Dissertations / Theses on the topic 'XPS'
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El, Kazzi Mario. "ETUDE PAR PHOTOEMISSION (XPS & XPD) D'HETEROSTRUCTURES D'OXYDES FONCTIONNELS EPITAXIES SUR SILICIUM." Phd thesis, Ecole Centrale de Lyon, 2007. http://tel.archives-ouvertes.fr/tel-00321458.
Full textDans ce contexte, l'objectif principal de ma thèse a été de mener une étude approfondie des propriétés physicochimiques et structurales de couches fines d'oxydes élaborées par Epitaxie par Jets Moléculaires (EJM) sur substrat silicium ou oxyde, en utilisant la spectroscopie de photoélectrons (XPS) et la diffraction de photoélectrons (XPD).
Nous avons étudié dans un premier temps la relaxation de films minces de LaAlO3 et de BaTiO3 épitaxiés sur des substrats de SrTiO3(001). Nous avons montré qu'au-dessous d'une certaine épaisseur critique ces deux oxydes sont contraints de façon pseudomorphiques sur SrTiO3(001). De plus nous avons clairement mis en évidence une forte augmentation de la déformation ferroélectrique pour une couche contrainte de BaTiO3.
Dans un deuxième temps, nous avons aussi étudié la croissance de LaAlO3 sur Si(001). LaAlO3 est amorphe pour des températures de croissance en dessous de 500°C. Pour des températures supérieures il y a formation de silicates à l'interface qui empêche la cristallisation. Pour surmonter cette difficulté, des procédés d'ingénierie d'interface ont été développés pour limiter les réactions interfaciales et réussir la croissance épitaxiale. Ils sont basés sur l'utilisation de couches tampons interfaciales d'oxydes comme SrO, SrTiO3 et Al2O3.
Enfin, nous avons comparé les modes de croissance et la stabilité d'interface d'Al2O3 et de Gd2O3 épitaxiés sur Si(111) et Si(001). Les résultats prouvent que la croissance de ces deux oxydes sur Si(111) a une orientation suivant [111]. Par contre sur Si(001) le mécanisme de croissance est plus complexe avec des relations d'épitaxie et des orientations inhabituelles.
Kazzi, Mario El. "Etude par photoemission (XPS & XPD) d'hétérostructures d'oxydes fonctionnels epitaxies sur silicium." Ecully, Ecole centrale de Lyon, 2007. http://www.theses.fr/2007ECDL0028.
Full textThis thesis is on one of the main INL axes, the goal of which is to develop the growth procedures of thin oxide single crystal on silicon. These oxides are meant to replace the presently used amorphous gate oxide (SiOxNy and HfSixOyNz) by a high-κ oxide in future “sub 22nm” CMOS. Besides, the interest in controlling the growth of these oxides goes far beyond this oxide gate application. This know-how would be a technological breakthrough to develop monolithic integration on silicon. In this context, the main objective of my thesis has been to study the physico-chemical and structural properties of thin oxide layers grown by Molecular Beam Epitaxy (MBE) on silicon or oxide substrate. We have used X-ray photoelectron spectroscopy (XPS) and X-ray photoelectron diffraction (XPD). First, the stress relaxation of LaAlO3 and BaTiO3 grown on SrTiO3 (001) substrate has been investigated. We have proved that below a critical thickness this two oxides can be grown pseudomorphically and that beyond a plastic relaxation occurs. In addition, we have evidenced that the ferroelectric deformation is strongly enhanced in strained BaTiO3 thin films. Second, we have studied the LaAlO3 growth on Si(001). LaAlO3 is amorphous for growth temperature below 500°C. For higher temperature, the formation of silicates at the interface prevents the crystallization. Thus, an interface engineering strategy has been set up to avoid these interfacial reactions and to succeed an epitaxial growth,. Using SrO, SrTiO3 and Al2O3 as buffer Finally, a comparison of the growth mode and interface stability has been done between Al2O3 and Gd2O3 grown either on Si(111) or Si(001) substrates. Results show that this two oxides grow along the [111] direction on Si(111). However, on Si(001), the growth mechanism is more complex leading to unusual orientations and epitaxial relationships
Kazzi, Mario Hollinger Guy. "Etude par photoemission (XPS & XPD) d'hétérostructures d'oxydes fonctionnels epitaxies sur silicium." Ecully : Ecole Centrale de Lyon, 2007. http://bibli.ec-lyon.fr/exl-doc/melkazzi.pdf.
Full textMartins, 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.
Full textFLAMENT, OLIVIER. "Etude xps des interfaces polyimide/isolant." Paris 7, 1990. http://www.theses.fr/1990PA077034.
