The static dipole polarizabilities and ionization potentials of the first and second main group elements, including the charged ions, are obtained from all-electron relativistic coupled-cluster theory using a scalar relativistic Douglas-Kroll Hamiltonian. Spin-orbit coupling effects are investigated using a fully relativistic four-component Dirac-Coulomb-Hartree-Fock scheme followed by a second-order many-body perturbation treatment to account for electron correlation. Periodic trends in the dipole polarizabilities and the ionization potentials are discussed. In each case, a detailed discussion on electron correlation and relativistic effects are given. A relationship for relativistic and electron correlation effects between the dipole polarizability and the ionization potential is established. Particular attention is paid to the evaluation of a near basis set limit quality of the dipole polarizabilities. This is accomplished by the evaluation of all-electron basis sets used, followed by an extensive study on the convergence behavior of the dipole polarizabilities with respect to a finite basis set expansion. The present all-electron dipole polarizabilities are believed to be very precise, especially for charged ions where the availability of experimental values are limited. Scalar relativistic small-core pseudopotentials are fitted and their performance is tested in terms of static dipole polarizabilities and ionization potentials. It is demonstrated that the small core definition of the pseudopotential (nine-valence electron for the main group 1 and ten-valence electron for the main group 2 elements) enables us to safely omit core-valence correlation without scarifying accuracy. Following atomic dipole polarizabilities, applications are made to molecules starting with alkali dimers and their singly charged ions. The scalar relativistic pseudopotentials of this study are used to calculate equilibrium bond lengths, dissociation energies, vibrational frequencies and the dipole polarizabilities of these dimers. The change in the molecular dipole polarizabilities from the corresponding atomic dipole polarizabilities are discussed in terms of molecular bonding models. Simple ammonia complexes of the alkali-metals and their singly charged ions are studied. The equilibrium geometries, dissociation energies, harmonic vibrational frequencies as well as the dipole polarizabilities of these complexes are given.

Thesis (M. App. Sc.)--Carleton University, 2004. / Includes bibliographical references (p. 110-113). Also available in electronic format on the Internet.

Electric field studies, electrochromism, were used to obtain excited-state data for analogous divalent sulfur compounds. The sulfides investigated were dimethyl sulfide and small cyclic sulfides including the three to six member ring compounds. The excited-state dipole moments and polarizabilities are reported for the first s, p, and d Rydberg absorption bands which occur in the near vacuum ultraviolet region from 230 to 170 nm. The excited-state data are interpreted in terms of the particular excited-state (s, p, or d) for the molecules and the bending differences due to the presence of the ring and the number of atoms in the ring. The next section describes the use of electrochromism to investigate the pressure effect of argon, carbon tetrafluoride and sulfur hexafluoride on the spectra for molecular Rydberg states.

abstract: Research on developing new algorithms to improve information on brain functionality and structure is ongoing. Studying neural activity through dipole source localization with electroencephalography (EEG) and magnetoencephalography (MEG) sensor measurements can lead to diagnosis and treatment of a brain disorder and can also identify the area of the brain from where the disorder has originated. Designing advanced localization algorithms that can adapt to environmental changes is considered a significant shift from manual diagnosis which is based on the knowledge and observation of the doctor, to an adaptive and improved brain disorder diagnosis as these algorithms can track activities that might not be noticed by the human eye. An important consideration of these localization algorithms, however, is to try and minimize the overall power consumption in order to improve the study and treatment of brain disorders. This thesis considers the problem of estimating dynamic parameters of neural dipole sources while minimizing the system's overall power consumption; this is achieved by minimizing the number of EEG/MEG measurements sensors without a loss in estimation performance accuracy. As the EEG/MEG measurements models are related non-linearity to the dipole source locations and moments, these dynamic parameters can be estimated using sequential Monte Carlo methods such as particle filtering. Due to the large number of sensors required to record EEG/MEG Measurements for use in the particle filter, over long period recordings, a large amounts of power is required for storage and transmission. In order to reduce the overall power consumption, two methods are proposed. The first method used the predicted mean square estimation error as the performance metric under the constraint of a maximum power consumption. The performance metric of the second method uses the distance between the location of the sensors and the location estimate of the dipole source at the previous time step; this sensor scheduling scheme results in maximizing the overall signal-to-noise ratio. The performance of both methods is demonstrated using simulated data, and both methods show that they can provide good estimation results with significant reduction in the number of activated sensors at each time step. / Dissertation/Thesis / M.S. Electrical Engineering 2012

When a molecule, which possess a permanent dipole moment is exposed to an intense electric field, its absorption spectrum may be altered. These alterations are manifest as shifts in energy and as changes in band shape and intensity. The electric dichroism of absorption bands can be used to probe the excited state that is formed when a molecule undergoes a transition. The properties that may be investigated include transition polarization, excited state dipole moment and mean polarizability, and field-induced mixing of symmetrically equivalent excited states. The theoretical model and experimental devices that have been developed to determine these properties are presented and discussed. The data, taken in total, and its combination with other existing evidence, adds credence to the assignment of the second excited singlet of aldehydes and ketones to be extravalent, accompanied by relatively large delocalization of electronic charge, and polarized in-planiie and perpendicularly to the C-0 axis.

