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Orban, Istvan. "Electron - Ion Recombination Studies of Astrophysically Relevant Ions : Storage Ring and Electron Beam Ion Trap Based Measurements /." Stockholm : Department of Physics, Stockholm University, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-33254.
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Diss. (sammanfattning) Stockholm : Stockholms universitet, 2010.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 6: Submitted. Paper 7: Submitted. Härtill 7 uppsatser.
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Ali, Safdar. "Electron - Ion Recombination Data for Plasma Applications : Results from Electron Beam Ion Trap and Ion Storage Ring." Doctoral thesis, Stockholms universitet, Fysikum, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-75311.
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This thesis contains results of electron-ion recombination processes in atomic ions relevant for plasma applications. The measurements were performed at the Stockholm Refrigerated Electron Beam Ion Trap (R-EBIT) and at the CRYRING heavy-ion storage ring. Dielectronic recombination (DR) cross sections, resonant strengths, rate coefficients and energy peak positions in H-like and He-like S are obtained for the first time from the EBIT measurements. Furthermore, the experimentally obtained DR resonant strengths are used to check the behaviour of a scaling formula for low Z, H-and He-like iso-electronic sequences and to update the fitting parameters. KLL DR peak positions for initially He- to B-like Ar ions are obtained experimentally from the EBIT measurements. Both the results from highly charged sulfur and argon are compared with the calculations performed with a distorted wave approximation. Absolute recombination rate coefficients of B-like C, B-like Ne and Be-like F ions are obtained for the first time with high energy resolution from storage ring measurements. The experimental results are compared with the intermediate coupling AUTOSTRUCTURE calculations. Plasma rate coefficients of each of these ions are obtained by convoluting the energy dependent recombination spectra with a Maxwell-Boltzmann energy distribution in the temperature range of 103-106 K. The resulting plasma rate coefficients are presented and compared with the calculated data available in literature.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Accepted. Paper 5: Accepted. Paper 6: Manuscript. Paper 7: Manuscript.
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Back, Tekla. "Laser spectroscopy of highly charged ions using an electronic beam ion trap." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.711594.
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Margolis, Helen Sarah. "Studies of highly ionized atoms using an electron beam ion trap." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240657.
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Crosby, David N. "Visible and laser spectroscopy of highly charged ions in an electron beam ion trap." Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491358.
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This thesis describes the development of visible and laser spectroscopy techniques for highly charged ions produced in an electron beam ion trap (EBIT). Visible spectroscopy measurements are reported of the 5D3 _5 D2 transition in titaniumlike Ag25+ and Sn28+, yielding results of 6314.81(4) Aand 4981.89(6) Arespectively. These are the most accurate measurements yet made in this system. Furthermore, the work points the way to extending the techniques t9 shorter wavelengths, in particular the vacuum ultraviolet, wherein significant improvements in the measurement of the QED sensitive ls2s 3So - ls2p 3 PO,1,2 transitions in heliumlike ions are anticipated to be possible. An measurement of the 2S1/ 2 - 2P3/ 2 transition in hydrogenlike nitrogen by a laser resonance method is reported. This is the first time that a laser induced transition has been observed in a highly charged ion confined within a trap. The measured result of 835.4(5) cm-1 although preliminary points towards the prospect of developing a critical test of the underlying theory. Additionally, the present status of the theory of the Lamb shift in the hydrogenlike systems and where there has been considerable development recently is reviewed.
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Groves, Paul David. "A study of the 2S Lamb shift of one-electron ions in an electron beam ion trap." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337827.
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Gaarde-Widdowson, Kristina. "Laser spectroscopy of medium-Z hydrogenic ions in the Oxford Electron Beam Ion Trap (EBIT)." Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.496894.
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Bieber, David Justin. "Emission spectroscopy in the VUV and visible from highly charged ions in an electron beam ion trap." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267952.
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Allen, Frances Isabel. "Electron capture by highly charged ions from surfaces and gases." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2008. http://dx.doi.org/10.18452/15720.
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In dieser Arbeit werden hochgeladene, mit einer Electron Beam Ion Trap produzierte Ionen für die Erforschung des Elektroneneinfangs von Oberflächen und Gasen eingesetzt. Die Untersuchungen mit Gastargets konzentrieren sich auf die Energieabhängigkeit der Verteilung der K-Schalen-Röntgenstrahlen, die nach Elektroneneinfang in Rydberg-Zustände von Ar-17+ und Ar-18+ Ionen am Ende einer Kaskade von Elektronenübergängen entstehen. Die Ionen werden von der Ionenquelle mit einer Energie von 2 keV/u extrahiert, ladungsselektiert und anschließend bis auf 5 eV/u abgebremst, um dann mit einem Argon Gastarget zu interagieren. Für abnehmende Stoßenergien wird eine Verschiebung des Elektroneneinfangs in Zustände mit niedrigen Drehumpulsquantenzahlen beobachtet. Zum Vergleich wird auch die K-Schalen-Röntgenstrahlung auf Grund des Elektroneneinfangs bei Ar-17+ und Ar-18+ von dem Restgas in der Falle gemessen. Dabei wird eine Diskrepanz zu den Resultaten der Extraktionsversuche festgestellt. Mögliche Erklärungen werden diskutiert. In den Untersuchungen zum Elektroneneinfang von Oberflächen werden hochgeladene Ionen von der Ionenquelle mit Energien von 2 bis 3 keV/u extrahiert, ladungsselektiert und auf Targets gelenkt. Diese bestehen aus Siliziumnitridmembranen mit einer Vielzahl nanometergroßer Löcher, welche mittels eines fokussierten Ionenstrahls in Kombination mit ionenstrahlinduzierter Abscheidung dünner Filme erstellt werden. Es werden hierbei Lochdurchmesser von 50 bis 300 nm mit Formfaktoren von 1:5 bis 3:2 erreicht. Bei den hochgeladenen Ionen handelt es sich um Ar-16+ und Xe-44+. Nach dem Transport durch die Kapillare passieren die Ionen einen elektrostatischen Ladungstrenner und werden detektiert. Der Anteil des Elektroneneinfangs von den Wänden der Löcher ist weitaus geringer als Modellberechnungen vorhersagen. Die Resultate werden an Hand eines Kapillareffekts zur Ionenleitung diskutiert.In this study highly charged ions produced in Electron Beam Ion Traps are used to investigate electron capture from surfaces and gases. The experiments with gas targets focus on spectroscopic measurements of the K-shell x-rays emitted at the end of radiative cascades following electron capture into Rydberg states of Ar-17+ and Ar-18+ ions as a function of collision energy. The ions are extracted from an Electron Beam Ion Trap at an energy of 2 keV/u, charge-selected and then decelerated down to 5 eV/u for interaction with an argon gas target. For decreasing collision energies a shift to electron capture into low orbital angular momentum capture states is observed. Comparative measurements of the K-shell x-ray emission following electron capture by Ar-17+ and Ar-18+ ions from background gas in the trap are made and a discrepancy in the results compared with those from the extraction experiments is found. Possible explanations are discussed. For the investigation of electron capture from surfaces, highly charged ions are extracted from an Electron Beam Ion Trap at energies of 2 to 3 keV/u, charge-selected and directed onto targets comprising arrays of nanoscale apertures in silicon nitride membranes. The highly charged ions implemented are Ar-16+ and Xe-44+ and the aperture targets are formed by focused ion beam drilling in combination with ion beam assisted thin film deposition, achieving hole diameters of 50 to 300 nm and aspect ratios of 1:5 to 3:2. After transport through the nanoscale apertures the ions pass through an electrostatic charge state analyzer and are detected. The percentage of electron capture from the aperture walls is found to be much lower than model predictions and the results are discussed in terms of a capillary guiding mechanism.
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Varney, Andrew John. "Development of x-ray spectrometers and x-ray spectroscopy for the Oxford electron beam ion trap." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282196.
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Yuan, Bing. "Variable Temperature Rate Coefficient Studies through a Coaxial Molecular Beam Radiofrequency Ring Electrode Ion Trap." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/242471.
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The dissertation focuses on the temperature dependent rate coefficient measurement of reactions in the interstellar medium using a coaxial molecular beam ring electrode ion trap apparatus. The first chapter introduces the previous studies of ion-molecule reactions in the ISM, the types of instruments mainly used in the reaction rate coefficient study, the former research on the ring electrode ion trap and the gas phase reaction mechanisms. Compare to other instruments, our molecular beam - ring electrode ion trap is extremely good at ion cooling and temperature control for both ions and neutral molecules. Chapter two describes each part of the instrument used in detail. Ions produced by electron impact in the ion source chamber, are mass filtered and then reach the ring electrode ion trap. In the trap, ions collide with molecules in the molecular beam where reaction takes place. When the reaction is done, all the ions remained in the trap (the reactant and product ions) come out and move to the detector. The molecular beam terminates at residual gas analyzer which is used for the number density calibration. The third chapter shows how the temperature of ions and molecules are controlled separately in order to find the reaction mechanism. Ions are cooled by the pulsed He buffer in the ring electrode trap and a chopped beam is used to make sure the ions are cooled to the desired low temperature when the reaction takes place. Chapters four to six describe the three reactions being studied using this instrument: N₂⁺ + H₂O charge transfer reaction, H₃O⁺ + C₂H₄ proton transfer reaction and H3O⁺ + (C₂H₂)₂/C₂H₂ dimer reaction. The temperature dependent rate coefficient data of these reactions are explained by the average dipole orientation theory, statistical theory and Colussi's acetylene dimer model, respectively. Two temperatures are defined and applied in the experimental rate coefficients analysis: ion-molecule center of mass collision temperature and the reaction statistical temperature which is based on the numbers of degrees of freedom of both reactants.
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Pacheco, Josè L. "An Electro- Magneto-static Field for Confinement of Charged Particle Beams and Plasmas." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc500001/.
