Dissertations / Theses on the topic 'Resonant; lattice'
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Kozar, A. I. "Electromagnetic wave scattering by pyramid-shaped photonic crystal from resonant magnetodielectric spheres." Thesis, Eskisehir Technical University, 2021. https://openarchive.nure.ua/handle/document/18637.
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The solution of the problem of scattering electromagnetic waves with a discrete convex polyhedron - a pyramid of resonant magnetodielectric spheres based on a complex rhombic crystal lattice is presented.
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Kawai, Daisuke. "The study on quantum field theories from numerical approaches." Kyoto University, 2018. http://hdl.handle.net/2433/232236.
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Chakhmakhchyan, Levon. "Entangled states and coherent interaction in resonant media." Thesis, Dijon, 2014. http://www.theses.fr/2014DIJOS026/document.
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Nous analysons les caractéristiques d'intrication de quelques matériaux à l'état solide ainsi que des systèmes particuliers d'atomes et de champs en interaction. Une étude détaillée de la riche structure de phase des modèles de spins de basse dimension, décrivant le minéral naturel d'azurite et les composés de coordination à base de cuivre, a révélé des régimes à comportement d'intrication des plus robustes. En utilisant l'approche des systèmes dynamiques, la structure de phase de certains modèles classiques en réseaux hiérarchiques (récursifs) a aussi été étudiée et, pour la première fois, la transition entre régime chaotique et régime périodique au moyen de la bifurcation tangente a été détectée.Nous présentons une description détaillée des propriétés d'intrication de trois atomes piégés dans la limite dispersive. Une relativement simple accordabilité de la force atomique d'interaction de ce système et son étroite relation aux problèmes de frustration magnétique est démontrée. Les effets de propagation de pulses laser intenses dans un système atomique de type [lambda] avec des forces d'oscillateurs différentes sont analysés. Les résultats obtenus sont d'extrême importance dans des problèmes d'information quantique, comme par exemple, dans l'analyse du mécanisme de transfert de population dans des milieux ayant les propriétés définies ci-avant. Enfin, nous avons analysé les effets dissipatifs dans un protocole de distillation de l'intrication à variable continue récemment proposé. Malgré des contraintes additionnelles sur les paramètres du protocole, il est encore possible d'implémenter ce schéma de distillation évoqué ci-avant dans les technologies émergentesThe entanglement features of some solid state materials, as well as of particular systems of interacting atoms and fields are analyzed. A detailed investigation of the rich phase structure of low dimensional spin models, describing the natural mineral azurite and copper based coordination compounds, has revealed regimes with the most robust entanglement behavior. Using the dynamical system approach, the phase structure of some classical models on hierarchical (recursive) lattices has been also studied and, for the first time, the transition between chaotic and periodic regimes by means of tangent bifurcation has been detected.A detailed description of entanglement properties of three atoms trapped in a cavity within the dispersive limit is presented. A relatively simple tunability of the atomic interaction strength of the above system and its close relation to the problems of frustrated magnetism is shown. Furthermore, the propagation effects of two intense laser pulses in a medium of [lambda] atoms with unequal oscillator strengths are investigated. Obtained results are crucial in some problems of quantum information theory, as, e.g., in the analysis of population transfer mechanism in media possessing the above properties. Finally, the dissipation effects in a recently proposed compact continuous-variable entanglement distillation protocol have been analyzed. Despite additional constraints on the parameters of the protocol, the discussed entanglement distillation scheme in quantum memories is still possible to implement within emerging technologies
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Kallarackal, Jim. "The Higgs boson resonance from a chiral Higgs-Yukawa model on the lattice." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2011. http://dx.doi.org/10.18452/16332.
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Das Higgs-Teilchen ist essentiell für die Erzeugung von Massen für Fermionen und Eich- bosonen der schwachen Wechselwirkung. Ziel dieser Arbeit ist es, die Masse und die Zerfallsbreite des Higgs-Teilchens einzugrenzen. Grundlage für die Berechnung physikalischer Größen ist dabei das Pfadintegral, welches mittels Monte-Carlo Simulationen bestimmt wird. Ein polynomieller Hybrid-Monte- Carlo-Algorithmus berücksichtigt dabei alle dynamischen Freiheitsgrade der Fermionen. Die chirale Natur der Fermionen werden mit Hilfe des Neuberger- Overlap-Operators beschrieben. In dieser Arbeit wird das Standardmodell auf den Higgs-Yukawa-Sektor eingegrenzt, welcher keine Eichbosonen enthält und lediglich ein degeneriertes Quark-Doublet berücksichtigt. Anhand des Higgs-Teilchen-Propagators werden die Ergebnisse aus der Git- terstörungsrechnung bis zu einer Schleife mit denen aus der Monte-Carlo- Simulation verglichen. Für die untersuchten Parameter, stimmen die Ergeb- nisse aus der Störungstheorie mit den Monte-Carlo-Daten sehr gut überein. Ein Schwerpunkt dieser Arbeit ist die Analyse der Resonanzparameter des Higgs-Teilchens. Die Resonanzmasse und die Resonanzbreite werden bei schwachen als auch bei starken quartischen Kopplungen untersucht. Das Higgs-Teilchen erscheint nicht als asymptotisch stabiles Teilchen, sondern als Resonanz. In allen Fällen liegt die Resonanzbreite unter 10% der Resonanzmasse. Die Resonanzmasse wird sodann mit der Propagatormasse verglichen. Für alle betrachteten Kopplun- gen gibt es eine hervorragende Übereinstimmung beider Größen. Zuletzt gilt es, den Einfluss einer schweren vierten Generation von Quarks auf die obere und untere Massenschranke des Higgs-Teilchens zu untersuchen. Alle numerischen Resultate involvieren eine umfassende Analyse der Volu- menabhängigkeit und erfordern zwingend eine Extrapolation ins unendliche Volumen.The Higgs boson is a central part of the electroweak theory and is crucial to generate masses for fermions and the weak gauge bosons. The goal of this work is to set limits on the mass and the decay width of the Higgs boson. The basis to compute the physical quantities is the path integral which is here evaluated by means of Monte Carlo simulations thus allowing for fully non perturbative calculations. A polynomial hybrid Monte Carlo algo- rithm is used to incorporate dynamical fermions. The chiral symmetry of the electroweak model is incorporated by using the Neuberger overlap operator. Here, the standard model is considered in the limit of a Higgs-Yukawa sector which does not contain the weak gauge bosons and only a degenerate doublet of top- and bottom quarks are incorporated. Results from lattice perturbation theory up to one loop of the Higgs boson propagator are compared with those obtained from Monte Carlo simulations. At all values of the investigated couplings, the perturbative results agree very well with the Monte Carlo data. A main focus of this work is the investigation of the resonance parameters of the Higgs boson. The resonance width and the resonance mass are investigated at weak and at large quartic couplings. The Higgs boson does not appear as an asymptotic stable state but as a resonance. In all considered cases the Higgs boson resonance width lies below 10% of the resonance mass. The obtained resonance mass is compared with the mass obtained from the Higgs boson propagator. The results agree perfectly at all values of the quartic coupling considered. Finally, the effect of a heavy fourth generation of fermions on the upper and lower Higgs boson mass bound is studied. All numerical results presented in this work involve extensive finite volume analysis and an extrapolation to infinite volume is inevitable.
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Holder, Jonathan Paul. "Resonant tunnelling spectroscopy of vertical GaAs/AlGaAs structures." Thesis, University of Exeter, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312281.
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Dapore-Schwartz, Samuel. "An atomic beam magnetic resonance study of a superconductor's magnetic vortex lattice /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487856906257537.
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Alexandrou, Constantia, Luka Leskovec, Stefan Meinel, John Negele, Srijit Paul, Marcus Petschlies, Andrew Pochinsky, Gumaro Rendon, and Sergey Syritsyn. "P -wave π π scattering and the ρ resonance from lattice QCD." AMER PHYSICAL SOC, 2017. http://hdl.handle.net/10150/625756.
