Dissertations / Theses on the topic 'Hyperfine interactions'
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衛翰戈 and Hon-gor Wai. "The covalency effect in spin interactions." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1986. http://hub.hku.hk/bib/B31207479.
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Borges, de Araujo M. A. "Hyperfine interactions studied by low temperature nuclear orientation." Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355725.
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McMorrow, D. F. "Crystal fields and hyperfine interactions in holmium compounds." Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377728.
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Lataifeh, Mahdi Salem Q. M. "Hyperfine interactions of holmium in single crystals of magnetic compounds." Thesis, University of Manchester, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.257471.
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Vezvaee, Arian. "Quantum spins in semiconductor nanostructures: Hyperfine interactions and optical control." Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/104870.
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Quantum information technologies offer significantly more computational power for certain tasks and secure communication lines compared to the available classical machines. In recent years there have been numerous proposals for the implementation of quantum computers in several different systems that each come with their own advantages and challenges. This dissertation primarily focuses on challenges, specifically interactions with the environment, and applications of two of such systems: Semiconductor quantum dots and topological insulators. The first part of the dissertation is devoted to the study of semiconductor quantum dots as candidates for quantum information storage and sources of single-photon emission. The spin of the electron trapped in a self-assembled quantum dot can be used as a quantum bit of information for quantum technology applications. This system possesses desirable photon emission properties, including efficiency and tunability, which make it one of the most advanced single-photon emitters. This interface is also actively explored for the generation of complex entangled photonic states with applications in quantum computing, networks, and sensing. First, an overview of the relevant developments in the field will be discussed and our recent contributions, including protocols for the control of the spin and a scheme for the generation of entangled photon states from coupled quantum dots, will be presented. We then look at the interaction between the electron and the surrounding nuclear spins and describe how its interplay with optical driving can lead to dynamic nuclear polarization. The second part of the dissertation follows a similar study in topological insulators: The role of time-reversal breaking magnetic impurities in topological materials and how spinful impurities enable backscattering mechanisms by lifting the topological protection of edge modes. I will present a model that allows for an analytical study of the effects of magnetic impurities within an experimental framework. It will be discussed how the same platform also enables a novel approach for applications of spintronics and quantum information, such as studying the entanglement entropy between the impurities and chiral modes of the system.Doctor of Philosophy
Quantum information science has received special attention in recent years due to its promising advantages compared to classical machines. Building a functional quantum processor is an ongoing effort that has enjoyed enormous advancements over the past few years. Several different condensed matter platforms have been considered as potential candidates for this purpose. This dissertation addresses some of the major challenges in two of the candidate platforms: Quantum dots and topological insulators. We look at methods for achieving high-performance optical control of quantum dots. We further utilize quantum dots special ability to emit photons for specific quantum technology applications. We also address the nuclear spin problem in these systems which is the main source of destruction of quantum information and one of the main obstacles in building a quantum computer. This is followed by the study of a similar problem in topological insulators: Addressing the interaction with magnetic impurities of topological insulators. Included with each of these topics is a description of relevant experimental setups. As such, the studies presented in this dissertation pave the way for a better understanding of the two major obstacles of hyperfine interactions and the optical controllability of these platforms.
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Shah, N. J. "Hyperfine interactions in amorphous and crystalline alloys containing rare earth metals." Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377743.
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Hamilton, William David. "Investigations into metal-ligand diatomics, the fine and hyperfine spectroscopy of cobalt fluoride, and insights into computational analysis of hyperfine interactions." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0018/NQ54592.pdf.
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Étilé, Asénath. "Etude de la structure nucléaire de noyaux exotiques à ALTO : développements et résultats de deux nouvelles installations." Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112396/document.
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ALTO (Accélérateur Linéaire et Tandem d’Orsay) est une installation équipée de deux accélérateurs pour la recherche et les applications industrielles (un tandem de 15 MV et une accélérateur linéaire). Mon travail de thèse consiste à l’instrumentation pour la recherche fondamentale de la partie accélérateur linéaire d’ALTO qui fournir des faisceaux de noyaux radioactifs. Les faisceaux de noyaux radioactifs riches en neutrons sont produits par la technique de séparation isotopique en ligne (ISOL). Cette méthode de production permet trois types d’expérience : la mesure de masse, l’orientation nucléaire et les expériences de décroissances radioactives. Parmi ces trois types d’expériences, j’ai participé aux développements de deux nouvelles plateformes expérimentales dans le cadre du projet de l’instrumentation de l’installation ISOL d’ALTO. Le premier, BEDO (BEta Decay studies in Orsay) est un ensemble de détecteurs dédié à la spectroscopie β-γ des noyaux décroissants par désintégration β produits par ALTO. Je présente ici, la mise en fonctionnement de cette plateforme expérimentale, ses caractéristiques techniques et les développements d’outils permettant d’aboutir aux premiers résultats. Pour cette expérience un faisceau de la masse 82 a été produit, saisissant cette opportunité, une ré-investigation de la décroissance de ⁸²Ge vers ⁸²As a permis d’établir un nouveau schéma de niveaux pour ⁸²As et de donner les premières indications de la présence d’états issus de configurations intruses dans les isotones impair-impair N=49. Le second projet développé est POLAREX (POLARization of EXotic nuclei), il s’agit d’une plateforme expérimentale dédiée aux expériences d’orientation nucléaire. Mon travail traite ici de l’entière réhabilitation du cryostat à dilution ³He-⁴He (élément principal et le plus complexe de l’installation) et des développements techniques et R&D apportés à l’ensemble de la plateforme. L’ensemble de ces contributions a permis la validation du fonctionnement de l’installation avec les premières mesures physiques sur les noyaux de ⁵⁴Mn, ⁵⁶Co, ⁵⁷Co créés par activation d’une feuille de Fer avec des deutons produits par le TandemALTO (Accélérateur Linéaire et Tandem d’Orsay) is a facility composed of two accelerators dedicated to research and industrial applications. There is a 15 MV tandem and a linear accelerator. My PhD work was to develop the instrumentation of the linear accelerator part of ALTO which provides radioactive beams for fundamental research. These radioactive beams are produced using the Isotope Separation On-Line method (ISOL). This technique allows three kinds of experiments: mass measurement, nuclear orientation and radioactivity experiments. Among those three types of experiments, I worked on the development of two new experimental platforms for the ALTO instrumentation. The first one, BEDO (BEta Decay studies in Orsay) is an ensemble of detectors dedicated to β-γ spectroscopy of β-decaying nuclei produced by ALTO. I present in this thesis, the commissioning of this new experimental set-up, its technical characteristics and the tools development leading to the first results. For this commissioning experiment a mass 82 radioactive beam was produced, taking this opportunity the ⁸²Ge vers ⁸²As decay was re-investigated allowing to establish a new level scheme for ⁸²As and giving the first evidences for the presence of intruder states in the N=49 odd-odd isotones. The second project, which is developed, is POLAREX (POLARization of EXotic nuclei), a new facility for nuclear orientation experiments. My thesis deals with the entire reconditioning of a ³He-⁴He dilution refrigerator (major and most complex element of the facility) and R&D and technical developments of the platform. These contributions allowed the successful commissioning of the new experimental platform with the first physical measurements on ⁵⁴Mn, ⁵⁶Co, ⁵⁷Co created by activation of an iron foil with deuterons produced by the Tandem
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Schef, Peter. "Weak Atomic Interactions." Doctoral thesis, Stockholm : Physics Department, Stockholm University, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-1064.
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Mosbah, Daw Saad. "A nuclear orientation study of nuclei in the A approx = 182-188 mass range." Thesis, University of Sussex, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260917.
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Desfonds, Pascal. "Interaction hyperfine spin du trou-spin des noyaux dans les boites quantiques d’InAs/GaAs." Paris 6, 2010. http://www.theses.fr/2010PA066718.
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Le spin d’un trou confiné à l’intérieur d’une boite quantique d’InAs/GaAs constitue un observable bien protégé des interactions avec l’environnement extérieur. La symétrie de type p de la fonction de Bloch du trou limite en théorie l’efficacité des mécanismes de relaxation exaltés par le confinement tels que l’interaction hyperfine avec les spins nucléaires. Cependant il a été montré dans ce travail de thèse que les contraintes ressenties en cours de croissance par les boites sont à l’origine d’un fort mélange entre états de trous lourds et de trous légers. Ce mélange favorise une relaxation du spin du trou par interaction hyperfine dipôle-dipôle avec les noyaux. Du point de vue du spin du trou, cette interaction, profondément anisotrope, est équivalente à l’action d’un champ magnétique aléatoire de l’ordre du mT en un temps caractéristique d’une dizaine de nanosecondes. Pour caractériser la dynamique associée à ce phénomène, une étude expérimentale par spectroscopie pompe sonde sous champ magnétique (Faraday et Voigt) a été menée sur une population de boites quantiques d’InAs/GaAs dopées p. Elle a permis de montrer, conformément aux prévisions de notre modèle théorique, que l’interaction hyperfine dipôle-dipôle ressentie par le spin du trou est du même ordre de grandeur que l’interaction hyperfine de contact ressentie par le spin de l’électron. Ce résultat pose la question de la capacité de l’interaction hyperfine dipôle-dipôle à polariser l’environnement nucléaire des boites quantiques
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Russ, Jennifer Lynn. "Studies of Solution Paramagnetic-Substrate Nuclear and Electron Intermolecular Interactions." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/27050.
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Advanced nuclear and electron magnetic resonance techniques (i.e. nuclear magnetic resonance (NMR), dynamic nuclear polarization (DNP), and magnetic resonance imaging (MRI)) were used to study the attitude and dynamics of TEMPO (2,2,6,6-tetramethylpiperidinyloxy)-substrate systems and the relaxivity properties of water-soluble trimetallic nitride template functionalized endohedral metallofullerenes (TNT-fMF). The attitude and average distance of interaction for each TEMPO-substrate system was determined from comparing density functional theory (DFT) calculation results with experimental hyperfine coupling constants leading to an improved understanding of solution dynamics. The short-lived solvent-solute interactions of the TEMPO-substrate molecules, such as transient complex formation, are governed by weak hydrogen-bonding interactions. The collisions in solution were explained by determining the favored orientations of the two molecules interacting using calculated relative energy minima and reproducibility of the experimental results by the calculated coupling constants.
Water-soluble TNT-fMFs are studied as candidates for the next generation MRI contrast agents as diagnostic agents and also as possible therapeutic agents to kill cancer cells and decrease tumors. The TNT-fMFs are being studied as part of a multi-modal platform dependent upon which metal atoms are encapsulated inside: Gd â MRI contrast agent (diagnostic), Lu and Ho â radio labeled for use as a therapeutic agent, Tb â fluorescence, and Lu â x-ray contrast. The current commercial MRI contrast agent, OmniscanTM, contains one gadolinium atom; however, the metal is complexed to, not encapsulated in, the molecule. TNT-fMFs fully encapsulate three metal atoms to ensure the patient does not run the risk of metal poisoning. The r1 and r2 relaxivities of TNT-fMFs containing either Gd, Lu, Ho, or Sc metals were measured at 0.35T. The data for the Gd containing TNT-fMFs indicated the metallofullerene has significantly higher relaxivities than OmniscanTM, and can be the next generation MRI contrast agent. The Ho containing species has a high r2/r1 ratio compared to the other samples showing it is a potential T2 agent, and has therapeutic capabilities.Ph. D.