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A system is presented that is capable of confining an ion beam or plasma within a region that is essentially free of applied fields. An Artificially Structured Boundary (ASB) produces a spatially periodic set of magnetic field cusps that provides charged particle confinement. Electrostatic plugging of the magnetic field cusps enhances confinement. An ASB that has a small spatial period, compared to the dimensions of a confined plasma, generates electro- magneto-static fields with a short range. An ASB-lined volume thus constructed creates an effectively field free region near its center. It is assumed that a non-neutral plasma confined within such a volume relaxes to a Maxwell-Boltzmann distribution. Space charge based confinement of a second species of charged particles is envisioned, where the second species is confined by the space charge of the first non-neutral plasma species. An electron plasma confined within an ASB-lined volume can potentially provide confinement of a positive ion beam or positive ion plasma. Experimental as well as computational results are presented in which a plasma or charged particle beam interact with the electro- magneto-static fields generated by an ASB. A theoretical model is analyzed and solved via self-consistent computational methods to determine the behavior and equilibrium conditions of a relaxed plasma. The equilibrium conditions of a relaxed two species plasma are also computed. In such a scenario, space charge based electrostatic confinement is predicted to occur where a second plasma species is confined by the space charge of the first plasma species. An experimental apparatus with cylindrical symmetry that has its interior surface lined with an ASB is presented. This system was developed by using a simulation of the electro- magneto-static fields present within the trap to guide mechanical design. The construction of the full experimental apparatus is discussed. Experimental results that show the characteristics of electron beam transmission through the experimental apparatus are presented. A description of the experimental hardware and software used for trapping a charged particle beam or plasma is also presented.
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Ullmann, Falk. "Untersuchung der Erzeugung hochgeladener Ionen in einer Raumtemperatur-Elektronenstrahl-Ionenfalle." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1138260035821-97208.
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Hochgeladene Ionen stellen einen extremen Zustand der Materie dar, wie sie vornehmlich in kosmischen Plasmen zu finden ist. Die labormäßige Erzeugung und (spektroskopische) Untersuchung hochgeladener Ionen liefert wichtige Daten und Erkenntnisse für die Astrophysik und Fusionsforschung. Aufgrund ihrer zum Teil exotischen Eigenschaften besitzen hochgeladene Ionen ein großes Potential für eine Vielzahl neuer Anwendungen. Die bisher weltweit einzige Elektronenstrahl-Ionenfalle, die hochgeladene Ionen bis hin zu vollständig ionisierten Ionen unter Raumtemperaturbedingungen erzeugen und bereitstellen kann, die Dresden EBIT, ist Gegenstand der vorgelegten Arbeit. Die Dresden EBIT zeichnet sich neben ihrer Kompaktheit und einer einfachen Bedienung durch ihre Langzeitstabilität aus. Sowohl über Röntgenspektren als auch über die Extraktion der Ionen aus der EBIT konnte für eine Reihe von Elementen der Nachweis der Erzeugung von vollständig ionisierten Ionen bis Z=28 erbracht werden. Für schwere Elemente können Ionenladungszustände bis hin zu neonähnlichen Ionen erzeugt werden. Entscheidenden Einfluss auf den erzielten mittleren Ladungszustand hat die Ioneneinschlusszeit. Die zeitliche Entwicklung der Ladungszustandsverteilung, wie sie im Zusammenspiel der verschiedenen atomaren Prozesse simuliert werden kann, ist sowohl an einer Reihe von röntgenspektroskopischen Messungen als auch anhand von Extraktionsspektren untersucht worden. Neben der Beladung der EBIT mit gasförmigen Elementen ist insbesondere die Beladung mit Metallen, d. h. mit einem möglichst breiten Spektrum an Elementen gefordert. Die Beladung mit leichtflüchtigen metallorganischen Verbindungen, die über das Gaseinlassventil eingebracht werden können, hat sich als erfolgreiche und preiswerte Alternative zu einer MEVVA-Quelle erwiesen. Die Beladung mit Metallionen ist am Beispiel verschiedener Untersuchungen gezeigt. Der monoenergetische Elektronenstrahl gestattet neben der Untersuchung von Anregungs- und Ionisationsprozessen insbesondere die der wichtigen Rekombinationsprozesse des Strahlenden Einfangs und der Dielektronischen Rekombination. Der Einsatz eines Kristalldiffraktionsspektrometers erlaubt trotz einer aufwendigen Kalibrierung und sehr langen Messzeiten die Auflösung einzelner Übergänge in hochgeladenen Ionen. Hauptanwendungsfeld der Dresden EBIT wird der Einsatz als Ionenquelle sein. Aus den Untersuchungen des extrahierten Gesamtionenstroms können die Bedingungen für einen möglichst großen Ionenstrom und einen optimalen Ionenstrahltransport abgeleitet werden. Eine optimale Ausnutzung der Eigenschaften hochgeladener Ionen erfordert die Separation der einzelnen Ladungszustände. Der Nachweis der sehr kleinen Ionenströme erfolgt über die kapazitive Messung in einem Faradaycup. Die Messung der Ladungszustandsverteilung in Abhängigkeit von den Parametern der EBIT gibt zusätzliche Aufschlüsse über die Eigenschaften der Ionenfalle.
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Dobrodey, Stepan [Verfasser], and López-Urrutia José Ramon [Akademischer Betreuer] Crespo. "Charge-exchange studies of bare and hydrogen-like low-Z ions in the X-ray and extreme-ultraviolet ranges inside an electron beam ion trap / Stepan Dobrodey ; Betreuer: José R. Crespo López-Urrutia." Heidelberg : Universitätsbibliothek Heidelberg, 2019. http://d-nb.info/1199348821/34.
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Khalili, Guyve. "Réalisation d'une source d'électrons par ionisation d'un jet d'atomes de césium refroidis par laser." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112103/document.
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Les faisceaux d’électrons et d’ions sont au cœur de nombreuses techniques instrumentales servant à explorer, analyser et agir sur des matériaux à l’échelle du micromètre au nanomètre (Microscopie électronique, spectrométrie d’électrons, techniques de « FIB »). Les limites de résolution spatiale et énergétique de ces techniques dépendent en grande partie des propriétés des sources qu’elles utilisent et en particulier de leur température de fonctionnement. De fait, depuis plus de 10 ans, le potentiel des atomes froids ionisés comme nouveau type de source d’électrons ou d’ions est intensivement exploré.Le projet expérimental réalisé au LAC et décrit dans cette thèse utilise un jet d’atomes de césium issu d’un piège magnéto-optique à deux dimensions. La température transverse du jet est de l’ordre de 100 µK. Malgré cela, le jet est encore trop divergent après la sortie de la zone de refroidissement pour notre expérience. Afin guider le jet d’atomes jusqu’à la zone d’ionisation, nous avons étudié une méthode particulière de guidage dipolaire. L’utilisation d’un seul laser convenablement réglé nous a permis de guider et pousser les atomes du jet en même temps tout en limitant le chauffage. Nous avons ainsi pu compresser avec ce laser pousseur-guideur le jet d’atomes sur un diamètre de 400 µm à 60 cm de la zone de refroidissement du PMO-2D.Le jet est ensuite ionisé par la méthode d’ionisation en champ électrique statique d’atomes de Rydberg. Les atomes sont tout d’abord excités par laser sur un état de Rydberg (n~30) en présence d’un champ électrique uniforme et homogène. Les atomes du jet ainsi excités voyagent vers une zone présentant un fort gradient de champ où ils vont alors s’ioniser autour de la même valeur de potentiel, réduisant ainsi la taille de la zone d’ionisation et donc de la dispersion en énergie potentielle initiale du faisceau d’électron. La probabilité d’ionisation des atomes dans le champ dépend grandement de l’état de Rydberg préalablement excité. Le choix de l’état de Rydberg optimal, i.e. qui a une probabilité d’ionisation la plus grande possible, nécessite une étude de l’ionisation des états de Rydberg du césium. Un modèle à deux niveaux est présenté dans cette thèse qui permet de retrouver le comportement d’ionisation d’état de Rydberg observé expérimentalement. Ce modèle simple nous a permis de comprendre quel type d’état nous devions exciter. Enfin une étude expérimentale est également présentéeElectron and Ion beams are at the base of many instrumental techniques used to explore, to analyse and to modify materials from the micrometer to the manometer scale (Electronic Microscopy, Electron Spectrometry, Focused Ion beams techniques…). Spatial and Energetic resolutions of these techniques are strongly dependent on its source‘s properties and particularly their working temperature. In fact, for more than ten years, the potential of ionised cold atoms have been intensively studied. Our experiment at LAC, described in this thesis, uses a 2 dimensional magneto-optical trap (2D-MOT) to create a caesium atomic beam. The transverse temperature of the beam is around 100 µK. Despite this, the beam is still too divergent after exiting the cooling area. To guide the atomic beam up to the ionisation area, we have studied and implemented a particular method of dipolar guiding. The use of a unique laser properly set allowed us to push and guide altogether the atoms of the beam while limiting the heating effect. Thus, we have managed to compress the atomic beam’s size to 400 µm at 60 cm from the output of the MOT.Afterward, the atomic beam is ionised by the method of Rydberg (static) field ionisation. The atoms are firstly excited by laser on a Rydberg state (n~30) as a static homogeneous and uniform electric field is applied. The excited atoms of beam travel therefore to a high-gradient field area where they ionise around the same electric potential value, therefore reducing the ionisation area’s size and the initial potential energy spread of the electron beam. The ionisation probability of the atoms in the field depends greatly on the excited Rydberg state. The choice of an optimal Rydberg state , i.e. with the highest probability of ionisation, needs better knowledge of the ionisation of cesium Rydberg states. A two levels model us to describe the ionisation behaviour of some Ryberg. This simple models helps to understand what kind of states we want to excite in order to optimise the ionisation area‘s size. An experimental study of cesium Rydberg states is also presented
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Fuchs, Tino. "Spektroskopische Untersuchungen hochgeladener Krypton-Ionen im Röntgen-Bereich." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2000. http://dx.doi.org/10.18452/14477.
