Momentos de quadrupólo elétricos de estados isoméricos nucleares com vidas médias entre 10 nanosegundos e 100 milisegundos podem ser medidos com o método Espectroscopia de Mistura de Níveis (Level Mixing Spectroscopy- LEMS), utilizando campos magnéticos variáveis aplicados em núcleos implantados em materiais hospedeiros que possuam gradientes de campo elétrico. O Campo magnético externo pode ser substituido pelo campo hiperfino de materiais ferromagnéticos e sua variação poderia ser controlada variando a temperatura. O objetivo deste trabalho é verificar a viabilidade desta substituição. Implementamos o método LEMS no Laboratório Pelletron usando como caso teste o estado isomérico de 398 KeV do 69Ge que possui todas as suas propriedades nucleares conhecidas (meia vida, spin, momento magnético, momento de quadrupolo elétrico). Ele foi produzido pela reação 56Fe(16O, 2pn)69Ge com o feixe de 16O à 53 MeV (LAB) de energia, e depois implantado em Gadolínio que é ferromagnético abaixo de Tc = 289K. Medimos a anisotropia da radiação gama emitida por esse núcleo em função da temperatura. A comparação entre as medidas da anisotropia em função da temperatura, com medidas da anisotropia em função do campo magnético externo, feita pelo grupo de Leuven/Bélgica, nos levou a duas interpretações possíveis. Na primeira, supondo a interação elétrica constante e independente da temperatura, obtemos um campo magnético hiperfino anômalo para o Gd. Na segunda análise, obtivemos o campo hiperfino variando linearmente com a magnetização, admitindo gradientes de campo elétrico dependentes da temperatura. Medidas futuras usando monocristal de Gd poderão resolver esta ambiguidade, bem como medidas TDPAD (Time Diferencial Perturbed Angular Distribuition) em função da temperatura, na qual se mede diretamente o campo hiperfino. / The Level Mixing Spectroscopy method allows to measure the eletric quadrupole moments of high spin isomeric nuclear states (10ns < t < 100ms) produced in nuclear reactions. The magnetic interaction is usualy created by an intense external magnetic field. The eletric quadrupole interaction can be created by recoi-implantation of the nuclei in non-cub crystals, used as hosts. The external magnetic field can then be replaced by the hiperfine fields of ferromagnetic materials, controling its intensity by temperature variation. The purpose of the research performed for this work is to verify the viability of this replacement. We adapt the LEMS method to be used in the Pelletron Laboratory. We choose the isomeric state at 398 KeV exitation energy in the 69Ge nucleus as a test case, because it has all nuclear properties well known (half-life, spin, magnetic moment, eletric quadrupole moment). It was produced by the 56Fe(16O, 2pn)69Ge reaction, with a 16O beam at 53 MeV, and implanted and stopped in a Gadolinium host, which is a ferromagnet from low temperatures up to Tc=289 K. We measure the anisotropy of the emitted gama ray as a function of the temperature of the host. The comparison of this measurement with another of the anisotropy as a function of an external magnetic field strength, done by the Leuven/Belgium group, show us two possibilities. In the first, we suppose that the eletric interaction is cosntant and independent of temprature and we obtain an anomalous magnetic hyperfine field for Gd. In the second one, we obtain a hyperfine field that follows the magnetization if we assume eletric field gradientes that are temperature dependent. New measurements by using Gd monocrystal and the TDPAD (Time Diferencial Perturbed Angular Distribution) method may solve this ambiguity.

Contributions to the second order collision efficiency function S ⁽²⁾ (b), used in semiclassical perturbation approaches to pressure broadening of microwave and infrared spectra, due to several leading terms, dipole and quadrupole components, in the expansion of the intermolecular interaction energy are derived by method of irreducible spherical tensor operators for molecules of arbitrary symmetry. Results are given explicitly in terms of dipole and quadrupole line strengths. General expressions for dipole moment line strength in the asymmetric rotor basis as well as quadrupole moment line strength for the special case of molecules with two independent quadrupole moment components are derived. Computer programs for calculating linewidth parameters in the rotational spectrum of ¹⁴NO₂ based on Anderson and Murphy and Boggs theories are presented.

