spectroscopic investigation". Licentiate thesis, Uppsala universitet, Teoretisk kemi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-275074.
Texto completo da fonteLourenço-Martins, Hugo. "Experiment and theory of plasmon coupling physics, wave effects and their study by electron spectroscopies". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS284/document.
Texto completo da fonteSurface 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
Pankow, Joel Walter. "Effects of dopant molecules on the electronic properties of organic thin films: Solid state conductivity measurements and surface electron spectroscopic techniques". Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185399.
Texto completo da fonteErnstorfer, Ralph. "Spectroscopic investigation of photoinduced heterogeneous electron transfer". [S.l. : s.n.], 2004. http://www.diss.fu-berlin.de/2004/268/index.html.
Texto completo da fonteBhatta, Rudra Prasad. "Electron Spectroscopic Study of Indium Nitride Layers". Digital Archive @ GSU, 2008. http://digitalarchive.gsu.edu/phy_astr_diss/23.
Texto completo da fonteOsikowicz, Wojciech. "Conjugated materials and their interfaces in organic electronics studied by photoelectron spectroscopies /". Linköping : Univ, 2004. http://www.bibl.liu.se/liupubl/disp/disp2004/tek880s.pdf.
Texto completo da fonteGoode, Angela Erin. "Correlation of electron and X-ray spectroscopies in nanoscale systems". Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/14421.
Texto completo da fonteMartins, Emanuel. "X-ray spectroscopic study of the electronic structure of sulfur compounds". Thesis, Queen Mary, University of London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283717.
Texto completo da fonteHassan, Randa Saad Ali. "Spectroscopic studies of optical and electronic processes in quantum cascade lasers". Thesis, University of Sheffield, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.575367.
Texto completo da fonteBrumboiu, Iulia Emilia. "The Electronic Structure of Organic Molecular Materials : Theoretical and Spectroscopic Investigations". Licentiate thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-218225.
Texto completo da fonteSinha, S. "Electron spectroscopic studies of some hydrogen implanted metals". Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 1986. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/3257.
Texto completo da fonteNdoye, Chérif A. A. "Electronic spectroscopy of small organic and organometallic molecules : electronic correlation, vibronic and spin-orbit couplings". Université Louis Pasteur (Strasbourg) (1971-2008), 2008. https://publication-theses.unistra.fr/public/theses_doctorat/2008/NDOYE_Cherif_AA_2008.pdf.
Texto completo da fonteTheory is sometime necessary to predict molecular spectroscopic properties and interpret experimental spectra. A first step study can be limited to the electronic spectroscopy in Born-Oppenheimer approximation which consists in considering nuclei fixed and electronic states independent from each other. The scope of this thesis is to first study the electronic structure of small organic and orgnometallic molecules in the Born-Oppenheimer approximation and ultimatly go beyond by taking into account effects such as vibronic or spin-orbit couplings between electronic states. The first chapter is dedicated to the ab initio methods used to obtain the results presented in the following chapters. Electronic structure methods in the Born-Oppenheimer approximation are first presented followed by the methods that treat vibronic and spin-orbit couplings. The second chapter is a study of the electronic structure and potential energy curves of MCH+2 (M=Fe, Co, Ni) transition metal carbenes. Chapter three reports simulated vibronic spectra of fluoroethylenes, they are compared to experimental spectra to indentify the origin of the different spectroscopic contributions. A last chapter deals with the spin-orbit effects in water and its heavy homologous (H2X with X=O, Te, Po)
Qazilbash, Muhammad Mumtaz. "Tunneling and Raman spectroscopies of the electron-doped high-temperature superconductors". College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1780.
Texto completo da fonteThesis research directed by: Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
SALVINELLI, GABRIELE. "PROBING OXIDE HETEROSTRUCTURE INTERFACES THROUGH ANGLE RESOLVED AND RESONANT ELECTRON SPECTROSCOPIES". Doctoral thesis, Università degli Studi di Milano, 2015. http://hdl.handle.net/2434/262157.
Texto completo da fonteSharma, Nikhil. "Microscopic and spectroscopic studies of growth and electronic structure of epitaxial graphene". Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/33844.
Texto completo da fonteBakboord, Joan Vanessa. "Synthesis and spectroscopic studies of novel phthalocyanines-toward new electronic absorption properties". Thesis, University of East Anglia, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323290.
Texto completo da fonteHill, C. A. S. "The synthesis and studies of compounds with novel electronic and spectroscopic properties". Thesis, University of the West of England, Bristol, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305721.
Texto completo da fontePeggs, Derek William. "Spectroscopic studies of the opto-electronic properties of quantum wells and superlattices". Thesis, University of Sheffield, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364305.
Texto completo da fonteChalla, Jagannadha Reddy. "Electronic and Vibrational Dynamics of Heme Model Compounds-An Ultrafast Spectroscopic Study". Case Western Reserve University School of Graduate Studies / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=case1181323422.
Texto completo da fonteMassat, Pierre. "Spectroscopie Raman du supraconducteur FeSe". Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCC059/document.