Full textDwyer, V. M. "Elastic scattering in quantitative Auger/XPS analysis." Thesis, University of York, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374164.
Full textFerrah, Djawhar. "Etude des propriétés physico-chimiques d'interfaces par photoémission." Thesis, Ecully, Ecole centrale de Lyon, 2013. http://www.theses.fr/2013ECDL0048/document.
Full textThe main objective of this thesis is to study the chemical and physical properties at the surface or at the interface between thin layers by photoemission spectroscopy (XPS), photoelectron diffraction (XPD), and time resolved photoemission (PTR) . The experiments were conducted using an Alka source at INL or soft -X ray synchrotron radiation at Soleil, the French national Synchrotron facility. The first photoemission study has been performed on platinum deposited on thin Gd2(h layers grown by Molecular Bearn Epitaxy (MBE) on Si (111) substrate. The charge transfer between Pt and 0 at the interface causes a chemical shift to higher binding energies without changing the characteristic shape of the metal XPS peak. The XPD study shows that Pt is partially crystallized into two (111)-oriented do mains on Gd20 3 (111) with the in-plane epitaxial relationships [11 0] Pt (111) / / [11 0] Gd203 (111) and [101] Pt(111)/ / [11 0] Gd20 3 (111). In addition to bi-domains formation of platinum Pt (111) on Gd20 3 (111), a new ordered phase of platinum oxide Pt02 at the Pt/ Gd203 interface have been observed. The study of the background of the polar curves depending of the morphology has shown, that the film of Pt does not wet on the oxide, due to the low energy of interaction at the interface compared to the Pt thin layer. The second study has been interested to the photoemission time-resolved study of non-reactive metal / semiconductor model system. We have studied the thin layer gold (Au) growth on silicon (Si) substrate before and during annealing in TEMPO beam line (synchrotron Soleil).The XPS study, shows before annealing the formation of silicon native oxide on heterostructure at ambient temperature. The desorption of silicon oxide during annealing at low temperature induce photoemission intensity decreases with time. The desorption of oxide and alloy formation (AuSi) induce distribution of pits with cubic form at silicon surface due to gold etching activity. The third photoemission study has concerned thin films of a few layers of graphene obtained by solid-state graphitization from 6H-SiC (0001) substrates have been studied by X-ray photoelectron spectroscopy (XPS) and X-ray photoelectron diffraction (XPD). The Cls core-level has been resolved into components, which have been associated with carbon from bulk SiC, carbon from graphene and carbon at the interface graphene/ 6H-SiC (0001). Then, the intensity of each of these components has been recorded as a function of polar (azimuth) angle for several azimuth (polar) angles. These XPD measurements provide crystallographic information which clearly indicates that the graphene sheets are organized in graphite-like structure on 6H-SiC(0001), an organization that results of the shrinking of the 6H-SiC (0001) lattice after Si depletion. Finally the decoupling of graphene from 6H-SiC (0001) substrate by oxygen intercalation has been studied from the XPS point of view. Finally, photoemission study has concerned thin film of InP (phosphor indium ) islands grown by Molecular Bearn Epitaxy (MBE) on SrTi03 (001) bulk substrate have been investigated by X-ray photoelectron spectroscopy and diffraction (XPS/ XPD).Integration of III-V semi-conductor on silicon wafer, via SrTi03 buffer is currently the subject of intense research because of its potentially interesting applications in future nano-optoelectronics. The Ols, Sr3d, Ti2p, In3d, and P 2p core level area have been studied as function of azimuth angle for different polar angles. Comparison of the XPD azimuth curves of Sr3d and In3d shows that islands InP are oriented (001) with an in-plane epitaxial relationship [110] InP(001 ) // [100] SrTi03 (001). AFM images shows that InP islands are regularly dispersed on the surface. Their shape is a regularly facetted half-sphere
Blundell, Rebecca K. "XPS of quaternary ammonium and phosphonium ionic liquids." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/34589/.
Full textHung, Wing Wa. "FTIR and XPS of congruent and stoichiometric LiNbO3." HKBU Institutional Repository, 2003. http://repository.hkbu.edu.hk/etd_ra/442.
Full textIshii, Masaru. "Nanofabrication and STM/XPS Studies of Automotive Model Catalysts." Thesis, University of Reading, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485372.
Full textALMEIDA, CLARA MUNIZ DA SILVA DE. "XPS AND AFM ANALYSIS OF PVC/PHB BLENDS SURFACES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2005. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=7338@1.