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We calculate the parameters describing elastic I = 1, P-wave pp scattering using lattice QCD with 2 + 1 flavors of clover fermions. Our calculation is performed with a pion mass of m(pi) approximate to 320 MeV and a lattice size of L approximate to 3.6 fm. We construct the two-point correlation matrices with both quark-antiquark and two-hadron interpolating fields using a combination of smeared forward, sequential and stochastic propagators. The spectra in all relevant irreducible representations for total momenta vertical bar(P) over right arrow vertical bar <= root 32 pi/L are extracted with two alternative methods: a variational analysis as well as multiexponential matrix fits. We perform an analysis using Luscher's formalism for the energies below the inelastic thresholds, and investigate several phase shift models, including possible nonresonant contributions. We find that our data are well described by the minimal Breit-Wigner form, with no statistically significant nonresonant component. In determining the rho resonance mass and coupling we compare two different approaches: fitting the individually extracted phase shifts versus fitting the t-matrix model directly to the energy spectrum. We find that both methods give consistent results, and at a pion mass of am(pi) = 0.18295(36)(stat) obtain g(rho pi pi) = 5.69(13)(stat)(16)(sys), am(rho) = 0.4609(16)(stat)(14)(sys), and am(rho)/am(N) = 0.7476(38)(stat)(23)(sys), where the first uncertainty is statistical and the second is the systematic uncertainty due to the choice of fit ranges.
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Jiang, Kefeng. "Investigation of Stochastic Resonance in Directed Propagation of Cold Atoms." Miami University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=miami1626991662334714.
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Groves, Ronald William. "O17 spin-lattice relaxation solid state NMR studies of pure and doped ices." Columbus, Ohio : Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1021903674.
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Thesis (Ph. D.)--Ohio State University, 2002.Title from first page of PDF file. Document formatted into pages; contains xx, 128 p.; also contains graphics. Includes abstract and vita. Co-advisors: Charles H. Pennington and James V. Coe, Dept. of Chemistry. Includes bibliographical references (p. 124-128).
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Hauglin, Harald. "Vortex lattice structure in single crystal YBCO studied with atomic beam magnetic resonance /." The Ohio State University, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487943341526625.
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Bouganne, Raphaël. "Probing ultracold ytterbium in optical lattices with resonant light : from coherent control to dissipative dynamics." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS391.
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Dans ce manuscrit je décris une série d'études expérimentales portant sur la dynamique d'un nuage d'atomes d'ytterbium bosonique dégénérés chargés dans un réseau optique et soumis à de la lumière résonante. L'interaction atome-lumière permet d'étudier les propriétés de cohérence quantique du gaz. Dans un premier temps, je démontre la manipulation cohérente de l'état interne des atomes sur la transition d'horloge, dont l'état excité est métastable et ne peux pas émettre de photons spontanément, protégeant ainsi la cohérence du gaz. La dynamique temporelle de l'état interne d'atomes chargés dans un réseau optique profond permet de mesurer les propriétés collisionelles à basse température pour les états horloges de l'ytterbium. Dans un second temps, j'utilise l'émission spontanée associée à la transition d'intercombinaison, ce qui permet un couplage aux degrés de liberté externes des atomes. Je présente l'étude de la diffusion en impulsion d'un superfluide excité sur cette transition. Les fortes interactions entre atomes conduisent à l'observation d'une décohérence ralentie aux temps longs et caractérisée par un régime sous-diffusif. Un modèle simple de type Bose-Hubbard incluant la dissipation permet de rendre compte de ces observations. Une étude théorique des effets à N-corps dans l'interaction atome-lumière vient en compléter l'analyseIn this manuscript I present an experimental investigation of the dynamics of an ultracold gas of bosonic ytterbium loaded into optical lattices and exposed to resonant light. The interaction between atoms and light makes it possible to study the coherence properties of the gas. The resonant driving is performed on the relevant optical transitions featured by ytterbium. On the one hand, I demonstrate the coherent driving of the internal state of the atoms on the clock transition, the excited state of which is metastable and can not spontaneously decay, thus preserving the coherence of the gas. The temporal internal dynamics in a deep lattice allows me to measure the collisional properties at low temperature for both clock states. On the other hand, I use the spontaneously emitted photons of the intercombination transition excited level to induce a coupling to the atomic external degrees of freedom. I present the momentum diffusion of a superfluid excited on this transition. Strong interactions between atoms slow down the decoherence and lead to an anomalous sub-diffusive relaxation. A simple model comprising atomic motion, interactions and dissipation accounts for our observations. A theoretical study of the dissipative dynamics in optical lattices sheds light on complementary phenomena such as induced dipole-dipole interactions or collective effects in spontaneous emission
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Solbrig, Stefan. "Topology in SU(2) lattice gauge theory and parallelization of functional magnetic resonance imaging." kostenfrei, 2008. http://www.opus-bayern.de/uni-regensburg/volltexte/2008/1005/.
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Lee, Jae Hoon. "Sub-Wavelength Resonance Imaging and Addressing of Cesium Atoms Trapped in an Optical Lattice." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/228193.
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We demonstrate a resonance imaging protocol for optical lattices that enables robust preparation and single qubit addressing of atoms with sub-wavelength resolution in 1D. A 3D optical lattice consisting of three sets of independent 1D counter- propagating laser beams provides the trapping potential for the atoms. On this optical lattice platform, a long-period 1D superlattice is imposed by interfering two laser beams at a shallow angle centered at the atoms. This superlattice creates a position-dependent shift of the qubit transition frequency defined between two spin states in the ground manifold. Isolated 2D planes of atoms are prepared by flipping the resonant spins with a microwave pulse and removing the non-resonant spins by pushing them out of the lattice with a resonant laser beam. The periodic planes of atoms that are prepared can be imaged by applying another microwave pulse and detecting the fluorescence from the spins that flip back to the initial state, as a function of superlattice displacement between the preparation and read-out pulses. By employing these new techniques for sub-wavelength imaging, we tested the effectiveness of using composite pulses for addressing the trapped atoms in an optical lattice. Composite pulse techniques can be used to reduce the sensitivity of the addressing to small variations in the relative position and intensity of the lattices. This robustness is achieved by applying numerically generated composite pulses that have a constant atomic response within a target range of relative lattice positions and intensities. We designed a composite microwave pulse that flips the spin with near unit fidelity for all atoms that are positioned within a target spatial region, while conserving the spin of the atoms outside of that region. This cannot be accomplished with plain pulses due to off-resonant excitation. We also expanded the concept of this technique for robustly addressing spins even further to implement independent unitaries, or single qubit quantum gates, across several adjacent lattice sites. Finally, in order to quantitatively measure the fidelity of these robust composite pulses, we perform a randomized benchmarking procedure, which was first proposed by Knill.
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Le, Gros Mark. "NMRON studies of insulating magnetic materials." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30569.
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Selective excitation pulsed NMRON, CW-NMRON and Thermal NMR methods have been used to study the low temperature ⁵⁴Mn nuclear spin-lattice relaxation mechanisms in magnetic insulators.
The selective single and double quantum excitation sequences have been used for the first time in NMRON to obtain single and double quantum rotation patterns, Free Induction Decays, Hahn spin echoes and pulsed T₁ measurements.
Two insulating magnets have been studied; MnCl₂.4H₂O and Mn(COOCH₃ )₂ .4H₂O. In the ⁵⁴Mn-MnCl₂ .4H₂O system the temperature dependence of the ⁵⁴Mn spin-lattice relaxation time at zero field was measured between 35 mK and 90 mK and it was found that the dominant relaxation process between 65 mK and 90 mK is an electronic magnon Raman process and below 65 mK a direct relaxation process dominates.
Single and double quantum Free Induction Decays and Hahn spin echoes have been used to determine the magnitude and nature of the spin-spin relaxation mechanism for ⁵⁴Mn oriented in MnCl₂.4H₂O at zero applied field.
NMRON was observed for the first time in the paramagnetic phase of MnCl₂.4H₂O. The resonance lines are inhomogeneously broadened and 300 kHz wide. A value of <⁵⁴AS>/h=-513.6(3) MHz has been determined for the paramagnetic phase hyperfine coupling constant, and this value has been used to determine the zero point spin deviation of the antiferromagnetic phase.
The field and temperature dependence of the ⁵⁴Mn T₁ was measured for values of field above the spin flop paramagnetic phase transition and a field dependent T₁ minimum was discovered at Ba=2.64 T.
For the ⁵⁴Mn-Mn(COOCH₃) .4H₂O system two ⁵⁴Mn resonances have been observed and the value of the hyper fine coupling constants for the two sites were found to be <⁵⁴AS>/h=-435 (1) MHz for the ⁵⁴Mn1 site and <⁵⁴AS>/h=-478(1) MHz for the ⁵⁴Mn2 site. The high field spin-lattice relaxation behavior has also been investigated and a T₁ minimum at Ba =2.74 T analogous to that observed in MnCl₂ .4H₂O was discovered.