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Tam, Hungsze. "Microwave Spectra of ¹³C Isotopic Species of Methyl Cyanide in the Ground, v₈=1 and v₈=2 Vibrational States." Thesis, North Texas State University, 1988. https://digital.library.unt.edu/ark:/67531/metadc332039/.
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The problem of the quadrupole interaction occurring in a vibrating-rotating C₃v symmetric top molecule has been studied in detail. The quadrupole interaction has been treated as another perturbation term to a general frequency expression accounting for the vibrating-rotating interaction of the molecule so that a complete frequency formula is obtained for both interactions, and from which hyperfine spectral components are predicted and measured. The hyperfine transitions in the ground, and v₈=1 and v₈=2 excited vibrational states of the ¹³C isotopes of methyl cyanide have been investigated in the frequency range 17-72 GHz, primarily in the low J transitions (0≤J≤3). The study of the ground state of isotope i3CH3i3CN, and the v₈=1, v₈=2 excited vibrational states for all the isotopes have been conducted here for the first time. A substantial perturbation has been discovered and discussed at the ΔJ=3→4 transitions within the Kl=1 sets in the v₈=1 mode for isotopes ¹³CH₃CN and CH₃¹³CN. A total of 716 hyperfine transitions have been assigned from measurements, only 7 of which have been measured previously. A total of 84 molecular constants have been reported; 70 of these constants are derived for the first time from microwave data.
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Santos, Brianna Bosch dos. "Investigação do magnetismo local em compostos intermetálícos do tipo RZn(R = Ce, Gd, Tb, Dy) e GdCu pela espectroscopia de correlação angular gama-gama perturbada." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-02082011-102537/.
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Neste trabalho foi feito um estudo sistemático, sob um ponto de vista atômico, do magnetismo local em compostos intermetálicos magnéticos do tipo RZn (R = Ce, Gd, Tb, Dy) e RCu, por meio de medida das interações hiperfinas utilizando a técnica de Correlação Angular Gama-Gama Perturbada com os núcleos de prova 111In111Cd e 140La140Ce. O magnetismo nesses compostos tem origem no momento angular dos elétrons 4f das terras raras. Assim, o estudo sistemático da série RZn é interessante para verificar o comportamento do campo hiperfino magnético com a variação do número de elétrons da camada 4f. A utilização do núcleo de prova 140La140Ce é interessante, pois o Ce+3 íon possui um elétron 4f que pode contribuir para o campo hiperfino total, e os resultados encontrados mostraram um comportamento anômalo. A análise feita com o núcleo de prova 111Cd mostrou que, para os compostos ferromagnéticos, o campo hiperfino magnético segue o comportamento da função de Brilluoin com a temperatura e, em função da projeção do spin, este campo diminui linearmente com o aumento do número atômico da terra rara, mostrando que a principal fonte para o campo hiperfino vem da polarização dos elétrons de condução. O gradiente de campo elétrico para 111Cd RZn mostrou uma forte diminuição com o aumento do número atômico da terra rara. Supõe-se assim que a maior parte da contribuição ao gradiente de campo elétrico tenha origem nos elétrons da camada 4f da terra rara. Já para as medidas de 111Cd GdCu, quando este composto é submetido a um ciclo térmico, sua rede cristalina passa a coexistir em dois sistemas, tanto na estrutura cúbica do tipo CsCl, como na estrutura ortorrômbica do tipo FeB. As medidas com esses dois núcleos foram de fundamental importância, pois ainda não foram vistos trabalhos desses compostos com estas pontas de prova.This work presents, from a microscopic point of view, a systematic study of the local magnetism in RZn (R = Ce, Gd, Tb, Dy) and GdCu intermetalic compounds through measurements of hyperfine interactions using the Perturbed Angular Correlation Gamma- Gamma Spectroscopy technique with 111In 111Cd and 140La 140Ce as probe nuclei. As the magnetism in these compounds originates from the 4f electrons of the rare-earth elements it is interesting to observe in a systematic study of RZn compounds the behavior of the magnetic hyperfine field with the variation of the number of 4f electrons in the R element. The use of probe nuclei 140La 140Ce is interesting because Ce+3 ion posses one 4f electron which may contribute to the total hyperfine field, and the results showed anomalous behavior. The results for 111Cd probe showed that the temperature dependence of the magnetic hyperfine field follows the Brillouin function, and the magnetic hyperfine field decreases linearly with increase of the atomic number of rare earth when plotted as a function of the rare-earth J spin projection, showing that the main contribution to the magnetic hyperfine field in RZn compounds comes from the polarization of the conduction electrons. The results for the electric field gradient measured with 111Cd for all compounds showed a strong decrease with the atomic number of the rare-earth element. We have therefore assumed that the major contribution to the electric field gradient originates from the 4f electrons of the rare-earths. The measurements of the electric field gradient for GdCu with 111Cd, after temperature decreases and increases again showed that two different structures, CsCl-type cubic and FeB-type orthorhombic structures co-exist. Finally, it is the first time that measurements of hyperfine parameters have been carried out with theses two probe nuclei in the studied RZn.
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CORDEIRO, MOACIR R. "Investigação de interações hiperfinas em Zn(1-x)MT(x)O, onde MT=(V, Cr, Mn, Fe, Co, Ni, Cu) pela técnica de correlação angular gama-gama perturbada." reponame:Repositório Institucional do IPEN, 2012. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10073.
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Made available in DSpace on 2014-10-09T12:34:26Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:09:48Z (GMT). No. of bitstreams: 0
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Randtke, Jie Min. "Rotational Spectroscopy of Simple Metal Carbon Clusters: Resolving the Beauty of Fine and Hyperfine Interactions in Metal Monoacetylides and Metal Carbides." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/603492.
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Pure rotational spectra of simple metal carbon clusters that relevant to transition metal synthesis and catalysis have been obtained using Fourier transform microwave (FTMW) techniques combined with millimeter-wave direct-absorption methods. Rotational spectra of metal acetylides (CuCCH, ZnCCH, Li/Na/KCCH, MgCCH, AlCCH, CrCCH), diatomic metal monocarbide (CrC) and T-shape metal dicarbides (YC₂ and ScC₂) were recorded in the 4–650 GHz frequency regime. Measurements of weaker isotoplogues including ⁶⁶ZnCCH, ⁶⁸ZnCCH, Zn¹³C¹³CH, ZnCCD, Li/Na/KCCD, CrCCD, Y¹³C¹²C, Y¹³C¹³C, Sc¹³C¹³C, were also studied to aid in structural determinations. This work is the first study of ZnCCH and ScC₂ by any type of spectroscopic technique. Hyperfine splittings in MgCCH and Li/Na/KCCH have also been resolved and the weak isotoplogues of YC₂ have been measured for the first time. Potential interstellar molecules ScO and FeCN were studied using the FTMW techniques in the 4–62 GHz frequency regime. Spectra of the zinc insertion product ClZnCH₃ were additionally recorded in the 10–30 GHz (FTMW) and 260–296 GHz (direct absorption) frequency ranges, along with weaker isotopologues Cl⁶⁶ZnCH₃ and Cl⁶⁸ZnCH₃. This works is the first measurement of zinc insertion products using the FTMW-DALAS techniques. The data were analyzed implementing an effective Hamiltonian, allowing for accurate spectroscopic parameters to be established. From rotational constants, the molecular geometries were accurately determined. Electronic properties were also assessed, including the degree of covalent vs ionic character in a chemical bond, and the molecular orbital composition. The fundamental physical and chemical properties of these benchmark species were obtained in order to gain insight into their role in larger molecular systems, test theoretical calculations, and, in certain cases, provide accurate rest frequencies for astronomical searches.
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Corrêa, Brianna Bosch dos Santos. "Investigação das interações hiperfinas nos compostos ternários RMn2Si2 e RMn2Ge2 (R = La, Nd, Pr) pela espectroscopia de correlação angular γ - γ perturbada." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-07012016-144716/.