Full textNeste trabalho, foram estudadas blendas formadas pelo polímero Policloreto de Vinila (PVC) e pelo polímero biodegradável Poli Hidroxibutirato (PHB), com diferentes concentrações relativas de cada polímero. As blendas foram preparadas em forma de membrana, com concentrações de PHB variando de 2 a 40%. A técnica utilizada para o preparo das amostras foi a evaporação do solvente, sendo dicloroetano o solvente utilizado. A composição química das superfícies das blendas foi caracterizada utilizando a técnica de espectroscopia de fotoelétrons induzida por raios-X (XPS). A morfologia e as propriedades mecânicas das amostras foram estudadas com o auxílio da microscopia de força atômica (AFM). Medidas de calorimetria diferencial exploratória foram realizadas a fim de conhecermos a miscibilidade das blendas formadas. Nas blendas formadas observou-se uma segregação de PHB para a superfície, sendo o percentual de PHB na superfície na faixa de 18±2%, mesmo para blendas com mais baixa concentração relativa de PHB. Entretanto o grau de cristalização do PHB em cada blenda aumenta com a incorporação do polímero na blenda. Foi observado um aumento na dureza conforme aumentamos a concentração de PHB na blenda. As blendas foram caracterizadas como parcialmente miscíveis.
In this work, the study of polymer blends surfaces formed by a biodegradable polymer (poly3-hydroxybutyrate, PHB) and PVC (polyvinyl chloride) with different molar percentages of PHB is presented. The blends samples were prepared as membranes with PHB molar concentrations from 2 to 40%. The technique used to prepare the membranes was the solvent-casting technique, using dichloroethene as solvent. The chemical composition of the blends samples surfaces were characterized by X-ray photoelectron spectroscopy (XPS). Their morphologies and mechanical properties were studied by atomic force microscopy (AFM). Differential scanning calorimeter measures were obtained in order to know the blends miscibility. A PHB surface segregation of 18±2% was observed, even for the blends with lower PHB concentrations. However, the degree of the PHB crystallization in each blend increases with the increasing incorporation of PHB in the blend volume. An increase in the blends hardness was observed while the PHB blends concentration increases. The blends were founded to be partially miscible.
Clarke, Coby James. "Ionic liquids as designer molecules for XPS peak fitting." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/33303/.
Full textAlvær, Ingrid, and Silje Henriette Westgaard. "Implementation of Company-Specific Production Systems (XPS) in Multinational Companies : A comparative case study concerning implementation of XPS in two subsidiaries of Elkem." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for industriell økonomi og teknologiledelse, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-20978.
Full textJahel, Ali. "Étude de l'ajout d'un promoteur au système Pt-Sn supporté sur alumine chlorée utilisé en reformage catalytique." Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20233.
Full textThis work consists of a detailed study on the effect of indium in alumina supported trimetallic PtSnIn-based naphtha reforming catalysts. These catalysts were reproduced using different preparation protocols and the indium effect was investigated using 119Sn Mössbauer spectroscopy, XANES, EXAFS spectroscopies, IR-CO, STEM, CO chemisorption, TPR and TPD. It appears that the nature of the metallic active centres depends on the method with which indium was introduced. When co-precipitating the indium precursor with the Al source, PtxSn alloys were formed, whereas when metals were impregnated on the surface, substitutional Pt-Sn alloys were observed. Increasing the In content in the frst type of catalysts leads to an increase in the Sn concentration in PtxSn alloys, whereas a gradual replacement of Sn by indium in susbstitutinal alloys is observed in the second type of catalysts. These results allowed preparing catalysts with high Pt3Sn alloy contents using the effect of indium in catalysts prepared by Sn organometallic controlled surface reactions (CSR). From a catalytic point of view, n-heptane reforming tests show that trimetallic PtSnIn-based catalysts are less selective to hydrogenolysis and hydrocracking reactions, and highly selective to isomerisation, compared to the bimetallic PtSn-based catalyst
Kozłowska, Magdalena. "Winkelaufgelöste XPS: Optimierung der mathematischen Modellierung und deren experimentelle Überprüfung." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=976612089.
Full textUntiedt, Ingo. "XPS- und SIMS-Untersuchungen an Systemen vom Typ LaNi5-xMexDy." [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=967391385.
Full textKozlowska, Magdalena. "Winkelaufgelöste XPS: Optimierung der mathematischen Modellierung und deren experimentelle Überprüfung." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1126554580144-69045.
Full textCass, Lindsey Margaret Rose. "An EPR and XPS study of paramagnetic species in wool." Thesis, Cardiff University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329602.
Full textKozlowska, Magdalena. "Winkelaufgelöste XPS: Optimierung der mathematischen Modellierung und deren experimentelle Überprüfung." Doctoral thesis, Technische Universität Dresden, 2004. https://tud.qucosa.de/id/qucosa%3A24564.