A Hahn echo study of the low field single quantum spin-spin relaxation processes has been performed and anomalous behavior of the spin echo amplitude revealed.Science, Faculty of
Physics and Astronomy, Department of
Graduate
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Brosten, Tyler Ryan. "Flow and transport studies of porous systems by magnetic resonance microscopy and Lattice Boltzmann simulations." Diss., Montana State University, 2010. http://etd.lib.montana.edu/etd/2010/brosten/BrostenT0510.pdf.
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Nuclear magnetic resonance experiments and Lattice-Boltzmann simulations are powerful techniques for studying pore scale dynamics in porous media. Several applications of these methods to the study of pore scale hydrodynamics and transport are discussed. Of special interest are concepts relating to pore structure characterization. In the first application it is shown that nuclear magnetic resonance measurements of pre-asymptotic transport dynamics in random open cell foams provide a characteristic structure length scale. These measurements and Lattice-Boltzmann simulations for a model foam structure demonstrate dynamical behavior similar to lower porosity consolidated granular porous media; suggesting a generalized approach to pore structure characterization. Normalizing the data by the characteristic length collapses data for different foam samples and mono-disperse packed beds. The non-equilibrium statistical mechanics theory of pre-asymptotic dispersion is used to model the hydrodynamic dispersive dynamics. In the second application transport of hard sphere colloidal particles under flow through an open cell foam is studied using nuclear magnetic resonance. The temporal dynamics of the colloidal particles and suspending fluid phase are obtained through spectral chemical resolution. The data is interpreted in the broader context of classic hydrodynamic dispersion theory and mechanisms of transport for each phase. In the third application pore scale hydrodynamics of flow over a model porous surface are investigated using three dimensional Lattice-Boltzmann simulations and nuclear magnetic resonance. The Lattice-Boltzmann and nuclear magnetic resonance data are used to interpret classic interfacial hydrodynamic boundary conditions. Finally, in the fourth application a study of magnetic resonance microscopy to novel tape cast porous ceramics is conducted.
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Staron, Alexander. "Stochastic Resonances and Velocity Sorting in a Dissipative Optical Lattice." Miami University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=miami1596451157122873.
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Bray, Christina L., Robert G. Bryant, M. J. Cox, Gianni Ferrante, Y. Goddard, Sandip Sur, and Joseph P. Hornack. "The proton Nuclear Magnetic Resonance spin-lattice relaxation rate of some hydrated synthetic and natural sands." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-192008.
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The proton nuclear magnetic resonance (NMR) spin-lattice relaxation rate (R1) of hydrated sands is often used to determine porosity characteristics of near-surface aquifers using magnetic resonance sounding. Large variations in R1 have been reported in laboratory measurements on hydrated sands. To understand these variations, the R1 values of several fully hydrated sands were studied as a function of grain diameter (d) and magnetic field strength (BB0).
We conclude the variations are a consequence of trace paramagnetic metals in the sand grains. R1 values from magnetic resonance sounding data should not be used to predict void size in aquifers unless the exact chemical composition of the grains is known.
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Bray, Christina L., Robert G. Bryant, M. J. Cox, Gianni Ferrante, Y. Goddard, Sandip Sur, and Joseph P. Hornack. "The proton Nuclear Magnetic Resonance spin-lattice relaxation rate of some hydrated synthetic and natural sands." Diffusion fundamentals 10 (2009) 8, S. 1-3, 2009. https://ul.qucosa.de/id/qucosa%3A14098.
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The proton nuclear magnetic resonance (NMR) spin-lattice relaxation rate (R1) of hydrated sands is often used to determine porosity characteristics of near-surface aquifers using magnetic resonance sounding. Large variations in R1 have been reported in laboratory measurements on hydrated sands. To understand these variations, the R1 values of several fully hydrated sands were studied as a function of grain diameter (d) and magnetic field strength (BB0).
We conclude the variations are a consequence of trace paramagnetic metals in the sand grains. R1 values from magnetic resonance sounding data should not be used to predict void size in aquifers unless the exact chemical composition of the grains is known.
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Erben, Felix Benjamin [Verfasser]. "A Lattice QCD study of the rho resonance and the timelike pion form factor / Felix Benjamin Erben." Mainz : Universitätsbibliothek Mainz, 2018. http://d-nb.info/1173910301/34.
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Werner, Markus Alexander Oliver [Verfasser]. "Hadron-Hadron Interactions from Nf = 2+1+1 Lattice QCD : The ρ–resonance / Markus Alexander Oliver Werner." Bonn : Universitäts- und Landesbibliothek Bonn, 2020. http://d-nb.info/1204479690/34.
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Bhat, Vinayak S. "A Study of Periodic and Aperiodic Ferromagnetic Antidot Lattices." UKnowledge, 2014. http://uknowledge.uky.edu/physastron_etds/25.
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This thesis reports our study of the effect of domain wall pinning by ferromagnetic (FM) metamaterials [1] in the form of periodic antidot lattices (ADL) on spin wave spectra in the reversible regime. This study was then extended to artificial quasicrystals in the form of Penrose P2 tilings (P2T). Our DC magnetization study of these metamaterials showed reproducible and temperature dependent knee anomalies in the hysteretic regime that are due to the isolated switching of the FM segments. Our dumbbell model analysis [2] of simulated magnetization maps indicates that FM switching in P2T is nonstochastic. We have also acquired the first direct, two-dimensional images of the magnetization of Permalloy films patterned into P2T using scanning electron microscopy with polarization analysis (SEMPA). Our SEMPA images demonstrate P2T behave as geometrically frustrated networks of narrow ferromagnetic film segments having near-uniform, bipolar (Ising-like) magnetization, similar to artificial spin ices (ASI). We find the unique aperiodic translational symmetry and diverse vertex coordination of multiply-connected P2T induce a more complex spin-ice behavior driven by exchange interactions in vertex domain walls, which differs markedly from the behavior of disconnected ASI governed only by dipolar interactions.
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Humphrey, Alastair Dalziell. "Exploration of how light interacts with arrays of plasmonic, metallic nanoparticles." Thesis, University of Exeter, 2015. http://hdl.handle.net/10871/19365.
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The content of this thesis is based upon the interaction of light with metallic nanoparticles arranged in different array geometries. An incident electric field (light) can force the conduction electrons of a metallic nanoparticle to oscillate. At particular frequencies, in the optical regime for gold and silver particles, absorption and scattering of the light by the particle is enhanced, corresponding to the particle plasmon resonance. The spectral position and width of the particle plasmon resonance of an isolated single particle may be tuned by adjusting its size and shape, thus changing the surface charge distribution. Periodic arrays of particles offer additional control over the frequency and width of the resonance attributed to the re-radiating (scattering) property of plasmonic particles. By fabricating arrays with a pitch comparable to the wavelength of an isolated single particle plasmon resonance, a coherent interaction between particles may be produced, known as surface lattice resonances (SLRs). The electromagnetic coupling between in-plane particle plasmon modes for different particle array geometries is explored through experiment and theory. Firstly, SLRs in square, hexagonal and honeycomb arrays are investigated by normal-incidence extinction measurements and compared to a simple-coupled dipole model. Secondly, to verify the nature of the coupling between the scattered electric field associated with particle resonances, the incident electric field polarization-dependence of the extinction of rectangular arrays and chains is studied. Thirdly, the optical response of square arrays with a symmetric two-particle basis is investigated, particularly the retardation of the scattered electric field between particles in a pair. Fourthly, square arrays with an asymmetric two-particle basis are fabricated to explore the symmetric (dipole moments of both particles are parallel) and anti-symmetric (dipole moment of both particles anti-parallel) SLRs, excited by normal-incidence light.
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Gutzwiller, Simone [Verfasser], and Meinulf [Akademischer Betreuer] Göckeler. "Scattering phase shift for elastic two pion scattering and the rho resonance in lattice QCD / Simone Gutzwiller. Betreuer: Meinulf Göckeler." Regensburg : Universitätsbibliothek Regensburg, 2012. http://d-nb.info/1027010156/34.
