Este trabalho teve como foco principal a caracterização espectroscópica dos haletos de berílio, BeCl, BeBr e BeI. O conhecimento acerca dessas espécies foi ampliado significativamente através do cálculo de parâmetros de difícil caracterização experimental. Como os poucos trabalhos experimentais realizados para esses haletos apresentam resultados inconclusivos para a transição C 2Σ+ - X 2Σ+, através do cálculo acurado de probabilidades de transição foi possível oferecer uma nova interpretação para os dados existentes, apresentando inclusive resultados para as outras transições eletrônicas até o presente desconhecidas. Cálculos utilizando o método de Interação de Configurações Multirreferencial (MRCI) com um conjunto de funções de base consistentes na correlação de qualidade quintupla-zeta foram utilizados para se obter as curvas de energia potencial associadas ao primeiro e segundo canais de dissociação para os estados dubleto e quarteto dessas espécies. Parâmetros espectroscópicos como as constantes vibracionais we, wexe, a constante rotacional Be e a distância de equilíbrio foram determinados para os estados de mais baixa energia. Além disso, foram calculadas a energia de excitação (Te) e a energia de dissociação (De) com e sem a inclusão de efeitos spin-órbita. Os resultados obtidos expandiram significativamente nosso conhecimento sobre os estados eletrônicos dessa espécies. Para os estados já investigados experimentalmente, houve boa coerência entre os parâmetros calculados e experimentais. As diferenças de energia entre os dois canais no limite de dissociação para as moléculas BeCl, BeBr e BeI obtidas neste trabalho foram, respectivamente: 21835, 21889 e 21998 cm-1, em concordância com o respectivo resultado experimental das três espécies (21980 cm-1). A determinação teórica da energia de dissociação D0 foi bastante satisfatória. Obtivemos 92,24; 72,77 e 51,75 kcal·mol-1, respectivamente, para as moléculas BeCl, BeBr e BeI incluindo os efeitos spin-órbita, comparados a 91,78, 71 e 57 kcal·mol-1. Para uma análise mais completa das curvas de energia potencial, elas também foram obtidas considerando-se os efeitos relativísticos. A constante de acoplamento spin-órbita calculada na região de equilíbrio de cada uma das moléculas BeCl, BeBr e BeI foi, respectivamente: 41, 207 e 324 cm-1, em boa concordância com os resultados experimentais: 52,8, 198 e 361,1 cm-1, respectivamente. A separação spin-órbita no limite de dissociação calculada foi de 823, 3446 e 6975 cm-1 (BeCl, BeBr e BeI), também coerentes com resultados experimentais: 882, 3685,24 e 7603,15 cm-1, respectivamente. Foi ainda realizada uma análise detalhada sobre os canais de dissociação das moléculas HBeP e BePH. A construção de um diagrama de energias relativas permitiu obter um conjunto de dados importantes a respeito de todos os possíveis canais de dissociação. Em particular é mostrado a estabilidade relativa e a energia no limite de dissociação. Para a energia no limite de dissociação obtivemos resultados consistentes com os valores experimentais. Nossos cálculos para os três primeiros canais de dissociação HBeP = H + Be resultaram nos seguintes valores: H (2Sg) + Be (X 4Σ+), 0 cm-1; H (2Sg) + Be (a 2π), 426 cm-1 (exp. 502 cm-1); H (2Sg) + Be (b 2Σ-), 1896 cm-1 (exp. 1976 cm-1). Por fim, pela primeira vez na literatura, o calor de formação e de atomização foram calculados para estas espécies. Para os isômeros HBeP e BePH, a energia de atomização a 298,15 K calculada foi de 119,02 kcal·mol-1 e 107,40 kcal·mol-1, respectivamente; para o calor de formação a 298,15 K, obtivemos 86,14 e 97,76 kcal·mol-1 para as espécies HBeP e BePH, respectivamente. / This work has mainly focused on the spectroscopic characterization of the beryllium halides, BeCl, BeBr and BeI. Knowledge about these species was substantially increased through the calculation of parameters that are difficult to access in an experimental characterization. As the few experimental works carried out for these halides presented inconclusive results for the C 2Σ+ - X2Σ+ transition, we carried out accurate calculations of transition probabilities, thus offering a new interpretation about the existing data, including also results for other electronic transitions as yet unknown. Calculations using the method Multireference Configuration Interaction (MRCI) along with correlation-consistent basis set functions of quintuple-zeta quality were used to obtain the potential energy curves associated with the first and second dissociation