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Diese Dissertation widmet sich der spektroskopischen Untersuchung verschiedener Aspekte der Strahlungsemis\-sion hochgeladener Krypton-Ionen mit Relevanz für die Fusionsforschung. Die Experimente hierzu erfolgten an der Berliner Elektronenstrahl-Ionenfalle (EBIT). Der erste Teil der Arbeit hat die Messung kanalspezifischer Wirkungsquerschnitte für die dielektronische Rekombination (DR) der KL$n$-Resonanzserie ($n$=2, \ldots, 5) von Helium- bis Kohlenstoff-ähnlichen Kr-Ionen ($\mbox{Kr}^{(34\, \ldots\,30)+}$) zum Inhalt, die relativ zum Wirkungsquerschnitt der nichtresonanten strahlenden Rekombination (RR) bestimmt wurden. Die Anpassung der Anregungskurven durch eine Modellfunktion aus berechneten Resonanzst ärken ermöglichte den Vergleich mit theoretischen DR-Wirkungsquerschnitten. Es zeigt sich, dass Vorhersagen des HULLAC-Atomstrukturcodes für die Resonanz\-st"ar\-ken der Kr-Ionen durch das Experiment innerhalb der Me"sunsicherheiten best"a\-tigt werden. Darüber hinaus wurde auch die Relaxation der einfach angeregten Ionen nach erfolgtem DR-Stabilisierungsübergang analysiert. Die zur Auswertung der DR-Anre\-gungs\-kurven angewandte Technik eröffnet gleichzeitig eine spektroskopische Methode für die Bestimmung der relativen Konzentration hochgeladener Ionen in EBIT. Die Messung der Strahlungskühlungsrate von Krypton, die den zweiten inhaltlichen Schwerpunkt der Dissertation darstellt, wäre ohne diese in situ Diagnostik der Ladungbilanz nicht möglich gewesen. Hier wurde die Ionenfalle so eingestellt, dass sich eine Ladungsverteilung herausbildet, die dem Ionisationsgleichgewicht eines Plasmas bei einer Temperatur von etwa $5\;\mbox{keV}$ entspricht. Die Bestimmung der Strahlungsk"uhlungsrate profitierte von dem Potential einer EBIT, die gefangenen Ionen mit Elektronenenergien aus einem weiten Bereich abzutasten und einzelne Strahlunsprozesse selektiv anzuregen. Die Röntgenemission verschiedener Strahlungskanäle, wie Bremsstrahlung, strahlende Rekombination, dielektronische Rekombination und Linienstrahlung nach direkter Anregung wurde separat erfaßt. Hieraus konnten erstmals kanalspezifische Strahlungskühlungsraten bestimmt werden. Es stellte sich heraus, dass der dominante Beitrag zur Strahlungskühlungsrate durch die direkt angeregte Linienstr ahlung des L-Schalen-Spektrums zustande kommt, die etwa 75\% der gesamten Verlustleistung ausmacht. Beim Vergleich der totalen Strahlungsverlustleistung mit Vorhersagen der Theorie sind Abweichungen festzustellen. Die berechneten Werte sind je nach Modell um einen Faktor 1.5 - 2.0 kleiner als das Ergebnis der Messung. Dieser Unterschied liegt außerhalb der experimentellen Unsicherheit von maximal 30\%.This thesis deals with the spectroscopic investigation of various aspects of the x-ray emission of highly charged krypton ions with relevance for fusion research. The experiments have been performed at the Berlin electron beam ion trap (EBIT). One part of the work was devoted to the measurement of channel-specific cross sections for dielectronic recombination (DR) via the KL$n$ ($n$=2, \ldots, 5) resonance series of He- to C-like krypton ions ($\mbox{Kr}^{(34\, \ldots\,30)+}$). The DR cross sections were determined relative to the cross section for non-resonant radiative recombination (RR). A fit procedure was used to compare the measured data with theoretical calculations. Predictions of the HULLAC atomic structure code are confirmed within the experimental uncertainties. Additionally, the radiative relaxation mechanism following the stabilizing transition in the DR process was analyzed. The approach used to obtain the DR excitation function opens up a spectroscopic method to determine the relative abundance of the highly charged ions in the trap. This in situ diagnostic of the charge state balance allowed for the measurement of the radiative cooling rates of krypton being the second focus of the thesis. For this purpose EBIT was tuned to a charge state distribution approaching the ionization balance of a plasma at a temperature of about $5\;\mbox{keV}$. EBIT's capability to sample a wide range of electron-beam energies and distinguish between different radiation channels was utilized to determine the cooling rate. The x-ray emission from the various plasma radiation channels, like bremsstrahlung, radiative recombination, dielectronic recombination, and line radiation following electron-impact excitation was analyzed. For the first time, channel-specific cooling rates could be obtained from these data. It was found, that the dominant contribution to the cooling rate is made up by the directly excited x-rays of the L-shell spectra of krypton, producing more than 75\% of the total radiation loss. A difference with theoretical calculations is noted for the total cooling rate. The predicted values are lower by a factor of 1.5 - 2.0, depending on the theoretical model. This discrepancy is clearly beyond the experimental uncertainty of 30\% at maximum.
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Wang, Junting. "Miniaturized Electrostatic Ion Beam Trap Mass Analyzer." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3610.
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The electrostatic ion beam trap (EIBT) was designed by D. Zajfman during the previous decade. This ion trap combines many properties of the Fourier-transform ion cyclotron resonance (FTICR) mass analyzer and time-of-flight (TOF) mass analyzer. There are several advantages for the electrostatic ion beam trap. First, large mass-to-charge particles in an electrostatic field could be easier to analyze. Second, there is a folded flight path, which could make the mass analyzer smaller compared to conventional TOF mass analyzer. This principle of operation of this ion trap is analogous to an optical resonator. The ions are trapped in a voltage valley and oscillate between the two parallel sets of mirror electrodes with high voltages. In this thesis, I first describe a new type of miniaturized electrostatic ion beam trap mass analyzer that consists of two printed circuit boards (PCBs). The facing surfaces of these boards are imprinted with copper electrodes. The center of the boards is field free and at ground potential with ion mirrors and Einzel lenses on either side. A charge detector is attached to the center for recording the time-dependant motion of the ions in the field. The PCB-based EIBT design is easier to construct than the original EIBT mass analyzer. The electrostatic fields are optimized by adjusting the potential on the mirror electrodes as well as the geometry of the electrodes. Although nondestructive charge detection is much less sensitive for small ions, this detection is ideal for analysis of large ions. The planar electrostatic ion beam trap is inexpensive, small, and simple to operate. The PCB EIBT device was designed, built, and tested using metal samples such as copper and nickel. The electric field of the PCB EIBT is not the same as that of the original EIBT. Unfortunately, there were no ion signals captured in image charge detector. Another new type of miniaturized electrostatic ion beam trap was made by depositing electrodes onto Kapton film. Seven thin tin/copper traces (1 mm wide by 0.015 mm thick) were deposited onto each side of a flat, flexible circuit board substrate (Kapton film 0.15 mm thickness). The film was rolled to form a cylinder. The flexible EIBT is small (4.5 cm × 8 cm), and lightweight (~1 g). This device was tested using laser ablation of CsI. The CsI signals were detected by the charge detector, amplified and sent to the oscilloscope. Fourier transformation was used to convert the data to the frequency domain spectrum. The resolution of Cs+ is around 1000 (m/Δm) from initial flexible EIBT test. The mass accuracy of the Cs+ peak is better than 0.1%.
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Saifullah, Mohammad Sultan Mohiddin. "Electron and ion beam nanolithography using inorganic resists." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624675.
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Turnbull, Susan B. "Characterisation of focused ion beam nanostructures by transmission electron microscopy." Thesis, University of Glasgow, 2009. http://theses.gla.ac.uk/572/.
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Ion irradiation is an effective tool for the modifcation and control of the properties of magnetic thin films. Basic magnetic properties such as coercivity and local anisotropy direction can be altered in NiFe (Permalloy) films, whilst for Co/Pd multilayers, ion irradiation results in a transition from perpendicular to in-plane magnetisation. This ability to tailor magnetic properties in a controlled manner can be used as a tool for nanoscale patterning. Results are presented from investigations into the effect of Ga+ ion dose on the magnetic and structural properties of permalloy thin film systems. Systems consisting of a permalloy layer of either 10nm or 20nm, and one or more non-magnetic layers of Al or Au were deposited by thermal evaporation and irradiated in a focused ion beam (FIB) with a 30kV Ga ion source. The presence of the non-magnetic layers allows irradiation induced mixing with the magnetic layer, effectively creating alloyed regions with different properties to the rest of the film. At low ion doses, no signifcant effect on either the magnetic or structural properties were observed. Bright field TEM images of the irradiated regions revealed that increasing the dose to 1x10^15 ions/cm^2 and above caused an increase in mean grain size from ~5nm to ~30nm. The Fresnel mode of Lorentz microscopy revealed that a reduction in the mean moment was also observed at these doses but no clear changes in coercivity or magnetisation reversal behaviour were observed until the systems were rendered non-magnetic. This occurred at 1x10^16 and 3x10^16 ions/cm^2 for systems with 10nm NiFe and 20nm NiFe respectively. Milling of the samples was evident at these high doses, meaning that it was not possible to magnetically pattern these systems without occasioning a change of 2nm and 6nm respectively in the thickness of the samples. Based on the above, structures were created to control the location of magnetic domain walls (DW). Lines were written by FIB in simple elements with dimensions <1micron, the aim being to create a higher density of DW than could be realised in equivalent homogeneous elements. Structures containing high DW densities are attractive for measuring domain wall magnetoresistive effects and have potential application in DW-based storage or logic devices. One geometry of interest is an element with `zigzag' edges. Results are be presented in chapter 4 showing how these can support either quasi-uniform magnetisation or multi-domain structures separated by DW with spacing <100nm. In chapter 5 irradiation of magnetic structures was again carried out, but this time in magnetic wires to create defect or pinning sites. Domain wall traps fabricated by ion irradiation were characterised, and irradiation line defects introduced along the wire. The lines were patterned at 90± and 45± to the length of the wire, and successfully pinned the domain walls at predefned locations. A 90 degree line irradiated at a dose of 1x10^15 ions/cm^2 was not able to provide a strong enough pinning site for a domain wall. However, when the angle of the line was changed to ±45 degrees it was possible to reproducibly pin domain walls at these sites. A relationship between the orientation of the irradiated line and the chirality of the domain wall that pinned at the site was observed. The effcts of irradiation on Co/Pd multilayers with perpendicular magnetic anisotropy was investigated in chapter 6. Irradiation causes magnetic systems with perpendicular magnetisation to undergo a transition from out-of-plane magnetisation to in-plane. A grid pattern was devised so that magnetic states with both in-plane and out-of-plane magnetisation could be observed. A combination of differential phase contrast microscopy and simulations of integrated magnetic induction were used to determine the orientation of magnetisation within the lines.