No description available.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第22246号 / 理博第4560号 / 新制||理||1655(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 永江 知文, 教授 田中 貴浩, 教授 萩野 浩一 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22659号 / 工博第4743号 / 新制||工||1741(附属図書館) / 京都大学大学院工学研究科電子工学専攻 / (主査)教授 山田 啓文, 教授 川上 養一, 准教授 杉山 和彦 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Die drei-dimensionalen Topologische Isolatoren Bi2Se3 and Bi2Te3 sind Modell-Systeme einer neuen Klasse von Isolatoren mit metallischen Oberflächenzuständen. Ihre kleinen Bandlücken und die schweren Elemente sind essentiell für die topologisch nicht-triviale Bandstruktur, sind aber ebenso verantwortlich für andere bemerkenswerte Eigenschaften, wie etwa für ihre Leistungsfähigkeit als Thermoelektrika. Diese Arbeit untersucht die elektronischen Eigenschaften der Topologischen Isolatoren Bi2Se3 und Bi2Te3 mittels zahlreicher experimenteller Methoden. Es wird gezeigt, dass Ferromagnetismus in Mn gedoptem Bi2Te3 durch sintern unterdrückt werden kann. Zudem werden ein überraschend großer Magnetoresistiver Effekt und ein ladungsträgerunabhängiger Vorzeichenwechsel des Seebeck-Koeffizienten mit zunehmenden Mn Gehalt diskutiert. Kernmagnetische Resonanz (NMR) von 125Te Kernen in Bi2Te3 Einkristallen lässt auf eine ungewöhnliche elektronische SpinSuszeptibilität and komplexe NMR Verschiebungen schließen. Es wird gezeigt dass die Quadrupolwechselwirkung von 209Bi Kernen in Bi2Se3 Einkristallen eine Signatur der Bandinversion ist, in quantitativer Ubereinstimmung mit DFT Rechnungen. Weiterhin wird argumentiert dass die starke Spin-Bahn Kopplung der Leitungselektronen zu einer nicht-trivialen Orientierungsabh¨angigkeit der 209Bi Quadrupolaufspaltung führt.:Contents List of Figures List of Tables List of abbreviations Introduction 1 Topological insulators in three dimensions 2 Theoretical background 3 Methods I: structural, electronic and magnetic properties 4 Methods II: nuclear magnetic resonance 5 Sample preparation and basic characterisation6 Magnetic and electronic properties of Mn doped Bi2Te3 7 NMR of spin 1/2 nuclei: 125Te in Bi2Te3 8 NMR of quadrupole nuclei: 209Bi in Bi2Se3 Conclusions and outlook Appendix Bibliography / The three-dimensional topological insulators Bi2Se3 and Bi2Te3 are model systems of a new class of materials with an insulating bulk and gapless surface states. Their small band gaps and the heavy elements are essential for the topologically non-trivial band structure, but these features are similarly responsible for other remarkable properties, such as their high thermoelectric performance. This thesis investigates the electronic properties of the topological insulators Bi2Se3 and Bi2Te3 with a broad range of experimental methods. Ferromagnetism in Mn doped Bi2Te3 is shown to disappear under sample sintering. A surprisingly large magnetoresistance and a charge carrier independent change in the sign of the thermopower with increasing Mn content are discussed.125Te nuclear magnetic resonance (NMR) of Bi2Te3 single crystals suggest an unusual electronic spin susceptibility and complex NMR shifts. The quadrupole interaction of 209Bi nuclei in Bi2Se3 single crystals is shown to be a signature of the band inversion in quantitative agreement with first-principle calculations. Furthermore, it is proposed that the strong spin-orbit coupling of conduction electrons causes a non-trivial orientation dependent quadrupole splitting of the 209Bi resonance.:Contents List of Figures List of Tables List of abbreviations Introduction 1 Topological insulators in three dimensions 2 Theoretical background 3 Methods I: structural, electronic and magnetic properties 4 Methods II: nuclear magnetic resonance 5 Sample preparation and basic characterisation6 Magnetic and electronic properties of Mn doped Bi2Te3 7 NMR of spin 1/2 nuclei: 125Te in Bi2Te3 8 NMR of quadrupole nuclei: 209Bi in Bi2Se3 Conclusions and outlook Appendix Bibliography

In this work, an innovative approach for effective modeling of substrate integrated waveguide (SIW) devices is firstly proposed. Next, a novel substrate integrated waveguide power splitter is proposed to feed antenna array elements in series. This feed network inherently provides uniform output power to eight quadrupole antennas. More importantly, it led to a compact configuration since the feed network can be integrated inside the elements without increasing the overall array size. Its design procedure is also presented. Then, a series feed network was used to feed a novel compact omnidirectional antenna array. Targeting the 5G 26 GHz mm-wave frequency band, simulated results showed that the proposed array exhibits a broad impedance bandwidth of 4.15 GHz and a high gain of 13.6 dBi, which agree well with measured results. Its attractive features indicate that the proposed antenna array is well suitable for millimeter-wave wireless communication systems.