channels for the doublet and quartet states of these species. Spectroscopic parameters such as vibrational constants We, WeXe, the rotational constant Be and the equilibrium distance were determined for the low-lying states. Furthermore, we also calculated the excitation energy (Te) and the dissociation energy (De) with and without the inclusion of spin-orbit effects. The obtained results significantly expanded our knowledge about the electronic states of this species. For states already investigated experimentally, there was good consistency between the calculated and the experimental parameters. The energy differences between the two channels in the dissociation limit for BeCI, BeBr and Bel molecules obtained in this work were: 21835, 21889 and 21998 cm-1, in agreement with the corresponding experimental results of the three species (21 980 cm-1). The theoretical determination of the dissociation energy D0 was very satisfactory. We obtained 92.24, 72.77, and 51.75 kcal·mol-1, respectively, for the BeCl, BeBr and BeI molecules including spin-orbit effects, compared to 91.78, 71 and 57 kcal . mol-1. For a more complete analysis of the potential energy curves, they also were obtained considering relativistic effects. The calculated spin-orbit coupling constants in the equilibrium region of BeCl, BeBr and BeI molecules were respectively 41, 207 and 324 cm-1, in good agreement with the experimental results: 52.8, 198, and 361.1 cm-1, respectively. The calculated spin-orbit splitting in the dissociation limit was 823, 3446 and 6975 cm-1 (BeCl, BeBr and BeI) also consistent with the experimental results: 882, 3685.24 and 7603.15 cm-1, respectively. Additionally, a detailed analysis of the dissociation channels of HBeP and BePH molecules was performed. The construction of a relative energies diagram allowed us to derive a set of important data for all the possible dissociation channels. In particular, it is shown the relative stability and the energy in the dissociation limit. For the energy in the dissociation limit, we obtained results consistent with the experimental values. Our calculations for the first three dissociation channels HBeP = H + Be resulted in the following values: H (2Sg) + Be (X 4Σ+), 0 cm-1; H (2Sg) + Be (a 2π), 426 cm-1 (exp. 502 cm-1); H (2Sg) + Be (b 2Σ-), 1896 cm-1 (exp. 1976 cm-1). Finally, for the first time in the literature, the heat of formation and the atomization energy were calculated for these species. For the HBeP and BePH isomers, the atomization energy calculated at 298.15 K was 119.02 and 107.40 kcal . mol-1, respectively; for the heat of formation at 298.15 K, we obtained 86.14 and 97.76 kcal· mol-1 for HBeP and BePH species, respectively.

No description available.

The present work demonstrates the application of molecular simulations (MD) in two different areas: proton transport in bulk water and estimation of the dipole moment of polar organic compounds. In both areas, relatively few successful and robust methodologies exist. In the first part, a new polarizable water model is developed for MD simulations of the proton transport process. The model was parametrized from a combination of quantum chemical calculations and experimental water properties. The model was implemented in MD simulation studies of liquid water at room temperature, as well as with excess protons. For pure water the model gave good agreement with experimental properties. The proton transport rate for a single excess proton also gave a good match with the experimental value. The water model was further extended to include chloride ions. At 0.2 M concentration the resulting density and structure agreed well with experiment, and the proton transport rate was found to be slightly reduced. The model was further extended to include multiple excess protons. For the second part of the project, an open source ab initio MD program, SIESTA, was used to perform simulations of several organic compounds which potentially have multiple stable conformations, to determine their average dipole moments. A series of methods was developed. The most robust method involved modifications to the SIESTA code and statistical analysis of the resulting configurations, in order to more accurately predict the average dipole moment. The resulting dipole moments were in good agreement with the experimental values for cases in which experimental values were reliable. Based on this study, a general method to estimate the average dipole moment of any compound is proposed.

