Tesis sobre el tema "Ultra high vacuum"
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Barreto, Suzana Maria. "Towards autonomous sample positioning for ultra high vacuum chambers". Thesis, Aberystwyth University, 2018. http://hdl.handle.net/2160/77e7f40d-eb63-4062-bc1f-e5e4e7d102a9.
Texto completoSchambach, Philip [Verfasser]. "Tip-enhanced Raman spectroscopy in ultra-high vacuum / Philip Schambach". Berlin : Freie Universität Berlin, 2013. http://d-nb.info/104348079X/34.
Texto completoWoodburn, Charles N. "Development of low-temperature, ultra high vacuum, scanning tunnelling microscope". Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264506.
Texto completoPires, Ellis John. "Electrical conductivity of single organic molecules in ultra high vacuum". Thesis, Cardiff University, 2013. http://orca.cf.ac.uk/56796/.
Texto completoBaily, Christopher John. "UHV studies of the adsorption of small adsorbate molecules on low index platinum single crystals". Thesis, University of Southampton, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288413.
Texto completoAl-Rawi, S. A. N. "Silicon sublimation at ultra high vacuum with microprocessor monitoring and measurements". Thesis, University of Kent, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382189.
Texto completoEbert, Helen Diane. "The study of adsorbed species using electrochemical and ultra high vacuum techniques". Thesis, University of Southampton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.255669.
Texto completoʿAẓīm, Muḥammad. "Ultra high vacuum-scanning electron microscope studies of Cs/Si(100)-2x1". Thesis, University of Sussex, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385984.
Texto completoNewton, Mark A. "Alloy effects in catalysis : the structure and reactivity of the CuPd[85:15]{110}p(2x1) surface". Thesis, University of Liverpool, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240235.
Texto completoLee, King Hung. "Ellipsometric studies of the nucleation of zinc sulphide films in ultra-high vacuum". Thesis, Queen's University Belfast, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335519.
Texto completoHöfer, Katharina. "All in situ ultra-high vacuum study of Bi2Te3 topological insulator thin films". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-220737.
Texto completoDer Begriff "Topologischer Isolator" (TI) beschreibt eine neuartige Klasse von Verbindungen deren Inneres (engl. Bulk) isolierend ist, dieses Innere aber gleichzeitig und zwangsläufig eine metallisch leitende Oberfläche aufweist. Dies ist begründet in der nicht-trivialen Topologie dieser Materialien, welche durch eine spezielle Invertierung einzelner Bänder in der Bandstruktur und der Spin-Bahn-Kopplung im Materialinneren hervorgerufen ist. Diese topologisch geschützten, metallischen Oberflächenzustände sind gekennzeichnet durch eine masselose Dirac Dispersionsrelation und gekoppelte Helizität der Spinpolarisation, welche die Rückstreuung der Ladungsträger verbietet und somit zur Stabilisierung der Zustände gegenüber Störungen beiträgt. Auf Grundlage dieser außergewöhnlichen Merkmale haben Theoretiker eine Fülle neuer Phänomene und spannender Experimente vorhergesagt. Deren experimentelle Überprüfung steht jedoch noch aus, geschweige denn deren Umsetzung in Anwendungen, wie zum Beispiel die Erzeugung von Majorana Teilchen, fortgeschrittene Spintronik, oder die Realisierung von Quantencomputern. Aufgrund ihrer relativ einfachen Bandstruktur, welche nur einen Dirac-Kegel an der Oberfläche aufweist, haben die 3D TI Bi2Te3 und Bi2Se3 in den letzten Jahren großes Interesse erlangt. Weiterhin besitzen diese Materialien eine merkliche Bandlücke von bis zu ~0,3 eV, welche sogar Anwendungen bei Raumtemperatur ermöglichen könnten. Dennoch ist deren experimentelle Umsetzung nachwievor eine enorme Herausforderung. Das Haupthindernis, welches bis jetzt insbesondere die elektrische Charakterisierung the topologischen Oberflächenzustände behindert hat, ist die zusätzliche Leitfähigkeit