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Neste trabalho foi realizado um estudo sistemático, das interações hiperfinas (campo hiperfino magnético e campo hiperfino elétrico), nos compostos do tipo RMn2Si2 e RMn2Ge2 (onde R = La, Nd, Pr), sendo que, para a amostra de La foi estudada a série LaMn2(Si(1-x)Gex)2 (onde x = 0, 0.2, 0.4, 0.6, 0.8, 1), por meio da técnica de correlação angular gama-gama perturbada (CAP), utilizando os núcleos de prova 111In(111Cd) e 140La(140Ce). Além disso, foram realizadas medições para a caracterização estrutural utilizando a técnica de difração de raios X, para a caracterização magnética, a nível macroscópico, através de medições de magnetização, caracterização nuclear utilizando a técnica de espectrometria da radiação gama e um estudo complementar por cálculos de primeiros princípios somente para as amostras de LaMn2Ge2 e LaMn2Si2. A maior contribuição para o comportamento magnético nesses compostos tem origem no ordenamento magnético da sub rede do Mn, que aparece em temperaturas relativamente altas, da ordem de 480 K, sendo que, esses compostos possuem um ordenamento antiferromagnético e próximo a temperatura ambiente passam a possuir um ordenamento ferromagnético. Além disso, para o caso especifico dos compostos PrMn2Ge2 e NdMn2Ge2, abaixo de 40K é observado, também, o ordenamento ferromagnético dos spins da sub rede da terra rara. O núcleo de prova 111In(111Cd) foi utilizado para medir, tanto as interações de quadrupolo elétrico, como de dipolo magnético na rede do Mn (interação matrizmatriz). Esses resultados evidenciaram a transição de fase magnética (antiferromagnética para ferromagnética), sendo que, o campo hiperfino magnético, para as duas fases magnéticas, segue o comportamento da função de Brillouin. Já o núcleo de prova 140La(140Ce) permitiu medir a interação de dipolo magnético, tanto originada pela rede do Mn, como pela rede da terra rara. Mas, nesse caso, pode ser verificado somente o campo hiperfino magnético da fase ferromagnética da rede do Mn. Para a análise dos resultados PAC levou-se em conta uma interação matriz-impureza, pois o íon Ce3+ possui um elétron 4f desemparelhado, que pode contribuir para o campo hiperfino total. O composto LaMn2Si2 apresentou o comportamento do campo hiperfino magnético com a temperatura que segue o comportamento da função de Brillouin. Já os compostos LaMn2Ge2, PrMn2Ge2 e NdMn2Ge2 apresentaram um comportamento anômalo ao da função de Brillouin. Esse comportamento pode ser associado a uma forte hibridização da banda 4f do Ce com a banda 3d do Mn, tal conclusão foi reforçada pelos resultados do DOS (densidade de estados), resultados dos cálculos de primeiros princípios, dos compostos LaMn2Si2 e LaMn2Ge2.This thesis reports a systematic study of the hyperfine interactions (magnetic hyperfine field and electric field gradient) in the RMn2Si2 and RMn2Ge2 ( R = La, Nd, Pr) compounds as well as in LaMn2(Si(1-x)Gex)2 (where x = 0, 0.2, 0.4, 0.6, 0.8, 1) mixed compounds. The hyperfine interactions were measured through Perturbed Angular Correlation Gamma-Gamma Spectroscopy technique using 111In(111Cd) and 140La(140Ce) as probe nuclei. Structural, magnetic and chemical analysis characterization were carried out by X-ray diffraction, magnetization measurements and gamma radiation spectrometry, respectively. An additional study by first-principles calculations for LaMn2Ge2 e LaMn2Si2 samples were also performed. The magnetic behavior in these compounds is mainly associated with the ordering of the magnetic moments of Mn sublattice, which appears at high temperature around 480 K. All studied compounds undergo a transition from antiferromagnetic to ferromagnetic ordering around room temperature. Specifically for PrMn2Ge2 and NdMn2Ge2 compounds, an additional ferromagnetic ordering due to the polarization of Pr or Nd magnetic moments is also observed below 40 K. 111In(111Cd) probe nuclei were used to measure the temperature dependence of the electric quadrupole and the dipole magnetic interactions at the Mn sublattice (matrix-matrix interaction). The results show the magnetic transition (antiferromagnetic to ferromagnetic phase), where the magnetic hyperfine field associated to both magnetic phases follows the Brillouin function. For the 140La(140Ce) probe nuclei, only dipole magnetic interaction measurements in the ferromagnetic phase were possible, also caused by the Mn sublattice and, for R = Pr, Nd, by the rare earth sublattice. The analysis of results considers a matrix-impurity interaction because the Ce3+ has an unpaired 4f electron, which can contribute to the total hyperfine field. The compound LaMn2Si2 presents a behavior for the temperature dependence of the magnetic hyperfine field that could be fitted by a Brillouin function. On the other hand, LaMn2Ge2, PrMn2Ge2 and NdMn2Ge2 compounds showed an anomalous Brillouin function behavior. This behavior can be associated with a strong hybridization Ce 4f band with the Mn 3d band. Such conclusion was reinforced by the DOS (density of stats), first-principles calculations, results to LaMn2Si2 and LaMn2Ge2.
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Suárez, Eduardo Díaz. "Simulações computacionais de moléculas com aplicações em biociências." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-11012016-152800/.
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In the present work we performed electronic structure calculations within the Kohn-Sham scheme of the density functional theory (DFT). We studied two molecules with potential applications in life sciences and medicine: ferrioxamine B and 5,10,15,20-tetrakis(1-methyl-4-pyridyl)-21H,23H (TMPyP) porphyrin. We used different methods and different exchange and correlation functionals, analyzing optical and vibrational properties and hyperfine interactions. In the case of ferrioxamine B, results in the crystalline phase (molecular crystal), and gas phase were compared with experimental results obtained using Mössbauer spectroscopy from the literature. We analyzed hyperfine parameters such as the electric quadrupole splitting, asymmetry parameter, hyperfine field and isomer shift. In the case of TMPyP porphyrin we analyzed vibrational properties in the gas phase and optical properties. For the electronic absorption, solvent effects and electronic charges states were analyzed.In the present work we performed electronic structure calculations within the Kohn-Sham scheme of the density functional theory (DFT). We studied two molecules with potential applications in life sciences and medicine: ferrioxamine B and 5,10,15,20-tetrakis(1-methyl-4-pyridyl)-21H,23H (TMPyP) porphyrin. We used different methods and different exchange and correlation functionals, analyzing optical and vibrational properties and hyperfine interactions. In the case of ferrioxamine B, results in the crystalline phase (molecular crystal), and gas phase were compared with experimental results obtained using Mössbauer spectroscopy from the literature. We analyzed hyperfine parameters such as the electric quadrupole splitting, asymmetry parameter, hyperfine field and isomer shift. In the case of TMPyP porphyrin we analyzed vibrational properties in the gas phase and optical properties. For the electronic absorption, solvent effects and electronic charges states were analyzed.
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Silva, Andréia dos Santos. "Investigações de interações hiperfinas de DNA e anticorpos de diferentes linhagens de camundongos frente à infecção por T. cruzi pela espectroscopia de correlação angular gama-gama perturbada." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-10092012-103415/.
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No presente trabalho, a técnica de Espectroscopia de Correlação Angular Perturbada (CAP) foi usada para medir a interação de quadrupolo elétrico em amostras de DNA de diferentes linhagens de camundongos (A/J, C57BL/6, B6AF1, BXA1 e BXA2), amostras de antiimunoglobulinas pertencentes as subclasses (IgG1, IgG2a e IgG2b) e de porções ativas de imunoglobulinas fracionadas ou inteiras, correspondentes a parte diversificada da imunoglobulina, responsável pelo padrão de resposta imunológica apresentado pelos organismos. Também foram realizadas medidas da interação de quadrupolo elétrico em amostras de bases nitrogenadas do DNA (adenina, citosina, guanina e timina). As medidas CAP foram realizadas utilizando os núcleos de prova 111In111Cd; 111mCd111Cd; 111Ag111Cd; e 181Hf181Ta, nas temperaturas ambiente e do nitrogênio líquido para investigar as interações dinâmicas e estáticas, respectivamente. As biomoléculas foram marcadas por meio direto, onde os átomos dos núcleos de prova devem se ligar a um determinado sítio da biomolécula. Os materiais biológicos e os núcleos de prova foram escolhidos com o objetivo de verificar, em todos os seus aspectos, a possibilidade de aplicação da espectroscopia de CAP na investigação dos parâmetros hiperfinos em um núcleo de prova de um átomo metálico ligado às biomoléculas (incluindo o uso de diferentes núcleos de prova, resultantes do decaimento do núcleo pai de quatro diferentes metais) e estudar, por meio dos parâmetros hiperfinos medidos, o comportamento dessas diferentes moléculas. Os resultados obtidos mostram as diferenças entre a interação das biomoléculas estudadas com os núcleos de prova Estas diferenças foram observadas por meio de variações nos parâmetros hiperfinos medidos, que depende do tipo de molécula, mostrando que o núcleo de prova em alguns casos ligou-se as moléculas e em outros não houve esta ligação.In the present work perturbed angular correlation (PAC) spectroscopy was used to measured electric quadrupole interactions in DNA biomolecules of different mice lineages (A/J, C57BL/6, B6AF1, BXA1 e BXA2), samples of different isotypes of immunoglobulin G (IgG1, IgG2a e IgG2b) and active portions of complete and fragmented immunoglobulin responsible by the immune response. Electric quadrupole interactions were also measured in DNA nitrogenous bases (adenine, cytosine, guanine, thymine). PAC measurements were performed using 111In111Cd; 111mCd111Cd; 111Ag111Cd; e 181Hf181Ta as probe nuclei, and carried out at room temperature and liquid nitrogen temperature, in order to investigate dynamic and static hyperfine interactions, respectively. The biomolecule samples were directly marked with the radioactive parent nuclei, whose atom link to a certain site in the biomolecules. The biological materials as well as the probe nuclei were chosen to investigate the possibility to use PAC spectroscopy to measure hyperfine parameters at nuclei from metallic elements bound to biomolecules (including the use of different probe nuclei produced in the decay of parent nuclei of four different metals) and also to study the behavior of different biomolecules by means of the measured hyperfine parameters. Results show differences in the hyperfine interactions of probe nuclei bound to the studied biomolecules. Such differences were observed by variations in the hyperfine parameters, which depend on the type of biomolecule and the results also show that the probe nuclei atom bound to the molecule in some cases and in others do not.
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Scherthan, Lena [Verfasser]. "Exploring hyperfine interactions and molecular vibrations of Dy and Fe containing single-molecule magnets using synchrotron-based nuclear resonant scattering / Lena Scherthan." Düren : Shaker, 2020. http://d-nb.info/1215461739/34.
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Koh, Young. "Nuclear structure studies involving polarised iodine, samarium and europium : experimental techniques and theoretical models." Thesis, University of Oxford, 1994. http://ora.ox.ac.uk/objects/uuid:fa4e489d-a235-4787-aab1-60f5a3b14c23.
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Low Temperature Nuclear Orientation (LTNO) is an important technique in the study of nuclei far from stability. The theory of LTNO and its application to the measurement of static nuclear moments and other quantities of spectroscopic interest are reviewed. The off-line facility at Oxford was used to study the decay of 133I→133Xe and 135I→135Xe. 133I having Z=53 and N=80 has three protons above the closed shell Z=50 and two neutrons holes in N=82 shell, while 135I has fully closed neutron shell since it has N=82, and they are of considerable theoretical interest since a wide variety of the theoretical nuclear models may be used to describe the observed levels close to the stable double closed shell structure. Another aim is to search for the nuclear magnetic dipole moment of the ground state of 135I. Nuclear orientation of 133IFe and 135IFe enabled the mixing ratios of several transitions in the decay scheme of 133I and 135I to be determined. From temperature dependence for 135I, the nuclear magnetic moment of 135I has been deduced. Also temperature dependence for 133I, analysed using a simple model, gave value for the magnetic hyperfine field that differed from previous published values. The method of combining nuclear orientation with NMR has become a very popular technique in recent years for determining nuclear magnetic dipole moments very precisely. The purpose of the NMR/ON experiment was to measure the hyperfine field with greater precision and to get some idea of the proportion of nuclei subject to it. Light Eu and Sm nuclei have attracted attention as systems with the number of protons right below the Z=64 subshell gap and the number of neutrons approaching N=82 major shell closure. Odd-proton, odd-neutron and odd-odd nuclei near the A=140 region have been investigated in the framework of the particle-triaxial rotor model. Main attention has been paid to explanation of experimental magnetic dipole and electric quadrupole moments of ground and isomeric states. Model predictions for deformation parameters of 136-142Sm even-even cores have been extracted.
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Cordeiro, Moacir Ribeiro. "Investigação de interações hiperfinas em Zn1 - x MTx O, onde MT=(V,Cr,Mn, Fe, Co, Ni, Cu) pela Técnica de Correlação Angular γ - γ Perturbada." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-05032012-143945/.