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Kong, David Sun 1979. "Nanostructure fabrication by electron and ion beam patterning of nanoparticles." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28346.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2004.Includes bibliographical references (leaves 82-83).
Two modes of energetic beam-mediated fabrication have been investigated, namely focused ion beam (FIB) direct-writing of nanoparticles, and a technique for electrostatically patterning ionized inorganic nanoparticles, termed nanoxerography. A FIB has been used to directly pattern thin films of organometallic Ag-precursors down to a resolution of 100 nm. The sensitivity of the resist to 30 keV Ga+ ions was measured to be approximately 5 C/cm2. Using this technique arbitrary structures were fabricated in two and three dimensions with resistivity on the order of 1x10 4 Q-cm and 1x1 0-5 Q-cm for single- and multi-layer structures, respectively. A new unit of merit for characterizing direct-write processes, termed resistivity-dose (Q-jC/cm), has been introduced. A Nanocluster Source capable of generating a beam of charged, inorganic nanoparticles has been characterized. The relationship between power supplied to the magnetron of the source and the size of deposited clusters has been plotted. Techniques for utilizing such clusters to develop latent electrified images patterned by an electron beam (EB) have been proposed. The charge-storing characteristics of a variety of substrates such as mylar and polyimide were studied by developing EB-patterned charge images with toner particles.
David Sun Kong.
S.M.
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Breitenfeldt, Christian [Verfasser]. "Cooling of anionic metal clusters stored in an electrostatic ion beam trap / Christian Breitenfeldt." Greifswald : Universitätsbibliothek Greifswald, 2017. http://d-nb.info/1136029753/34.
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O'Neill, Robin W. "Characterisation of micron sized ferromagnetic structures fabricated by focussed ion beam and electron beam lithography." Thesis, University of Glasgow, 2007. http://theses.gla.ac.uk/6256/.
Full textAbstract:
Traditionally electron beam lithography (EBL) has been used to fabricate micron and sub-micron sized devices, such as Γ and Τ gates for metal-semiconductor devices for study within the semiconductor industry. EBL is also used for the fabrication of ferromagnetic elements for use as components in magnetic random access memory (MRAM) and read/write heads in hard disk drives (HDD). MRAM is being investigated as a direct replacement to standard semiconductor RAM as it has lower power consumption and is a non-volatile memory solution, although the areal density, at present, is not as great. Smaller read/write heads are necessary for HDD as recent advances now allow for perpendicular magnetisation (as opposed to parallel magnetisation) of films and increase the areal density to 100 Gb/inch2, four times the current value. In this thesis, the physical and magnetic properties of such micron-sized devices that have been fabricated by focussed ion beam (FIB) lithography for comparison to those fabricated by the EBL method are discussed. In addition to this work, the physical and magnetic properties of micron-sized element that have been irradiated using the 30 keV gallium ion source are also discussed. Also in this thesis, the results of 10×10 μm2 arrays of 50 nm thick polycrystalline cobalt elements (270×270 nm2 with a 400 nm period) that are fabricated by EBL to determine if there is any magnetic superdomain structure present are discussed. Bright field imaging in a transmission electron microscope (TEM) is used to investigate the physical structure of the ferromagnets, such as the grain size, element roughness and dimensions. Additional information about the topography is measured by atomic force microscopy (AFM). The magnetic properties, such as the magnitude of the applied field at which irreversible events happen and the domain structure, are investigated by the Fresnel imaging and the differential phase contrast modes of Lorentz microscopy. A programme known as object orientated micromagnetic framework (OOMMF) is used to model the magnetic properties of such structures.
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Cooper, D. "Off-axis electron holography of focused ion beam prepared semiconductor devices." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597966.
Full textAbstract:
Off-axis electron holography promises to fulfill the requirements of the semiconductor industry for a technique that can be used to provide quantitative information about dopant potentials in semiconductors with nanometer spatial resolution. The technique involves using an electron biprism in a transmission electron microscope (TEM) to interfere a coherent electron wave that has passed through a specimen with a reference wave that has passed only through vacuum. The focused-ion-beam (FIB) miller is the preferred method of sample preparation for semiconductor TEM analysis. In the FIB, a 30kV Ga ion beam is used to thin the specimen in the region of interest. It is increasingly recognised that this method of TEM specimen preparation and subsequent treatments have a profound influence on the phase shifts measured from doped semiconductors. In addition to the effect on the phase shift of surface depletion resulting from the presence of the specimen surfaces, the electrostatic potential in the specimen may be affected by the combined effects of oxidation, physical damage and the implantation of ions such as Ar and Ga during preparation of the sample for electron microscopy, as well as by the effects of irradiation by high-energy electrons during examination in the TEM. Semiconductor specimens have been prepared for examination using electron holography by combining advanced sample preparation techniques such as annealing and Ar ion milling in order to assess the effect of these treatments on the measured phase shifts across the junctions.
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Kucheyev, Sergei Olegovich, and kucheyev1@llnl gov. "Ion-beam processes in group-III nitrides." The Australian National University. Research School of Physical Sciences and Engineering, 2002. http://thesis.anu.edu.au./public/adt-ANU20030211.170915.
Full textAbstract:
Group-III-nitride semiconductors (GaN, InGaN, and AlGaN) are important for the fabrication of a range of optoelectronic devices (such as blue-green light emitting diodes, laser diodes, and UV detectors) as well as devices for high-temperature/high-power electronics. In the fabrication of these devices, ion bombardment represents a very attractive technological tool. However, a successful application of ion implantation depends on an understanding of the effects of radiation damage. Hence, this thesis explores a number of fundamental aspects of radiation effects in wurtzite III-nitrides. Emphasis is given to an understanding of (i) the evolution of defect structures in III-nitrides during ion irradiation and (ii) the influence of ion bombardment on structural, mechanical, optical, and electrical properties of these materials.
¶
Structural characteristics of GaN bombarded with keV ions are studied by Rutherford backscattering/channeling (RBS/C) spectrometry and transmission electron microscopy (TEM). Results show that strong dynamic annealing leads to a complex dependence of the damage buildup on ion species with preferential surface disordering. Such preferential surface disordering is due to the formation of surface amorphous layers, attributed to the trapping of mobile point defects by the GaN surface. Planar defects are formed for a wide range of implant conditions during bombardment. For some irradiation regimes, bulk disorder saturates below the amorphization level, and, with increasing ion dose, amorphization proceeds layer-by-layer only from the GaN surface. In the case of light ions, chemical effects of implanted species can strongly affect damage buildup. For heavier ions, an increase in the density of collision cascades strongly increases the level of stable implantation-produced lattice disorder. Physical mechanisms of surface and bulk amorphization and various defect interaction processes in GaN are discussed.
¶
Structural studies by RBS/C, TEM, and atomic force microscopy (AFM) reveal anomalous swelling of implanted regions as a result of the formation of a porous structure of amorphous GaN. Results suggest that such a porous structure consists of N$_{2}$ gas bubbles embedded into a highly N-deficient amorphous GaN matrix. The evolution of the porous structure appears to be a result of stoichiometric imbalance, where N- and Ga-rich regions are produced by ion bombardment. Prior to amorphization, ion bombardment does not produce a porous structure due to efficient dynamic annealing in the crystalline phase.
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The influence of In and Al content on the accumulation of structural damage in InGaN and AlGaN under heavy-ion bombardment is studied by RBS/C and TEM. Results show that an increase in In concentration strongly suppresses dynamic annealing processes, while an increase in Al content dramatically enhances dynamic annealing. Lattice amorphization in AlN is not observed even for very large doses of keV heavy ions at -196 C. In contrast to the case of GaN, no preferential surface disordering is observed in InGaN, AlGaN, and AlN. Similar implantation-produced defect structures are revealed by TEM in GaN, InGaN, AlGaN, and AlN.
¶
The deformation behavior of GaN modified by ion bombardment is studied by spherical nanoindentation. Results show that implantation disorder significantly changes the mechanical properties of GaN. In particular, amorphous GaN exhibits plastic deformation even for very low loads with dramatically reduced values of hardness and Young's modulus compared to the values of as-grown GaN. Moreover, implantation-produced defects in crystalline GaN suppress the plastic component of deformation.
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The influence of ion-beam-produced lattice defects as well as a range of implanted species on the luminescence properties of GaN is studied by cathodoluminescence (CL). Results indicate that intrinsic lattice defects mainly act as nonradiative recombination centers and do not give rise to yellow luminescence (YL). Even relatively low dose keV light-ion bombardment results in a dramatic quenching of visible CL emission. Postimplantation annealing at temperatures up to 1050 C generally causes a partial recovery of measured CL intensities. However, CL depth profiles indicate that, in most cases, such a recovery results from CL emission from virgin GaN, beyond the implanted layer, due to a reduction in the extent of light absorption within the implanted layer. Experimental data also shows that H, C, and O are involved in the formation of YL. The chemical origin of YL is discussed based on experimental data.
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Finally, the evolution of sheet resistance of GaN epilayers irradiated with MeV light ions is studied {\it in-situ}. Results show that the threshold dose of electrical isolation linearly depends on the original free electron concentration and is inversely proportional to the number of atomic displacements produced by the ion beam. Furthermore, such isolation is stable to rapid thermal annealing at temperatures up to 900 C. Results also show that both implantation temperature and ion beam flux can affect the process of electrical isolation. This behavior is consistent with significant dynamic annealing, which suggests a scenario where the centers responsible for electrical isolation are defect clusters and/or antisite-related defects. A qualitative model is proposed to explain temperature and flux effects.