des Materialinneren, welche durch Kristalldefekte und Beimischungen, sowie die Verunreinigung der Probenoberfläche durch Luftexposition bedingt wird. Die vorliegende Arbeit liefert einen Beitrag zu aktuellen den Anstrengungen in der Verbesserung der Probenqualität der TI um die Leitfähigkeit des Materialinneren zu unterdrücken, sowie die anschließende Untersuchung der elektrischen Eigenschaften unter kontrollierten Bedingungen durchzuführen. Weiterhin sollen geeignete Deckschichten identifiziert werden, welche die besonderen elektronischen Merkmale der TI nicht beeinflussen sowie diese gegen äußere Einflüsse schützen, und somit die Durchführung anspruchsvoller ex situ Experimente ermöglichen können. Die untersuchten Bi2Te3 Schichten wurden mittels Molekularstrahlepitaxie (MBE) hergestellt. Es konnte gezeigt werden, dass es allein durch Optimierung der Wachstumsbedingungen möglich ist Proben herzustellen, die gleichbleibend isolierende Eigenschaften des TI Inneren aufweisen und Eindomänen-Ausrichtung besitzen. Die zentralen Faktoren sind hierbei die Aufrechterhaltung eines Flussratenverhältnisses von Te/Bi ~8 der einzelnen Elemente, sowie die Wahl einer ausreichend hohen Substrattemperatur, um ein vollständiges Abdampfen (Destillation) des überschüssigen Tellur zu erreichen. Weiterhin müssen Substrate mit gut angepassten Gitterparametern verwendet werden, welches bei BaF2 (111) gegeben ist. Optimales MBE Wachstum konnte durch ein Zwei-Stufen Prozess bei Substrattemperaturen von 220°C und 250°C und einer Bi-Verdampfungsrate von 1 Å/min erreicht werden. Die nachfolgende Charakterisierung der strukturellen Eigenschaften, Photoelektronenspektroskopie, sowie temperaturabhängige Leitfähigkeitsmessungen wurden alle in einem zusammenhängenden Ultrahochvakuum-System durchgeführt. Auf diese Weise wird eine zuverlässige Erfassung der intrinsischen Eigenschaften der TI sichergestellt. Zur Überprüfung, ob die Leitfähigkeit der Proben tatsächlich nur durch die Oberflächenzustände hervorgerufen wird, wurden Filme mit Schichtdicken im Bereich von 10 bis 50 Quintupel-Lagen (QL; 1QL~ 1 nm) hergestellt und charakterisiert. Winkelaufgelöste Photoelektronenspektroskopie (ARPES) belegt, dass das chemische Potential (Fermi-Niveau) in allen Proben innerhalb der Bandlücke der Bandstruktur des Materialinneren liegt und nur von den topologisch geschützten Oberflächenzuständen gekreuzt wird, welche die charakteristische lineare Dirac Dispersionsrelation aufweisen. Die temperaturabhängigen Widerstandsmessungen zeigen ein metallisches Verhalten aller Proben. Bei der Variation der Schichtdicke von 10 zu 50QL wird eine Streuung des Flächenwiderstandes vom Faktor 1,3 bei 14K und 1,5 bei Raumtemperatur beobachtet. Dies beweist, dass die gemessene Leitfähigkeit vorrangig durch die topologisch geschützten Oberflächenzustände hervorgerufen wird. Eine geringe Oberflächenladungsträgerkonzentration im Bereich von 2–4*10^12 cm^−2 und hohe Mobilitätswerte von bis zu 4600 cm2/Vs wurden erreicht. Weiterhin wurden die negativen Auswirkungen auf die Eigenschaften der TI durch Luftexposition quantifiziert, welches die Notwendigkeit belegt, die Oberfläche der TI vor Umgebungseinflüssen zu schützen. Die Proben verhalten sich inert gegenüber reinem Sauerstoff, daher ist Wasser aus der Luftfeuchte höchstwahrscheinlich der Hauptgrund für die beobachtbare Verschlechterung. Darüber hinaus konnte epitaktisch gewachsenes Tellur als geeignete Deckschicht ausfindig gemacht werden, welches die Eigenschaften der Bi2Te3 Filme nicht beeinflusst, sowie gegen Veränderungen durch Luftexposition schützt. Die gewonnenen Erkenntnisse stellen eine ideale Grundlage für weiterführende Untersuchungen dar und ebnen den Weg zur Entwicklung von Bauelementen welche die spezifischen Besonderheiten der topologischen Oberflächenzustände
Lain, amador Lucia. "Production of ultra-high-vacuum chambers with integrated getter thin-film coatings by electroforming". Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCD006/document.