Submitted by Lucienne Costa (lucienneferreira@ufcg.edu.br) on 2018-07-12T19:21:57Z No. of bitstreams: 1 IRENE CRISTINA PEREIRA CORRÊA – DISSERTAÇÃO (PPGMET) 2016.pdf: 4134297 bytes, checksum: e164027e58e1412658c53000de876d14 (MD5) / Made available in DSpace on 2018-07-12T19:21:57Z (GMT). No. of bitstreams: 1 IRENE CRISTINA PEREIRA CORRÊA – DISSERTAÇÃO (PPGMET) 2016.pdf: 4134297 bytes, checksum: e164027e58e1412658c53000de876d14 (MD5) Previous issue date: 2016-12-09 / As variabilidades interanual e interdecenal da precipitação do Nordeste Brasileiro (NEB) e sua relação com os fenômenos El Niño Oscilação Sul (ENOS), dipolo do Atlântico, Oscilação Decenal do Pacifico (ODP) e Oscilação Multidecenal do Atlântico (OMA) tem sido o objetivo de muitos estudos. O presente trabalho teve por objetivo estudar as variabilidades interanual e interdecenal do clima do estado do Ceará utilizando os índices climáticos efetivos de umidade (Im) e aridez (Ia) de Thornthwaite (1948) e o índice de aridez da UNEP (IaUNEP), pois estes são bastantes usados para produzir classificação climática. Foram feitas a análise das variabilidades interanual e interdecenal dos índices utilizando a análise harmônica e a análise de ondaletas e a classificação climática, para estado do Ceará, no período de 1951 a 2014. Os resultados obtidos mostraram que de acordo com os índices IaUNEP e Im é classificado como sendo um clima Semiárido, com uma variabilidade interanual muito grande, pois numa mesma localidade apresenta clima árido, em um período, e úmido, em outro. Durante os 64 anos, a maioria dos municípios analisados apresentou o seu maior percentual de tempo no clima semiárido. Já para o estudo da variabilidade interanual e interdecenal dos índices de IaUNEP e Im a Análise de Ondaletas e Análise Harmônica mostraram que variabilidade interanual e interdecenal são decorrentes do ciclo de ENOS, do gradiente de anomalia de TSM no Atlântico Tropical, das oscilações das fases frias e quentes da OMA e ODP que suavizam ou intensificam a aridez do clima do Ceará produzindo variabilidade de frequência. / The interannual and interdecadal variability of the Brazilian Northeast (NEB) precipitation and its relationship with the El Niño Southern Oscillation (ENSO), Atlantic dipole, Pacific Decadal Oscillation (ODP) and Atlantic Multidecadal Oscillation (AOM) phenomena has been the objective Of many studies. The objective of this study was to study the interannual and interdecadal variability of the climate of the state of Ceará using the effective humidity indexes (Im) and aridity (Ia) of Thornthwaite (1948) and the aridity index of UNEP (IaUNEP), since These are enough used to produce climatic classification. The interannual and interdecadal variability of the indices were analyzed using harmonic analysis and the analysis of waveforms and climatic classification for the State of Ceará, from 1951 to 2014. The results obtained showed that according to the IaUNEP and Im Is classified as being semi-arid climate, with a very high interannual variability, because in the same locality it presents arid climate, in one period, and humid, in another. During the 64 years, most of the municipalities analyzed presented their highest percentage of time in the semi-arid climate. For the study of the interannual and interdecadal variability of the IaUNEP and Im indexes the Wavelet Analysis and Harmonic Analysis showed that interannual and interdecadal variability are due to the ENSO cycle, the SST anomaly gradient in the Tropical Atlantic, the cold phase oscillations And warm periods of OMA and ODP that soften or intensify the aridity of the climate of Ceará producing frequency variability.