Texto completo da fonteThe discovery in 2008 of the iron-based superconductors opened a new field of investigation of high-temperature superconductivity. In particular, the nematic phase of these materials may play a major role in the mecanism of superconductivity. We studied the FeSe compound using Raman spectroscopy, at ambient pressure and under hydrostatic pressure. This material does not display any static magnetic order at ambient pressure and is therefore an excellent choice to study the nematic order. We observed the charge nematic fluctuations. Their evolution in the tetragonal phase proves the existence of an electronic nematic instability, which drives the structural transition. In the orthorhombic phase, the behaviour of the phonons underlines the role of the spin-phonon coupling in the nematic transition. Besides, the shape of the superconducting Raman response is compatible with the existence of two s-wave gaps, one of which is anisotropic. Under hydrostatic pressure, the nematic fluctuations reduce rapidly. The associated electronic quantum critical point is situated at very low pressure, just before the appearance of magnetic order. The nematic fluctuations completely disappear around 2 GPa, when the structural transition changes from second order to first order. An anomaly of the phonons also occurs close to this pressure, which indicates a modification of the electronic structure of the system. Our measurements additionally reveal the existence of a pseudogap. Its temperature of appearance reduces significantly simultaneously to the disappearance of magnetic order, when the critical temperature of superconductivity reaches its maximum. Finally, the Raman response in the superconducting state at 7.8 GPa shows a clear signature of a full gap
Mrezguia, Hela. "Croissance et propriétés électroniques du silicène hétéroépitaxié sur B : Si(111)-(√3×√3)R30° et Ag/Si(111)-(√3×√3)R30°". Electronic Thesis or Diss., Aix-Marseille, 2020. http://www.theses.fr/2020AIXM0502.
Texto completo da fonteWe realized the heteroepitaxy of silicene on Si(111) substrates passivated in two ways, either by B or Ag atoms. We deposited Si atoms on the UHV-prepared substrates B:Si(111)-(√3×√3)R30° and Ag/Si(111)-(√3×√3)R30° kept at controlled temperatures. we used LEED, AES, IPES/ARIPES. According to LEED, the adsorption of roughly one monolayer of Si on both substrates leads to the formation of a compact Si bidimensional layer which adopts the (√3×√3)R30° symmetry of the substrates. TCS and the evolution of the work function indicate strong perturbations of the substrate space-charge layer, while IPES reveals the disappearance of the surface states characteristic of each substrate. On Ag/Si(111)-(√3×√3)R30°, the disappearance of the well-known S1 « free-electron-like » surface state induces a metal/insulator transition. Instead of these surface states, new unoccupied electronic states UB and U0 appear which are associated to silicene on each substrate, with dispersions profiles which do not show the characteristics of a (√3×√3)R30° symmetry. Their limited overall bandwidths (resp. ~0.3 and ~0.45 eV) indicate rather large effective masses for electrons and suggest possible correlation effects which could justify the rather large measured bandgaps (resp. 2 eV and ~1 eV). The positions of UB and U0, far from the Fermi level, manifest a non-covalent but sizable interaction silcene/substrate, most probably a charge transfer which may be spatially inhomogeneous. The dispersion profiles of UB and U0 measured by ARIPES are compatible with the symmetry of a silicene layer with the Γ-KSilicene direction oriented along the Γ-M√3 direction of the reconstruction (√3×√3)R30°
Archer, Anthony D. "Spectroscopic studies of field-induced electron emission from isolated microstructures". Thesis, Aston University, 1992. http://publications.aston.ac.uk/8241/.
Texto completo da fonteHilger, Daniel. "Electron paramagnetic resonance spectroscopic analyses of membrane transport proteins". Diss., lmu, 2010. http://nbn-resolving.de/urn:nbn:de:bvb:19-127330.
Texto completo da fonteGarrett, Simon. "Electron spectroscopic studies of Ti and Co-Ti alloys". Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46780.
Texto completo da fonteIncavo, Joseph A. "Spectroscopic studies of electron transfer reactions inside zeolite cavities /". The Ohio State University, 1989. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487671640056801.
Texto completo da fonteRiccardi, Elisa. "Spectroscopie raman des excitations électroniques du graphène". Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCC166/document.
Texto completo da fonteSince its discovery, the exceptional electronic properties of graphene have been studied in an impressive number of academic works, giving birth to a new research field dealing with two-dimensional crystals. Raman spectroscopy is a quick, non-destructive and symmetry-selective way to probe the dynamics of electrons and to their coupling with the other degrees of freedom of a material. Until now, nonetheless, this technique had been almost exclusively reserved to the characterization of graphene's vibrational properties, which probe its electronic properties only indirectly. In this work I unravel the electronic Raman signal of mono- and multi-layer graphene tuning it with a gate voltage. In order to do so, I combined advanced techniques of device fabrication with a Raman microscope specifically designed for this goal. By means of the electric field effect, I identified and quantified for the first time the intensity of the electronic Raman continuum of graphene due to the inter-band transitions through the Dirac cone. The spectra, with the presence of a Pauli blocking of electronic excitations, match perfectly with theoretical expectations. The polarization resolved measurements revealed an original property of Raman spectroscopy: it is a unique probe of chiral electronic excitations. This property, attributed to a quantum interferences phenomenon between scattering amplitudes, opens very interesting perspectives in the study of other two-dimensional crystals and of topological phases
Coxon, Paul R. "Studies of silicon and carbon nanomaterials by electron and X-ray spectroscopies". Thesis, University of Newcastle Upon Tyne, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.519575.
Texto completo da fonteBrooker, Alan D. "A study by Auger electron and X-ray spectroscopies of vacuum brazing". Thesis, University of Surrey, 1986. http://epubs.surrey.ac.uk/848467/.
Texto completo da fonteDennison, John Robert. "(e,2e) spectroscopic investigations of the spectral momentum densities of thin carbon films". Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/53869.
Texto completo da fontePh. D.