Texto completoTitanium Zirconium Vanadium (TiZrV) thin film coatings are used in particle accelerators and synchrotron light sources to maintain ultra-high vacuum conditions. They are deposited on the internal walls of the vacuum chambers, transforming them from a gas source into a chemical pump. The trend in electron accelerators design consists in approaching the poles of the steering magnets close to the electron beam. This implies reducing the bore hosting the vacuum chamber and using very small diameter vacuum pipes. The application of physical vapor deposition (PVD) in such small diameter chambers becomes then very difficult. The aim of this project is to develop a novel procedure of coating/assembly, using a sacrificial aluminium mandrel as substrate of the thin film together with the creation of a surrounding copper chamber by electroforming. The first part of the study deals with the production and characterization of the electroformed chambers. The mechanical robustness of the assembly is checked, and the film characterization is performed by secondary electron microscopy (SEM), X-ray diffraction analysis (XRD), X-ray Fluorescence Spectroscopy (XRF) and X-Ray Photoelectron Spectroscopy (XPS). Moreover, the pumping performance is measured and compared with reference values of coatings produced by the standard PVD technique. The second part of the study evaluates the impurities included during the different steps of the process: PVD coating, electroforming and chemical etching of the mandrel. Thermal desorption spectroscopy and XPS depth profiling allow to quantify the impurities in the electroformed copper and the TiZrV thin film. Furthermore, the presence of hydrogen trapped in the electroformed copper is studied for different copper sulphate baths. One of them, without additives, require the use of pulse currents. The electrochemical behaviour of the bath allows the selection of different pulse parameters, derived from typical situations on the transient curves. Finally, the development of real-scale prototypes was achieved with the creation of a 4 mm diameter, 2 meters TiZrV coated vacuum chamber, which is unrivalled up to date
Taylor, Martin. "The ultra-selective hydrogenation of furfural on PtCu supported bimetallic nanoparticles and on Pt(111) under ultra-high vacuum". Thesis, Aston University, 2017. http://publications.aston.ac.uk/33308/.
Texto completoGedik, Abdullah. "Energy threshold for laser induced breakdown on a metal surface under high and ultra high vacuum conditions". Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/28165.
Texto completoHamann, Christian [Verfasser]. "An Electrospray Ion Source for Ultra-High Vacuum Deposition of Organic Molecules / Christian Hamann". Kiel : Universitätsbibliothek Kiel, 2011. http://d-nb.info/104859226X/34.
Texto completoFostner, Shawn. "Ultra high vacuum fabrication of metallic contacts for molecular devices on an insulating surface". Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=95011.
Texto completoLa préparation et la caractérisation de fils métalliques sur des substrats isolants par une variété de mécanismes a été explorée. Une approche multi-échelle utilisant des masques-stencils microfabriqués de silicium, l'électromigration contrôlée par rétroaction, et le dépôt induit par champ en nouvelle géométrie d'agrégats métalliques, a été explorée sur des substrats de bromure de potassium (KBr), de phosphure d'indium (InP) et d'oxyde de silicium sous Ultra Haut Vide (UHV). Le dépôt initial de fils d'or et de tantale entre cent nanomètres et quelques micromètres a été réalisé en utilisant des nanostencils au silicium renforcé. La fabrication des stencils a été discutée, et un examen de la déformation des structures intégrées dans le cas du dépôt de couches de tantale sous hautes contraintes a montré qu'elle était significativement plus petite que pour les structures typiques. Les fils métalliques déposés à l'aide de ces stencils, ainsi que la lithographie par faisceau électronique ont été mis sous contrainte électriquement et les caractéristiques de rupture analysées. Des vides typiques à l'échelle du nanomètre ont été observés, ainsi que des structures communément retrouvées dans la rupture de structure de type bambou dans les fils d'or de 100nm et moins, en particulier avec une résistance en série importante. Ces vides plus grands devraient être plus applicables pour le dépôt par la suite d'agrégats métalliques et la préparation de dispositifs moléculaires. Une étape a été franchie vers la connexion des fils déposés initialement ainsi que de molécules localisées de façon imageable, en réalisant un modèle et des expériences de dépôt induit par champ d'agrégats d'or sur KBr et InP. Le dépôt sur des substrats InP avec derrière un gaz d'électrons 2D comme contre-électrode a démontré la faisabilité de cette technique de dépôt sous UHV. Des dépôts ultérieurs sur ou
Manzoor, Tahir. "Ellipsometric studies of the nucleation and growth of thin films in ultra high vacuum". Thesis, Queen's University Belfast, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335428.
Texto completoLuhman, Xavier D. "Sulfurizing and selenizing metal films in ultra-high vacuum by hydride gas kinetic control". Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122393.
Texto completoThesis: S.B., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2019
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (page 30).
Molecular beam epitaxy (MBE) is an important, well-established method for creation of thin films. The addition of gaseous sources of hydrogen sulfide and hydrogen selenide is not currently a well-documented or common modification to such systems. While the thermodynamics of using such sources for the production of various chalcogenide thin films are favorable, the actual results thus far do not demonstrate the desired outcome. This indicates that the kinetics of the desired reactions are inhibiting the process. Compared to oxygen, reactions involving sulfur and selenium are slow. In order to ensure that the hydride gases have the opportunity to react as desired, it is necessary to keep the system free of oxygen and to maximize the collisions of gas molecules with the substrate. The first requirement should be achieved simply by using MBE for the process. The second requirement is not provided for in a typical MBE system. Thus, modifications are necessary to increase the reaction rate of the gases, namely by extending the source lines to be closer to the substrate. This thesis addresses the design process for tubing inserts in an existing MBE system.
by Xavier D. Luhman.