Made available in DSpace on 2014-12-17T14:56:02Z (GMT). No. of bitstreams: 1 CiroAPT.pdf: 868504 bytes, checksum: d74079034ebc48de53a5dc4be812ec74 (MD5) Previous issue date: 2003-10-17 / This master dissertation introduces a study about some aspects that determine the aplication of adaptative arrays in DS-CDMA cellular systems. Some basics concepts and your evolution in the time about celular systems was detailed here, meanly the CDMA tecnique, specialy about spread-codes and funtionaly principies. Since this, the mobile radio enviroment, with your own caracteristcs, and the basics concepts about adaptive arrays, as powerfull spacial filter was aborded. Some adaptative algorithms was introduced too, these are integrants of the signals processing, and are answerable for weights update that influency directly in the radiation pattern of array. This study is based in a numerical analysis of adaptative array system behaviors related to the used antenna and array geometry types. All the simulations was done by Mathematica 4.0 software. The results for weights convergency, square mean error, gain, array pattern and supression capacity based the analisis made here, using RLS (supervisioned) and LSDRMTA (blind) algorithms. / Esta disserta??o de mestrado vem trazer um estudo sobre alguns aspectos que influenciam na aplica??o de antenas adaptativas em sistemas celulares DS-CDMA (ou simplesmente CDMA). Foram detalhados alguns conceitos b?sicos a respeito do sistema celular e em geral, bem como sua evolu??o ao longo do tempo, dando ?nfase ? t?cnica CDMA, no que diz respeito aos c?digos de espalhamento e princ?pio de funcionamento. A partir disso, o ambiente de r?dio m?vel, com suas caracter?sticas peculiares, foi abordado, bem como os conceitos b?sicos em que se baseiam o sistema de antenas adaptativas com sua poderosa capacidade de filtragem espacial, capaz de reduzir significativamente o efeito de sinais indesejados. Tamb?m alguns algoritmos adaptativos foram discutidos, esses s?o integrantes do processamento dos sinais captados pelos arranjos, e s?o respons?veis pela atualiza??o dos pesos que de certa forma controlar?o o diagrama de radia??o do arranjo. Mais especificamente, esse trabalho fundamentou-se na an?lise, mediante simula??es computacionais, do comportamento do sistema de antenas adaptativas face ao tipo de antena e ao tipo (geometria) de arranjo empregados. Todas as simula??es foram feitas utilizando o software Mathematica 4.0. Os resultados para a converg?ncia dos pesos, erro m?dio quadr?tico, ganho, diagrama de radia??o e capacidade de supress?o foram as grandezas que basearam as an?lises aqui feitas, utilizando para isso, os algoritmos RLS (supervisionado) e LSDRMTA (cego).

Le contrôle et l'optimisation des propriétés d'émission des nanomatériaux peuvent être obtenus par un couplage efficace entre nanoémetteurs et nanostructures permettant d’obtenir une directivité plus élevée, une dynamique d’émission plus rapide. Il est pour cela nécessaire d’obtenir l'accord spectral de l'émetteur avec les modes de nanostructures, le positionnement spatial du nanoémetteur à l'endroit où l'intensité du mode résonant de la nanostructure est maximale, et une orientation du dipôle nanoémetteur parallèle au champ électrique résonant. En plasmonique les résonances larges des modes permettent un accord spectral facile. L’accord spatial est plus difficile, mais des stratégies ont été mises en œuvre avec succès. Le contrôle de l'orientation du dipôle reste lui un défi. En plasmonique, par exemple, une interaction efficace ne peut être obtenue que pour des dipôles orthogonaux à la surface métallique. La détermination de l'orientation du dipôle émetteur est donc cruciale pour les dispositifs plasmoniques tels que les nano-antennes.Dans ma thèse, j'ai contribué au développement d'une méthode polarimétrie visant à analyser le dipôle émetteur d'un nanoémetteur et son orientation. J'ai effectué des expériences et les ai analysées. Le modèle décrit l'émission d'un dipôle proche d'une interface plane dans un large éventail de conditions expérimentales réalistes, en particulier le cas où le nanoémetteur se trouve à proximité d’un film d'or. Dans cette situation, pour des nanocristaux de CdSe/CdS assimilable à deux dipôles orthogonaux dégénérés, l'imagerie défocalisée n'est pas suffisamment sensible pour fournir des informations quantitatives fiables sur l'orientation de l'émetteur. A contrario, la polarimétrie permet de répondre à cette question. Avec le même modèle, le diagramme d'émission correspondant à l'émission dipolaire en champ lointain pour toutes ces conditions expérimentales a été calculé. En combinant la polarimétrie et l’étude des diagrammes de rayonnement, on peut obtenir des informations sur la structure dipolaire et l’orientation des dipôles. J'ai appliqué cette méthode pour étudier les nanoplaquettes semi-conductrices colloïdales de CdSe/CdS avec différentes formes géométriques : plaquettes carrées minces, plaquettes rectangulaires minces et plaquettes cubiques. J'ai établi une relation entre les structures géométriques des plaquettes et la nature et l'orientation de leurs dipôles émetteurs associés. / Control and optimization of nanomaterial emission properties, can be obtained thanks to efficient coupling between nanoemitters and nanostructures for achieving higher directivity, quicker dynamics. The requirements are the spectral tuning of the emitter to the nanostructures modes, the spatial positioning of the nanoemitter at the location of maximum intensity of the resonant nanostructure mode, and a proper orientation of the dipole nanoemitter. In plasmonics, the spectrally broad resonances make the spectral tuning easy. Whereas for spatial tuning, many strategies have been implemented successfully, the control of the dipole orientation remains a challenge. In plasmonics, for example, efficient interaction can only be achieved for dipoles orthogonal to the metallic surface. The determination of the orientation of the emitting dipole is thus very crucial for plasmonic devices such as nanoantennas. In my thesis, I contributed to the development of a polarimetric method aiming at the analysis of a nanoemitter’s emitting dipole and its orientation. I performed experiments and analyzed them. The model I used describes the emission of a dipole close to a plane interface in a wide range of realistic experimental conditions, including a very common case in plasmonics when the nanoemitter lies close a gold film. In this situation for CdSe nanocrystals which can be considered as two orthogonal degenerated emitting dipoles, the more standard defocused imaging method is not sufficiently sensitive to provide reliable quantitative information on the emitter’s orientation. With the same model, I also computed the emission diagram corresponding to the dipolar emission in far field for all these experimental conditions. By analyzing the emission’s polarization together with the emission pattern, I could determine the three-dimensional orientation of an emitting dipole. I applied this method to investigate the dipolar structure and orientation of colloidal semiconducting CdSe/CdS nanoplatelets with different geometries: thin square platelets, thin rectangular platelets, and cubic platelets. I established a relationship between the geometric structures of the platelets and the dimensionality and orientation of their associated emitting dipoles.