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Klemens, Fabian [Verfasser], and G. [Akademischer Betreuer] Thäter. "Combining computational fluid dynamics and magnetic resonance imaging data using lattice Boltzmann based topology optimisation / Fabian Klemens ; Betreuer: G. Thäter." Karlsruhe : KIT-Bibliothek, 2020. http://d-nb.info/1221186922/34.
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Frison, Julien. "Calcul Ab-initio de propriétés de résonances hadroniques légères." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4082.
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Il est établi depuis maintenant 40 ans que l'interaction nucléaire forte peut être décrite par la Chromodynamique Quantique (QCD). Le confinement des quarks dans cette théorie masque cependant ses degrés de liberté élémentaires dans les processus de basse énergie, qui doivent être calculés non-perturbativement. La QCD sur réseau est à ce jour la seule méthode permettant de mener à bien de tels calculs, et arrive dorénavant à maturité. Cependant, et alors que le spectre des hadrons stables est calculée avec précision, l'étude des désintégrations reste délicate. Nous présentons ici l'application du formalisme de Lüscher au calcul des propriétés de résonances se désintégrant sous l'interaction forte, ainsi qu'un calcul avec précision de la largeur de désintégration dans le cas particulier du meson rhoIt has been established for now 40 years that the strong nuclear interaction can be described by Quantum Chromodynamics (QCD). However, the confinement of quarks in this theory hides its elementary degrees of freedom in low-energy processes, which have to be computed non-pertubatively. Lattice QCD is, to date, the only method allowing to go through such a computation, and is now reaching maturity. However, although the spectrum of stable hadrons is computed with precision, the study of decays is still delicate. We hereby present the application of Lüscher's formalism to the study of strong-decaying resonance properties, along with a precise computation of the decay width in the particular case of the rho meson
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Métivet, Thibaut. "Lattice QCD at the physical point : pion-pion scattering and structure of the nucleon." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112243/document.
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La Chromodynamique Quantique (QCD) sur réseau permet d'étudier de façon ab-initio et non-perturbative les processus d'interaction forte. Ce formalisme, qui permet une régularisation covariante de la théorie de l'interaction forte, fournit aussi un cadre naturel pour le calcul et la simulation numérique de la Chromodynamique Quantique. Dans cette thèse, après un tour d'horizon des principales propriétés de la QCD et une présentation détaillée de notre discrétisation de cette théorie sur un réseau, nous étudions de façon approfondie deux problèmes de physique hadronique : le phénomène de diffusion résonante et la structure du nucléon. Les calculs sont réalisés avec les configurations de jauge de la Collaboration Budapest-Marseille-Wuppertal, générées avec une action de Wilson améliorée avec 2+1 saveurs de quarks dynamiques. Elles couvrent une large gamme de pas de réseau, de volumes et de masses des quarks différents, permettant ainsi une étude fine de la sensibilité de nos résultats à ces paramètres, et fournissant un bon contrôle sur l'extrapolation au continu. Notre étude de la diffusion de particules sur le réseau est menée grâce à une méthode proposée par M. Lüscher. Nous avons choisi le cas particulier de la diffusion pion-pion dans le canal résonant du méson rho, et analysé nos données avec une méthode variationnelle aux valeurs propres généralisées. Nous présentons les déphasages pion-pion ainsi que les paramètres de la résonance obtenus de façon détaillée, tout en garantissant un bon contrôle de nos erreurs systématiques. Nos résultats apportent une avancée importante dans le panorama des études de diffusion sur le réseau car ce sont les premiers réalisés à la masse physique du pion, pour laquelle la désintégration du rho en deux pions peut effectivement avoir lieu. Les valeurs obtenues pour les paramètres de la résonance du méson rho sont accord avec l'expérience, et confirment la faible dépendance du couplage entre le rho et les deux pions à la masse du pion. L'exploration de la structure du nucléon se fait à travers un calcul complet des facteurs de forme électrofaibles isovectoriels, avec une étude approfondie du rayon de charge électrique et de la charge axiale. Notre analyse présente aussi des données à la masse physique du pion, ce qui s'avère crucial pour maîtriser les extrapolations au point physique, étant données les variations violentes prédites par la perturbation chirale de ces quantités. Notre calcul utilise une projection sur les états du nucléon à la source et au puits, et une méthode de fit combinant les fonctions de corrélation à deux et trois points afin de réduire et de contrôler au maximum les contaminations pouvant venir des états excités. Bien que davantage de données seraient nécessaires pour déterminer très précisément le rayon et la charge axiale au point physique avec une évaluation pertinente des erreurs systématiques, les valeurs que nous obtenons sont en bon accord avec l'expérience, et suggèrent que les effets dus aux états excités sont faibles et sous contrôle. Notre analyse souligne aussi que l'utilisation de configurations de jauge avec des masses de pion proches de la valeur physique et avec des grands volumes semble indispensable à une étude précise de la structure du nucléon sur réseauThe formalism of Quantum Chromodynamics on the lattice (or Lattice QCD) allows to perform ab-initio non-perturbative studies of strong-interaction driven processes, as it provides both a covariant regularisation of the theory of QCD and a natural framework for numerical computations. In this work, after a review of the main features of QCD and a step-by-step presentation of our discretization of QCD on a lattice, we undertake detailed studies of two problems of hadronic physics: the phenomenon of resonant scattering and the structure of the nucleon. The lattice calculations are performed with the Budapest-Marseille-Wuppertal Collaboration's 2+1-flavour gauge configurations, which give access to a wide range of lattice spacings, volumes and quarks masses, thereby allowing to study the sensibility of our results on these parameters, and to perform a complete continuum extrapolation. These configurations include dynamical quarks, and use a clover-improved Wilson QCD action. To investigate the scattering of particles on the lattice, we set up a Lüscher analysis for the emblematic case of pion-pion scattering in the channel of the rho meson resonance. We analyse our data with a variational generalized eigenvalue method, and give an in-depth calculation of the scattering phase-shifts and the corresponding resonance parameters, with a full control of the systematic errors. Our results provide an important step for lattice studies of scattering states, as they are the first to be performed at the physical pion mass, where one can see the actual decay of the rho into two pions. The obtained rho meson parameters are in good agreement with the experimental values, and consistent with a weak pion mass dependence of the coupling between the rho and two pions. As for our probe of the structure of the nucleon, we present a complete extraction of the electroweak isovector form factors, with a comprehensive study of the electric charge squared radius and of the axial charge. Our analysis also feature data at the physical pion mass, which turns out to be crucial in order to perform safe extrapolations to the physical point, as the chiral perturbation theory predicts violent variations of these quantities near the massless-quarks point. Our calculation includes source and sink projections onto the nucleon state, as well as a combined fit method between the two-point and three-point correlation functions to control the contamination of our data by excited states. Although one would need more data to perform a high-accuracy determination of the nucleon radius and axial charge at the physical point with a relevant estimation of the systematic errors, the results we obtain are in good agreement with the experiment and suggest that the excited-state effects are under control. Our analysis also highlights that gauge configurations ensembles near the physical pion mass and with large volumes must be used in order to extract accurate information about the nucleon structure from lattice calculations
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Fahy, Brendan. "Properties of the ρ Resonance from ππ Elastic Scattering and the Spectrum of Excited ρ Mesons Using the Stochastic LapH Method in Lattice QCD." Research Showcase @ CMU, 2014. http://repository.cmu.edu/dissertations/534.
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Inclusion of multi-meson operators allows lattice QCD calculations to extract energies of resonances above two-meson thresholds, as well as to study two-meson scattering. Previously, temporal correlations involving multi-hadron operators were difficult to evaluate due to contributions from quark propagators which begin and end on the same time slice.
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Kallarackal, Jim [Verfasser], Michael Akademischer Betreuer] Müller-Preußker, Karl [Akademischer Betreuer] Jansen, and C. J. David [Akademischer Betreuer] [Lin. "The Higgs boson resonance from a chiral Higgs-Yukawa model on the lattice / Jim Kallarackal. Gutachter: Michael Müller-Preußker ; Karl Jansen ; C.-J. David Lin." Berlin : Humboldt Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2011. http://d-nb.info/1015081517/34.
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Xu, Bo. "Proton NMR relaxation investigations of particle exfoliation and distribution in polymer/clay nanocomposites." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/42936.