¶
The work presented in this thesis has resulted in the identification and understanding of a number of both fundamental and technologically important ion-beam processes in III-nitrides. Most of the phenomena investigated are related to the nature and effects of implantation damage, such as lattice amorphization, formation of planar defects, preferential surface disordering, porosity, decomposition, and quenching of CL. These effects are often technologically undesirable, and the work of this thesis has indicated, in some cases, how such effects can be minimized or controlled. However, the thesis has also investigated one example where irradiation-produced defects can be successfully applied for a technological benefit, namely for electrical isolation of GaN-based devices. Finally, results of this thesis will clearly stimulate further research both to probe some of the mechanisms for unusual ion-induced effects and also to develop processes to avoid or repair unwanted lattice damage produced by ion bombardment.
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Epstein, Charles S. "Development of a polarized Helium-3 ion source for RHIC using the electron beam ion source." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/84388.
Full textAbstract:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 39-40).
This thesis presents my work on the design and development of a source of polarized Helium-3 ions for the Relativistic Heavy Ion Collider at Brookhaven National Lab, Upton, NY. The 3He atoms will be polarized using the technique of metastability exchange optical pumping (MEOP), and will then be flowed into the newly commissioned Electron Beam Ion Source (EBIS). Fully stripped 3He++ ions will be extracted and their polarizations measured at low energies before acceleration in the RHIC complex.
by Charles Samuel Epstein.
S.B.
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Cybart, Shane A. "Planar Josephson junctions and arrays by electron beam lithography and ion damage." Diss., Connected to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2005. http://wwwlib.umi.com/cr/ucsd/fullcit?p3190007.
Full textAbstract:
Thesis (Ph. D.)--University of California, San Diego, 2005.Title from first page of PDF file (viewed March 8, 2006). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 108-111).
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Cevro, Mirza. "A study of the deposition of oxide thin films by ion beam techniques." Thesis, University of Salford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262666.
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Borodi, Gheorghe. "On the combination of a low energy hydrogen atom beam with a cold multipole ion trap." Doctoral thesis, Universitätsbibliothek Chemnitz, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-200900932.
Full textAbstract:
Der erste Teil der Aktivitäten dieser Arbeit bestand in der Entwicklung einer modernen Ionenspeicher Apparatur zur Untersuchung chemischer Prozesse mit atomarem Wasserstoff. Die Integration eines differentiell gepumpten Radikalenstrahls in eine vorhandene temperaturvariable 22-Pol Speicherapparatur erforderte größere Änderungen an dieser. Da astrophysikalische Fragestellungen im Vordergrund standen, führt die Einleitung zunächst in das Gebiet der Astrophysik und -chemie ein. Die Grundlagen der Ionenspeicherung in temperaturvariablen Hf-Speichern sind ausführlich in der Literatur dokumentiert. Daher ist die Beschreibung der Apparatur (Kapitel 2) relativ kurz gehalten. Viel Mühe wurde in die Entwicklung einer intensiven und stabilen Quelle für Wasserstoffatome aufgewandt, deren kinetische Energie variiert werden kann. Das Kapitel 3 beschreibt dieses Modul in vielen Details, wobei der Einsatz von magnetischen Hexapolen zum Führen der Atome und die chemische Behandlung der Oberflächen zur Reduzierung der H-H Rekombination einen wesentlichen Platz einnimmt. Durch die außergewöhnliche Empfindlichkeit der Speichertechnik kann das neue Instrument zur Untersuchung von vielen Reaktionen eingesetzt werden, die von astrochemischer und fundamentaler Bedeutung sind. Die Ergebnisse dieser Arbeit sind im Kapitel 4 zusammengestellt, einige Reprints und Entwürfe von Publikationen findet man im Anhang. Die Reaktionen von CO2+ mit Wasserstoffatomen und -molekülen erwiesen sich als sehr geeignet, um in situ H and H2 Dichten über den gesamten Temperaturbereich der Apparatur zu bestimmen (10 K - 300 K). Zum ersten mal wurden Reaktionen von H- and D-Atomen mit den Kohlenwasserstoffionen CH+, CH2+, and CH4+ bei Temperaturen des interstellaren Raums untersucht. Ein sehr interessantes, noch nicht ganz verstandenes Stoßsystem ist die Wechselwirkung von protoniertem Methan mit H-Atomen. Im Ausblick der Arbeit werden einige Ideen aufgezeigt, wie man das Instrument verbessern kann, und es werden einige Reaktionen erwähnt, die man als nächste untersuchen könnte. Diese Dissertation ist einen Beitrag zum Projekt 5 der Forschergruppe Laboratory Astrophysics: Structure, Dynamics and Properties of Molecules and Grains in Space, die von der DFG im Zeitraum von 2000 bis 2006 unterstützt wurdeThe first part of the activities of this thesis was to develop a sophisticated ion storage apparatus dedicated to study chemical processes with atomic hydrogen. The integration of a differentially pumped radical beam source into an existing temperature variable 22-pole trapping machine has required major modifications. Since astrophysical questions have been in the center of our interest, the introduction first gives a short overview of astrophysics and -chemistry. The basics of ion trapping in temperature variable rf traps is well-documented in the literature; therefore, the description of the basic instrument (Chapter 2) is kept rather short. Much effort has been put into the development of an intense and stable source for hydrogen atoms the kinetic energy of which can be changed. Chapter 3 describes this module in detail with emphasis on the integration of magnetic hexapoles for guiding the atoms and special treatments of the surfaces for reducing H-H recombination. Due to the unique sensitivity of the rf ion trapping technique, this instrument allows one to study a variety of reactions of astrochemical and fundamental interest. The results of this work are summarized in Chapter 4, some reprints and drafts are reproduced in the appendix. Reactions of CO2+ with hydrogen atoms and molecules have been established as calibration standard for in situ determination of H and H2 densities over the full temperature range of the apparatus (10 K - 300 K). For the first time, reactions of H- and D-atoms with the ionic hydrocarbons CH+, CH2+, and CH4+ have been studied at temperatures of interstellar space. A very interesting, not yet fully understood collision system is the interaction of protonated methane with H. The outlook presents some ideas, how to improve the new instrument and a few reaction systems are mentioned which may be studied next. This thesis is a contribution to the project 5 of the research unit Laboratory Astrophysics: Structure, Dynamics and Properties of Molecules and Grains in Space which has been supported by the DFG from 2000 to 2006
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Stude, Joan. "Design and Implementation of an Ion Beam Profiling System." Thesis, Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-3700.
Full textAbstract:
The work describes the development of a reliable device for profiling anion beam in the intensity cross section. A sensor head consisting of a Faradaycup in combination with a Channel Electron Multiplier was designedand built together with electronics including power supply and front endelectronics. The design was chosen considering financial and long term lifeaspects. Testing, first calibration and error analysis were done using the ionbeam facilities where the unit is supposed to be installed permanently. Theprofiling system performed as designed and the profile of the ion beam couldbe measured reliably with an accuracy down to the femto ampere range.
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Collins, Clair Louise. "Analytical electron microscopy of HSLA steels prepared using a focused ion beam system." Thesis, University of Glasgow, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412940.
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Brown, Karl. "Coupled electron gases fabricated by in situ ion beam lithography and MBE growth." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319460.
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Brieda, Lubos. "Development of the DRACO ES-PIC code and Fully-Kinetic Simulation of Ion Beam Neutralization." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/33755.
Full textAbstract:
This thesis describes development of the DRACO plasma simulation code. DRACO is an
electro-static (ES) code which uses the particle-in-cell (PIC) formulation to track plasma
particles through a computational domain, and operates within the Air Force COLISEUM
framework. The particles are tracked on a non-standard
mesh, which combines the benefits of a Cartesian mesh with the surface-resolving power
of an unstructured mesh. DRACO contains its own mesher, called VOLCAR, which is also
described in this work.
DRACO was applied to a fully kinetic simulation of an ion-beam neutralization. The
thruster configuration and running parameters were based on the NASA's 40cm NEXT ion thruster.
The neutralization process was divided into three steps. Electron dynamics was studied
by assuming an initial beam neutralization, which was accomplished by injecting both electrons
and ions from the optics. Performing the simulation on a full-sized domain with cell
size much greater than the Debye length resulted in a formation of a virtual anode. Decrease
of the cell size to match the Debye length was not feasible, since it would require a
million-fold increase in the number of simulation nodes. Instead, a scaling scheme was devised.
Simulations were performed on thruster scaled down by a factor of 100, but its operating
parameters were also adjusted such that the produced plasma environment did not change.
Loss of electrons at the boundary of the finite simulation domain induced a numerical instability.
The instability resulted in a strong axial electric field which sucked out electrons from the beam.
It was removed by introducing an energy based particle boundary condition.
Combination of surface scaling and energy boundary resulted in physically sound simulation results.
Comparison were made between the Maxwellian and polytropic temperatures, as well as between simulation
electron density and one predicted by the Boltzmann relationship.
The cathode was modeled individually from the beam by introducing a positively charged collector
plate at a distance corresponding to the beam edge. The local Debye length at the cathode tip
was too small to be resolved by the mesh, even if mesh-refinement was incorporated. Since the
simulation was not concerned with the near-tip region, two modifications were performed. First,
the a limiting value of charge density at the tip was imposed. Second, the cathode potential was allowed
to float. These two modifications were necessary to prevent development of a strong potential gradient
at the cathode tip.
The modified cathode model was combined with ion injection from the optics to model the actual
beam neutralization. Three configurations were tested: a single thruster, a 2x2 cluster with individual
cathodes and a similar cluster with a single large neutralizer. Neither of the cases achieved
neutralization comparable to one in the base-line pre-neutralized case. The reason for the discrepancy
is not known, but it does not seem to be due a loss of electrons at the walls.
The difference could be due to limited extent of the modeled physics.
An additional work is required to answer this question.Master of Science
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Blom, Tobias. "Fabrication and Applications of a Focused Ion Beam Based Nanocontact Platform for Electrical Characterization of Molecules and Particles." Doctoral thesis, Uppsala universitet, Experimentell fysik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-122940.