Nous investiguons dans ce travail la dynamique des excitons dans une couche mince d’agrégats H autoassemblés hélicoïdaux de molécules de sexithiophène. Le couplage intermoléculaire (J=100 meV) place ce matériau dans la catégorie des semi-conducteurs à couplage de type intermédiaire. Le désordre énergétique et la forte interaction électronsphonons causent une forte localisation des excitons. Les espèces initiales se ramifient en deux états distincts : un état d’excitons autopiégés (rendement de 95 %) et un état à transfert de charge (rendement de 5%). À température de la pièce (293K), les processus de sauts intermoléculaires sont activés et l’anisotropie de la fluorescence décroît rapidement à zéro en 5 ns. À basse température (14K), les processus de sauts sont gelés. Pour caractériser la dynamique de diffusion des espèces, une expérience d’anisotropie de fluorescence a été effectuée. Celle-ci consiste à mesurer la différence entre la photoluminescence polarisée parallèlement au laser excitateur et celle polarisée perpendiculairement, en fonction du temps. Cette mesure nous donne de l’information sur la dépolarisation des excitons, qui est directement reliée à leur diffusion dans la structure supramoléculaire. On mesure une anisotropie de 0,1 après 20 ns qui perdure jusqu’à 50ns. Les états à transfert de charge causent une remontée de l’anisotropie vers une valeur de 0,15 sur une plage temporelle allant de 50 ns jusqu’à 210 ns (période entre les impulsions laser). Ces résultats démontrent que la localisation des porteurs est très grande à 14K, et qu’elle est supérieure pour les espèces à transfert de charge. Un modèle numérique simple d’équations différentielles à temps de vie radiatif et de dépolarisation constants permet de reproduire les données expérimentales. Ce modèle a toutefois ses limitations, notamment en ce qui a trait aux mécanismes de dépolarisation des excitons. / In this work, we investigate exciton dynamics in a thin film of sexithiophene molecules in self-assembled chiral H-aggregate supramolecular stacks. The intermolecular coupling energy J=100 meV places those molecules in the intermediate coupling regime. The energetic disorder and the strong phonon-electron interactions leads to high localization of the photoexcitations. The initial photoexcited species branches into two distinct states : self-trapped exciton (95% yield) and charge-transfer excitons (5% yield). At room temperature (293K), the intermolecular hopping processes are thermaly activated and the fluorescence anisotropy goes to zero within 5 ns. At low temperature (14K), hopping processes are frozen. To characterize exciton diffusion mechanisms, a fluorescence anisotropy experiment has been done. This measurement consists of monitoring the difference between the parallel and perpendicular composants of the photoluminescence (with respect to the laser beam), as a function of time. The fluorescence anisotropy gives us information about the depolarization of the excitons, which is directly connected with their diffusion within the supramolecular stack. We measure an anisotropy of 0,1 after 20 ns which stays constant for 50 ns. Chargetransfer states induce a rise of the anisotropy up to 0,15 between 50 ns and 210 ns (the period between adjacent laser pulses). Those measurements shows that exciton localization is very strong at 14K and higher for the charge-transfer states than the self-trapped ones. A simple mathematical model based on the resolution of a system of differential equations with constants radiative and depolarization lifetimes can reproduce the experimental data. This model has some limitations, especially for the description of the depolarization mechanisms of the self-trapped excitons.

The observed imbalance of matter and anti-matter in the universe is one of physics' most fundamental unresolved questions. The leading theories to explain this imbalance require CP violation, and the neutron electric dipole moment (nEDM) is a sensitive parameter in its determination. Many new theories of physics beyond the standard model can be constrained or ruled-out by setting limits on the nEDM. Many next generation nEDM experiments require Ultra Cold Neutrons (UCN), produced in superfluid helium. One such experiment is cryoEDM. This thesis explores various types of UCN detection technologies applicable to cryoEDM or any high-density high-efficiency cryogenic nEDM experiment. Cryogenic Phonon Scintillation detectors (CPSD) are modified for this application by operating at 500 mK, and by using a titanium transition edge sensor for phonon signal readout. A CPSD is stabilised in the transition using a novel infra-red light feedback system which reduced the response time to O</m>(100 &mu;s). The detector is characterised and calibrated using an ²⁴¹Am &alpha; source. It was found to operate reliably at this elevated temperature and measure an alpha spectrum with 11% resolution at 5.5 MeV. Scintillators are identified as a promising technology for UCN detection at low temperature. Suitable materials that are bright with fast decay times and low &gamma; sensitivity are studied in the temperature range 300 - 6 K. Their light yield to alpha excitation, their decay time characteristics and spectroscopic properties under VUV excitation are investigated. This study includes the first comprehensive investigation of the luminescence properties of plastic scintillators and of ⁶LiF/ZnS(Ag) down to 6 K. It is found that there is no degradation of the luminescence or kinetic properties of these materials across the whole temperature range, revealing them as suitable cryogenic detector materials. Using a plastic scintillator, a prototype UCN detector for operation in liquid helium is designed, manufactured and tested. It is read out using WLS optical fibres to a room temperature photomultiplier. The detector is successfully tested with cold neutrons at the ISIS neutron science facility and found to effectively measure neutrons, with a signal that is clear from background. Recommendations are made for its integration into a cryogenic neutron EDM experiment. This low-cost detector offers a promising method for the passive detection of UCN in a challenging cryogenic environment, with minimal electric interference and low background sensitivity. This technology offers the potential for improved UCN detection efficiency and thus improved sensitivity of the measurement of the neutron EDM.