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In the past two decades polymer/clay nanocomposites (PCNs) have emerged as promising materials that exhibit remarkably improved properties when compared to conventional composites and pristine polymers. Such improvements strongly depend on the dispersion of clay nanoparticles in the polymer matrix. In spite of great efforts expended in characterizing clay dispersion, effective, simple and quantitative techniques are still needed. This work addresses this challenge by presenting new aspects of 1H solid-state NMR for quantifying clay dispersion in PCNs filled with clay containing paramagnetic ions. Employing these 1H solid-state NMR methods, some structure-processing-deformation relationships of PCNs were derived, and basic insights into nuclear relaxation and spin diffusion in PCNs were gained as well.
Detailed models and analyses were described for 1H spin-lattice relaxation in the presence of paramagnetic clays in PCNs. Relaxation recovery was analytically correlated to clay dispersion in two ways: one is the initial relaxation recovery which is related to clay surface area, and the other is the spin-lattice relaxation time which is related to interparticle spacing. These two NMR observables were employed to quantitatively observe the evolution of clay morphology in poly(propylene)/clay (PP/MMT) nanocomposites upon equibiaxial stretching, as well as upon in situ uniaxial deformation. The initial relaxation recovery was independently utilized to determine the polymer-clay interfacial surface area and the degree of clay exfoliation. We demonstrated the capabilities of our models in quantitatively characterizing several materials, including poly(vinyl alcohol), nylon 6, poly(å-caprolactone) (PCL), poly(lactic acid) (PLA) and PP nanocomposites. These results were used to examine the dependence of clay morphology upon processing (strain ratio, strain rate, temperature), deformation (extension), component characteristics (polymer molecular weight, clay surface modification) and clay content. Effects of paramagnetic Fe3+ concentration and external magnetic field strength on 1H spin-lattice relaxation in PCNs were also investigated and discussed. In particular, low field separates the initial relaxation recovery into two stages: one related to clay content and the other related to the polymer-clay interfacial surface area. The low field was observed to enhance the paramagnetic contribution to the spin-lattice relaxation rate, increasing its sensitivity to clay morphology. In addition, measurements of long-distance spin diffusion coefficients for a variety of polymers and paramagnetic characteristics of organically modified clay were explored. Overall, the utility of NMR relaxometry in characterizing PCNs has been significantly expanded and successfully demonstrated in this dissertation.
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QUINA, ANTONIO de J. A. de. "Estudos das Propriedades de Termoluminescência (TL), Ressonância Paramagnética (EPR) e Absorção Ótica (AO) para caracterização do mineral Monticelita." reponame:Repositório Institucional do IPEN, 2016. http://repositorio.ipen.br:8080/xmlui/handle/123456789/26943.
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Foram estudados as propriedades de absorção ótica, de termoluminescência e de ressonância paramagnética eletrônica do mineral natural de silicato de nome MONTICELITA do grupo Olivina, para caracterização desse mineral, cuja formula química é CaMgSiO4. A absorção ótica mostrou que há três bandas de absorção em 450 nm, 660 nm e 1050 nm. As duas primeiras bandas, a primeira no azul e a segunda no amarelo-vermelho são responsáveis pela cor verde da Monticelita. Essas duas bandas são consequência do elemento cromo contido no mineral absorver fótons do feixe universal no visível de frequências centradas em 450 nm e 660 nm. A banda em 1050 nm é devido ao Fe2+. As curvas de emissão de uma amostra de Monticelita irradiada com raios gama de doses entre 10 e 1000 Gy apresenta três picos em 150 °C , 270 °C e 370 °C . Pelo método da deconvolução e de várias taxas de aquecimento foram obtidos energia E1=1,35 eV e fator de frequência s1=4,98x1011 s-1 para o pico 270 °C e E2=1,70 eV e s2=1,88x1011 s-1 para pico 370 °C . A irradiação com raios gama de doses entre 5 kGy e 50 kGy produziram pico TL de 380 °C com intensidade TL em função da dose linear e crescente. Este resultado e importante para dosimetria da radiação de altas doses. O espectro EPR de uma amostra natural, mostrou um resultado não esperado e interessante. Além dos sinais típicos de interação hiperfina do Mn2+, um sinal avantajado de g =6,34 indica que o ferro formou moléculas de hematita, Fe2O3. Esse sinal desaparece com aquecimento acima de 800 °C de recozimento, dando origem dipolos magnéticos de Fe3+, que dá origem a um sinal típico em g =2. Esta descrição mostra bem a caracterização do mineral Monticelita.
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
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Jurczuk, Krzysztof. "Calcul parallèle pour la modélisation d'images de résonance magnétique nucléaire." Thesis, Rennes 1, 2013. http://www.theses.fr/2013REN1S089.
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L'objet de cette thèse est la modélisation computationnelle de l'Imagerie par Résonance Magnétique (IRM), appliquée à l'imagerie des réseaux vasculaires. Les images sont influencées par la géométrie des vaisseaux mais aussi par le flux sanguin. Par ailleurs, outre la qualité des modèles développés, il est important que les calculs soient performants. C'est pourquoi, le calcul parallèle est utilisé pour gérer ce type de problèmes complexes. Dans cette thèse, trois solutions sont proposées. La première concerne les algorithmes parallèles pour la modélisation des réseaux vasculaires. Des algorithmes dédiés à différentes architectures sont proposés. Le premier est basé sur le modèle de « passage de messages » pour les machines à mémoires distribuées. La parallélisation concerne l'irrigation de nouvelles zones de tissu par les vaisseaux existants. Le deuxième algorithme est dédié aux machines à mémoire partagée. Il parallélise également le processus de perfusion mais des processeurs différents se chargent de gérer les différents arbres vasculaires. Le troisième algorithme est une combinaison des approches précédentes offrant une solution pour les architectures parallèles hybrides. Les algorithmes proposés permettent d'accélérer considérablement la croissance des réseaux vasculaires complexes, ce qui rend possible la simulation de structures vasculaires plus précises, en un temps raisonnable et aide à améliorer le modèle vasculaire et à tester plus facilement différents jeux de paramètres. Une nouvelle approche de modélisation computationnelle des flux en IRM est également proposée. Elle combine le calcul de flux par la méthode de Lattice Boltzmann, la simulation IRM par le suivi temporel de magnétisations locales, ainsi qu'un nouvel algorithme de transport des magnétisations. Les résultats montrent qu'une telle approche intègre naturellement l'influence du flux dans la modélisation IRM. Contrairement aux travaux de la littérature, aucun mécanisme additionnel n'est nécessaire pour considérer les artéfacts de flux, ce qui offre une grande facilité d'extension du modèle. Les principaux avantages de cette méthode est sa faible complexité computationnelle, son implémentation efficace, qui facilitent le lancement des simulations en utilisant différents paramètres physiologiques ou paramètres d'acquisition des images. La troisième partie du travail de thèse a consisté à appliquer le modèle d'imagerie de flux à des réseaux vasculaires complexes en combinant les modèles de vaisseaux, de flux et d'acquisition IRM. Les algorithmes sont optimisés à tous les niveaux afin d'être performants sur des architectures parallèles. Les possibilités du modèle sont illustrées sur différents cas. Cette démarche de modélisation peut aider à mieux interpréter les images IRM grâce à l'intégration, dans les modèles, de connaissances variées allant de la vascularisation des organes jusqu'à la formation de l'image en passant par les propriétés des flux sanguinsThis PhD thesis concerns computer modeling of magnetic resonance imaging (MRI). The main attention is centered on imaging of vascular structures. Such imaging is influenced not only by vascular geometries but also by blood flow which has to been taken into account in modeling. Next to the question about the quality of developed models, the challenge lies also in the demand for high performance computing. Thus, in order to manage computationally complex problems, parallel computing is in use. In the thesis three solutions are proposed. The first one concerns parallel algorithms of vascular network modeling. Algorithms for different architectures are proposed. The first algorithm is based on the message passing model and thus, it is suited for distributed memory architectures. It parallelizes the process of connecting new parts of tissue to existing vascular structures. The second algorithm is designed for shared memory machines. It also parallelizes the perfusion process, but individual processors perform calculations concerning different vascular trees. The third algorithm combines message passing and shared memory approaches providing solutions for hybrid parallel architectures. Developed algorithms are able to substantially speed up the time-demanded simulations of growth of complex vascular networks. As a result, more elaborate and precise vascular structures can be simulated in a reasonable period of time. It can also help to extend the vascular model and to test multiple sets of parameters. Secondly, a new approach in computational modeling of magnetic resonance (MR) flow imaging is proposed. The approach combines the flow computation by lattice Boltzmann method, MRI simulation by following discrete local magnetizations in time and a new magnetization transport algorithm together. Results demonstrate that such an approach is able to naturally incorporate the flow influence in MRI modeling. As a result, in the proposed model, no additional mechanism (unlike in prior works) is needed to consider flow artifacts, what implies its easy extensibility. In combination with its low computational complexity and efficient implementation, the solution is a user-friendly and manageable at different levels tool which facilitates running series of simulations with different physiological and imaging parameters. The goal of the third solution is to apply the proposed MR flow imaging model on complex vascular networks. To this aim, models of vascular networks, flow behavior and MRI are combined together. In all the model components, computations are adapted to be performed at various parallel architectures. The model potential and possibilities of simulations of flow and MRI in complex vascular structures are shown. The model aims at explaining and exploring MR image formation and appearance by the combined knowledge from many processes and systems, starting from vascular geometry, through flow patterns and ending on imaging technology
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Wykhoff, Jan. "Elektronenspinresonanz in Yb-basierten Kondogitter-Systemen." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-39395.