S.B.
S.B. Massachusetts Institute of Technology, Department of Materials Science and Engineering
Lautenschlager, Eric J. "Silicon nanoclusters : ultra high vacuum laser ablation fabrication and in situ scanning tunneling microscopy characterization /". Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
Texto completoDay, Brian Scott. "The Dynamics of Gas-Surface Energy Transfer in Collisions of Rare Gases with Organic Thin Films". Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/29860.
Texto completoPh. D.
Morse, Michael Ty. "Growth of erbium-doped Si/SiGe double heterostructures by ultra-high vacuum chemical vapor deposition". Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10380.
Texto completoStojilovic, Nenad. "Interaction of gases with Zr(0001) and Zircaloy-4 surfaces under ultra-high vacuum conditions". University of Akron / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=akron1132677151.
Texto completoMagnano, Graziano. "Elestrospray deposition in ultra-high vacuum : the development of a deposition system for non-volatile molecules". Thesis, University of Nottingham, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546586.
Texto completoKURIMOTO, Shinji, Kenji HIROTA, Daisuke TOKUMOTO y Toshihiko MORI. "Improving High Precision and Continuous Process of Ultra-Fine Piercing by SiC Fiber Punch". The Japan Society of Mechanical Engineers, 2004. http://hdl.handle.net/2237/9036.
Texto completoHaglund, Adam. "Reduction of hydrogen embrittlement on Electrogalvanized Ultra High Strength Steels". Thesis, Uppsala universitet, Institutionen för kemi - Ångström, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-236603.
Texto completoWeiss, Christian [Verfasser]. "STM beyond vacuum tunnelling : scanning tunnelling hydrogen microscopy as a route to ultra-high resolution / Christian Weiss". Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2012. http://d-nb.info/1028003706/34.
Texto completoCooper, Kevin W. "Characterization of Diamond Like Carbon Thin Films Fabricated by Unbalanced Magnetron Sputtering under Ultra-High Vacuum Conditions". Ohio University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1373458861.
Texto completoClark, Kendal. "Ultra High Vacuum Low Temperature Scanning Tunneling Microscope for Single Atom Manipulation on Molecular Beam Epitaxy Grown Samples". Ohio University / OhioLINK, 2005. http://www.ohiolink.edu/etd/view.cgi?ohiou1125611713.
Texto completoTekiel, Antoni. "Ultra-high vacuum fabrication of nanoscale systems for studying single-electron charging by room-temperature atomic force microscopy". Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=119570.
Texto completoDans ce travail, nous décrivons la fabrication sous ultra haut vide (UHV) d'un système à l'échelle nanométrique qui révèle le blocage de Coulomb à température de la pièce, ainsi que sa caractérisation par microscopie à force électrostatique sensible à un électron (single-electron sensitive electrostatic force microscopy, e-EFM). Le système est constitué de nanoparticules d'or séparées d'une électrode de Fe(001) par un film cristallin ultra mince de NaCl. Dû à la petite taille des nanoparticules (3.5 nm maximum), le blocage de Coulomb est observable à température ambiante. Un cantilever de microscope à force atomique (MFA) est utilisé comme une grille électrique déplaçable pour charger individuellement les nanoparticules par le passage de charge élémentaire par effet tunnel à partir de l'électrode. Ce passage d'électron est détecté en mesurant simultanément le changement de fréquence de résonance, ainsi que l'amortissement de l'oscillation du cantilever. La technique e-EFM permet de contourner certaines limitations inhérentes aux techniques de caractérisation basées sur la fabrication par lithographie. Toutefois, cette technique a été appliquée avec succès seulement à basses températures. Dans ce travail, nous étendons la technique e-EFM à température ambiante par un ajustement minutieux du design de l'échantillon et de sa fabrication en fonction de la réponse du cantilever de sorte à maximiser la sensibilité de la mesure. Pour croître une jonction tunnel définie à l'échelle atomique, nous étudions la morphologie de couches minces de MgO et de NaCl sur une surface de Fe(001) par microscopie à force atomique non-contact et par diffraction d'électrons lents (Low Energy Electrons Diffraction, LEED). Premièrement, nous démontrons que la qualité des couches minces de MgO, typiquement crûes sous UHV par évaporation sous faisceau d'électrons (electron-beam evaporation), peut être améliorée par l'utilisation d'une méthode de déposition réactive qui donne un contrôle total sur les espèces gazeuses présentes dans le faisceau d'évaporation. Deuxièmement, nous étudions l'effet de la température et de la présence d'oxygène sur la croissance du NaCl sur une surface de