In this thesis, we investigated several photoelectric material systems consisted of conjugated polymers by means of computer simulation. We combined several theory and simulation methods to meodeling different subjects from atomic to mesoscopic scale. We dealt with the problems such as quantum efficiency, structure characteristic, and the phase behavior in material. We hope to have better understanding of the relationship between structure characteristic and functional property in material. It will help an engineering designer to adjust the variables that optimize characteristics linking the synthesis of advanced materials with desired physical properties. This work can be divided into three parts. Long side chain substituted PPV polymers applied in light-emitting diode material : Molecular dynamics simulations were employed to investigate structure features and segment orientation of four poly(phenylene vinylene) (PPV)-like conjugated polymers with long flexible side chains at room temperature. In the simulations, the main chains of the polymers were found to be semi-rigid and to exhibit a tendency to coil into ellipsoidal helices or form zigzag conformations of only limited regularity. It was shown that continuous segments of a chain which are quasi-coplanar along the backbone are in a range of 2~4 repeat units. This implies that long-range electron transfer along same backbones of these polymers may not happen but may be mediated by interchain interactions. The ordered orientation and coupling distance of interchain aromatic rings are found to correlate with important optical properties of materials. Then we combined molecular dynamics simulation and density matrix methods modeling of amorphous light-emitting polymers. A simplified method combining molecular dynamics (MD) simulation and density matrix (DM) theory was developed for the prediction of optical properties of long side chain substituted poly(phenylene vinylene) (PPV) polymers. This MD+DM method takes account of the complexity of molecular packing of polymer chains. The method has been tested to simulate the absorption spectra of four model systems. The wavelengths of absorption maxima of the calculated spectra of these four conjugated polymers are in reasonable agreement with experimental data. The simulation also demonstrated that the importance of including interchain interactions in the calculation. Ion-conducting polymer sPBI-PS(Li+): To understand the mechanism of ionic migration in the amorphous matrixes of polymer electrolytes is crucial for their applications in modern technologies. Here, molecular dynamics (MD) simulation was carried out to investigate the ionic conduction mechanism of a particular conjugated rigid-rod polymer, sPBI-PS(Li+). The backbone of this polymer is poly[(1, 7- dihydrobenzo[1, 2-d:4,5-d¡¦]diimidazole- 2,6-diyl)-2-(2-sulfo)-p-phenylene]. The polymer has pendants of propane sulfonate Li+ ionomer. The MD simulations showed that the main chains of sPBI-PS(Li+) are in layer-like structure. The further detailed structure analysis suggested that the £k-electron of this polymer is not delocalized among aromatic rings. This agrees with the experimental result that sPBI-PS(Li+) shows no electronic conductivity and the conductivity of this polymer is mainly ionic. The calculated migration channels of lithium ions and electrostatic potential distributions indicated clearly that the polymer matrix is anisotropic for the migrations of ions. The migration of lithium ions along the longitudinal direction is more preferable than that along the transverse direction. The relaxations of the polymer host were found to play important roles in the transfer process of lithium ions. The hopping of lithium ion from one -SO3-1 group to another is correlated strongly with characteristic motions of -SO3-1 group on a time scale of about 10-13 s. Self-assembly functional material. Dissipative particle dynamics (DPD) simulations were carried out to investigate mixed ionic and non-ionic molecules, sodium tetradecyl sulfate (STS) and tetradecyl triethoxylated ether (C14E3) aqueous system. Different types of mixed micelles are formed depending on the concentrations of STS and C14E3. Our results are in good agreement to the early NMR measurements. From the investigation of surfactant aggregation, we understand the self-assembly mechanism and classical phase behavior in general diblock copolymer. Further, we investigated the self-assembly process on a particular mushroom-shaped supramolecular film material from molecular character to phase behavior. The miniaturized rod-coil triblock copolymers (PS-PI-RCBC) HEMME had been found to self-assemble into well-ordered nanostructures and unusual head to tail multilayer structure. The purpose of our study is to obtain fundamental understanding the connection of the inherent morphological characterization of single molecule and the mechanism of phase behavior of this polar self-assembly system. Dissipative particle dynamics simulation was carried out to study the mechanism of phase behavior of the solvent-copolymers system. We found that the solvent-induced polar effect under different temperature is important in the process of self-assembly of block copolymers. In different temperature the solvent induces hybrid structure aggregation. Our results are consistent with experimental observations and give evidence for a special mechanism governing the unusual phase behavior in thin films of modulated phases. The sizes and stabilization energies of mushroom-shaped supramolecular clusters were predicted by molecular modeling method. Clusters of sizes from 16 to 90 molecules were found to be stable. In combination of classical and simple quantum mechanical calculations, the band gaps of HEMME clusters with various sizes were estimated. The band gap was converged at 2.45 eV for cluster contains 90 molecules. Nonlinear optical properties of the material were investigated by the semi-empirical quantum mechanical calculations of molecular dipole moment and hyperpolarizabilities. Significant second-order nonlinear optical properties were shown from these calculated properties.