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O presente trabalho realiza a investigação de interações hiperfinas em amostras de óxido de zinco dopado com metais de transição por meio da técnica de Correlação Angular γ - γ Perturbada (CAP), baseada em interações hiperfinas. Para a realização das medidas, utilizou-se núcleos de prova radioativos de 111In -> 111 Cd que decaem através da cascata gama 171-245keV com nível intermediário de 245keV (I = 5+/2, Q = 0.83b, T1/2 = 84.5ns). Inicialmente, amostras de óxido de zinco dopadas com diferentes metais de transição foram confeccionadas por meio de um processo sol-gel para a obtenção de amostras óxidas. Realizou-se, então, o processo de caracterização destas amostras por meio de diferentes técnicas (Difração de Raios-X, Microscopia Eletrônica de Varredeura e Espectroscopia EDS) onde se sucedeu a investigação de interações hiperfinas (por meio da técnica CAP) a fim de se obter maior compreensão a respeito das interações quadrupolares elétricas presentes nas amostras, bem como a possibilidade da existência de comportamento ferromagnético à temperatura ambiente, aspecto este que vem sendo intensamente investigado, e que é de elevado interesse no que diz repeito à futuras aplicações. Os resultados obtidos foram analisados e discutidos em face dos modelos e das informações encontradas na literatura. As discussões foram realizadas em função das diferentes temperaturas de medida, tratamentos térmicos, tamanho das partículas, tipo e concentração de elementos dopantes, possibilitando uma discussão detalhada bem como a interpretação física dos resultados obtidos, apresentando-se as respectivas conclusões.In the present work, a microscopic investigation of hyperfine interactions in zinc oxide samples doped with transition metals was carried out by means of Perturbed Angular γ γ Correlation technique (PAC), which is based on hyperfine interactions. This technique makes use of 111In -> 111 Cd radioactive probe nuclei, which decay through the well known cascade 171-245keV with an intermediate level of 245keV (I = 5+/2 ,Q = 0.83b, T1/2 = 84.5ns). First, zinc oxide samples doped with different transition metals were obtained by means of a sol-gel method for production of oxide samples. Then, samples were characterized by means of different techniques (X-Ray Difraction, Scanning Electronic Microscopy and Energy Dispersive Spectroscopy), followed by the investigation of hyperfine interactions (using PAC technique), in order to increase the understanding concerning electric quadrupole interactions in these samples, as well as the possibility of obtaining ferromagnetic behavior at room temperature, which has been extensively investigated and is an aspect of high interest concerning future applications. Results obtained from measurements were analyzed and compared with the information found in literature. Discussions were made as function of different measurement temperatures, annealing procedures, particle size, type and concentration of doping elements, making possible to produce a detailed discussion as well as the physical interpretation of the results obtained, presenting the respective conclusions.
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Sajieddine, Mohammed. "Anisotropie magnétique et interactions hyperfines dans les multicouches Tb/Fe, Er/Fe, Eu/Fe et Gd/Fe." Nancy 1, 1994. http://www.theses.fr/1994NAN10064.
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Dans les multicouches terre rare/fer, l'anisotropie magnétique perpendiculaire dépend de la nature de la terre rare, de la température de substrat et des épaisseurs des couches. Dans ces multicouches, l'interface est plus étendue pour les échantillons élaborés à haute température de substrat et correspond à un alliage amorphe terre rare-fer. Les états aligné et twisté dans les multicouches Gd/Fe sont mis en évidence microscopiquement par spectrométrie Mössbauer avec 57Fe. Les résultats sont en bon accord avec les calculs numériques utilisant le modèle du champ moléculaire qui ont permis de déterminer les orientations des spins et leurs amplitudes dans chaque couche
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AMARAL, ANTONIO A. "Aplicação da espectroscopia de correlação angular perturbada na investigação de interações hiperfinas em compostos de háfnio, indio e cádmio com os ligantes Fsup(1-), OHsup(1-) e EDTA." reponame:Repositório Institucional do IPEN, 2011. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10006.
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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
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T'Jampens, Benoît. "Développement de méthodes asymptotiques pour l'étude des interactions entre atomes froids : détermination de longueurs de diffusion du sodium et du césium." Paris 11, 2002. https://tel.archives-ouvertes.fr/tel-00011676.
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Une connaissance précise des propriétés de collision entre atomes froids est essentielle pour l'étude de la condensation de Bose-Einstein ou la formation de molécules froides. Dans ces expériences, les phénomènes importants ont lieu principalement à des distances interatomiques grandes, c'est-à-dire dans la zone asymptotique. Nous avons développé une méthode purement asymptotique qui nous permet de décrire les propriétés collisionnelles des atomes alcalins froids sans avoir recours à la partie interne des potentiels moléculaires, qui est connue avec une précision moindre. Le point clé de la méthode est l'utilisation des lignes de nœuds, qui sont des lignes joignant les nœuds des fonctions d'onde radiales successives proches du seuil de dissociation du fondamental. Dans le cadre de l'approximation de Born-Oppenheimer, l'utilisation de ces lignes de nœuds, obtenues par intégration de l'équation de Schrödinger radiale dans la zone asymptotique uniquement, fournit un moyen simple pour déterminer des longueurs de diffusion à partir des positions expérimentales de niveaux liés. La méthode a ensuite été étendue au cas des potentiels couplés. Elle apparaît comme une véritable méthode paramétrique dans laquelle quelques paramètres décrivant des lignes de nœuds bien choisies remplacent la partie interne des potentiels. Ces paramètres sont ajustés sur des résultats expérimentaux. Une fois ces paramètres connus, toutes les propriétés de collision telles que les longueurs de diffusion, les décalage en fréquence des horloges atomiques ou encore les résonnances de Feshbach induites par un champ magnétique, peuvent en principe être déduites. Cette méthode a été utilisée pour obtenir les propriétés de collision entre atomes de sodium et de césium ultrafroidsPrecise knowledge of cold-atom collision properties is essential for the studies of Bose-Einstein condensation or cold molecule formation. In such experiments, the interaction mainly occurs at rather large interatomic distance, in the so-called asymptotic region. We have developed a purely asymptotic method which allows us to fully describe the collision properties of cold alkali atoms without using the inner part of the molecular potentials, which is often known with a poor precision. The key point of the method is the nodal lines, which are the lines connecting the nodes of successive radial wavefunctions near the ground state threshold. Within the framework of Born-Oppenheimer approximation, computing such nodal lines, by numerical integration of the radial Schrödinger equation in the asymptotic region only, provides a very simple way to derive scattering lengths from observed bound level positions. The method has been extended to the multichannel case and appears now as a genuine parametric method, in which a few parameters (some chosen nodal lines) replace the inner part of the potentials. These nodal lines are used as fitting parameters, which are ajusted on experimental results. Once these parameters have been determined, any collision property such as scattering lengths, clock shifts or magnetic field induced Feshbach resonances can be deduced in principle. This method has been applied to obtain the collision properties of ultracold sodium and cesium atoms
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Longdell, Jevon Joseph, and jevon longdell@anu edu au. "Quantum Information Processing in Rare Earth Ion Doped Insulators." The Australian National University. Research School of Physical Sciences and Engineering, 2004. http://thesis.anu.edu.au./public/adt-ANU20061010.105020.
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A great deal of theoretical activity has resulted from blending the fields of computer science and quantum mechanics. Out of this work has come the concept of a quantum computer, which promises to solve problems currently intractable for classical computers. This promise has, in turn, generated a large amount of effort directed toward investigating quantum computing experimentally.
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Quantum computing is difficult because fragile quantum superposition states of the computers register must be protected from the environment. This is made more difficult by the need to manipulate and measure these states.
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This thesis describes work that was carried out both to investigate and to demonstrate the utility of rare earth ion dopants for quantum computation. Dopants in solids are seen by many as a potential means of achieving scalable quantum computing. Rare earth ion dopants are an obvious choice for investigating such quantum computation. Long coherence times for both optical and nuclear spin transitions have been observed as well as optical manipulation of the spin states. The advantage that the scheme developed here has over nearly all of its competitors is that no complex nanofabrication is required. The advantages of avoiding nano-fabrication are two fold. Firstly, coherence times are likely to be adversely effected by the damage to the crystal structure that this manufacture represents. Secondly, the nano-fabrication presents a very serious difficulty in itself.
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Because of these advantages it was possible to perform two-qubit operations between independent qubits. This is the first time that such operations have been performed and presents a milestone in quantum computation using dopants in solids. It is only the second time two-qubit operations have been demonstrated in a solid.
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The experiments performed in this thesis were in two main areas: The first was the characterisation of hyperfine interactions in rare earth ion dopants; the second, simple demonstrations directly related to quantum computation.
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The first experiments that were carried out were to characterise the hyperfine interactions in Pr[superscript 3]+:Y[subscript 2]SiO[subscript 5]. The characterisation was the first carried out for the dopants in a site of such low symmetry. The resulting information about oscillator strengths and transition frequencies should prove indispensable when using such a system for quantum computation. It has already enabled an increase in the coherence times of nuclear spin transitions by two orders of magnitudes.
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The experiments directly related to the demonstration of quantum computation were all carried out using ensembles. The presence of a significant distribution of resonant frequencies, or inhomogeneous broadening, meant that many different sub-ensembles could be addressed, based on their resonant frequencies. Furthermore, the properties of the sub-ensembles could be engineered by optically pumping unwanted members to different hyperfine states away from resonance with the laser.
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A previously demonstrated technique for realising ensembles that could be used as single qubits was investigated and improved. Also, experiments were carried out to demonstrate the resulting ensembles utility as qubits. Further to this, ions from one of the ensembles were selected out, based on their interaction with the ions of another. Elementary two qubit operations were then demonstrated using these ensembles.
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Salutte, Caio de Oliveira. "Investigação do óxido semicondutor CeO2 dopado com Fe e La pela espectroscopia de correlação angular gama-gama perturbada." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-25022014-142726/.
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Amostras de dióxido de cério dopadas com La e Fe foram confeccionadas e caracterizadas por uma técnica nuclear baseada em interações hiperfinas conhecida como Correlação Angular Gama-Gama Perturbada (CAP). Como o composto em questão não é radioativo, foram utilizados núcleos radioativos como ponta de prova 111In 111Cd, que decaem através de uma cascata gama-gama 171-245 keV, com nível intermediário possui uma meia-vida de 84ns, spin 5/2- e um momento de quadrupolo elétrico Q= 0,83. Inicialmente uma metodologia para a produção das amostras precisou ser elaborada. As amostras de dióxido de cério e seus dopantes foram produzidas através do processo Sol-Gel, passando por uma calcinação e sinterização até a finalização da amostra. Sendo caracterizada por diversos tipos de técnicas (Difração de Raios-X e Microscopia Eletrônica de Varredura) culminando no estudo através da técnica CAP, para uma compreensão das interações quadrupolares elétricas das amostras e também a possibilidade da existência de comportamento magnético (assunto intensamente investigado dado o interesse na área da spintrônica). Os resultados encontrados foram analisados frente aos conhecimentos encontrados na literatura e as discussões foram feitas em função da variação do elemento dopante, tipos de tratamentos térmicos usados na sinterização e as diferentes temperaturas de medidas. Permitindo uma discussão e interpretação física dos resultados encontrados.Samples of cerium dioxide doped with La and Fe were fabricated and characterized by a technique based on nuclear hyperfine interactions known as Perturbed Angular Gamma-Gamma Correlation (PAC). As the used compound is not radioactive and the PAC technique requires a radioactive decaying through a cascade gamma-gamma, a radioactive probe nuclei were used (111In 111Cd - 171-245 keV), with intermediate has a half-life of 84ns, spin 5/2- and a moment of electric quadrupole Q= 0,83. Initially a methodology for the production of the samples had to be prepared. The cerium dioxide and its dopants were produced by the Sol-Gel process, undergoing a calcining and sintering. The sample are characterized by various types of techniques (X-ray Diffraction and Scanning Electron Microscopy) succeeding study through hyperfine Interactions, with the PAC technique, to an understanding of the electric quadrupole inteirações samples and also the possibility of the existence of magnetic behavior (subject intensively investigated given the interest in the field of spintronics). The results were analyzed taking the knowledge found in the literature and discussions were made on the basis of the variation of the doping element, thermal treatments used in the sintering temperatures and the different measures. Allowing a discussion and physical interpretation of results.