Full textSwarbrick, Janine Cathy. "Hydrogen bonded nanostructures on surfaces : STM, XPS and electrospray deposition." Thesis, University of Nottingham, 2006. http://eprints.nottingham.ac.uk/10245/.
Full textShamout, Karim [Verfasser], Carsten [Akademischer Betreuer] Westphal, and Mirko [Gutachter] Cinchetti. "MgO/Co/GaAs(001) - an interface analysis by means of XPS and XPD / Karim Shamout ; Gutachter: Mirko Cinchetti ; Betreuer: Carsten Westphal." Dortmund : Universitätsbibliothek Dortmund, 2018. http://d-nb.info/1173421467/34.
Full textTRAVAGLIA, ELISABETTA. "Study of the growth and of the electronic and structural properties of two-dimensional materials." Doctoral thesis, Università degli Studi di Trieste, 2018. http://hdl.handle.net/11368/2919624.
Full textIn the past ten years, after the isolation of graphene and the discovery of its outstanding properties, the scientific community has aimed its attention on a new class of materials, the two-dimensional (2D) atomic crystals, and particularly on the transition metal dichalcogenides (TMDCs). Though much effort is spent in the perspective of scaling up the production and integrating these materials in future electronic and optoelectronic devices, so far, a way towards sizable growth of 2D-TMDCs is still a challenge. This thesis is focused on the growth mechanism of TMDCs and studies aspects related to the nucleation process and the steps that lead to the formation of the crystals, in order to identify the optimal conditions to promote the increase of the domain size of the layers. In addition, the thesis investigates on the methods to produce TMDCs samples with a single domain orientation that allows to obtain better quality layers, thanks to the reduce presence of grain boundaries formed by the coalescence of islands with different orientations, and allows to open the path towards novel device concepts such as those based on the spin-valleytronic. This thesis is mainly devoted to the growth of MoS2 on different metallic substrates, namely Au(111), Ag(111) and Ag(110), with the aim of investigating the effect of the interaction between adlayer and substrate, and the effect of the substrate symmetry in the formation of extended layers of MoS2. In order to obtain a single domain orientation with respect to the substrate, a new growth protocol was developed on Au(111) and adapted also for the other substrates. The electronic structure of the MoS2/Au(111) sample was characterized, with a special attention to the out-of plane spin polarization of the bands near K and -K points of the Brillouin zone. We have subsequently explored the growth of single layer WS2 on Au(111) in order to evaluate the versatility of the developed growth method. By finding the proper growth parameters, we obtained high quality WS2 samples with a single orientation, that has been subsequently used to study the electron-phonon coupling thus deriving useful information for electronic device applications. The last part of the thesis is dedicated to the oxygen intercalation under graphene grown on Ir(111), with the aim of verifying whether the presence of graphene changes the adsorption geometry of the oxygen atoms on Ir(111). By comparing the results of oxygen adsorption on the bare Ir surface with those in the presence of graphene, it was possible to see that the oxygen overstructures formed under graphene can be reproduced on bare Ir(111) by dosing strongly oxidizing species such as NO2, concluding that graphene does not affect the adsorbate-substrate interaction.
Zier, Michael. "Untersuchungen zu Schichtwachstum und Grenzflächen an Ta-basierten Dünnschichten mittels XPS." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1196176876848-09306.
Full textChalker, Paul R. "The oxidation of nickel and titanium studied by XPS and XAES." Thesis, University of Liverpool, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371219.
Full textChallinor, David Clive. "An XPS study of the reactivity of tin and magnesium surfaces." Thesis, Cardiff University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375919.
Full textFraser, Stuart. "Angle resolved XPS study of the migration of a silane additive." Thesis, University of Sheffield, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369936.
Full textValov, Ilia, Bjoern Luerßen, Eva Mutoro, and Jürgen Janek. "In situ XPS study on the electrochemical nitrogen incorporation in YSZ." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-187944.
Full textValov, Ilia, Bjoern Luerßen, Eva Mutoro, and Jürgen Janek. "In situ XPS study on the electrochemical nitrogen incorporation in YSZ." Diffusion fundamentals 12 (2010) 66, 2010. https://ul.qucosa.de/id/qucosa%3A13896.
Full textLunt, Patrick Joseph Brian. "XPS studies of surface ageing and discharge processes in polymeric insulators." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/xps-studies-of-surface-ageing-and-discharge-processes-in-polymeric-insulators(2329d184-6677-4981-988e-e17b95bae229).html.
Full textTaylor, Michael. "To F-SIMS/XPS chemical depth profiling of synthetic polymer hydrogels." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/38755/.