Nous investiguons dans ce travail la dynamique des excitons dans une couche mince d’agrégats H autoassemblés hélicoïdaux de molécules de sexithiophène. Le couplage intermoléculaire (J=100 meV) place ce matériau dans la catégorie des semi-conducteurs à couplage de type intermédiaire. Le désordre énergétique et la forte interaction électronsphonons causent une forte localisation des excitons. Les espèces initiales se ramifient en deux états distincts : un état d’excitons autopiégés (rendement de 95 %) et un état à transfert de charge (rendement de 5%). À température de la pièce (293K), les processus de sauts intermoléculaires sont activés et l’anisotropie de la fluorescence décroît rapidement à zéro en 5 ns. À basse température (14K), les processus de sauts sont gelés. Pour caractériser la dynamique de diffusion des espèces, une expérience d’anisotropie de fluorescence a été effectuée. Celle-ci consiste à mesurer la différence entre la photoluminescence polarisée parallèlement au laser excitateur et celle polarisée perpendiculairement, en fonction du temps. Cette mesure nous donne de l’information sur la dépolarisation des excitons, qui est directement reliée à leur diffusion dans la structure supramoléculaire. On mesure une anisotropie de 0,1 après 20 ns qui perdure jusqu’à 50ns. Les états à transfert de charge causent une remontée de l’anisotropie vers une valeur de 0,15 sur une plage temporelle allant de 50 ns jusqu’à 210 ns (période entre les impulsions laser). Ces résultats démontrent que la localisation des porteurs est très grande à 14K, et qu’elle est supérieure pour les espèces à transfert de charge. Un modèle numérique simple d’équations différentielles à temps de vie radiatif et de dépolarisation constants permet de reproduire les données expérimentales. Ce modèle a toutefois ses limitations, notamment en ce qui a trait aux mécanismes de dépolarisation des excitons. / In this work, we investigate exciton dynamics in a thin film of sexithiophene molecules in self-assembled chiral H-aggregate supramolecular stacks. The intermolecular coupling energy J=100 meV places those molecules in the intermediate coupling regime. The energetic disorder and the strong phonon-electron interactions leads to high localization of the photoexcitations. The initial photoexcited species branches into two distinct states : self-trapped exciton (95% yield) and charge-transfer excitons (5% yield). At room temperature (293K), the intermolecular hopping processes are thermaly activated and the fluorescence anisotropy goes to zero within 5 ns. At low temperature (14K), hopping processes are frozen. To characterize exciton diffusion mechanisms, a fluorescence anisotropy experiment has been done. This measurement consists of monitoring the difference between the parallel and perpendicular composants of the photoluminescence (with respect to the laser beam), as a function of time. The fluorescence anisotropy gives us information about the depolarization of the excitons, which is directly connected with their diffusion within the supramolecular stack. We measure an anisotropy of 0,1 after 20 ns which stays constant for 50 ns. Chargetransfer states induce a rise of the anisotropy up to 0,15 between 50 ns and 210 ns (the period between adjacent laser pulses). Those measurements shows that exciton localization is very strong at 14K and higher for the charge-transfer states than the self-trapped ones. A simple mathematical model based on the resolution of a system of differential equations with constants radiative and depolarization lifetimes can reproduce the experimental data. This model has some limitations, especially for the description of the depolarization mechanisms of the self-trapped excitons.