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ROSSETTO, DANIEL de A. "Investigação de interações hiperfinas em pó e filmes finos de dióxido de háfnio pela técnica de correlação angular gama-gama perturbada." reponame:Repositório Institucional do IPEN, 2011. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10134.
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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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SANTOS, BRIANNA B. dos. "Investigacao do magnetismo local em compostos intermetalicos do tipo RZn (Ce, Gd, Tb, Dy) e GdCu pela espectroscopia de correlacao angular gama-gama perturbada." reponame:Repositório Institucional do IPEN, 2010. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9566.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Tanaka, Hisaaki, Hideshi Nishiyama, Shin-ichi Kuroda, Takami Yamashita, Minoru Mitsumi, and Koshiro Toriumi. "ESR observation of optically generated solitons in the quasi-one-dimensional iodo-bridged diplatinum complex Pt_2(n-pentylCS_2)_4I." American Physical Society, 2008. http://hdl.handle.net/2237/11299.
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Amaral, Antonio Acleto. "Aplicação da espectroscopia de correlação angular perturbada na investigação de interações hiperfinas em compostos de háfnio, indio e cádmio com os ligantes F1-, OH1- e EDTA." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-25082011-155907/.
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O presente trabalho realiza a investigação dos parâmetros hiperfinos, incluindo a sua natureza dinâmica, em compostos ligantes em solução a temperatura ambiente (295 K) e resfriada (77K) através da espectroscopia de Correlação Angular γγ Perturbada (CAP). Para a realização das medidas experimentais, utilizou-se núcleos de prova radioativos de 111In111Cd, 181Hf181Ta e 111mCd111Cd, que decaem através de cascata gama. As amostras foram preparadas diluindo-se soluções com os núcleos radioativos em água, quando se investigou a interação do núcleo de prova com o ligante água; adicionando-se soluções com os núcleos radioativos em solução tampão, quando se investigou a interação do núcleo de prova com os íons ligantes provenientes do próprio tampão (CO32- e HCO31-) e com o OH1-; e adicionando-se soluções com os núcleos radioativos em soluções do ligante ácido etilenodiaminotetracético (EDTA), este em pH entre 4,0 e 5,0, (que corresponde ao pH da própria solução saturada do EDTA) e em solução tampão de pH entre 9 e 10. Assim foi possível investigar os efeitos gerados por cada um desses métodos de preparação de amostras nas medidas CAP. Finalmente foi feita uma análise comparativa para os vários métodos de inserção dos núcleos de prova na amostra, considerando-se aspectos químicos e nucleares. A inexistência de medidas para esse tipo de amostra, justifica a importância dos resultados obtidos.In this study the hyperfine parameters, including the dynamical nature, Perturbed Angular Correlation (PAC) spectroscopy was used to measure the hyperfine parameters in molecules of ligand compounds in solutions. The measurements were carried out at 295 K and 77 K using 111In111Cd, 181Hf181Ta and 111mCd111Cd, as probe nuclei. Samples were prepared by adding a small volume of radioactive solution containing the probe nuclei in aqueous solution, buffer solution and ethylenediaminetetraacetic acid (EDTA) used as a ligand with pH 4.3 which correspond to the pH of the saturated EDTA solution and in buffer solution with pH between 9 and 10. The results made possible to understand the impact of each method for PAC measurements. Finally a comparative analysis for the several methods of inserting of the probe nuclei in the sample was made, considering chemical and nuclear aspects. The lack of measurements in this kind of samples justifies the importance of the obtained results.
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Jee, Bettina. "Cw and pulsed EPR spectroscopy of Cu(II) and V(IV) in metal-organic framework compounds: metal ion coordination and adsorbate interactions." Doctoral thesis, Universitätsbibliothek Leipzig, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-126200.
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Metal-organic framework (MOF) compounds as a new class of porous coordination polymers consists of metal ions or clusters linked by organic molecules. They have gained recent interest because of their large surface areas and huge variety of the porous network structures. They exhibit interesting adsorption properties and therefore are potential candidates for various technical applications.
In this work, continuous wave (cw) and pulsed electron paramagnetic resonance (EPR) methods such as pulsed electron-nuclear double resonance (ENDOR) and hyperfine sublevel correlation (HYSCORE) spectroscopy are applied to study metal-organic frameworks with respect to different aspects of their properties: The host-guest interactions between Cu2+ ions in [Cu3(btc)2]n (HKUST-1; btc: 1,3,5-benzenetricaboxylate) with adsorbed methanol (CH3OH), 13C enriched carbon monoxide and dioxide (13CO, 13CO2), hydrogen (H2), deuterium (D2) and mixed isotopic HD. In [Cu3(btc)2]n, the Cu2+ ions are connected to binuclear Cu/Cu paddle wheel units. Since the Cu2+ ions in the [Cu3(btc)2]n are antiferromagnetically coupled, the new compound [Cu2.97Zn0.03(btc)2]n is synthesized by isomorphous substitution containing about 1 % paramagnetic Cu/Zn paddle wheel units. The modified Cu/Zn paddle wheel units prove to be a very sensitive probe for the interactions with the adsorbed molecules.
Secondly, the exchange interactions of antiferromagnetically coupled Cu/Cu paddle wheel units as well as additional inter-paddle wheel exchange interactions between the Cu/Cu pairs are studied in [Cu2(bdc)2(dabco)]n, a layered MOF with 1,4-benzenedicaboxylate (bdc) as linker and 1,4-diazabicyclo[2.2.2]octane (dabco) acting as pillars between the layers. In comparison to [Cu3(btc)2]n, the additional inter-paddle wheel exchange interactions are much easier disturbed by incorporation of Zn2+ ions into the framework structure.
Third, the structural dynamics of the framework is investigated in the compound [Al(OH)(bdc)]n (MIL-53) which was isomorphously substituted by V(III)/V(IV) species. The 51V hyperfine structure revealed to be sensitive to the so-called breathing effect, a flexible structural behaviour upon guest adsorption/desorption or upon thermal treatment. It is shown that the aluminum ions can be substituted by vanadium but the octahedral coordination environment changes slightly to a pseudo-octahedral or a square-pyramidal coordination.
Based on the hyperfine interactions between the electron spin and the nuclear spins of the surrounding atoms, structural models can be derived from orientation-selective measurements. In such a way, structural information of materials like powder samples and adsorbate complexes can be obtained which are hardly or even not accessible by other methods.
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Crozet, Marielle. "Etudes des interactions hyperfines des 13C par RPE pulsée et RMN à haute résolution en solide sur des complexes à 4Fe et 4S, modèles de sites actifs de métalloprotéines." Université Joseph Fourier (Grenoble), 1995. http://www.theses.fr/1995GRE10193.
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Ce travail se situe dans le cadre de l'etude des proprietes magnetiques de sites actifs de metalloproteines constitues de quatre atomes de fer et de quatre atomes de soufre. Les etudes par eseem-ft sur monocristaux ainsi que de rmn du #1#3c a l'etat solide developpees dans ce travail, presentent l'avantage de fournir des informations precises sur l'etat de spin et/ou la localisation de la densite de spin au sein du cubane a 4 fe et 4 s. Precedemment, c'etaient les protons des composes modeles etudies qui servaient de sondes pour la determination de la densite de spin grace a des etudes d'endor. Le choix a ete fait ici d'utiliser les atomes de carbone proches du centre paramagnetique et moins nombreux que les protons. Ce travail a donc ete d'etudier par eseem-ft puis par rmn du #1#3c a l'etat solide un complexe modele enrichi en #1#3c soit fe#4s#4(s#1#3ch#2ph)#4
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T'Jampens, BenoÎt. "Développement de méthodes asymptotiques pour l'étude des interactions entre atomes froids ; détermination de longueurs de diffusion du sodium et du césium." Phd thesis, Université Paris Sud - Paris XI, 2002. http://tel.archives-ouvertes.fr/tel-00011676.
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Une connaissance précise des propriétés de collision entre atomes froids est essentielle pour l'étude de la condensation de Bose-Einstein ou la formation de molécules froides. Dans ces expériences, les phénomènes importants ont lieu principalement à des distances interatomiques grandes, c'est-à-dire dans la zone asymptotique. Nous avons développé une méthode purement asymptotique qui nous permet de décrire les propriétés collisionnelles des atomes alcalins froids sans avoir recours à la partie interne des potentiels moléculaires, qui est connue avec une précision moindre. Le point clé de la méthode est l'utilisation des lignes de noeuds, qui sont des lignes joignant les noeuds des fonctions d'onde radiales successives proches du seuil de dissociation du fondamental. Dans le cadre de l'approximation de Born-Oppenheimer, l'utilisation de ces lignes de noeuds, obtenues par intégration de l'équation de Schrödinger radiale dans la zone asymptotique uniquement, fournit un moyen simple pour déterminer des longueurs de diffusion à partir des positions expérimentales de niveaux liés. La méthode a ensuite été étendue au cas des potentiels couplés. Elle apparaît comme une véritable méthode paramétrique dans laquelle quelques paramètres décrivant des lignes de noeuds bien choisies remplacent la partie interne des potentiels. Ces paramètres sont ajustés sur des résultats expérimentaux. Une fois ces paramètres connus, toutes les propriétés de collision telles que les longueurs de diffusion, les décalage en fréquence des horloges atomiques ou encore les résonnances de Feshbach induites par un champ magnétique, peuvent en principe être déduites. Cette méthode a été utilisée pour obtenir les propriétés de collision des atomes de sodium et de césium ultrafroids.
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Azevedo, W. M. de. "The hyperfine interaction of terbium in magnetically ordered compounds." Thesis, University of Manchester, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375060.
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Jiang, Zijian. "Spin States in Bismuth and Its Surfaces: Hyperfine Interaction." Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/101787.