Full textRIGOLDI, AMERICO. "Sulfur chemical state at mineral surfaces - An XPS and XAES investigation." Doctoral thesis, Università degli Studi di Cagliari, 2011. http://hdl.handle.net/11584/266328.
Full textPolčák, Josef. "Analýza povrchů pevných látek pomocí fotoelektronů - počítačové řízení experimentů." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-233975.
Full textGrissa, Rabeb. "Apport de la Spectroscopie Photoélectronique à rayonnement X à l’étude de nouveaux matériaux d’électrodes pour microbatteries au lithium." Thesis, Pau, 2017. http://www.theses.fr/2017PAUU3002.
Full textThe main evolutions required for microelectronic applications aim to integrate an energy microsource operating at lower potential than current systems. Thus, in order to meet this demand, this research work has been focused on the study, mainly by X-ray photoelectron spectroscopy (XPS), of two positive electrode materials operating at 3 V vs Li+/Li: the spinel-type material LiMn2O4 and the Nasicon-type one Fe2(MoO4)3. The bismuth, a potential negative electrode material likely to replace the metallic lithium and to undergo the soldering process conventionally used in microelectronics (the solder reflow), has also been studied in this work. Before studying these materials in all-solid-state systems, the first step consists in investigating their electrochemical behaviors in liquid electrolytes. For this purpose, 500 nm-thick thin films are prepared by magnetron sputtering after a step of deposition parameters optimization (power, partial and total pressures in the sputtering chamber, annealing temperature, etc.). Physicochemical proprieties of the deposited thin films are then investigated by XRD, SEM, XPS, RBS and ICP analyses. The analyses of the electrodes by XPS at the end of discharge and charge has allowed better understanding of the electrochemical reactions occurring within the electrode materials and at the electrode/electrolyte interfaces in lithium cells. A comparative study with cycling against sodium has also been carried out in the case of iron molybdate and bismuth materials. This has allowed identifying specific behaviors of the thin films during the insertion/extraction of the two alkalis. The homogeneity of the thin films lithiation/sodiation has also been studied from various XPS analyses realized after etching process which allows eliminating the passivation layer formed at the electrode/electrolyte interface.This study contributes to a better knowledge of three potential electrode materials candidates for lithium micro-batteries and presents very interesting perspectives of materials integration in all solid state systems
Wang, Danghan. "An EPR and XPS study of transition metal ions doped on wool." Thesis, Cardiff University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305135.
Full textPokorný, David. "Studium morfologie velmi tenkých vrstev XPS analýzou více spektrálních čar jednoho prvku." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-402568.
Full textPISU, MANUELA. "Stability of dental alloys in artificial saliva: an electrochemical and XPS investigation." Doctoral thesis, Università degli Studi di Cagliari, 2014. http://hdl.handle.net/11584/266430.
Full textJiang, Tingming. "Adsorption of chalcogen-based aromatic organic molecules on metal and dielectric surfaces by self-assembly and molecular beam expitaxy." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS581.
Full textIn this thesis, formation of self-assembled monolayers of different chalcogenide molecules and organic semiconductor thin films was investigated. Their electronic and structural characteristics have been investigated primarily by synchrotron based X-ray photoelectron, near edge X-ray absorption fine structure spectroscopy, Atomic force microscopy and low energy electron diffraction. In addition, the adsorption characteristics of selenium and sulfur were studied as a complement to the study of adsorptions of chalcogen headgroup molecules. The high resolution XPS was employed to investigate the self assembled monolayers of benzeneselenol and selenophene on Cu(111). The detailed study of characteristic core level peaks demonstrated the existence of different absorption sites of the molecules and also along with NEXAFS measurements the occurrence of Se-C bond cleavage. These conclusions are supported by the study of atomic selenium adsorptions showing also different absorption sites for the atomic selenium with different chemical environments based on high resolution XPS study of characteristic Se3d, Se3p spectra and LEED imaging. The adsorptions of polythiophene molecules (nT, n=1-4, 6) as well as for α, ω-diquaterthiophene (DH4T) and dihexylsexithiophene (DH6T) on Au(111) and Au films grown on mica was studied. The results indicate that the XPS S2p peaks have contributions from intact molecules on different adsorption sites and broken molecules complemented. These conclusions are supported by existing DFT calculations. Spontaneous dissociation appears to a variable extent in different cases, which could be related to different surface morphologies, existence of defects and ensuing differences reactivity.α-Sexithiophene (6T) ultrathin films were grown on CaF2(111)/Si(111) planar surfaces and on CaF2(110)/Si(001) ridged surfaces by molecular beam epitaxy. The AFM image of 6T on CaF2(111) shows large islands with flat terraces without in-plane preference, while narrow and elongated islands following the substrate corrugation are formed for 6T on CaF2(110). XPS and NEXAFS spectra indicate that the interactions between 6T and surfaces are negligible, and the molecules align with their long axis perpendicular to the surfaces for both cases
Boucly, Anthony. "Catalytical reactions and environmental chemistry modifications as seen by synchrotron radiation NAP-XPS." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066237/document.