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Die Elektronenspinresonanz (ESR) untersucht die im quasistatischen Magnetfeld resonante Absorption eines an die Probe angelegten Mikrowellenmagnetfeldes.
Es wurde das System Yb1-w A1-w (Rh1-x Cox)2 (Si1-y Gey) 2 mit A=La, bzw. Lu, sowie das System YbIr2Si2 mittels ESR untersucht.
Unter Kondo-Wechselwirkung vieler Leitungselektronen mit einem lokalen 4f-Moment des Kondo-Ions bildet sich ein nicht-magnetisches Grundzustands-Singlett, was zur Abschirmung des magnetischen Moments führt.
YbRh2Si2 ist das erste Schwere-Fermionen-System mit Kondo-Ionen, das ohne Dotierung zusätzlicher ESR-Sonden ein ESR-Signal unterhalb der Kondo-Temperatur aufweist.
Es zeigt sich, dass das ESR-Signal nicht mittels gängiger ESR-Theorien konsistent beschrieben werden kann.
Die Messungen, die im Rahmen dieser Arbeit angestellt wurden, flossen in die Entwicklung von weiterführenden Theorien (z.B. [1], [2]) ein.
Die Temperaturabhängigkeit des ESR-g-Faktors konnte damit erfolgreich beschrieben werden, womit erstmals der Nachweis einer Kondo-Wechselwirkung in Kondo-Gitter-Systemen mittels ESR gelang. Ferner konnte die Bedeutung von ferromagnetischen Fluktuationen für eine kleine, beobachtbare Linienbreite beschrieben werden. Der ESR-Methode ist somit die Kondo-Spindynamik direkt zugänglich. Dieser Zugang ist neu und einzigartig, denn andere Methoden (NMR, inelastische Neutronenstreuung) charakterisieren die Kondo-Spindynamik auf indirekte Weise.
[1] P. Wölfle und E. Abrahams. Phenomenology of esr in heavy-fermion systems: Fermi-liquid und nicht-fermi-liquid regimes Phys. Rev. B, 80(23): 235112, 2009.
[2] B. I. Kochelaev, S. I. Belov, A. M. Skvortsova, A. S. Kutusov, J. Sichelschmidt, J. Wykhoff, C. Geibel und F. Steglich. Why could electron spin resonance be observed in a heavy fermion kondo lattice? Eur. Phys. J. B, 72(4): 485, 2009.
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Schneider, Philipp-Immanuel. "Theoretical description of strongly correlated ultracold atoms in external confinement." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2013. http://dx.doi.org/10.18452/16829.
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Heutzutage können ultrakalte Atome in unterschiedlichsten optischen Fallenpotenzialen eingefangen werden, während sich ihre Wechselwirkung durch die Ausnutzung von magnetischen Feshbachresonanzen kontrollieren lässt. Der Einschluss und die resonante Wechselwirkung können zu einer starken Korrelation der Atome führen, welche es erlaubt, mit ihnen physikalische Phänomene zu simulieren, deren Simulation mit heutigen Computern nicht durchführbar wäre. Eine maßgeschneiderte Kontrolle der Korrelationen könnte es schließlich ermöglichen, mit ultrakalten Atomen einen Quantencomputer zu implementieren. Um die Flexibilität und gute Kontrollierbarkeit ultrakalter Atome voll ausnutzen zu können, ist das Ziel dieser Dissertation die präzise theoretische Beschreibung stark korrelierter, eingeschlossener Atome an einer Feshbachresonanz. Das Wechselspiel zwischen dem Einschluss der Atome und einer Feshbachresonanz wird in dieser Arbeit zunächst anhand eines von Grund auf hergeleiteten analytischen Modells einer Feshbachresonanz zwischen Atomen in einer harmonischen Falle untersucht. Basierend auf diesem Modell wird ein Ansatz entwickelt, wechselwirkende Atome an einer Feshbachresonanz in einem optischen Gitter über ein Bose-Hubbard-Modell zu beschreiben. Im Gegensatz zu aufwendigeren numerischen Methoden erlaubt das Bose-Hubbard-Modell mit der Einbeziehung nur weniger Blochbänder die präzise Vorhersage der Eigenenergien und des dynamischen Verhaltens der Atome im optischen Gitter. Weiterhin wird eine Methode zur Lösung der zeitabhängingen Schrödingergleiung für zwei wechselwirkende Atome in einem dynamischen optischen Gitter entwickelt. Schließlich wird ein Ansatz vorgestellt, wie sich mit ultrakalten Atomen in einem dynamischen optischen Gitter ein Quantencomputer implementieren ließe. Als Quantenregister dient der korrelierte Mott-Zustand von repulsiv wechselwirkenden Atomen. Quantenoperationen werden durch periodisches Wackeln des optischen Gitters getrieben.Today, ultracold atoms can be confined in various optical trapping potentials, while their mutual interaction can be controlled by magnetic Feshbach resonances. The confinement and resonant interaction can lead to a strong correlation of the atoms, which allows for the quantum simulation of physical phenomena whose classical simulation is computationally intractable. A tailored control of these correlations might eventually enable the implementation of a quantum computer with ultracold atoms. In order to take advantage of the flexibility and precise control of ultracold atoms, this thesis aims to provide a precise theoretical description of strongly correlated, confined atoms at a magnetic Feshbach resonance. The interplay between the confinement of the atoms and the Feshbach resonance is investigated by deriving from first principles a model that enables the complete analytic description of harmonically trapped ultracold atoms at a Feshbach resonance. This model is subsequently used to develop a Bose-Hubbard model of atoms in an optical lattice at a Feshbach resonance. In contrast to more elaborate numerical calculations, the model can predict the eigenenergies and the dynamical behavior of atoms in an optical lattice with high accuracy including only a small number of Bloch bands. Furthermore, a method id developed that solves the time-dependent Schrödinger equation for two interacting atoms in a dynamic optical lattice. Finally, a proposal for the implementation of a quantum computer with ultracold atoms in a dynamic optical lattice is presented. It utilizes the correlated Mott-insulator state of repulsively interacting atoms as a quantum register. Quantum operations are driven by a periodic shaking of the optical lattice.
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Lam, James. "Hydrogen diffusion in concentrated metal hydrides." Thesis, University of Sheffield, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301906.
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Danilov, Artem. "Design, characterisation and biosensing applications of nanoperiodic plasmonic metamaterials." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0110/document.