Full textAbstract:
The hyperfine interaction between carrier spins and nuclear spins is an important component in exploring spin-dependent properties in materials with strong spin orbit interaction.However hyperfine interaction has been less studied in bismuth (Bi), a heavy element exhibiting a strong Rashba-like spin-orbit interaction in its two-dimensional surface states due to the broken spatial inversion symmetry. In this dissertation we experimentally explore the carrier spin polarization due to transport under strong spin-orbit interaction and the nuclear polarization resulting from the relatively unexplored hyperfine interaction on Bi(111) films.The carrier and nuclear spin polarizations are expected to dynamically interact, a topic with ramifications to other materials where surface states with noteworthy properties play a role.To achieve this goal, an optimized van der Waals epitaxy growth technique for Bi(111) on mica substrates was developed and used, resulting in flat Bi surfaces with large grain sizes and a layered step height of 0.39±0.015 nm, corresponding to one Bi(111) bilayer height. A comparison between Bi(111) films grown on three different substrates (mica, InSb(111)B, and Si(111)) is discussed, for which scanning electron microscopy and atomic force microscopy are applied to obtain the structural and morphological characteristics on the film surface. Magnetotransport measurements are carried out to extract the transport properties of theBi(111) films. Using the high quality Bi(111) film deposited on mica, we develop quantum magnetotransport techniques as delicate tools to study hyperfine interaction. The approach is based on measuring quantum corrections to the conductivity due to weak antilocalization, which depend on the coherence of the spin state of the carriers. The carrier spin polarization is generated by a strong DC current in the Bi(111) surface states (here called the Edelstein effect), which then induces dynamic nuclear polarization by hyperfine interaction. Quantum transport antilocalization measurements in the Bi(111) thin-films grown on mica indicate a suppression of antilocalization by the in-plane Overhauser field from the nuclear polarization, and allow for the quantification of the Overhauser field, which is shown to depend on both polarization duration and the DC current magnitude. Various delay times between the polarization and the measurement result in an exponential decay of the Overhauser field, driven by relaxation time T1. We observe that in the Bi surface states, the appreciable electron density and strong spin-orbit interaction allow for dynamic nuclear polarization in the absence of an external magnetic field.Doctor of Philosophy
This dissertation focuses on the heavy element bismuth (Bi), a semimetal with strong spin-orbit interaction at its two-dimensional surface. Given the challenge to grow high qualityBi(111) films, we present an optimized van der Waals epitaxy technique to grow Bi(111)films on mica substrates, which show a flat surface with large grain sizes and a layered step height of 0.391±0.015 nm, corresponding to one Bi(111) bilayer height. To demonstrate the high quality of the Bi(111) surface, a comparison of surface morphology was conducted among Bi(111) films deposited on three different substrates (mica, Si(111), and InSb(111)B),along with a comparison between their electronic transport properties. By applying a DC current on the high quality Bi(111) film on mica, a carrier spin polarization is established via mainly what we here call the Edelstein effect, which then induces dynamic nuclear polarization by hyperfine interaction and generates a non-equilibrium nuclear spin polarization without externally applied magnetic field. We quantified the Overhauser field from the nuclear polarization all-electrically by conducting quantum transport antilocalization experiments, which showed a suppression of antilocalization by the in-plane Overhauser field.Comparative measurements indicated that the magnitude of the Overhauser field depends onthe spin-polarizing DC current magnitude and the polarization duration. The experiments also show that antilocalization forms a sensitive probe for hyperfine interaction and nuclear polarization.
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Petersen, Philippe Alexandre Divina. "Cálculos ab initio de interações entre Cd e bases nitrogenadas do DNA." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-30092011-163810/.
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As interações hiperfinas são uma ótima ferramenta para estudar um sítio específico e obter informações importantes sobre o sistema. No presente trabalho analisamos de forma teórica as propriedades eletrônicas, estruturais e hiper nas do Cádmio (Cd) ligado às bases nitrogenadas do DNA. A motivação surgiu da colaboração com o grupo do prof. Artur W. Carbonari do Instituto de Pesquisas Energéticas e Nucleares (IPEN) e que tem como objetivo investigar o DNA e anticorpos de linhagens de camundongos infectados pela cepa Y de Trypanosoma cruzi, protozoário causador da doença de Chagas. A técnica Time Differential Perturbed Angular Correlation (TDPAC) foi utilizada para obter as medidas das interações hiperfinas do DNA. O núcleo de prova das medidas foi o 111Cd. Utilizamos uma abordagem quântica ab initio all-electron, dentro da Teoria do Funcional da Densidade (DFT), através do código computacional CP-PAW que combina o método Projector Augmented Wave (PAW) e a dinâmica molecular quântica de Car-Parrinello (CPMD). Ressaltamos que, até o presente momento, nenhum estudo com esta abordagem teórica e com este código computacional foi realizado para investigar as propriedades hiper nas do Cd ligado as bases nitrogenadas do DNA.The Hyperfine interactions are good tools to study speci c sites and obtain important information about a given system. In this work we study electronic, structural and hyper ne properties of the Cadmium (Cd) coordinated to the DNA nitrogenous bases. The motivation for this study arose from a collaboration with the group of prof. Arthur W. Carbonari at the Institute of Energy and Nuclear Research (IPEN), which aims to investigate DNA and antibodies to strains of mice infected with the Trypanosoma cruzi, the protozoan that causes Chagas disease. The Time Differential Perturbed Angular Correlation (TDPAC) technique was used to obtain hypefine interactions measurements at a Cd probe bonded to DNA. We use ab initio all-electron calculations, within the Density Functional Theory (DFT) and we use the computer code CP-PAW that combines the Projector Augmented Wave (PAW) method and the Car-Parrinello (CP) quantum molecular dynamics approach to. We emphasize that, until now, no study with this theorectical approach and with this computer code was conducted to investigate the hyper ne properties of the Cd binding to the DNA bases.
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Eble, Benoit. "Interaction hyperfine dans les boîtes quantiques d'InAs/GaAs sous pompage optique orienté." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2006. http://tel.archives-ouvertes.fr/tel-00197618.
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Le spin d'un électron piégé dans une boîte quantique d'InAs est une observable a priori bien protégée des perturbations de l'environnement solide. En particulier, les mécanismes de relaxation présents habituellement dans les matériaux massifs ou puits quantiques sont inhibés en raison de la discrétisation des niveaux d'énergie. Le spin représente de ce fait un système très attractif pour la réalisation d'une porte logique quantique dans la matière condensée. Toutefois, le fort confinement exalte d'autres mécanismes dépendant du spin. C'est le cas de l'interaction hyperfine avec les spins nucléaires.Celle-ci, équivalente pour le spin électronique µa un champ magnétique aléatoire de quelques dizaines de mT d'amplitude, est à l'origine d'un mécanisme de déphasage en un temps de l'ordre de la nanoseconde.
Ce travail de thèse mets en lumière le rôle fondamental joué par ce couplage hyperfin lors des expériences d'orientation optique des porteurs dans des boîtes quantiques InAs dont la charge est contrôlée par une tension de grille. La spectroscopie haute résolution de la photoluminescence de boîtes uniques, ainsi que des mesures sur ensemble, résolues en temps ou en présence d'un champ magnétique, permettent de dresser un panorama assez complet. En particulier, la polarisation dynamique des noyaux et la relaxation de spin induite par l'interaction hyperfine apparaissent comme deux manifestations majeures et antagonistes du couplage hyperfin intrinsèques au système "électron-noyaux".
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Carboni, C. "The hyperfine interaction of holmium in some uniaxial compounds at low temperature." Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382790.
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Eble, Benoît. "Interaction hyperfine dans les boîtes quantiques d'InAs/GaAs sous pompage optique orienté." Paris 6, 2006. https://tel.archives-ouvertes.fr/tel-00197618.
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Seiller, Thomas. "Logique dans le facteur hyperfini : Géométrie de l' interaction et complexité." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4064.
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Cette thèse est une étude de la géométrie de l'interaction dans le facteur hyperfini (GdI5), introduite par Jean-Yves Girard, et de ses liens avec les constructions plus anciennes. Nous commençons par montrer comment obtenir des adjonctions purement géométriques comme une identité entre des ensembles de cycles apparaissant entre des graphes. Il est alors possible, en choisissant une fonction qui mesure les cycles, d'obtenir une adjonction numérique. Nous montrons ensuite comment construire, sur la base d'une adjonction numérique, une géométrie de l'interaction pour la logique linéaire multiplicative additive où les preuves sont interprétées par des graphes. Nous expliquons également comment cette construction permet de définir une sémantique dénotationnelle de MALL, et une notion de vérité. Nous étudions finalement une généralisation de ce cadre afin d'interpréter les exponentielles et le second ordre. Les constructions sur les graphes étant paramétrées par une fonction de mesure des cycles, nous entreprenons ensuite l'étude de deux cas particuliers. Le premier s'avère être une version combinatoire de la GdI5, et nous obtenons donc une interprétation géométrique de l'orthogonalité basée sur le déterminant de Fuglede-Kadison. Le second cas particulier est une version combinatoire des constructions plus anciennes de la géométrie de l'interaction, où l'orthogonalité est basée sur la nilpotence. Ceci permet donc de comprendre le lien entre les différentes versions de la géométrie de l'interaction, et d'en déduire que les deux adjonctions — qui semblent à première vue si différentes — sont des conséquences d'une même identité géométriqueThis work is a study of the geometry of interaction in the hyperfinite factor introduced by Jean-Yves Girard, and of its relations with ancient constructions. We start by showing how to obtain purely geometrical adjunctions as an identity between sets of cycles appearing between graphs. It is then possible, by chosing a function that measures those cycles, to obtain a numerical adjunction. We then show how to construct, on the basis of such a numerical adjunction, a geometry of interaction for multiplicative additive linear logic where proofs are interpreted as graphs. We also explain how to define from this construction a denotational semantics for MALL, and a notion of truth. We extend this setting in order to deal with exponential connectives and show a full soundness result for a variant of elementary linear logic (ELL). Since the constructions on graphs we define are parametrized by a function that measures cycles, we then focus our study to two particular cases. The first case turns out to be a combinatorial version of GoI5, and we thus obtain a geometrical caracterisation of its orthogonality which is based on Fuglede-Kadison determinant. The second particular case we study will giveus a refined version of older constructions of geometry of interaction, where orthogonality is based on nilpotency. This allows us to show how these two versions of GoI, which seem quite different, are related and understand that the respective adjunctions are both consequences of a unique geometrical property. In the last part, we study the notion of subjective truth
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Nejadsattari, Farshad. "Theoretical and Experimental Studies of Electronic Structure, Magnetic, and Hyperfine Interaction Properties of Novel Compounds." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34572.