Fe(001). Conséquemment, un protocole pour la croissance de films de NaCl sur une surface de Fe(001)-p(1x1)O déposés couche par couche. Ces films plats à l'échelle atomique présentent des terrasses de 40-60 nm de large et contiennent beaucoup moins de défauts cristallins que les films de MgO.En utilisant ces couches minces de NaCl comme jonction tunnel facilement ajustables par une modification de leur épaisseur, nous caractérisons le chargement d'électron à température ambiante de nanoparticules individuelles formées par évaporation thermique sur un film de 6 monocouches de NaCl. Nous montrons comment la combinaison de la technique e-EFM et de simulations électrostatiques par éléments finis peut être utilisée pour révéler les propriétés électroniques et morphologiques de nanoparticules d'or individuelles. Ainsi, l'énergie de chargement, la capacitance, la fréquence de passage par effet tunnel et la forme approximative des nanoparticules ont été déterminées. Des simulations numériques montrent que la capacitance totale est dominée par la capacitance mutuelle entre la nanoparticule et l'électrode. En comparant avec les valeurs expérimentales, déterminées par une mesure de l'énergie de chargement, on montre que les nanoparticules devraient être modélisées par des sphères tronquées pour réduire la capacitance mutuelle avec le substrat. Cette observation a un impact fondamental pour le design de circuits nanoélectroniques dans lesquels les composantes doivent avoir des capacitances définies, étant donné que celles-ci déterminent les effets de couplage et de chargement.La flexibilité de la technique de fabrication et le fait que toutes les mesures ont été effectuées in situ sur des échantillons dans des conditions ultra propres rendent le système attrayant pour de futures études.
Roos, Mathias. "Emissão de eletrons por efeito de campo em diamante policristalino dopado com boro e desenvolvimento de um novo sistema de ultra alvo vacuo". [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259948.
Texto completoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
Made available in DSpace on 2018-08-11T10:03:42Z (GMT). No. of bitstreams: 1 Roos_Mathias_M.pdf: 4816472 bytes, checksum: 51a357faa29ccbd01723b1d6ca5abf27 (MD5) Previous issue date: 2007
Resumo: Na primeira parte deste trabalho amostras de diamante poli-cristalino dopado com boro foram crescidas por deposição química a vapor assistida por filamento quente. As características de emissão de campo foram investigadas. A dopagem (NB) em amostras diferentes foi variada pelo controle da concentração B/C no fluxo de gases durante o processo de crescimento. Os campos limiares (Eth) para emissão de campo foram medidos e relacionados com as concentrações B/C usadas. Assim, a influência das bordas entre os grãos, a dopagem e a morfologia da superfície na emissão de campo foram investigadas. A saturação da dopagem foi observada para altas concentrações B/C. O transporte de cargas através das bordas entre os grãos e as propriedades locais de emissão na superfície foram modeladas por dois mecanismos que afetam a emissão de campo. Correntes de emissão de 500 nA·cm-2 foram obtidas para campos elétricos de 8 V·µm-1. Na segunda parte desta tese, a construção de um novo sistema de ultra alto vácuo (UHV) para realizar medições de emissão de campo é descrita. A construção inclui o projeto integral de uma câmara de UHV com sistema de bombas, conjunto de manipuladores, suportes mecânicos e a infraestrutura do laboratório
Abstract: In the first part of this thesis, the study of field emission properties of hot filament chemical vapor deposited boron doped polycrystalline diamond is described. The doping level (NB) of different samples was varied controlling the B/C concentration in the gas feed during the growth processes. The threshold field (Eth) for electron emission in dependence on different B/C concentrations was measured and the influence of grain boundaries, doping level and surface morphology on the field emission properties was investigated. For high B/C ratios doping saturation was observed. Carrier transport through conductive grains and local emission properties of surface sites figured out to be two independent limiting effects on field emission. Emitter currents of 500 nA·cm-2 were obtained using electric fields less than 8 V·µm-1. In the second part the construction of a new UHV system for field emission measurements is described, including the complete project of a UHV chamber with pump system, manipulators and sample transfer system, mechanical supports and the infrastructural requirements of the laboratory
Mestrado
Eletrônica, Microeletrônica e Optoeletrônica
Mestre em Engenharia Elétrica
Cao, Yuan. "Thin Cr2O3 (0001) Films and Co (0001) Films Fabrication for Spintronics". Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc822733/.