Full textThe NAP-XPS is a revolutionary new tool that makes possible to use the advantages of a standard XPS analysis (sensitivity to the different chemical elements as well as their states) at a near-ambient pressure (mbar range) thus enabling in situ studies closer to real conditions. Two fields fully benefit from this new machine: environmental chemistry and catalysis. In our case for the field of environmental chemistry we are interested in studying the hydration of so-called swelling clays. I have here demonstrated that it is indeed possible to follow the hydration of counter-ions and highlighted different behavior according to their natures. Moreover, I have been able to demonstrate a beam induced pyridine photolysis phenomenon in the presence of water in these confined media. Concerning catalysis, I studied the oxidation of CO on nanocatalysts composed in particular of platinum an excellent catalyst but sensitive to the CO poisoning. This reaction is for us a prototypical reaction to test the behavior of Pt, Zn, PtZn nanocatalysts. Here, I have been able to determine the onset temperature of the CO oxidation reaction. Moreover, by adding zinc to platinum and forming a bimetallic nanocatalyst, I have improved its resistance to oxidation and proved that zinc alone is also capable of catalyzing the oxidation of CO in the form of creation / destruction of carbonate
Selwyn, John. "A Mass Spectrometry and XPS Investigation of the Catalytic Decompostion of Formic Acid." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/22911.
Full textSegala, Maximiliano. "Calculos de energias de ligação de camada interna pelo uso da teoria do funcional de densidade e suas aplicações." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/249741.
Full textTese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica
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Mueanngern, Yutichai. "Mechanistic Studies of Crotonadehyde Partial Hydrogenation and Ethanol Steam Reforming Reactions on Planar Catalysts—A Gas-Phase and Ambient Pressure XPS Study." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1576076945070127.
Full textDally, Pia. "Cellules Solaires à base de Matériaux Pérovskites : De la caractérisation des matériaux à l’amélioration des rendements et de la stabilité." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAI093.
Full textIn the past few years, hybrid perovskite solar cells have attracted a considerable amount of research and have undergone rapid development as next generation photovoltaics. The power conversion efficiency has then been rapidly increasing and has recently exceeded 25%. This class of materials has interesting optoelectronic properties such as a high optical absorption, a large diffusion length of the charge carriers as well as a low manufacturing cost. Nevertheless, there are several challenges that need to be addressed before commercialization will be possible, most significantly the long-term stability. In this thesis work, the main goal is to understand and improve the performance and stability under illumination of N-I-P perovskite-based solar cells. A detailed study of the reference system using CH3NH3PbI3 perovskite (MAPI) is presented by studying the formation mechanism of MAPI and its thermal behavior after annealing by XRD techniques. It showed that MAI and PbCl2 precursors initially form a MAPbCl3 layer, which transforms to MAPbI3 in an anion exchange reaction during thermal annealing, inducing a high level of strain in the MAPI layers. Solar cells were aged under continuous illumination (1 sun / 35°C) and showed severe efficiency loss. The origin of devices instability under illumination were investigated in depth thanks to the differential aging. It consists in aging the different layers under illumination before the deposition of top layers in order to determine the key parameter (layer or interface) responsible of this degradation. Results have shown that for long time scales, the upper layers (P-layer and gold electrode are responsible of solar cells degradation, while the N layer / MAPI interface causes degradation at the first hundred hours. To get further insight into the role of ETL / MAPI interface on device behavior; advanced characterization methods, combining XPS and ToFSIMS, were developed and made it possible to study the degradation of the stack glass / ITO / N layer / MAPI, aged under illumination. Improved system with double cations perovskite Cs0.05FA0.95Pb (I 0.83Br0.17)3 have also been studied and show better stability under illumination of complete cells
PATERA, LAERTE LUIGI. "In situ and in operando study of graphene growth and properties on metal surfaces." Doctoral thesis, Università degli Studi di Trieste, 2016. http://hdl.handle.net/11368/2907990.