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Cette thèse considère de nouvelles architectures prometteuses des métamatériaux plasmoniques pour biosensing, comprenant: (I) des réseaux périodiques 2D de nanoparticules d'Au, qui peuvent supporter des résonances des réseaux de surface couplées de manière diffractive; (II) Reseaux 3D à base de cristaux plasmoniques du type d'assemblage de bois. Une étude systématique des conditions d'excitation plasmonique, des propriétés et de la sensibilité à l'environnement local dans ces géométries métamatérielles est présentée. On montre que de tels réseaux peuvent combiner une très haute sensibilité spectrale (400 nm / RIU et 2600 nm / RIU, ensemble respectivement) et une sensibilité de phase exceptionnellement élevée (> 105 deg./RIU) et peuvent être utilisés pour améliorer l'état actuel de la technologie de biosensing the-art. Enfin, on propose une méthode de sondage du champ électrique excité par des nanostructures plasmoniques (nanoparticules uniques, dimères). On suppose que cette méthode aidera à concevoir des structures pour SERS (La spectroscopie du type Raman à surface renforcée), qui peut être utilisée comme une chaîne d'information supplémentaire à un biocapteur de transduction optiqueThis thesis consideres novel promissing architechtures of plasmonic metamaterial for biosensing, including: (I) 2D periodic arrays of Au nanoparticles, which can support diffractively coupled surface lattice resonances; (II) 3D periodic arrays based on woodpile-assembly plasmonic crystals, which can support novel delocalized plasmonic modes over 3D structure. A systematic study of conditions of plasmon excitation, properties and sensitivity to local environment is presented. It is shown that such arrays can combine very high spectral sensitivity (400nm/RIU and 2600 nm/RIU, respectively) and exceptionally high phase sensitivity (> 105 deg./RIU) and can be used for the improvement of current state-of-the-art biosensing technology. Finally, a method for probing electric field excited by plasmonic nanostructures (single nanoparticles, dimers) is proposed. It is implied that this method will help to design structures for SERS, which will later be used as an additional informational channel for biosensing
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Hirschinger, Jérôme. "Etude par resonance magnetique nucleaire de la structure et de la dynamique moleculaire des copolymeres p(vf : :(2)-trfe)." Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13196.
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La structure et la dynamique moleculaire des copolymeres de difluoroethylene et trifluoroethylene sont etudiees en resonance du proton et du fluor par l'analyse du signal de precision libre, la relaxation spin-reseau dans le repere du laboratoire et a plusieurs angles du champ applique dans le referentiel tournant et par l'effet overhauser transitoire. Les resultats montrent l'existence d'une segregation de phases. Interpretation de la relaxation spin-reseau dans la phase ferroelectrique. Dans la phase paraelectrique, on demontre que la dependance en l'inverse de la racine de la frequence de la densite spectrale du mouvement cristallin et du mode rapide dans la phase amorphe ne provient pas de diffusion de "kinks" le long des chaines
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Labouze, Xavier. "Etude par résonances nucléaires des propriétés magnétiques des cuprates supraconducteurs dans leurs phases isolantes." Grenoble 1, 1994. http://www.theses.fr/1994GRE10042.
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Cette these porte sur l'etude des proprietes magnetiques des cuprates supraconducteurs dans leurs phases isolantes. Les techniques experimentales utilisees sont la resonance nucleaire, magnetique (rmn) et quadrupolaire (rqn). La premiere partie presente une revue des proprietes essentielles des cuprates supraconducteurs. La deuxieme explique particulierement comment utiliser la rqn. L'etude des composes au plomb type ybco (partie iii) montre que le magnetisme des cuprates doit etre quasi-2d quasi-heisenberg. La partie iv traite des composes ybco substitues au calcium. L'etude statique par mesures de largeurs de raie rqn a permis de determiner les temperatures de transition des composes intermediaires. Un modele de l'influence des porteurs de charges a ete construit. Une etude dynamique par mesures du temps de relaxation spin/reseau a aussi ete menee. On compare ces resultats avec ceux des composes monoplans lsco
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Cornut, Myriam. "Polarisation par pompage optique d'hélium 3 liquide ou en solution dans l'hélium 4, en dessous de 500 mK." Grenoble 1, 1993. http://www.theses.fr/1993GRE10022.
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Ce memoire presente les procedures experimentales que nous avons developpees dans le but d'etudier l'influence de l'aimantation sur les proprietes physiques de l'helium 3 liquide, pur ou en solution dans de l'helium 4. La premiere partie est consacree a la description de l'ensemble experimental. Le refrigerateur a dilution (amagnetique) que nous avons construit autorise une etude dans une gamme de temperature comprise entre 200 mk et 500 mk. Pour refroidir nos echantillons polarises en un temps inferieur au temps de relaxation nucleaire longitudinal t#1, nous avons developpe un interrupteur de chaleur base sur la difference de conductivite thermique entre l'helium 4 liquide et gazeux. Nous parvenons ainsi a preparer de l'helium 3 liquide a 250 mk, dont le taux initial de polarisation est de 30%. Nous decrivons dans une deuxieme partie le principe de la mesure du potentiel chimique de l'helium 4, variable necessaire a la connaissance des proprietes thermodynamiques des melanges polarises. Nous avons reussi a preparer un tel systeme a une temperature de 500 mk, pour une concentration en helium 3 de 2% et un taux de polarisation de 16%. La caracterisation par resonance magnetique nucleaire pulsee a revele d'une part un t#1 superieur a une heure, et d'autre part une tres longue duree de vie du signal de precession de l'aimantation transverse. Dans une troisieme partie, nous analysons un processus physique observe lors de nos experiences, l'effet hevac dans les melanges helium 3-helium 4
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Letellier, Michel. "Etude du comportement microdynamique de l'eau dans les suspensions et gels d'argiles par la technique de resonance magnetique nucleaire : methode de determination d'aires de surfaces et application a la prise des ciments." Orléans, 1988. http://www.theses.fr/1988ORLE2009.
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Etude des temps de relaxation de l'eau normale, de l'eau lourde et des protons en contact avec une surface d'argile, analysant les phenomenes en fonction de la concentration, de la temperature et de la nature de l'argile. Mesure du volume de la couche d'eau absorbee a la surface du solide, deduction de son epaisseur et determination de l'aire de la surface hydratee. Fonde sur le concept de tactoide, ce travail nombre l'existence de forces d'interaction a courte portee entre une molecule d'eau et une surface argileuse. Dans la deuxieme partie, etude du composant principal d'un ciment (silicate tricalcique), mesurant aire d'absorption en fonction du temps de prise; la methode rmo est une technique de surface simple et non destructrice, pouvant mesurer l'effet des adjuvants
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Abreu, Rômulo Ferreira. "Caracterização da estrutura de curto alcance de cimentos de cinza de casca de arroz através da espectroscopia por ressonância magnética nuclear de alta resolução." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-24062008-135656/.
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A cinza obtida da queima controlada da casca de arroz é um material que apresenta propriedades pozzolânicas: reage na presença de água e dióxido de cálcio produzindo silicato de cálcio hidratado (C-S-H), o material que confere a resistência mecânica aos cimentos. Portanto, a cinza de casca de arroz é um material de potencial interesse para o desenvolvimento de cimentos não convencionais, baseados em subprodutos industriais ou agrícolas. Neste trabalho, os compostos presentes em cinzas de alta reatividade pozzolânica e os produtos obtidos de sua reação pozzolânica foram estudados através da Ressonância Magnética Nuclear (RMN) de alta resolução de 13C e 29Si. Na cinza não hidratada foram detectados domínios de sílica amorfa, o componente principal, e quantidades menores de sílica cristalina (cristobalita e quartzo), carbono amorfo e cadeias de siloxanos. Foi estudada a evolução da reação em pastas obtidas da hidratação da cinza na proporção água: cal: cinza O,47H20+O,53(O,1CCA+O,9Cal)=1 (entre 8 e 134 dias de idade). Mediante a RMN de 29Si foi possível caracterizar a formação de C-S-H e disposição dos grupos silicatos na estrutura. A estrutura do C-S-H obtido é comparável à observada em cimentos convencionais e cimentos de escoria de alto forno, e é compatível com os modelos propostos. A quantidade de C-S-H produzido e a velocidade da reação são menores quando comparadas com os outros cimentos. Efeitos da carbonatação de C-S-H foram observáveis em atmosfera ambiente. Foi detectado também o efeito da hidratação sobre os componentes minoritários da cinza.The ashes obtained from burning rice husks have pozzolanic properties: in the presence of water and calcium dioxide the ashes react to produce calcium silicate hydrate (C-SH), the main binding agent in cementitiuos materials. Therefore, rice husk ashes are interesting materials in order to produce non-conventional cement, based in industrial or agricultural byproducts. The compounds present in a sample of rice husk ashes of high pozzolanic activity, and the products of hydration, were characterized using high resolution solid-state Nuclear Magnetic Resonance (NMR) of 13C and 29Si. Several compounds were detected in anhydrous ashes: amorphous silica (the main component), and minor quantities of crystalline silica (cristobalite and quartz), amorphous carbon and siloxane polymeric chains. Hardened pastes were prepared with a ratio water:calcium dioxide:ash O,47H20+O,53(O,1dioxide ash+O,9calcio)=1. The evolution of the hydration reaction was monitored at several ages between 8 to 134 days. The formation of C-S-H was detected by 29Si-NMR and the arrangement of the silicate groups was characterized. The structure of the C-S-H formed in these pastes agrees with the one observed in conventional cements and also b1ast furnace slag cements. Also, it is in agreement with the accepted structural models of C-S-H. The amount of C-S-H produced and the velocity of the reaction are minor than those observed in blast furnace slag cements. Carbonation effects were detected in ambient atmospheric conditions. Also, the effect of the hydration on the minority compounds was also detected.