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This thesis consists of the results of theoretical and experimental studies on the electronic structure, magnetic properties and hyperfine-interaction parameters of five compounds. The theoretical studies are based on ab-initio calculations, and the experimental studies are based on Mössbauer spectroscopy, magnetic measurements, and X-ray powder diffraction measurements. The calculated hyperfine-interaction parameters are shown to be in good agreement with the corresponding experimental parameters for all studied compounds.
Al13Fe4 crystallizes in the monoclinic space group 𝐶2/𝑚, in which Fe atoms are located at five inequivalent crystallographic sites. It is shown that the zero-field Mössbauer spectra can be decomposed into three quadrupole doublets. It is found that the shape of the Mössbauer spectrum measured in an external magnetic field can be accounted for with five component subspectra generated using the calculated EFG parameters at five inequivalent Fe sites. A pseudogap is observed in the density of states (DOS) in the vicinity of the Fermi level.
The recently discovered layered iron oxyselenide Na2Fe2Se2O is confirmed to be a Mott
insulator. It is demonstrated that Na2Fe2Se2O orders antiferromagnetically. The Debye
temperature of Na2Fe2Se2O is found to be 274(3) K.
The Fe2NiGa compound crystallizes in the cubic space group 𝐹4 ̅3𝑚 and is predicted to be half-metallic with covalent chemical bonding. It orders ferromagnetically. The saturation
magnetization per formula unit and the estimated Fe magnetic moments at the A and B sites are given. It is observed that the magnetic properties of Fe2NiGa are very strongly dependent on their heat treatment.
The presence of a mixture of strong covalent and weak ionic chemical bonding and of
metallic characteristics for the (Li0.8Fe0.2)OHFeSe superconductor is shown. The Mössbauer spectra consist of two quadrupole-doublet patterns. It is demonstrated that there is no magnetic ordering of the 2𝑎-site Fe magnetic moments down to 2.0 K.
The final compound is the Al76Ni9Fe15 approximant. The existence of a pseudogap in the calculated electronic density of states slightly above the Fermi level suggests electronic
stabilization according to the Hume-Rothery-type mechanism. High metallicity is predicted.
Both the Mössbauer spectra and magnetic susceptibility data indicate that Al76Ni9Fe15 is a
paramagnet down to 2.0 K.
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Adnet, Frédéric. "Mesures des interactions hyperfines dans les sites de fixation du calcium des calci-proteines." Paris 6, 1990. http://www.theses.fr/1990PA066005.
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Des mesures de correlations angulaires perturbees differentielles (capd) ont ete effectuees a temperature ambiante sur la cascade gamma-gamma 150-247 kev du cadmium 111m incorpore a la calmoduline et a la parvalbumine. Une anisotropie dependante du temps de la fonction de correlation a ete observee, son etude montre qu'il existe deux frequences d'interaction electrique quadrupolaire dans la calmoduline et une seule dans la parvalbumine. Ces parametres d'interaction quadrupolaire semblent montrer qu'il existe deux types de sites de fixation dans la camoduline et un dans la parvalbumine, celui-ci est analogue a un des deux types de sites de la calmoduline
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BAHLOUL, KHALED. "Des interactions hyperfines et de la conversion des isomeres de spin nucleaire de ch#3f." Paris 7, 1997. http://www.theses.fr/1997PA077090.
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La decouverte d'un nouveau procede de separation des composantes d'un melange gazeux, par irradiation optique, en 1989, a permis le developpement d'un nouveau genre de spectroscopie. Cette methode baptisee l. I. D (light induced drift) a permis de separer les isomeres de spin nucleaires, et d'etudier leurs relaxations thermiques. Les transitions rotationnelles en jeu sont originales car elles s'accompagnent d'une transition entre des etats de spin nucleaire differents de la molecule. Cette these est consacree a l'etude de ces relaxations dans un gaz compose de molecules ch#3f ou de ses isotopes. Trois interactions hyperfines contribuent aux processus : l'interaction dipolaire entre les spins nucleaires et les interactions spin-rotation issues des champs magnetiques crees soit par les electrons, soit par les noyaux. Il est montre que l'interaction dipolaire etait dominante dans #1#3ch#3f, bien que completee par l'interaction spin-rotation d'origine electronique. Au contraire, l'interaction spin-rotation d'origine nucleaire est largement dominante dans #1#2ch#3f. La comparaison avec les mesures experimentales a permis d'en deduire des estimations de plusieurs taux de relaxation rotationnelle ainsi que des composantes du tenseur de spin-rotation qui ne sont pas mesurables par d'autres techniques. Enfin, un certain nombre de nouvelles experiences sont proposees. Elles sont basees sur l'application d'un champ electrique ou magnetique pendant la conversion de spin nuceaire.
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Pfister, Olivier. "Etude expérimentale et théorique des interactions hyperfines dans la bande de vibration v3 de la molécule 28SiF4." Paris 13, 1993. http://www.theses.fr/1993PA132022.
Full textAbstract:
L'étude expérimentale des interactions hyperfines dans la bande 3 à 9,7 m de 28sif4, dans l'état électronique fondamental, a été réalisée par spectroscopie laser d'absorption saturée, à ultra-haute résolution, sur le spectromètre infrarouge 9-12 m du laboratoire de physique des lasers de l'université de Paris-nord. Les nombreuses coïncidences entre les transitions rovibrationnelles de 28sif4 et les raies laser des différents isotopes du co2 ont permis l'enregistrement de quelques 50 spectres hyperfins. La partie expérimentale de ce travail a bénéficié des constantes évolutions des matériels et techniques mis en œuvre sur le spectromètre, dont le pouvoir de résolution reste inégale dans le monde dans ce domaine 9-12 m: nouvelle génération de lasers à co2 scelles ultra-stables, utilisation de modulateurs acousto-optiques radiofréquences, et enfin mise en œuvre avec succès et pour la première fois sur l'expérience d'un modulateur électrooptique hyperfréquences, en collaboration avec le laboratoire de spectroscopie hertzienne de l'université de Lille i. La grande variété de structures enregistrées nous a permis de déterminer la plupart des constantes spectroscopiques hyperfines de 28sif4, dont beaucoup étaient encore inconnues à ce jour, ainsi que d'ajouter un nouveau cas de figure à l'étude des interactions hyperfines dans les toupies sphériques, suite aux travaux de notre groupe sur oso4 et sf6. Le formalisme théorique des tenseurs irréductibles doubles en physique moléculaire est appliqué à l'écriture des interactions hyperfines et au calcul des niveaux d'énergie. Nous mettons en évidence l'action des couplages hyperfins entre les différents niveaux rovibrationnels d'un même amas superfin. La structure hyperfine constitue alors un révélateur très sensible des effets de la dynamique moléculaire, telle la brisure spontanée de symétrie par distorsion centrifuge. Un exemple spectaculaire de ces effets est la levée par les interactions hyperfines de la dégénérescence en parité des doublets e au sein d'un amas superfin.
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Payette, Christopher. "Transport in weakly coupled vertical double quantum dots: single-particle energy level spectroscopy and hyperfine interaction effects." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=96713.
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Performing transport measurements on weakly coupled vertical double quantum dots, we study by magneto-resonant-tunneling spectroscopy, single-particle energy spectra of the constituent dots over a wide energy window. The measured energy spectra are well modeled overall by ideal spectra calculated for elliptical and parabolic in-dot-plane confinement potentials. However, in regions where single-particle energy levels are naively expected to cross, we observe pronounced level anti-crossing behaviour and strong resonant current variations (both enhancement and suppression). Within a coherent tunneling picture, these effects can be attributed to coherent level mixing induced by weak perturbations in the nearly ideal dot confinement potentials. We analyze the energy spectra in detail, and focus on examples of two-, three- and four-level crossings where we observe the suppression of an otherwise strong current resonance, a signature of dark state formation due to destructive interference. The mixing we measure and model at two three-level crossings represents an all-electrical analogue of coherent population trapping. We also explore the limitations of the applicability of the coherent level mixing model and demonstrate in-situ alteration of the coupling between levels.We further examine the electron spin-nuclear spin (hyperfine) interaction. In the familiar two-electron spin blockade regime, on application of an out-of-dot-plane magnetic field, we observe current switching and hysteresis, and a funnel-like structure in the leakage current, all hallmarks of the hyperfine interaction. The measurements bring to light a strong gate voltage dependence, significant device-to-device variations, and an intricate bias voltage history dependence not accounted for in any existing model. Unexpectedly, we also observe signatures of the hyperfine interaction at high bias, well outside the spin blockade regime. We characterize these features and suggest how the hyperfine interaction may play a role at high bias, although the electronic states involved generally can not easily be identified. As a first step toward understanding this new regime, we describe another hysteretic funnel-like structure observed at high bias where the electronic states involved can be identified as two-electron states, so allowing us to postulate a specific mechanism for this funnel.En effectuant des mesures de transport sur des boîtes quantiques doubles faiblement couplées, nous étudions, par la spectroscopie par effet tunnel magnetorésonant, les spectres d'énergie de particule simple dans une grande fenêtre d'énergie. Les spectres d'énergie mesurés sont modélisés par les spectres calculés pour des potentiels de confinement elliptique et parabolique. Cependant, dans les régions où les niveaux d'énergie de particule simple doivent se croiser, nous observons des comportements de croisements évités et des variations du courant résonnant. Dans le cadre de l'effet tunnel cohérent, ces effets peuvent être attribués au mélange cohérent des niveaux induit par les faibles perturbations du confinement. Nous analysons les spectres d'énergie et focalisons sur des exemples de croisements de deux à quatre niveaux où nous observons la suppression d'une résonance de courant qui est une signature de la formation d'un état sombre dû à de l'interférence destructive. Le mélange que nous mesurons et modélisons à deux croisements de trois niveaux représente un piégeage cohérent de population.Nous examinons plus en détail l'interaction hyperfine entre les spins des électrons et des noyaux. Dans le régime du blocage de spin avec deux électrons, lors de l'application d'un champ magnétique hors plan, nous observons un courant intermittent avec de l'hystérèse et une structure en entonnoir dans le courant de fuite, qui sont des aspects marquants de l'interaction hyperfine. Les mesures dévoilent une dépendance sur la tension de grille, des variations d'un dispositif à l'autre et une dépendance sur l'histoire de la tension de biais qui apparaît dans aucun modèle existant. Nous observons également des signatures de l'interaction hyperfine à biais élevé, au-delà du régime du blocage de spin. Nous caractérisons ces aspects et suggérons comment l'interaction hyperfine peut jouer un rôle à biais élevé, quoique les états électroniques impliqués ne puissent pas être identifiés facilement. Comme première étape vers la compréhension de ce nouveau régime, nous décrivons une autre structure hystérétique en entonnoir observée à biais élevé où les états électroniques impliqués peuvent être identifiés comme des états à deux électrons, ce qui nous permet de postuler un mécanisme spécifique pour cet entonnoir.
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Albedah, Mohammed. "Experimental and Theoretical Investigations of Magnetic, Electronic Structure, and Hyperfine Interaction Properties of New Fe-Based Superconductors and EuFeAs₂." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/41636.