Full textGraphene, a single layer of C atoms, has been recently proposed as a good candidate for post-silicon technology, providing a new platform that could allow improving electronic device performances, as described by the Moore’s Law. Chemical Vapour Deposition (CVD) is a suitable synthesis method for large-scale production of high quality graphene. This process exploits the catalytic activity of transition metal surfaces in dissociating hydrocarbon molecules. Among the possible catalysts, Ni is an appealing choice, due to the low price and the possibility to obtain graphene layers at temperature as low as 400°C. From a more fundamental point of view, graphene growth on the (111) surface of Ni represents a peculiar case of lattice-matched system, being a good model system for the study of the substrate effects on graphene properties. In this thesis, we study the growth process, the morphology and the electronic properties of graphene on Ni(111), by means of Scanning Tunneling Microscopy (STM), X-ray Photo-Emission Spectroscopy (XPS) and spectro-microscopy techniques. First, the different graphene structures are identified through a combined experimental and theoretical approach, revealing the coexistence of three epitaxial adsorption geometries and the possibility to obtain graphene domains that exhibits a rotation respect with the underlying substrate. Band structure mapping reveals specific changes in the electronic properties, depending on the degree of graphene orbital hybridization with the metal. Based on these findings, graphene growth is investigated by in-situ STM and XPS, clarifying the atomistic mechanisms under different experimental conditions and assessing the crucial roles played by surface carbide and C-contamination. In particular, we study the correlation between the CVD parameters, the growth process and the final graphene structures, being able to provide recipes for the synthesis of graphene layers with tailored morphologies. The atomic structure of graphene edges is studied, both during the growth, by means of high-speed STM measurements, and after cooling down to room temperature, addressing the importance of dangling bonds passivation. Then, employing the video-rate capability of our STM system, we identify the active sites for C attachment during growth, revealing the active role of Ni adatoms. Next, intrinsic defective structures are examined at the atomic scale by STM and ab-initio calculations, showing the presence of substitutional Ni adatoms trapped in the graphene matrix, as well as grain boundaries and lattice distortions. Finally, the growth and electronic properties of bi-layer graphene are investigated, revealing the possibility to exploit the lattice match between graphene and Ni(111) to limit the formation to two layers only.
Kotsis, Konstantinos. "Ab-initio-Rechnungen zu O1s-XPS-Spektren von reinen und adsorbatbedeckten ZnO-Oberflächen." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=982351348.
Full textLebiedz, Dirk. "Wasserstoffinduzierte Effekte im System Nd2(Fe/Co)14B eine SIMS- und XPS-Studie /." [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=967429897.
Full textTissot, Héloïse. "Beyond the gap of pressure : XPS studies of interfaces at near ambient pressures." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066615/document.
Full textIn many processes or technological objects, such as coating deposition, advanced material processing for electronics, magnetic or optical devices, electrochemical processes at an electrode, sensors and catalysis, etc. the interface between a surface of a solid and a liquid or a gas phase, plays a prominent role. Analogously, environmental sciences and sciences of the Living integrate into their models chemical reactions taking place at solid/liquid or liquid/gas interfaces.XPS is a powerful technique for interface analysis and has been widely use in the case of solid surface. The main advantage of XPS is its sensitivity to the material surface. Indeed, due to the low electron mean free path of electrons in a solid, only the photoelectrons at the extreme outer surface (1-10 nm) can escape the sample. However, XPS has traditionally been conducted under ultra-high vacuum (UHV) conditions. UHV conditions are utilized for two reasons. First, the analyzers are designed to work under UHV conditions. Second, the electrons must reach the detector and their mean free path is short at high pressures. For example at a pressure of 1 mbar, 100 eV electrons will travel 1 mm while under UHV conditions, the mean free path increases to 105 m. UHV chambers (10-10 mbar) help maximize the mean free path so that a high number of electrons will reach the detector/analyzer and the signal/noise ratio will increase making it possible to analyze the spectrum produced. This constraint makes UHV the standard environment of X-ray Photoelectron Spectroscopy (XPS) experiments.In order to make possible the use of XPS on a larger pressure range, a few groups around the world have designed photoemission equipment that can be operated under ambient pressure (up to 5 mbar). The Berkeley group (M. Salmeron LBNL-Materials Sciences Division, H. Bluhm LBNL-Chemical Sciences Division), who pioneered this field, has two such setups installed at the Advanced Light Source. The Fritz Haber Institute has built a high pressure XPS based on the Berkeley prototype, installed at BESSY synchrotron (Berlin), since 2002. The building of Ambient Pressure XPS (APXPS) analyzers of the Berkeley type, able to be operated at pressures in the range of 1 mbar, about 7 orders of magnitude higher than the pressure limit of conventional UHV equipment is both a technological and conceptual breakthrough. Differential pumping stages allow the sample to remain at environmental pressures, while maximizing the mean free path of emitted electrons, so they can reach the detector. Additionally, voltages are applied to electrostatic lenses in the unit to accelerate and focus the electrons onto the focal plane of the electron energy analyzer. A similar system Near-Ambient Pressure XPS, NAP-XPS), described in details in chapter 1, was delivered in December 2012 and installed at TEMPO beamline in February 2013. The first beamtime occurred in May 2013. During my thesis that started in October 2011 two different projects were developed, both related to interface analysis using the NAP-XPS instrument
Leroy, Stéphane. "Etude d'interfaces électrode/électrolyte dans les batteries Li-ionApproche par XPS et AFM." Pau, 2006. http://www.theses.fr/2006PAUU3033.