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Bačovský, Jaromír. "Zvýraznění kontrastu pro rozlišení tkání a detekci kontrastních nanočástic metodami magnetickorezonančního zobrazování." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230830.
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Magnetic resonance imaging is a routine and powerful diagnostic technique capable of providing detailed information about the structure and composition of the tissues. This diploma thesis is concerned with the mechanisms of contrast origin and contrast modifications by molecular and nanoparticle contrast agents. First sections of the thesis summarize basic knowledge about pulse sequences and it aims to provide an overview on MRI contrast agent with a special emphasis on paramagnetic gadolinium contrast agents and superparamagnetic nanoparticles. The main purpose of this study is to develop the software called MRICalc, which is able to optimize contrast in MRI images. Based on analysis of signal formula of typical pulse sequences, MRICalc is able to propose the parameters of the pulse sequence for compartment-specific enhancement of the contrast. User chooses from the list of the samples and after calculation he obtains the values of echo time, repetition time and flip angle, all of which simultaneously seem to create the appropriate setting to enhance the contrast. MRICalc also allows to plot contrast function with respect to the chosen parameter. Software, including its graphical user interface, is designed in Python. The sample consists from solution of CuSO4 and distilled water was designed to verify the correct function of MRICalc. Sulphate represents a contrast agent. Preclinical MR system Bruker BioSpec 94/30 USR located at Institute of Scientific Instruments of the ASCR, v.v.i was used to measure contrast curve of FLASH pulse sequence, which is a typical representative of gradient echo. Results of the measurement were compared to the theoretical model provided by MRICalc.
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Papadopoulos, Konstantinos. "Investigation of magnetic order in nickel-5d transition metal systems." Thesis, Uppsala universitet, Molekyl- och kondenserade materiens fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-383009.
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Double perovskite materials exhibit alterations in magnetic order through manipulation oftheir crystal structure. Certain ultra thin metallic bilayers can create an exotic magnetic stateof confined spin textures called skyrmions. In both cases, new atomic arrangements leadto new electrical and magnetic properties. The following work comprises two studies, bothof which examine the magnetic properties of transition metals in either powder or thin filmsamples. The first part is dedicated to a series of muon spin rotation and relaxation (muSR)experiments on a LaSrNiReO6, double perovskite, powder sample. In the muSR technique, aspin polarized muon beam is focused onto a powder envelope in low pressure and temperatureconditions. The spins of the implanted muons evolve depending on the intrinsic or externallyapplied magnetic field according to Larmor precession. The measurement is based onthe detection of decay positrons that carry this precession information on their preferreddecay directions. Measurements that were realized in wTF, ZF and LF setups, reveal asecond transition to magnetic order at Tc ≃ 22K, below a transition that was observed at T =261K from magnetic susceptibility measurements. The experimental results point to threemagnetic phases, paramagnetic for T > 261K, dilute ferrimagnetic for 22 < T < 261K and amagnetically ordered state for T < 22K, that may implicate ferro- and antiferromagnetismfrom Ni sublattices and Ni-Re interactions. The second part follows an attempt to produce and characterize ultra thin bilayer filmsfor the observation of interfacial chiral structures and skyrmions. Co/Fe/MgO (100) andW/Ni/Cu (100) bilayers were grown with magnetron sputter deposition in various layerthicknesses and their structure was determined by X-ray reflectometry (XRR). The XRRscans presented a relatively thick-layered Co/Fe/MgO film, while extremely thin and roughW/Ni/Cu bilayers, for the purposes of studying films with broken interfacial inversionsymmetry. This study was concluded with indicative magneto-transport measurements thatalso point to the reconfiguration of the growth procedure.
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Allam, Lévi. "Etude de la diffusion unidimensionnelle dans les chaines finies : application au tmmc-cd." Toulouse 3, 1987. http://www.theses.fr/1987TOU30063.
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Etude rpe de (ch::(3))::(4) nmn::(1-x) cd::(x) cl::(5) entre 20 et 300 k, pour x = 0,02; 0,08 et 0,2; mesure des temps de relaxation spin-reseau. Mise en evidence de variations importantes en fonction de la composition. Interpretation des resultats au moyen du formalisme de la fonction memoire et d'un modele de la fonction de correlation de spins des chaines finies
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Hsu, Anthony Chi-Pin. "Resonance in a finite volume in quantum chromodynamics." Thesis, 2013. http://hdl.handle.net/2440/82387.
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Quantum chromodynamics (QCD) is a theory which describes the strong interactions of the quarks. When the energy is lower than about 1 GeV, the QCD coupling become so large that we can not study it perturbatively. Lattice QCD can be used to study QCD non-perturbatively and is suitable for the low energy region. Much remains to be studied in QCD, such as resonances in scattering processes. Lüscher’s formula can relate the scattering process in finite volume lattices with phase shifts in the infinite volume scattering in the real world. In this study, we will construct a model for π - π scattering on a lattice. We will use this model to investigate Lüscher’s approach. ρ → ππ, and ρ → πω channels in the J = 1 isovector π - π scattering will be considered.Thesis (M.Sc.) -- University of Adelaide, School of Chemistry and Physics, 2013
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Elman, Vladimir [Verfasser]. "Increasing the atomic density in a near resonant dark optical lattice / vorgelegt von Vladimir Elman." 2005. http://d-nb.info/974296139/34.
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Elmiladi, Nouri Mokhtar [Verfasser]. "Proton spin lattice relaxation in colloidal aqueous solutions with resonant ultrasound / vorgelegt von Nouri Mokhtar Elmiladi." 2010. http://d-nb.info/100853613X/34.
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Lübbers, Rainer [Verfasser]. "Magnetism and lattice dynamics under high pressure studied by nuclear resonant scattering of synchrotron radiation / von Rainer Lübbers." 2000. http://d-nb.info/961623144/34.
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Lasscock, Ben Genery. "Baryon spectroscopy from lattice QCD." 2007. http://hdl.handle.net/2440/57425.
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Title page, abstract and table of contents only. The complete thesis in print form is available from the University of Adelaide Library.This thesis investigates the spectrum of baryon resonances in quenched lattice QCD.
http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1277637
Thesis (Ph.D.) -- University of Adelaide, School of Chemistry and Physics, 2007
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Amdjadi, Mohammed Hossein Ala. "Nuclear Quadrupole Resonance And Relaxation Studies In Chloropyridines And High Pressure Studies In Chlorates." Thesis, 1997. http://etd.iisc.ernet.in/handle/2005/1835.
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Cheng, Jiunn-Shouh, and 程俊碩. "Characteristics and Stress Sensing of Surface Lattice Resonance in Gold Nanodisk Arrays." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/86q6x7.
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碩士國立交通大學
光電工程研究所
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We propose a gold nanodisk array applied in the stress sensing by surface lattice resonance (SLRs). By reducing the half maximum full width (FWHM) of spectrum through surface lattice resonance, sensing resolution can be enhanced. Then, we propose elliptical nanodisk array to further enhance the sensitivity and resolution. In this thesis, we focus on light and matter interaction based on the SLRs with two kinds of structures, circular and elliptical gold nanodisk array. The geometry effect as radius and pitch on optical spectra are analyzed for both nanostructures by simulation, and measurement. In addition, the unique aspect ratio effect for the elliptical case is verified for a better optical resolution. Furthermore, the nanostructures are embedded into the polydimethylsiloxane (PDMS) for the application of stress sensing. The experimental sensitivity and FOM of circular nanodisk array are 3.8 nm/% and 0.07, respectively. In the case of elliptical nanodisk array, they are 6.82 nm/% and 0.43, respectively. The performance is benefit to the application of tunable lasers and colorations specially in the visible and near infrared region.