Texto completoWang, Guanyu. "The Dynamics of Gas-Surface Energy Transfer in Collisions of Diatomic Gases with Organic Surfaces". Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/51179.
Texto completoMaster of Science
Colazzo, Luciano. "On-Surface Supramolecular Networks: Structure and Dynamics of Formation in Ultra-High Vacuum and at the Solid/Liquid Interface". Doctoral thesis, Università degli studi di Padova, 2017. http://hdl.handle.net/11577/3422397.
Texto completoLa chimica supra-molecolare di superficie ha permesso la produzione di numerose nanostrutture tramite l'utilizzo di protocolli di sintesi innovativi. In questo modo si sono ottenuti, tramite controllo strutturale a livello atomico e molecolare, numerosi materiali a ridotta dimensionalità. L'applicazione di tali scoperte si sviluppa nell'ambito della ricerca relativa alla catalisi, all'elettronica organica, alla funzionalizzazione e alla sensibilizzazione della superfici. Poiché esistono diversi approcci per per la produzione di tali strutture, la ricerca ha spinto i propri interessi verso la nano-fabbricazione di materiali per ottenerne, sfruttando varie tecniche, di innovativi, più stabili ed efficienti. La fotochimica di superficie in questo senso, permette di ottenere materiali molto complessi ed inoltre permette di capire i fenomeni alla base dei processi di sintesi indotta dalla luce, che ad oggi, non sono del tutto semplici da interpretare. La microscopia a scansione di tunneling (STM) fornisce l'opportuna risoluzione spaziale per questo tipo di studi, i cui principi sono ancora oggi oggetto di dibattito.
Zhang, Yafen. "Ultrahigh Vacuum Studies of the Reaction Kinetics and Mechanisms of Nitrate Radical with Model Organic Surfaces". Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/78003.
Texto completoPh. D.
Alves, Otavio Brandão. "Estudo da eletrooxidação de monóxido de carbono em RuO2(110), e visualização morfológica e atômica de fases ricas em oxigênio na oxidação de Ru(0001) através da microscopia de varredura por tunelamento". Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/75/75131/tde-25102007-144021/.
Texto completoIn the last 30 years the parallel growth of the traditional Surface Science, under UHV environment, and Electrochemistry gave rise to a new interdisciplinary field: Surface Science and Electrochemistry. Techniques from both sciences give complementary information. Thus, in tandem, they are able to elucidate many atomic, structural and electronic phenomena, of an electrode in contact with a solution. The main goal of this Dissertation was the fundamental study of the Oxygen-rich Ru(0001) surface through electrochemical and morphologic characterizations using a coupled system which allowed the attachment of a miniature flow cell to UVH-chambers. Initially it is shown the construction and modifications of required equipments for the preparation of the binary system Au-Pt(111) and single crystal RuO2(110) oxide. Attainable morphological STM images demonstrated the anisotropic growth of the RuO2(110) over a Ru(0001) substrate. Results of the electrooxidation of CO on RuO2(110), obtained by means of Cyclic Voltammetry, corroborated theoretical calculations concerning the oxide superficial structure in a humid environment. Model surfaces based on Au, epitaxialy grown on a Pt(111) substrate, were prepared under UHV conditions. Electrochemical data and superficial composition were correlated, confirming that the substrate effect overcomes electronic strain effects.
Hackley, Jason. "A Liquid-Helium-Free High-Stability Cryogenic Scanning Tunneling Microscope for Atomic-Scale Spectroscopy". Thesis, University of Oregon, 2015. http://hdl.handle.net/1794/19211.
Texto completoLin, Tien-Chih 1966. "Interactions of Clean and Sulfur-modified Reactive Metal Surfaces with Aqueous Vapor and Liquid Environments : A Combined Ultra-high Vacuum/electrochemistry Study". Thesis, University of North Texas, 1998. https://digital.library.unt.edu/ark:/67531/metadc278914/.
Texto completoSchäfer-Nolte, Eike Oliver [Verfasser] y Jörg [Akademischer Betreuer] Wrachtrup. "Development of a diamond-based scanning probe spin sensor operating at low temperature in ultra high vacuum / Eike Oliver Schäfer-Nolte. Betreuer: Jörg Wrachtrup". Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2014. http://d-nb.info/1052894151/34.
Texto completoWilson, Karen E. "Investigations into the role of α-amino acids as chiral modifiers for Ni-based enantioselective heterogeneous hydrogenation catalysts". Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/3108.
Texto completoWang, Guanyu. "Interfacial Energy Transfer in Small Hydrocarbon Collisions with Organic Surfaces and the Decomposition of Chemical Warfare Agent Simulants within Metal-Organic Frameworks". Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/100746.