Full textAbstract:
The development of new materials with novel properties plays an important role in improving our lives and welfare. Research in Nanotechnology can provide e.g. cheaper and smarter materials in applications such as energy storage and sensors. In order for this development to proceed, we need to be able to characterize the material properties at the nano-, and even the atomic scale. The ultimate goal is to be able to tailor them according to our needs. One of the great challenges concerning the characterization of nano-sized objects is how to achieve the physical contact to them. This thesis is focused on the contacting of nanoobjects with the aim of electrically characterizing them and subsequently understanding their electrical properties. The analyzed nanoobjects are carbon nanosheets, nanotetrapods, nanoparticles and molecular systems. Two contacting strategies were employed in this thesis. The first strategy involved the development of a focused ion beam (FIB) based nanocontact platform. The platform consists of gold nanoelectrodes, having nanogaps of 10-30 nm, on top of an insulating substrate. Gold nanoparticles, double-stranded DNA and cadmium telluride nanotetrapods have been trapped in the gaps by using dielectrophoresis. In certain studies, the gold electrodes have also been coated with conducting or non-conducting molecules, prior to the trapping of gold nanoparticles, in order to form molecular junctions. These junctions were subsequently electrically characterized to evaluate the conduction properties of these molecular systems. For the purpose of better controlling the attachment of molecules to the nanoelectrodes, a novel route to synthesize alkanedithiol coated gold nanoparticles was developed. The second contacting strategy was based on the versatility of the FIB instrument as a platform for in-situ manipulation and electrical characterization of non-functionalized and functionalized carbon nanosheets, where it was found that the functionalized samples had an increased conductivity by more than one order of magnitude. Both contacting strategies proved to be valuable for building knowledge around contacting and electrical characterization of nanoobjects
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Lundkvist, Niklas. "Bremsstrahlung Luminosity Monitoring for SCRIT Project (Report part 1)." Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-173877.
Full textAbstract:
The purpose of the SCRIT project is to determine size and shape of short-lived and rarely-produced nuclei by elastic electron scattering, which is the best probe for the structure studies, for the first time. In traditional electron scattering, a solid target having an order of 1023 nuclei/cm^2 is normally used, which is not possible for short-lived and rarely-produced nuclei. In this project a Self Containing Radioactive Isotope Target scheme (SCRIT) is going to be employed. This innovative ion-trap method is shown to be a way to make measurements with a very small amount of nuclei, an order of only 106 nuclei. In order to determine the absolute cross section for elastic electron scattering for structure study, the simulates measurement of the bremsstrahlung from the trapped nuclei is required. Since the bremsstrahlung cross section for a nucleus of the atomic number Z is well know, the precise measurement of the bremsstrahlung provides the luminosity. My theme in this SCRIT project was a construction of a bremsstrahlung luminosity monitor. It consists of a position monitor for measuring the spatial distribution of bremsstrahlung and a Pb-glass Cerenkov detector for energy measurement. My efforts have been mainly devoted to the construction of a position monitor system using fiber scintillators. The construction of the position monitor was divided into five parts; detector construction, support construction, trigger detector construction, software programming, software testing and detector tests. The position monitor consists of two sets of fiber scintillation detectors. Each of them uses 16 fibers, Bicron BCF-10 with a cross section of 2x2mm^2, optically coupled to a multi-anode photomultiplier, (Hamamatsu H6568-10). The position monitor can measure the XY distribution of bremsstrahlung. Strictly speaking, the fiber detector detects not bremsstrahlung directly but electrons and/or positrons by pair creation of bremsstrahlung in a materials. The data acquisition system has been programmed in NI LabVIEW. The software is an advanced X/Y-coordinate counting system, which can additionally preform functions as save data to file and 3D-plot to determine the spreading of the bremsstrahlung luminosity. The results can be saved and transferred online to a server so that is possible to access the data from anywhere. The system has been tested using beta rays from 90Sr source. The results of the test shown that the detectors can detect minimum ionizing particle, i.e. electrons and positrons. The detector and software testings shows that the system is ready to use for luminosity measurements at SCRIT experiment. This system I constructed surely provides a new and useful information for the SCRIT experiments.SCRIT Project
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Menk, Sebastian [Verfasser], and Andreas [Akademischer Betreuer] Wolf. "Vibrational Auto-Detachment of the Sulfur Hexafluoride Anion in a Low-background Cryogenic Ion Beam Trap / Sebastian Menk ; Betreuer: Andreas Wolf." Heidelberg : Universitätsbibliothek Heidelberg, 2013. http://d-nb.info/1177248115/34.
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Lagaki, Varvara [Verfasser], Lutz [Gutachter] Schweikhard, and Gerald [Gutachter] Gwinner. "Development of an Electrostatic Ion Beam Trap for Laser Spectroscopy of Short-lived Radionuclides / Varvara Lagaki ; Gutachter: Lutz Schweikhard, Gerald Gwinner." Greifswald : Universität Greifswald, 2021. http://d-nb.info/1235139875/34.
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Khalil, Ali Saied, and askhalil2004@yahoo com. "Heavy-Ion-Irradiation-Induced Disorder in Indium Phosphide and Selected Compounds." The Australian National University. Research School of Information Sciences and Engineering, 2007. http://thesis.anu.edu.au./public/adt-ANU20070716.140841.
Full textAbstract:
Indium phosphide (InP) is an important III-V compound, with a variety of applications, for example, in light emitting diodes (LED), InP based photonic crystals and in semiconductor lasers, heterojunction bipolar transistors in integrated circuit applications and in transistors for microwave and millimeter-wave systems. The optical and electrical properties of this compound can be further tailored by ion implantation or prospectively by swift heavy ion beams.
¶
Thus knowledge of ion-induced disorder in this material is of important fundamental and practical interest. However, the disorder produced during heavy ion irradiation and the subsequent damage accumulation and recovery in InP is far from being completely understood. In terms of the damage accumulation mechanisms, the conclusions drawn in the numerous studies performed have often been in conflict with one another. A factor contributing to the uncertainties associated with these conflicting results is a lack of information and direct observation of the building blocks leading to the ultimate damage created at high ion fluences as an amorphous layer. These building blocks formed at lower fluence regimes by single ion impacts can be directly observed as isolated disordered zones and ion tracks for low energy and swift heavy ion irradiation, respectively.
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The primary aim of this work has thus been to obtain a better understanding of the disorder in this material through direct observations and investigation of disorder produced by individual heavy ions in both energy regimes (i.e. elastic and inelastic energy deposition regimes) especially with low ion fluence irradiations. In this thesis the heavy ion induced disorder introduced by low energy Au ions (100 keV Au+) and high energy Au (200 MeV Au+16) ion irradiation in InP were investigated using Transmission Electron Microscopy (TEM), Rutherford Backscattering Spectrometry (RBS/C) and Atomic Force Microscopy (AFM).
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The accumulation of damage due to disordered zones and ion tracks is described and discussed for both low energy and swift ion irradiation respectively.
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The in-situ TEM annealing of disordered zones created by 100 keV Au+ ion irradiation shows that these zones are sensitive to electron beam irradiation and anneal under electron energies not sufficient to elastically displace lattice atoms, i.e. subthreshold energies for both constituent atoms In and P.
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Ion tracks due to swift heavy ion irradiation were observed in this material and the interesting track morphology was described and discussed. The surface nanotopographical changes due to increasing fluence of swift heavy ions were observed by AFM where the onset of large increase in surface roughness for fluences sufficient to cause complete surface amorphization was observed.
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In addition to InP, the principle material of this project, a limited amount of TEM observation work has been performed on several other important compounds (apatite and monazite) irradiated by 200 MeV Au+ ions for comparative purposes. Again the observed segmental morphology of ion tracks were shown and possible track formation scenario and structure were discussed and similarities were drawn to the previously observed C60 cluster ion tracks in CaF2 as more knowledge and data base exist about defect dynamics and formation in that material.
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Chalkha, Achouak. "Glow discharge electron impact ionisation and improvements of linear ion trap operating mode for in-the-field detection of illegal substances." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4704/document.
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Bruchhaus, Lars [Verfasser], Heinz [Akademischer Betreuer] Hövel, and Thomas [Gutachter] Weis. "An ion beam complement to electron beam writers : a part of the development, characterisation and utilisation / Lars Bruchhaus. Betreuer: Heinz Hövel. Gutachter: Thomas Weis." Dortmund : Universitätsbibliothek Dortmund, 2012. http://d-nb.info/1105660508/34.
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Perng, John Kangchun. "High Aspect-Ratio Nanoscale Etching in Silicon using Electron Beam Lithography and Deep Reactive Ion Etching (DRIE) Technique." Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/11543.
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This thesis reports the characterization and development of nanolithography using Electron Beam Lithography system and nanoscale plasma etching. The standard Bosch process and a modified three-pulse Bosch process were developed in STS ICP and Plasma ICP system separately. The limit of the Bosch process at the nanoscale regime was investigated and documented. Furthermore, the effect of different control parameters on the process were studied and summarized in this report. 28nm-wide trench with aspect-ratio of 25 (smallest trench), and 50nm-wide trench with aspect ratio of 37 (highest aspect-ratio) have been demonstrated using the modified three-pulse process.
Capacitive resonators, SiBAR and IBAR devices have been fabricated using the process developed in this work. IBARs (15MHz) with ultra-high Q (210,000) have been reported.
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Friedbaum, Samuel Searle. "Studies of Dislocation Density Quantification Via Cross-Correlation EBSD." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/8115.
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One conventional method for studying dislocations uses the Transmission Electron Microscope (TEM), a complex and expensive piece of equipment which requires extensive specimen preparation in order to thin the specimens to electron transparent thickness. Newer High Resolution Electron Backscatter Diffraction (HREBSD) methods of determining geometrically necessary dislocation content via cross-correlation promise to be able to produce estimates of the dislocation density of the sample over a larger area with considerably less preparation time and using a much more accessible instrument. However, the accuracy of the new EBSD technique needs more experimental verification, including consideration of possible changes in the specimen dislocation density due to the different preparation methods. By comparing EBSD and TEM dislocation measurements of Electron Transparent platinum specimens prepared using the Focused Ion Beam (FIB), along with EBSD dislocations measurements of specimens prepared by both FIB and mechanical polishing techniques, this paper seeks to verify the accuracy of the new method and identify any changes in the specimens’ apparent dislocation density caused by the different preparation processes.