Le travail présenté porte sur l'analyse et l'interprétation théorique du spectre d'absorption du dioxyde de carbone dans le proche infrarouge: spectroscopie d'absorption ultrasensible et modélisation théorique des positions et intensités des raies d'absorption. Ce travail vise à affiner et étendre l'ensemble des paramètres des opérateurs effectifs nécessaires à la génération des listes de raies pour les bases de données spectroscopiques. Les résultats obtenus peuvent être divisés en trois parties.Dans la première partie, nous avons établi les équations relatives aux paramètres q0 J, qJ, q2J and q3J-types des éléments de matrice de l'opérateur moment dipolaire effectif en fonction des dérivées du moment dipolaire et des constantes de force obtenues par transformation de contact pour les isotopologues: 16O12C18O, 16O12C17O, 16O13C18O, 16O13C17O, 17O12C18O. En utilisant ces équations et les relations isotopiques obtenues pour les constantes moléculaires, des calculs numériques nous ont permis de dériver les paramètres effectifs du moment dipolaire des séries de transitions ∆P= 0, 2, 4, 6 et 8, pour les six isotopologues asymétriques ci-dessus. La comparaison des paramètres rapportés dans la littérature et obtenus dans ce travail a été effectuée et discutée.La deuxième partie est consacrée à l'analyse du spectre d'absorption du dioxyde de carbone hautement enrichi en 18O, enregistré avec une très grande sensibilité par spectroscopie CW-Cavity Ring Down Spectroscopy entre 5851 et 6990 cm-1 (1.71-1.43 µm). Au total, 19526 transitions appartenant à onze isotopologues (12C16O2, 13C16O2, 16O12C18O, 16O12C17O, 16O13C18O, 16O13C17O, 12C18O2, 17O12C18O, 12C17O2, 13C18O2 et 17O13C18O) ont été attribuées sur la base des prévisions du modèle de l'Hamiltonien effectif. Toutes les bandes identifiées correspondent aux séries de transitions ∆P= 8, 9 et 10, où P=2V1+V2+3V3 est le nombre de polyade (V1,V2,V3 sont les nombres quantiques vibrationnels). Les intensités des transitions les plus faibles sont de l'ordre de 2×10-29 cm/molécule. Les paramètres spectroscopiques précis de 211 bandes appartenant à neuf isotopologues ont été calculés. Au total, neuf perturbations de résonance de la structure rotationnelle de l'état supérieur ont été observées et identifiées pour les isotopologues 16O12C18O, 12C18O2, 13C18O2, 16O13C18O, 16O12C17O et 17O12C18O. Un nouvel ensemble de paramètres du Hamiltonien effectif a été obtenu par un ajustement global de nos données et de l'ensemble des données de la littérature. En utilisant une approche similaire, les ajustements globaux des intensités obtenues pour les transitions des séries ∆P= 8, 9 and 10 ont permis d'obtenir l'ensemble de paramètres effectifs du moment dipolaire.Dans la troisième partie, nous présentons l'analyse du spectre CW-CRDS du dioxyde de carbone naturel entre 7909 et 8370 cm-1 (1.26-1.19 µm). Au total, 3425 transitions appartenant à 61 bandes de six isotopologues - 12C16O2, 13C16O2, 16O12C18O, 16O12C17O, 16O13C18O et 16O13C17O- ont été attribuées. Dans la région spectrale étudiée, toutes les bandes appartiennent à la série ∆P=11. Les paramètres spectroscopiques précis des états supérieurs de 57 bandes ont été obtenus à partir d'un ajustement des positions mesurées (rms typiques des écarts de l'ordre de 0.6×10-3 cm-1). Les ajustements globaux des intensités obtenues ont permis de déterminer les paramètres effectifs du moment dipolaire de la série ∆P=11 des six isotopologues étudiés.Les résultats obtenus ont eu un grand impact sur la modélisation globale des spectres de du dioxyde de carbone. Ils ont permis d'affiner et d'étendre les mesures existantes et d'améliorer considérablement les paramètres de l'Hamiltonien et moment dipolaire effectifs. Les résultats obtenus ont d'ores et déjà été intégrés dans les bases de données spectroscopiques de CO2 les plus couramment utilisées (HITRAN, GEISA, CDSD). / This thesis is devoted to the investigation of the high resolution near infrared spectra of carbon dioxide and includes experimental measurements and theoretical modeling of line positions and intensities and refinement and extension of the set of effective operator parameters. The obtained results can be divided by three parts:In the first part, we present the equations for the q0 J, qJ, q2J and q3J-types parameters of the matrix elements of the effective dipole-moment operator in terms of the dipole-moment derivatives and force field constants derived by means of contact transformation method for the following carbon dioxide isotopologues: 16O12C18O, 16O12C17O, 16O13C18O, 16O13C17O, 17O12C18O and 17O13C18O. Using these equations and the obtained isotopic relations for the molecular constants, we derived the effective dipole-moment parameters for the ∆P= 0, 2, 4, 6 and 8 series of transitions of the six above asymmetric carbon dioxide isotopologues (P=2V1+V2+3V3 is the polyad number where V1,V2 and V3 are the vibrational quantum numbers). The comparison of the parameters reported in the literature and obtained in this work is performed and discussed.The second part is devoted to the analysis of the room temperature absorption spectrum of highly 18O enriched carbon dioxide recorded by very high sensitivity CW-Cavity Ring Down Spectroscopy between 5851 and 6990 cm-1 (1.71-1.43 µm ). Overall, 19526 transitions belonging to eleven isotopologues (12C16O2, 13C16O2, 16O12C18O, 16O12C17O, 16O13C18O, 16O13C17O, 12C18O2, 17O12C18O, 12C17O2, 13C18O2 and 17O13C18O) were assigned on the basis of the predictions of the effective Hamiltonian model. Line intensities of the weakest transitions are on the order of 2×10-29 cm/molecule. The line positions were determined with accuracy better than 1×10-3 cm-1 while the absolute line intensities are reported with an uncertainty better than 10%. All the identified bands correspond to the ∆P= 8, 9 and 10 series of transitions. The accurate spectroscopic parameters for a total of 211 bands belonging to nine isotopologues were derived. Nine resonance perturbations of the upper state rotational structure were identified for 16O12C18O, 12C18O2, 13C18O2, 16O13C18O, 16O12C17O and 17O12C18O isotopologues. New sets of Hamiltonian parameters have been obtained by the global modeling of the line positions within the effective Hamiltonian approach. Using a similar approach, the global fits of the obtained intensity values of the ∆P= 8, 9 and 10 series of transitions were used to derive the corresponding set of effective dipole moment parameters.In the third part, we report the analysis of the absorption spectrum of natural carbon dioxide by high sensitivity CW-Cavity Ring Down spectroscopy between 7909 and 8370 cm-1 (1.26-1.19 µm). Overall, 3425 transitions belonging to 61 bands of 12C16O2, 13C16O2, 16O12C18O, 16O12C17O, 16O13C18O and 16O13C17O were assigned. In the studied spectral region, all bands correspond to ∆P= 11 series of transitions. The accurate spectroscopic parameters of the upper states of 57 bands were derived from a fit of the measured line positions (typical rms deviations of about 0.6×10-3 cm-1). The global fits of the obtained intensity values of the ∆P= 11 series of transitions were used to determine the corresponding set of effective dipole moment parameters of the six studied isotopologues.The large set of new observations obtained in this thesis has an important impact on the global modeling of high resolution spectra of carbon dioxide. It has allowed refining and extending the sets of effective dipole moment and effective Hamiltonian parameters. The obtained results have allowed improving importantly the quality of the line positions and intensities in the most currently used spectroscopic databases of carbon dioxide (HITRAN, GEISA, CDSD).

Une étude théorique ab initio des structures électroniques des molécules Diatomiques polaires BN, SiN et LaH dans la représentation 2s+1Λ(+/-)Ont été effectués par la méthode du champ auto-cohérent de l'espace Actif complet (CASSCF), suivie par l'interaction de la configuration multiréférence (MRSDCI). La correction de Davidson, notée (MRSDCI+ Q), a ensuite été appliquée pour rendre compte de clusters ou agrégats quadruples non liés. L'ensemble de l'espace de configuration de CASSCF a été utilisé comme référence dans le calcul MRCI, qui a été effectués en utilisant le programme de calcul de chimie physique MOLPRO et en tirant parti de l'interface graphique Gabedit. Quarante-deux de plus bas états électroniques dans la représentation 2s+1Λ(+/-)au-dessous de 95000 cm-1 ont été étudiés de la molécule BN. Alors que vingt-huit états électroniques dans les représentations 2s+1Λ(+/-) jusqu'à 70000 cm-1 de la molécule de SiN ont été étudiés. D'autre part, les vingt-quatre bas états électroniques de LaH dans les représentations 2s+1Λ(+/-) au-dessous de 70000 cm-1 ont été étudiées par deux méthodes différentes et en prenant en considération l'effet des spin-orbite de la molécule LaH et nous avons observé la division énergétique des huit états électroniques. Les courbes d'énergie potentielle ont été construites avec la fréquence co-harmonique ωe, la distance internucléaire de l'équilibre re, les constantes de rotation Be. L'énergie électronique par rapport à l'état fondamentale Te a été calculé pour les états électroniques considérés comme des BN, SiN et la molécule LaH respectivement. En utilisant l'approche des fonctions canoniques, les valeurs propres Ev, les constantes rotationnelles Bv, la constante de distorsion centrifuge Dv et les abscisses des points de retournement Rmin and Rmax ont été calculés pour les états électroniques au niveau de vibration v=51 pour LaH molécule. Dix-huit et neuf états électroniques ont été étudiées pour la molécule BN et