Neste trabalho, descrevemos a construção de uma armadilha óptica de dipolo, tipo Quest, para átomos de Rydberg utilizando um laser de CO2 de alta potência. A amostra aprisionada apresenta aproximadamente 3 × 106 átomos de 85Rb numa densidade 4 × 1011 átomos/cm3, em temperaturas da ordem 30 µK. O tempo de vida da armadilha é da ordem de 200 ms. Neste sistema, observamos a fotoionização dos estados de Rydberg devido ao laser de CO2 em 10, 6 µm, contudo fomos incapazes de quantificá-lo. Além disso, medimos o tempo de vida do estado 37D do Rb na armadilha de dipolo, o resultado foi compatível ao encontrado na literatura. Em suma, o sistema esta operante para experimentos mais complexos. / In this work, we describe the implementation of a QUEST dipole trap for Rydberg atoms using a CO2 high power laser. The trapped atomic sample has approximately 3 × 106 85Rb atoms, at a density of 4 × 1011 atoms/cm3 and a temperature of about 30 µK. The trap lifetime is about 200 ms. We observed photoionization of the Rydberg states due to the CO2 laser at 10, 6 µK, however we were unable to quantify it. Furthermore, we measured the 37D state lifetime of the Rb in the dipole trap, the experimental result was in agreement with the literature. In summary, the system is fully operating for more complex experiments.

Neste trabalho, estudamos a fotoassociação de átomos de rubídio no regime de curto alcance. Realizamos espectroscopia por perda de átomos em uma armadilha magneto-óptica de 85Rb usando um laser de fibra de alta potência, o qual possuia largura de linha da ordem de 1MHz e 50W de potência no intervalo de 1060nm a 1070nm. Dois níveis vibracionais do potencial excitado 0u+ foram observados (v=137 e v=138). Além disso, medimos o tempo de vida de uma armadilha óptica de dipolo cruzada. Como esperado, o tempo de vida é menor quando o laser está sintonizado na ressonância. Um modelo teórico prevê a distribuição dessas moléculas nos níveis vibracionais do estado eletrônico fundamental após o processo de fotoassociação. Os resultados, nos sugerem perspectivas para a produção de moléculas de Rb2 no estado vibracional fundamental. / In this work, we studied short-range photoassociation of rubidium atoms. We realize trap-loss spectroscopy in a magneto-optical trap of 85Rb using high power fiber laser, which had around 1MHz linewidth and 50W power at 1060nm to 1070nm interval. Two vibrational levels of the 0u+ excited potential were observed (v=137 e v=138). Besides that, we measured the lifetime of a crossed optical dipole trapped. As expected, the lifetime is shorter when the laser is tuned on resonance. A theoretical model predicts the molecular distribution in the vibrational levels of electronic ground state. The results suggest us perspectives to produce Rb2 molecules in the ground vibrational state.