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Calmeiro, Tomás R. "Atomic force microscopy assisted with electron and ion beam microscopy for the direct measurement of biostructures and DNA samples." Master's thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/10851.
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Dissertation to obtain a Master degree in BiotechnologyStudies of atomic force microscopy (AFM), a technique commonly associated with material sciences, in the field of biotechnology, with special emphasis on molecular biology and bionanotechnology elements, are presented herein. DNA, insulin and restriction enzymes were analysed as isolated objects, in order to document properties like morphology and behaviour, and also on the interactions between each other. The interaction between DNA and the EcoRV restriction endonuclease was especially highlighted. Gold nanoparticles were also studied in an attempt to establish a relationship between functionalization and average diameter shifts, as perceived by AFM. Given the nature of these objects of study, both immobilization and preparation protocols were modified and evaluated, considering measurements in air or in liquid. To serve the objective of developing probes with higher sensitivity and resolution, especially for liquid measurements, AFM cantilevers were modified through metallic coatings and scanning electron microscopy assisted with focused ion beam (SEM-FIB). Tests performed with these probes confirmed that the modifications were successful, the probes are functional and can aid in the production of better quality images, through the acquisition of sharper data in comparison with non-modified probes.
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Kato, T., S. Iwata, Y. Yamauchi, S. Tsunashima, K. Matsumoto, T. Morikawa, and K. Ozaki. "Planar patterned media fabricated by ion irradiation into CrPt3 ordered alloy films." American Institite of Physics, 2009. http://hdl.handle.net/2237/12635.
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Rivera, Felipe. "Electron Microscopy Characterization of Vanadium Dioxide Thin Films and Nanoparticles." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/2975.
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Vanadium dioxide (VO_2) is a material of particular interest due to its exhibited metal to insulator phase transition at 68°C that is accompanied by an abrupt and significant change in its electronic and optical properties. Since this material can exhibit a reversible drop in resistivity of up to five orders of magnitude and a reversible drop in infrared optical transmission of up to 80%, this material holds promise in several technological applications. Solid phase crystallization of VO_2 thin films was obtained by a post-deposition annealing process of a VO_{x,x approx 2} amorphous film sputtered on an amorphous silicon dioxide (SiO_2) layer. Scanning electron microscopy (SEM) and electron-backscattered diffraction (EBSD) were utilized to study the morphology of the solid phase crystallization that resulted from this post-deposition annealing process. The annealing parameters ranged in temperature from 300°C up to 1000°C and in time from 5 minutes up to 12 hours. Depending on the annealing parameters, EBSD showed that this process yielded polycrystalline vanadium dioxide thin films, semi-continuous thin films, and films of isolated single-crystal particles. In addition to these films on SiO_2, other VO_2 thin films were deposited onto a-, c-, and r-cuts of sapphire and on TiO_2(001) heated single-crystal substrates by pulsed-laser deposition (PLD). The temperature of the substrates was kept at ~500°C during deposition. EBSD maps and orientation imaging microscopy were used to study the epitaxy and orientation of the VO_2 grains deposited on the single crystal substrates, as well as on the amorphous SiO_2 layer. The EBSD/OIM results showed that: 1) For all the sapphire substrates analyzed, there is a predominant family of crystallographic relationships wherein the rutile VO_2{001} planes tend to lie parallel to the sapphire's {10-10} and the rutile VO_2{100} planes lie parallel to the sapphire's {1-210} and {0001}. Furthermore, while this family of relationships accounts for the majority of the VO_2 grains observed, due to the sapphire substrate's geometry there were variations within these rules that changed the orientation of VO_2 grains with respect to the substrate's normal direction. 2) For the TiO_2, a substrate with a lower lattice mismatch, we observe the expected relationship where the rutile VO_2 [100], [110], and [001] crystal directions lie parallel to the TiO_2 substrate's [100], [110], and [001] crystal directions respectively. 3) For the amorphous SiO_2 layer, all VO_2 crystals that were measurable (those that grew to the thickness of the deposited film) had a preferred orientation with the the rutile VO_2[001] crystal direction tending to lie parallel to the plane of the specimen. The use of transmission electron microscopy (TEM) is presented as a tool for further characterization studies of this material and its applications. In this work TEM diffraction patterns taken from cross-sections of particles of the a- and r-cut sapphire substrates not only solidified the predominant family mentioned, but also helped lift the ambiguity present in the rutile VO_2{100} axes. Finally, a focused-ion beam technique for preparation of cross-sectional TEM samples of metallic thin films deposited on polymer substrates is demonstrated.
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Churchill, Layne Russell. "Trapping triply ionized thorium isotopes." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37161.
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Cold trapped ions have many applications in quantum information science and precision metrology. In this thesis, we present progress toward two objectives involving ions confined to linear RF traps: the strong coupling of Ba+ ions with a high finesse optical cavity, and the observation of an optical nuclear transition in 229Th3+. In pursuit of the first objective, a novel high-temperture vapor cell for the spectroscopy of neutral barium was constructed. Using this vapor cell, a new technique for isotope-selective photoionization loading of Ba+ in an ion trap was developed. In pursuit of the second objective, techniques ultimately to be used in creating, trapping, and observing 229Th3+ are studied using 232Th3+. Ion traps are loaded with 232Th3+ via laser ablation of thorium targets. 232Th3+ is detected optically using laser-induced fluorescence and electronically using a channel electron multiplier. A technique for creating ablation targets from trace quantities of thorium nitrate is presented. The primary loss mechanisms of Th3+, charge exchange and chemical reactions, are studied.
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Fagerland, Steffen Knut. "Investigation of Focused Ion Beam/Scanning Electron Microscope parameters for Slice and View and Energy Dispersive X-ray Spectroscopy of Embedded Brain Tissue." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for materialteknologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-25765.
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This Thesis investigates the optimization of a Focused Ion Beam/Scanning Electron Microscope (FIB/SEM) Slice and View protocol of brain tissue. Using a Slice and View protocol in a Dualbeam instrument, the ion and electron beams are used in sequence to alternately mill and image the newly exposed surface of a predefined volume. This creates serial section images that may be used for 3D reconstruction. Research questions addressed include finding FIB parameters most beneficial for accurate milling of the tissue, use of different software strategies and image processing for 3D reconstruction of selected subsets enclosed within the volume sectioned, and the use of Energy Dispersive X-ray Spectroscopy for revealing the volume contents \emph{a priori} of the Slice and View. The reults showed that FIB parameters of $30kV$ and $0.9nA$ provided sufficient accuracy and consistency; that the DAB labeling protocol provided characteristics easily identifiable of the morphology of selected interneurons which were reconstructed, but was difficult to use in a generalized semi-automatic reconstruction protocol; and a model created to test EDX tracing did show potential for its use to increase protocol efficiency by narrowing down the regions of interest of the FIB block.
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Yuan, Hui. "3D morphological and crystallographic analysis of materials with a Focused Ion Beam (FIB)." Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0134/document.
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L’objectif principal de ce travail est d’optimise la tomographie par coupe sériée dans un microscope ‘FIB’, en utilisant soit l’imagerie électronique du microscope à balayage (tomographie FIB-MEB), soit la diffraction des électrons rétrodiffusés (tomographie dite EBSD 3D). Dans les 2 cas, des couches successives de l’objet d’étude sont abrasées à l’aide du faisceau ionique, et les images MEB ou EBSD ainsi acquises séquentiellement sont utilisées pour reconstruire le volume du matériau. A cause de différentes sources de perturbation incontrôlées, des dérives sont généralement présentes durant l'acquisition en tomographie FIB-MEB. Nous avons ainsi développé une procédure in situ de correction des dérives afin de garder automatiquement la zone d'intérêt (ROI) dans le champ de vue. Afin de reconstruction le volume exploré, un alignement post-mortem aussi précis que possible est requis. Les méthodes actuelles utilisant la corrélation-croisée, pour robuste que soit cette technique numérique, présente de sévères limitations car il est difficile, sinon parfois impossible de se fier à une référence absolue. Ceci a été démontré par des expériences spécifiques ; nous proposons ainsi 2 méthodes alternatives qui permettent un bon alignement. Concernant la tomographie EBSD 3D, les difficultés techniques liées au pilotage de la sonde ionique pour l'abrasion précise et au repositionnement géométrique correct de l’échantillon entre les positions d'abrasion et d’EBSD conduisent à une limitation importante de la résolution spatiale avec les systèmes commerciaux (environ 50 nm)3. L’EBSD 3D souffre par ailleurs de limites théoriques (grand volume d'interaction électrons-solide et effets d'abrasion. Une nouvelle approche, qui couple l'imagerie MEB de bonne résolution en basse tension, et la cartographie d'orientation cristalline en EBSD avec des tensions élevées de MEB est proposée. Elle a nécessité le développement de scripts informatiques permettant de piloter à la fois les opérations d’abrasion par FIB et l’acquisition des images MEB et des cartes EBSD. L’intérêt et la faisabilité de notre approche est démontrée sur un cas concret (superalliage de nickel). En dernier lieu, s’agissant de cartographie d’orientation cristalline, une méthode alternative à l’EBSD a été testée, qui repose sur l’influence des effets de canalisation (ions ou électrons) sur les contrastes en imagerie d’électrons secondaires. Cette méthode corrèle à des simulations la variation d’intensité de chaque grain dans une série d’images expérimentales obtenues en inclinant et/ou tournant l’échantillon sous le faisceau primaire. Là encore, la méthode est testée sur un cas réel (polycritsal de TiN) et montre, par comparaison avec une cartographie EBSD, une désorientation maximale d'environ 4° pour les angles d’Euler. Les perspectives d’application de cette approche, potentiellement beaucoup plus rapide que l’EBSD, sont évoquéesThe aim of current work is to optimize the serial-sectioning based tomography in a dual-beam focused ion beam (FIB) microscope, either by imaging in scanning electron microscopy (so-called FIB-SEM tomography), or by electron backscatter diffraction (so-called 3D-EBSD tomography). In both two cases, successive layers of studying object are eroded with the help of ion beam, and sequentially acquired SEM or EBSD images are utilized to reconstruct material volume. Because of different uncontrolled disruptions, drifts are generally presented during the acquisition of FIB-SEM tomography. We have developed thus a live drift correction procedure to keep automatically the region of interest (ROI) in the field of view. For the reconstruction of investigated volume, a highly precise post-mortem alignment is desired. Current methods using the cross-correlation, expected to be robust as this digital technique, show severe limitations as it is difficult, even impossible sometimes to trust an absolute reference. This has been demonstrated by specially-prepared experiments; we suggest therefore two alternative methods, which allow good-quality alignment and lie respectively on obtaining the surface topography by a stereoscopic approach, independent of the acquisition of FIB-SEM tomography, and realisation of a crossed ‘hole’ thanks to the ion beam. As for 3D-EBSD tomography, technical problems, linked to the driving the ion beam for accurate machining and correct geometrical repositioning of the sample between milling and EBSD position, lead to an important limitation of spatial resolution in commercial softwares (~ 50 nm)3. Moreover, 3D EBSD suffers from theoretical limits (large electron-solid interaction volume for EBSD and FIB milling effects), and seems so fastidious because of very long time to implement. A new approach, coupling SEM imaging of good resolution (a few nanometres for X and Y directions) at low SEM voltage and crystal orientation mapping with EBSD at high SEM voltage, is proposed. This method requested the development of computer scripts, which allow to drive the milling of FIB, the acquisition of SEM images and EBSD maps. The interest and feasibility of our approaches are demonstrated by a concrete case (nickel super-alloy). Finally, as regards crystal orientation mapping, an alternative way to EBSD has been tested; which works on the influence of channelling effects (ions or electrons) on the imaging contrast of secondary electrons. This new method correlates the simulations with the intensity variation of each grain within an experimental image series obtained by tilting and/or rotating the sample under the primary beam. This routine is applied again on a real case (polycrystal TiN), and shows a max misorientation of about 4° for Euler angles, compared to an EBSD map. The application perspectives of this approach, potentially faster than EBSD, are also evoked
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Ostřížek, Petr. "Elektrotransportní vlastnosti nanostruktur připravených metodou FIB." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229474.