SiN respectivement. Pour LaH, vingt-trois états électroniques de la molécule LaH et l'effet de spin-orbite de molécule LaH sont donnés ici pour la première fois. La comparaison avec les données expérimentales et théoriques pour la plupart des constantes calculées démontre une très bonne précision. Enfin, ces résultats devraient ainsi mener à des études expérimentales plus poussées pour ces molécules. Nos résultats ont été publiés dans le Canadian Journal of Chemistry, Journal of Quantitative Spectroscopy and Radiative Transfer, nous avons deux autres articles en préparation à soumettre. / In the present work a theoretical investigation of the lowest molecular states of BN, SiN and LaH molecule, in the representation 2s+1Λ(+/-), has been performed via complete active space self-consistent field method (CASSCF) followed by multireference single and double configuration interaction method (MRSDCI). The Davidson correction noted as (MRSDCI+Q) was then invoked in order to account for unlinked quadruple clusters. The entire CASSCF configuration space was used as a reference in the MRCI calculation which has been performed via the computational chemistry program MOLPRO and by taking advantage of the graphical user interface Gabedit. Forty-two singlet, triplet, and quintet lowest electronic states in the 2s+1Λ(+/-) representation below 95000 cm-1 have been investigated of the molecule BN. While twenty-eight electronic states in the representation2s+1Λ(+/-)up to 70000 cm-1 of the SiN molecule have been investigated.On the other hand the Twenty four low-lying electronic states of LaH in the representation 2s+1Λ(+/-) below 35000 cm-1 have been studied by two different methods and by taking into consideration the spin orbit effect of the molecule LaH we give in the energy splitting of the eight electronic states. The potential energy curves (PECs) together with the harmonic frequency ωe, the equilibrium internuclear distance re, the rotational constants Be and the electronic energy with respect to the ground state Te have been calculated for the considered electronic states of BN, SiN and LaH molecule respectively. Using the canonical functions approach, the eigenvalues Ev, the rotational constants Bv ,the centrifugal distortion constants Dv and the abscissas of the turning points Rmin and Rmax have been calculated for electronic states up to the vibrational level v =51 for LaH molecule.Eighteen and Nine electronic states have been investigated here for the first time for the molecules of BN and SiN respectively, while for LaH, news results are performed for twenty three electronic states of LaH molecule and the spin-orbit effect of LaH molecule is given here for the first time. A comparison with experimental and theoretical data for most of the calculated constants demonstrated a very good accuracy. Finally, we expect that the results of our work should invoke further experimental investigations for these molecules. Our results have been published in Canadian journal of chemistry, Journal of Quantitative Spectroscopy and Radiative Transfer and we have two other papers in preparation to submit.

The subject of this dissertation is a theoretical and experimental study of electromagnetic and acoustic emission generated in the course of crack formation in solid dielectric materials. Theoretical part of this work is focused on the electromagnetic emission method, because it is related to a number of unsolved problems in the field of generated emission signals measurement, as well as in the field of the correct interpretation of obtained experimental data. Consequently, issues of emission signals detection by capacitance sensors and the transformation of crack primary parameters on the measured variables within the proposed transfer system have been dealt with. The results in this area were an extension of application range of the electromagnetic emission method on composite materials (especially on fiber reinforced polymer composites), identification and evaluation of the most significant emission sources in investigated composites and developing a methodology for evaluating of the crack primary parameters based on the measured emission signals waveforms in time and frequency domain. The experimental part of this dissertation was focused on a complex methodology for emission signals (including data from additional sensors) continual recording, processing and evaluation and for monitoring the response of stressed material to an applied mechanical load in real-time. Partial results from different research areas were also implemented into this methodology. This included the detection of emission signals, design and implementation of the appropriate measuring apparatus, analysis of measured signals in the time and frequency domain and advanced methods for processing and evaluation of measured data.