In the near future, Gen II, III, and IV nuclear reactors will be in operation. UO2 is a common fuel for reactors in each of these generations and molten salts are used as coolant/fuel in Gen IV molten salt reactors. This thesis investigates potential ways to measure thermal conductivity for these materials: Raman thermometry for UO2 and a needle probe for molten salts. Four Raman thermometry techniques are investigated in this thesis: The Two Laser Raman (TLR), Time Differential Domain Raman (TDDR), Frequency Resolved Raman (FRR), and Frequency Domain Raman (FDR). The TLR is a steady state method used with a thin film. The TDDR and FRR are both time domain methods used with thin cantilever samples. The FDR is a frequency domain method used with a thermally thick sample. Monte Carlo like simulations are performed for each technique. In the simulations, the affect introduced uncertainty has on the measurement of thermal conductivity and thermal diffusivity is measured. From the results, it is recommended that the TLR should be used for measuring thermal conductivity and the FRR used for measuring thermal diffusivity. The TDDR and FDR were heavily affected by the uncertainty which resulted in inconsistent measured thermal properties. For measuring the thermal conductivity of molten salt, a needle probe was designed and manufactured to withstand the corrosive environment found in using molten salts. The probe uses modulated joule heating and measures the temperature rise in a thermocouple. The phase delay and temperature amplitude of the thermocouple are used in determining the thermal conductivity. A new thermal quadrupole based analytical solution, which takes into consideration convection and radiation, to the temperature rise of the probe is presented. The analytical solution is verified using a numerical solution found using COMSOL. Preliminary data was obtained with the probe in water.

A new approach of making ion trap mass analyzers was developed in which trapping fields are created in the space between two ceramic plates. Based on microfabrication technology, a series of independently-adjustable electrode rings is lithographically patterned on the facing surfaces of each ceramic plate. The trapping field can be modified or fine-tuned simply by changing the RF amplitude applied to each electrode ring. By adjusting the potential function applied to the plates, arbitrary trapping fields can be created using the same set of ceramic plates. Unlike conventional ion traps, the electrodes of planar ion traps have a non-equipotential surface, thus the electric field is independent of electrode geometry and can be optimized electronically. The simple geometry and open structure of planar ion traps address obstacles to miniaturization, such as fabrication tolerances, surface smoothness, electrode alignment, limited access for ionization or ion injection, and small trapping volume, thereby offering a great opportunity for a portable mass spectrometer device. Planar ion traps including the planar quadrupole ion trap and the coaxial ion trap have been designed and tested using this novel method. The planar quadrupole trap has demonstrated a mass range up to 180 Da (Th), with mass resolution typically between 400-700. We have also developed a novel ion trap in which both toroidal and quadrupolar trapping regions are created simultaneously between a set of plates. This "Coaxial Trap" allows trapping and mass analysis of ions in two different regions: ions can be trapped and mass analyzed in either the toroidal or quadrupolar regions, and transferred between these regions. Some simulation work based on the ion motion between two different trapping regions in the coaxial ion trap has been performed. Using a one-dimensional simulation method, ion motion was investigated to transfer ions between these two regions. The effect of the mutipole components in the radial field and axial field, amplitude and frequency of the primary RF and supplementary AC signal were studied to obtain high mass resolution in the axial direction and high transfer efficiency in the radial direction. In all these devices, the independent control of each patterned electrode element allows independent control of higher-order multipole fields. Fields can be optimized and changed electronically instead of physically as is done in conventional traps.

The typical form for a molecular mechanics force field consists of a foundation of pair-wise terms to describe bonded and non-bonded atomic interactions, with multi-body correction terms to deal with the limitations of pair-wise terms. I present here the first attempts of a molecular mechanics model that is founded on multi-body terms, which are based on the Bond Valence Model (Brown, 2002) and recent developments in the Vectorial Bond Valence Model (Bickmore et al., 2013a; Harvey et al., 2006). I calibrated these models on pressure vs. energy curves for a set of SiO2 polymorphs. The average deviation for the best-fit iteration, with only six adjustable parameters was ±1.98 kcal/mol.