Texto completoDoctor of Philosophy
Dao, Tomáš. "Návrh nosné platformy pro nízkoteplotní UHV STM mikroskop". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231317.
Texto completoHöfer, Katharina [Verfasser], Liu Hao [Akademischer Betreuer] [Gutachter] Tjeng, Clemens [Gutachter] Laubschat y Kathrin [Gutachter] Dörr. "All in situ ultra-high vacuum study of Bi2Te3 topological insulator thin films / Katharina Höfer ; Gutachter: Liu Hao Tjeng, Clemens Laubschat, Kathrin Dörr ; Betreuer: Liu Hao Tjeng". Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://d-nb.info/1129080935/34.
Texto completoPlogmaker, Stefan. "Techniques and Application of Electron Spectroscopy Based on Novel X-ray Sources". Doctoral thesis, Uppsala universitet, Yt- och gränsskiktsvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-168799.
Texto completoLu, Jessica Weidgin. "Dynamics of Atmospherically Important Triatomics in Collisions with Model Organic Surfaces". Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/77045.
Texto completoPh. D.
Haque, Francia. "Réactivité de nanoparticules d'oxydes d'orientations définies". Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066420/document.
Texto completoThe analysis of adsorption from the first stage to saturation is necessary to understand gas/solid interactions. This is the motivation for surface analysis under vacuum. The common approach of dispersed materials surfaces is incomplete since working pressures, that are high enough to achieve reasonable reaction times, do not allow studies of powder surfaces from bare to fully covered. The aim of the present work is to examine the successive changes of ZnO, MgO and ZnxMg1-xO nanopowders upon exposure to water or hydrogen from UHV to the ambient by FTIR. It is shown that ZnO smokes behave in a same way as a collection of single crystals which exhibit (0001), (0001̅), (101̅0) and (112̅0) faces with a non-polar/polar ratio of 75/25. Combining FTIR with XPS and TPD techniques, three stages of hydroxylation were identified on MgO smokes: point defects (10-8 mbar), steps (10-6 mbar) then terraces (> 10-5 mbar). Results indicate a reorganisation of surface structure showing that water adsorption on MgO(100) is an irreversible process. The common model of MgO as a series of (100) facets is questioned. At low concentrations of zinc, the mixed oxide ZnxMg1-xO consists of crystals with similar structure as MgO. A segregation of Zn2+ toward low coordinated surface sites is suggested to explain the changes in reactivity of the ZnxMg1-xO with respect to water and hydrogen at low coverages. Furthermore, the mixture ZnO-MgO produced by combustion of ZnMg alloy combines the antibacterial properties of ZnO and the biocompatibility of MgO, interesting for potential applications. The overall results demonstrate the relevance of the study of powders in ultra-high vacuum conditions
Deshpande, Aparna. "Atomistic interactions in STM atom manipulation". Ohio : Ohio University, 2007. http://www.ohiolink.edu/etd/view.cgi?ohiou169849272.
Texto completoWeiller, Sébastien. "Etude de la relation entre porosité et étanchéité à l'ultra-vide de dépôts à base d'aluminium obtenus par projection dynamique par gaz froid ("cold spray")". Thesis, Université Paris sciences et lettres, 2021. http://www.theses.fr/2021UPSLM004.
Texto completoCold Spray is a thermal spray process, a key advantage of which is its capability to achieve highly-dense coatings. The practical objective of the study is to fully exploit this asset to obtain a metallic coating which exhibit gas-tightness in ultra-high vacuum conditions as requested for the targeted application. The thesis work consists in studying cold spray conditions to result in suitable properties. The study will focus on porosity formation mechanisms when spraying. A major objective is to determine a critical size for porosity above which gas-tightness no more meets the required specifications for the application. For this, relevant characteristics of pores (size, distribution, shape, ... ) will be assessed. More basically, the work aims to correlate, including using numerical simulation, these characteristics with the previously-mentioned formation mechanisms as a function of spraying conditions. The influence of the substrate (a metal or a polymer) onporosity will be studied in particular, through the study of modifications in the coating build-up. Coating-substrate bond strength will be determined, based on the study of adhesion mechanisms since an influence of these on gas-tightness can be expected
Peyrot, David. "Engineering 2D organic nanoarchitectures on Au(111) by self-assembly and on-surface reactions". Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLX007/document.