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The aim of this work is fabrication of nanostructures and measurement of their electrotransport properties. There are two different methods used for fabrication - electron beam lithography with sputtering of thin films and focused ion beam with deposition from gas phase. I-V characteristic was measured for characterisation of as prepared nanostructures - wires. Material of wires prepared by using of electron beam lithography was permalloy - an alloy of iron and nickel. Second types of wires prepared by using of chemical vapor deposition induced by focused ion beam was platinum based.
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Castro, Olivier de. "Development of a Versatile High-Brightness Electron Impact Ion Source for Nano-Machining, Nano-Imaging and Nano-Analysis." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS468/document.
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Les nano-applications utilisant des faisceaux d'ions focalisés nécessitent des sources d'ions à haute brillance avec une faible dispersion en énergie (ΔE) ce qui permet une excellente résolution latérale et un courant d'ions suffisamment élevé pour induire des vitesses d'érosion raisonnables et des rendements élevés d'émission électronique et ionique. Les objectifs de cette thèse sont le développement d'une source d'ions basée sur l'impact électronique ayant une brillance réduite Br de 10³ – 10⁴ A m⁻² sr ⁻ ¹ V⁻ ¹, une dispersion en énergie ΔE ≲ 1 eV et un choix polyvalent d'ions. Le premier concept évalué consiste à focaliser un faisceau d'électrons à une énergie de 1 keV entre deux électrodes parallèles distant de moins d'un millimètre. Le volume d'ionisation « micrométrique » est formé au-dessus d'une ouverture d'extraction de quelques dizaines de µm. En utilisant un émetteur d'électrons LaB₆ et une pression de 0.1 mbar dans la région d'ionisation, Br est proche de 2.10² A m⁻² sr ⁻ ¹ V ⁻ ¹ avec des tailles de source de quelques µm, des courants de quelques nA pour Ar⁺/Xe⁺/O₂ ⁺ et une dispersion en énergie ΔE < 0.5 eV. La brillance réduite Br est encore en dessous de la valeur minimum de notre objectif et la pression de fonctionnement très faible nécessaire pour l'émetteur LaB₆ ne peut être obtenue avec une colonne d'électrons compacte, donc ce prototype n'a pas été construit.Le deuxième concept de source d'ions évalué est basé sur l’idée d’obtenir un faisceau ionique à fort courant avec une taille de source et un demi-angle d’ouverture similaire aux résultats du premier concept de source, mais en changeant l’interaction électron-gaz et la collection des ions. Des études théoriques et expérimentales sont utilisées pour l’évaluation de la performance de ce deuxième concept et de son utilité pour les nano-applications basées sur des faisceaux d'ions focalisésHigh brightness low energy spread (ΔE) ion sources are needed for focused ion beam nano-applications in order to get a high lateral resolution while having sufficiently high ion beam currents to obtain reasonable erosion rates and large secondary electron/ion yields. The objectives of this thesis are: the design of an electron impact ion source, a reduced brightness Br of 10³ – 10⁴ A m⁻² sr⁻ ¹ V⁻ ¹ with an energy distribution spread ΔE ≲ 1 eV and a versatile ion species choice. In a first evaluated concept an electron beam is focussed in between two parallel plates spaced by ≲1 mm. A micron sized ionisation volume is created above an extraction aperture of a few tens of µm. By using a LaB₆ electron emitter and the ionisation region with a pressure around 0.1 mbar, Br is close to 2.10² A m⁻² sr ⁻ ¹ V ⁻ ¹ with source sizes of a few µm, ionic currents of a few nA for Ar⁺/Xe⁺/O₂ ⁺ and the energy spread being ΔE < 0.5 eV. The determined Br value is still below the minimum targeted value and furthermore the main difficulty is that the needed operation pressure for the LaB₆ emitter cannot be achieved across the compact electron column and therefore a prototype has not been constructed. The second evaluated source concept is based on the idea to obtain a high current ion beam having a source size and half-opening beam angle similar to the first concept, but changing the electron gas interaction and the ion collection. Theoretical and experimental studies are used to evaluate the performance of this second source concept and its usefulness for focused ion beam nano-applications
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Niehle, Michael. "Electron tomography and microscopy on semiconductor heterostructures." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17607.
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Elektronentomographie erlaubt die dreidimensionale (3D) Charakterisierung von Kristalldefekten auf der Nanometerskala. Die Anwendung in der Forschung an epitaktischen Halbleiterheterostrukturen ist bisher nicht durchgesetzt worden, obwohl kleiner werdende Bauteile mit zunehmend dreidimensionaler Struktur entsprechende Untersuchungen verlangen, um die Beziehung von Struktur und physikalischen Eigenschaften in entsprechenden Materialsystemen zu verstehen. Die vorliegende Arbeit demonstriert die konsequente Anwendung der Elektronentomographie auf eine III-Sb basierte Laser- und eine 3D (In,Ga)N/GaN Nanosäulenheterostruktur. Die unerlässliche Zielpräparation von Proben mittels FIB-SEM-Zweistrahlmikroskops wird herausgestellt. Die kontrollierte Orientierung der Probe während der Präparation und die sorfältige Auswahl eines Abbildungsverfahrens im STEM werden detailliert beschrieben. Die umfassende räumliche Mikrostrukturanalyse einer antimonidbasierten Schichtstruktur folgt der Dimensionalität von Kristalldefekten. Die Facettierung und Lage einer Pore (3D Defekt), deren Auftreten in der MBE gewachsenen GaSb-Schicht untypisch ist, werden bestimmt. Das Zusammenspiel von anfänglich abgeschiedenen AlSb-Inseln auf dem Si-Substrat, der Ausbildung eines Fehlversetzungsnetzwerkes an der Grenzfläche der Heterostruktur (2D Defekt) und dem Auftreten von Durchstoßversetzungen wird mit Hilfe der Kombination tomographischer und komplementärer TEM-/STEM-Ergebnisse untersucht. Die räumliche Anordnung von Versetzungen (1D Defekte), die das ganze Schichtsystem durchziehen, wird mit Elektronentomographie offenbart. Die Wechselwirkung dieser Versetzungen mit Antiphasengrenzen und anderen Liniendefekten sind ein einzigartiges Ergebnis der Elektronentomographie. Abschließend sind Unterschiede im Indiumgehalt und in der Schichtdicke von (In,Ga)N-Einschlüssen auf verschiedenen Facetten schief aufgewachsener GaN-Nanosäulen einmalig per Elektronentomographie herausgearbeitet worden.Electron tomography exhibits a very poor spread in the research field of epitaxial semiconductor heterostructures in spite of the ongoing miniaturization and increasing three-dimensional (3D) character of nano-structured devices. This necessitates a tomographic approach at the nanometre scale in order to characterize and understand the relation between structure and physical properties of respective material systems. The present work demonstrates the rigorous application of electron tomography to an III-Sb based laser and to an (In,Ga)N/GaN nanocolumn heterostructure. A specific target preparation using a versatile FIB-SEM dual-beam microscope is emphasized as indispensable. The purposeful orientation of the specimen during preparation and the careful selection of an imaging mode in the scanning-/transmission electron microscope (S/TEM) are regarded in great detail. The comprehensive spatial microstructure characterization of the antimonide based heterostructure follows the dimensionality of crystal defects. The facetting and position of a pore (3D defect) which is unexpected in the MBE grown GaSb layer, is determined. The interplay of the initially grown AlSb islands on Si, the formation of a misfit dislocation network at the heterostructure interface (2D defect) and the presence of threading dislocations is investigated by the correlation of tomographic and complementary S/TEM results. The spatial arrangement of dislocations (1D defects) penetrating the whole stack of antimonide layers is revealed by electron tomography. The interaction of these line defects with anti-phase boundaries and with other dislocations is exclusively observed in the 3D result. The insertion of (In,Ga)N into oblique GaN nanocolumns is uniquely accessed by electron tomography. The amount of incorporated indium and the (In,Ga)N layer thickness is shown to vary on the different facets of the GaN core.