Full textThe lithium-ion batteries are today the principal source of energy of portable electronics (telephones, computers. . . ). Their capacity (quantity of electricity being able to be provided) is controlled by the electronic and crystallographic structure materials of electrode, whereas their behaviour in cycling and their lifespan are strongly related to the interface électrode/électrolyte. In this work of thesis, we undertook the thorough study of interfacial layers using adapted techniques of analysis of surface allowing obtaining chemical and morphological information : the X-ray photoelectronic spectroscopy (XPS) and atomic force microscopy (AFM). A significant share of work was devoted to the study of the layers formed on the level of material of negative electrode (graphite) of a commercial lithium-ion battery : LiCoO2// EC/DMC/DEC (2/2/1); LiPF6 (1mol. L-1)// graphite. Original approaches of analysis were implemented : 1) Thorough study of reference's composed; various breakdown products of solvent and the salt of the electrolyte were characterized thoroughly by XPS. 2) Study of the process of formation of the layer by the means of systematic analyses XPS and AFM in various states of load by a follow-up step by step. 3) The influence of the electrolyte's nature was also examined. We then approached the study of the interfacial layers formed on the level of the positive electrode (LiCoO2) of the commercial battery Li-ion. An extension of work to other promising materials of negative electrode (Cu6Sn5, CoSn2) was also undertaken
Choudhury, Tanima. "An XPS study of the effect of ion bombardment on transition metal oxides." Thesis, Aston University, 1991. http://publications.aston.ac.uk/25142/.
Full textJackman, Mark. "The functionalisation and defects of titania : a photoemission study." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/the-functionalisation-and-defects-of-titania-a-photoemission-study(d199335c-cb3d-4f08-964f-d84541a464cc).html.
Full textEglizaud, Noëlle. "Rétention et réduction de l'uranium à la surface de la pyrite." Paris 11, 2006. http://www.theses.fr/2006PA112230.
Full textIn the hypothesis of a storage of the spent fuel in a deep geological formation, understanding the uranium dispersion in the environment is important. Pyrite is a reducing mineral present in the Callovo-Oxfordian argilites, the geological formation actually studied for such a storage. However, pyrite impact on uranium migration has already been poorly studied. The aim of the study was to understand the mechanisms of uranium(VI) retention and reduction on the pyrite surface (FeS2). Solution chemistry was therefore coupled with solid spectroscopic studies (XPS and Raman spectroscopy). All uranium-pyrite interactions experiments were performed under an anoxic atmosphere, in a glove box. Pyrite dissolution under anoxic conditions releases sulphoxyanions and iron(II), which can then be adsorbed on the pyrite surface. This adsorption was confirmed by interaction experiments using iron(II) isotopic dilution. Uranium (VI) is retained by an exchange reaction with iron(II) adsorbed on sulphur sites, with a maximal amount of sorbed uranium at pH ≥ 5. 5. Cobalt(II) and europium(III) are also adsorbed on the pyrite surface above pH 5. 5 confirming then that reduction is not required for species to adsorb on pyrite. When the concentration of uranium retained is lower than 4x10-9 mol g-1, an oxidation-reduction reaction leads to the formation of a uranium (VI) – (IV) mixed oxide and to solid sulphur (d. O. > -I). During this reaction, iron remains mostly at the +II oxidation degree. The reaction products seem to passivate the pyrite surface: at higher amounts of retained uranium, the oxidation-reduction reaction is no longer observed. The surface is saturated by the retention of (3. 4 ± 0. 8)x10-7 mol L-1 of uranium(VI). Modelling of uranium sorption at high surface coverage (≥ 4x10-9 mol g-1) by the Langmuir model yields an adsorption constant of 8x107 L mol-1. Finally, a great excess of uranium(VI) above the saturation concentration allows the observation of an oxidation-reduction reaction between unadsorbed uranium(VI) and iron(II), coming from pyrite dissolution. The reaction products are then reduced uranium, such as U4O9(s), and iron(III) (hydr)oxides, such as maghemite g-Fe2O3 (s), the remaining uranium(VI) in the supernatant being possibly adsorbed on this new formed phase