Texto completoOver the last few years, important technological developments were made following a trend towards miniaturization. In particular, lots of research efforts are put into the research on organic electronics and on 2D materials like graphene. Such 2D materials show great physical properties and are promising candidates for the development of future electronic devices.In this project, bottom-up approach consisting in assembling elementary building blocks together, was used to engineer novel twodimensional nanostructures on metal surfaces. The properties of these two-dimensional nanostructures were investigated using Scanning Tunneling Microscopy (STM) and X-ray Photoemission Spectroscopy (XPS). Two-dimensional nanostructures based on the self-assembly of organic building blocks stabilized by intermolecular interactions were engineered. In particular, nanostructures stabilized by hydrogen bonds, halogen bonds and ionic-organic interactions were investigated. Localized electronic states due to specific molecular lateral electronic coupling were observed. Four different ionic-organic nanoarchitectures were engineered varying the substrate temperature. Covalent organic nanostructures were also engineered by onsurface Ullmann coupling reaction. Two different star-shaped precursors with iodine and bromine substituents respectively, were investigated. Large periodic porous 2D covalent hexagonal carbon nanostructures weresuccessfully engineered by temperature driven hierarchal Ullmann coupling. These results open new perspectives for the development of 2D organic materials with controlled structures and properties
Lelaidier, Tony. "Organic semiconductor characterisation by scanning tunnelling microscopy and optical spectroscopy". Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4032/document.
Texto completoElectronic and self-assembling properties of two organic compound, the DHTAP and the bis-pyrene, have been studied by the means of low temperature scanning tunnelling microscopy (STM) under ultrahigh vacuum conditions. Optical properties have been studied by cavity ring-down (CRD) spectroscopy, also under ultrahigh vacuum conditions.The growth of DHTAP has been studied on different metallic substrate. The growth of bis-pyrene has been studied on Au(111). In each case, the optimal temperature conditions for the formation of a well-ordered first monolayer have been determined. The formation of second monolayers has also been studied. The evolution of the optical properties, studied by CRD, of bis-pyrene deposited on borosilicate glass combined with information obtained from STM allow us to identify these modifications as interactions between transition dipole moments of molecules in the first and in the second layer, and also determine the growth mode.Finally, the possibility to induce chemical modification of DHTAP molecules embedded in an ordered monolayer using the tunnelling current of the STM has been studied. It appears that the molecule embedded in the first ML can be doubly dehydrogenated which leads to the formation of a compound identified as 5,7,12,14-tetraazapentacene (TAP). In the second layer, the formation of two radicals in addition to the TAP has been observed. The TAP molecule is interesting because of that it cannot be synthesized using common organic chemical methods
Sordes, Delphine. "Imagerie, manipulation et contact électronique atome par atome sur la surface Si(100) : H avec le microscope à effet tunnel basse température à 4 pointes". Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30048/document.
Texto completoThe construction of electronic circuits of atomic section is one of the great challenges of the ultimate nanoelectronics. To build an atomic electronic circuit, it is necessary first to develop the dedicated instrument to build up and then to choose the support surface stabilizing this circuit. On the Au(111) surface prepared in ultra-vacuum, we implemented and stabilized the very first LT-UHV-4 STM. This STM 4-probes microscopes scanning at the same time and independently the same surface was built for the CEMES by the ScientaOmicron company. On Au(111), we reproduced all the experimental results obtained on the best LT-UHV-STM with one probe such as the precision in roughness of 2 pm, the IV characteristics recording without any average on a single atom for several tens of minutes and the atomic manipulation following the pulling, sliding and pushing modes of a single gold atom on the surface. Once this optimization was carried out, we applied our LT-UHV-4 STM to the surface of Si(100):H, probable support of the future electronic atomic circuits. The choice of this medium is discussed in detail before recording and analysis of the STM images. The samples used come either from the semi-industrial full-wafer silicon process developed at CEA-LETI or from their in-situ preparation, which takes place directly in the preparation chamber of the LT-UHV-4 STM. We have taken care to interpret the STM images of the surface Si(100):H in order to locate the position of each hydrogen atom. The atomic lithography by STM has been exploited, by using one tip from our LT-UHV-4 STM, by atom-per-atom vertical mode and faster scanning mode. The last makes atomic writing less accurate. We have constructed our own atomic wires and then atomic contact pads, small squares of Si(100)H defeated by a few nm sides. The leakage currents with 2 probes at the atomic scale have thus been able to be measured on the surface of Si(100):H between two of these pads. To prepare the atomic contacts at least 2 probes on an atomic wire or on nanometric contact pads, we studied in detail the different types of contact points STM-single dangling bond showing the difficulty of reaching a quantum of conductance at contact, due to a possible bands bending. It is therefore difficult without a complementary force measurement to determine, starting from the tunnel contact, the different steps of the mechanical, electronic contact at the chemical contact. Our results open the way to the characterization of electronic circuits constructed atom-by-atom and at atomic scale on the surface of a semiconductor