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This thesis presents the experimental studies of the magnetic and hyperfine interaction
properties of four novel Fe-based superconductors (ThFeAsN, CsEuFe4As4, Rb1-δEuFe4As4, and
EuFe0.97Ni0.03As2) and one new non-superconducting compound (EuFeAs2). It is supplemented by
ab-initio calculations of the electronic structure and magnetism of the three superconductors. The
experimental studies are based on the results of x-ray diffraction, magnetic susceptibility,
magnetization, and 57Fe and 151Eu Mössbauer spectroscopy measurements.
The superconductor ThFeAsN crystallizes in the tetragonal space group P4/nmm with the
lattice parameters a = 4.0356(1) Å and c = 8.5286(1) Å. It is shown that there is no magnetic order
of the Fe magnetic moments down to 2.0 K. We suggest that nonappearance of Fe magnetism in
ThFeAsN may be because of an internal uniaxial chemical pressure whose presence is manifested
by the unusually small c/a ratio. We provide theoretical evidence for a mixture of ionic and
covalent chemical bonding and metallic characteristics. We present a detailed analysis of the
calculated energy band structure of ThFeAsN. A quadrupole doublet well describes the shape of
the Mössbauer spectra with a small quadrupole splitting that increases with lowering temperature.
Good agreement is found between the calculated and extrapolated 0 K quadrupole splitting values.
A fair agreement is noted between the experimental Debye temperature 332(2) K and 370 K of the
calculated one.
We show that the superconductor CsEuFe4As4 crystallizes in the tetragonal space group
P4/mmm with the lattice parameters a = 3.8956(1) Å and c = 13.6628(5) Å. We show that the Fe
atoms carry no magnetic moment down to 2.1 K and that the ferromagnetic order is related to the
Eu magnetic moments. We establish that the Curie temperature Tc = 15.97(8) K found from the
temperature dependence of the hyperfine magnetic field at 151Eu nuclei is well-matched with the
temperature dependence of the transferred hyperfine magnetic field at 57Fe nuclei that is produced
by the ferromagnetically ordered Eu sublattice. The magnetic moments of the Eu atoms are shown
to be perpendicular to the crystallographic c-axis. The T 3⁄2 power-law perfectly describes the
temperature dependence of the principal component of the electric field gradient tensor, both at Fe
and Eu sites. The calculated and the measured parameters of the hyperfine-interaction are in
excellent agreement with each other. We determine that the Debye temperature of CsEuFe4As4 is
295(3) K.
Ab-initio calculations suggest a mixture of ionic, covalent, and metallic bonding between
the constituent atoms in the CsEuFe4As4 superconductor. We confirm that the strongly localized
Eu f states are the origin of the magnetic moment of CsEuFe4As4, in agreement with the
experimental results. We show that an almost zero magnetic moment carried by the Fe atoms is
caused by the spin-up and spin-down states' apparent symmetry. We show that the Fermi surfaces
have hole-like and electron-like pockets located at the center and corners of the Brillouin zone,
respectively.
The superconductor Rb1-δEuFe4As4 crystallizes in the tetragonal space group P4/mmm with
the lattice parameters a = 3.8849(1) Å and c = 13.3370(3) Å. We show that the Fe atoms carry no
magnetic moment down to 2.1 K and that the ferromagnetic order is associated solely with the Eu
magnetic moments. The Curie temperature Tc = 16.54(8) K is found from the temperature
dependence of both the hyperfine magnetic field at 151Eu nuclei and the transferred hyperfine
magnetic field at 57Fe nuclei induced by the ferromagnetically ordered Eu sublattice. We find that
the Eu magnetic moments lie in the ab plane. It is observed that the temperature dependence of the
principal component of the electric field gradient tensor, at both Fe and Eu sites, is well described
by a T3⁄2 power-law relation. There is good agreement between the calculated and measured
parameters of the hyperfine-interaction. We determine that the Debye temperature of
Rb1-δEuFe4As4 is 391(8) K.
Ab-initio calculations indicate the presence of a mixture of ionic, covalent, and metallic
bonding between the constituent atoms in the RbEuFe4As4 superconductor. We show that the
magnetic moment of RbEuFe4As4 is mainly a result of the strongly localized Eu f states. It is shown
that an almost zero magnetic moment carried by the Fe atoms originates from an apparent
symmetry of the spin-up and spin-down states. We show that the electrical and chemical properties
of RbEuFe4As4 are closely associated with the presence of the Fe 3d states in the Fermi energy
region. The Fermi surfaces display hole-like and electron-like pockets, respectively, at the center
and corners of the Brillouin zone.
We find that in both the EuFeAs2 compound and 14 K superconductor EuFe0.97Ni0.03As2
the antiferromagnetic ordering of the Fe sublattice is of a spin-density-wave type with the Néel
temperatures and Fe saturation magnetic moments of 106.2(1.9) K, 0.78(1) μB and 56.6(2.2) K,
0.47(1) μB, respectively. We show that the Néel temperatures and the saturation hyperfine
magnetic fields in the two compounds with the antiferromagnetically ordered Eu sublattice are
44.4(5) K, 294.2(7) kOe and 43.5(1) K, 290.5(1) kOe respectively. The 3% substitution of Fe by
Ni in EuFeAs2, aside from producing superconductivity in EuFe0.97Ni0.03As2, radically reduces the
strength of magnetism of the Fe sublattice and has nearly no impact on the magnetism of the Eu
sublattice. The appearance of antiferromagnetically ordered Fe and Eu sublattices in
EuFe0.97Ni0.03As2 verifies that superconductivity and magnetism coexist in this compond. The
growth of the magnitude of the main component of the electric field gradient tensor, at both Fe
and Eu sites, with reducing temperature, is well described by a T3⁄2 power-law relation. We
determine the Debye temperatures of EuFeAs2, EuFe0.97Ni0.03As2, and the FeAs2 impurity phase
to be 355(18), 428(14), and 594(25) K, respectively.
In summary, for all of the studied compounds, there is no magnetic ordering associated
with iron sub-lattices in the ThFeAsN, CsEuFe4As4, and Rb1-δEuFe4As4 compounds. The iron
sublattice is magnetically ordered in the EuFeAs2 and the EuFe0.97Ni0.03As2 superconductor. There
is a coexistence of magnetism and superconductivity associated with europium in the CsEuFe4As4,
Rb1-δEuFe4As4, EuFe0.97Ni0.03As2 compounds. There is a good agreement between the calculated
and the measured hyperfine and magnetic parameters for most studied compounds.
48
Boucard, Stéphane. "Calcul de haute précision d'énergies de transitions dans les atomes exotiques et les lithiumoïdes : corrections relativistes, corrections radiatives, structure hyperfine et interaction avec le cortège électronique résiduel." Phd thesis, Université Pierre et Marie Curie - Paris VI, 1998. http://tel.archives-ouvertes.fr/tel-00007148.
Full textAbstract:
Dans ce mémoire, nous présentons des calculs d'énergie de transition dans les ions lithiumoïdes et les atomes exotiques : 1) Les nouvelles
sources rendent possible la fabrication d'ions lourds fortement
chargés. Nous nous sommes intéressés à l'étude de la structure
hyperfine des ions lithiumoïdes. Cela nous permet d'examiner les
problèmes relativistes à plusieurs corps et la partie magnétique des
corrections d'Electrodynamique Quantique (QED). Dans les ions lourds,
ces dernières sont de l'ordre de quelques pour-cents par rapport à
l'énergie totale de la transition hyperfine. Nous avons également
évalué l'effet de Bohr-Weisskopf lié à la distribution du moment
magnétique dans le noyau. Nous avons calculé puis comparé ces
différentes contributions en incluant les corrections radiatives
(polarisation du vide et self-énergie) ainsi que l'influence du
continuum négatif. 2) Un atome exotique est un atome dans lequel un
électron du cortège est remplacé par une particule de même charge :
$\mu^(-)$, $\pi^(-)$, $\bar(p)$\ldots Des expériences récentes ont
permis de gagner trois ordres de grandeur en précision et en
résolution. Nous avons voulu améliorer la précision des calculs
d'énergies de transitions nécessaires à la calibration et à
l'interprétation dans deux cas : la mesure de paramètres de
l'interaction forte dans l'hydrogène anti-protonique ($\bar(p)$H) et
la détermination de la masse du pion grâce à l'azote pionique
($\pi$N). Nos calculs prennent en compte la structure hyperfine et le
volume de la distribution de charge de la particule. Nous avons
amélioré le calcul de la polarisation du vide qui ne peut plus être
traitée au premier ordre de la théorie des perturbations dans le cas
des atomes exotiques. Pour les atomes anti-protoniques, nous avons
également ajouté la correction du g-2. Elle provient du caractère
composite de l'anti-proton qui de ce fait possède un rapport
gyromagnétique g $\approx$ -5.5856 .
49
Hlimi, Bouchta. "Moments quadrupolaires déterminés par orientation nucléaire." Lyon 1, 1985. http://www.theses.fr/1985LYO19045.
Full textAbstract:
L'objet de ce travail est l'étude des interactions quadrupolaires utilisant la technique de l'orientation nucléaire à trés basse température. La première série de mesure a porté sur l'orientation à trés basse température des noyaux (195,197)**Hg(M), qui décroissent respectivement vers (195,197)**Au, en passant par des états isomères de longues durées de vie [. . . ]
50
Bréant, Christian. "Développement de lasers infrarouges accordables de haute pureté spectrale : application à la spectroscopie hyperfine des molécules HF et SF(6)." Paris 13, 1985. http://www.theses.fr/1985PA132010.
Full textAbstract:
Les développements de deux spéctromètres de saturation à ultra-haute résolution dans le domaine infrarouge, l'un dans la région spectrale 9-12 mu m et l'autre accordable de 2,3 a 3,2 mu m sont exposés en detail. La stabilisation en fréquence d'un laser à CO(2) conventionnel ou guide d'ondes au niveau de la dizaine de hertz ainsi que l'obtention d'une stabilité meilleure que 1 khz pour le laser à centres colores soulignent le role cle de ces oscillateurs dans la chaine de raccordement de fréquence de l'horloge à cesium vers le domaine visible. L'étude des interactions hyperfines est presentée dans le cas des molécules diatomiques héteronucleaires (hf) et des toupies spheriques du groupe ponctuel O(h) (sf(6)). Grace a l'enregistrement de structures hyperfines tres bien resolues, de nombreux effets ont etes mis en evidence et interpretes à l'aide du formalisme tensoriel (dans le groupe (l)o(3) x O(h)) en particulier : l'interaction de spin-vibration (bande upsilon (3) de sf(6)), les mélanges d'états de types de symétrie differents (sf(6)), les corrections ro-vibrationnelles à l'interaction de spin-rotation (hf et sf(6)), les structures superhyperfines (sf(6))