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.

Fluorescent proteins (FPs) are the workhorses of biological molecular imaging. Important imaging modalities (such as polarization microscopy or FRET imaging) exploit anisotropic optical properties of fluorescent proteins. In this thesis, we present the results of our polarization microscopy and X-ray diffraction experiments on FP crystals, as well as mathematical interpretation of these results, yielding information on the directionality of one- and two-photon absorption within the investigated fluorescent protein molecules. For the anisotropy of one-photon absorption, we determine the transition dipole moment (TDM) orientations in three representative fluorescent proteins. Validation with available quantum mechanical predictions values and an experimentally determined TDM orientation of the GFP gives confidence to the results obtained. For the two-photon absorption, we first test our hypothesis that two-photon absorptivity tensors of representative FPs exhibit vector-like behaviour and then examine the applicability of this simplification as a basis for the interpretation of our two-photon polarization microscopy data.

Les travaux de recherche documentés dans cette thèse s'inscrivent dans le cadre de la Collaboration UA9 au CERN. L'objectif principal de la collaboration est l'étude de la collimation et de l'extraction de faisceaux de particules de haute énergie. La thèse est principalement consacrée au développement des détecteurs et aux installations expérimentales correspondantes qui ont été mises en œuvre au SPS et au LHC au CERN. En ce qui concerne la nature de l'interaction des particules chargées avec une structure monocristalline, un cristal courbé peut être utilisé pour orienter le faisceau de particules de haute énergie au moyen de la canalisation de particules entre les plans atomiques du cristal. Un tel phénomène est étudié de manière approfondie par la Collaboration UA9. Un des principaux objectifs de la recherche présentée dans cette thèse est de développer des dispositifs sensibles pour mesurer le flux et les caractéristiques de faisceau des particules déviées par le cristal au SPS et au LHC. Pour cette thèse nous avons étudié les détecteurs Cherenkov (CpFM) et les détecteurs à pixel (Timepix). Depuis 2015, le CpFM (détecteur de Cherenkov pour la mesure du flux de protons) a été souvent modifié afin d'améliorer la précision pour le comptage des particules. La plage de fonctionnement du dispositif varie de 1 à 1000 particules par faisceau de particules (~3 ns) avec une résolution inférieure à 20% par proton. Fonctionnant dans le vide primaire de l’accélérateur et à des doses de rayonnement élevées, le détecteur a montré une grande stabilité et ayant la possibilité d’effectuer des études de contamination par faisceau. À son tour, le détecteur Timepix a été étalonné sur la ligne de faisceaux d'extraction de l'accélérateur SPS, fonctionnant dans le vide secondaire (Roman Pot). Une partie importante de la thèse est consacrée à la caractérisation et à l'étalonnage de ces détecteurs avec les développements des logiciels pour l'acquisition et l'analyse de données. Dans cette thèse, nous proposons également la mesure du moment dipolaire magnétique (MDM) de baryons à courte durée de vie. Le MDM est une caractéristique importante de l'interaction des particules avec un champ magnétique externe. Pour cette thèse, nous nous concentrons sur la mesure le MDM du baryon LambdaC+, qui pourrait fournir des informations sur le facteur gyromagnétique (g) du quark charme. Une valeur différente de g=2 indiquera une structure composite possible du c-quark et clairement la présence de physique au-delà du Modèle Standard (SM). Jusqu'ici, aucune mesure expérimentale du moment dipolaire magnétique des baryons avec des quarks lourds n'a été effectuée en raison d'une courte durée de désintégration de ces particules (environ 60 um). La proposition faite dans cette thèse est de produire des baryons charmés par interaction forte entre les protons extraits (à l’aide d’un premier cristal courbé) et une cible. Après la cible, un deuxième cristal courbé à grand angle (de plusieurs mrad) est utilisé pour canaliser les baryons et induire une rotation du vecteur de polarisation des baryons charmés. Cette configuration s'appelle une configuration à double cristal et l'expérience est proposée au LHC. Dans cette thèse, je me suis concentré principalement sur tous les tests et la validation nécessaires au SPS avant la mise en œuvre au LHC. Une configuration expérimentale possible pour les mesures MDM au niveau du SPS est également proposée avec une estimation de l'erreur absolue de la valeur mesurée du facteur g pour le baryon LambdaC+. / The research work documented in this thesis is done in a frame of the UA9 Collaboration at CERN. The main goal of the collaboration is the investigation of the high-energy particle beam collimation and extraction. The thesis is mainly devoted to the developments of detectors and the consequent experimental setups implemented at the SPS or LHC circulating machines at CERN. Regarding the nature of the charged particle interaction with a monocrystalline structure, a curved crystal can be used for the steering of the high-energy particle beam by means of the particle channeling between atomic planes of the crystal. Such a phenomenon is intensively studied by the UA9 Collaboration. Therefore, one of the main goals of the presented research is to develop sensitive devices for measuring the flux and the beam characteristics of the particles deflected by the crystal at the circulating machines. The detectors studied for this thesis are Cherenkov (CpFM) and pixel (Timepix). Since 2015, the CpFM (Cherenkov detector for proton Flux Measurement) has undergone various modifications to improve the particle counting characteristics. The range of the device operation varies from 1 to 1000 particles per bunch (~3 ns) with the particle resolution of less than 20% per single proton. Working in the primary vacuum of the accelerator and at high radiation doses, the detector showed high stability with the possibility to perform beam contamination studies. In turn, the Timepix detector has been calibrated at the extraction beamline and SPS accelerator, working in the secondary vacuum of the Roman Pot. A significant part of the thesis is devoted to the characterization and calibration of these detectors with the software developments for data acquisition and analysis. In this thesis, we also make a proposal for the measurement of the magnetic dipole moment (MDM) of short-lived baryons. The MDM is an important characteristic of the particle interaction with an external magnetic field. For the thesis, we concentrate on the measurement of the LambdaC+ MDM, which could provide information on the gyromagnetic (g) factor of the charm quark. Any discrepancy from g=2 will indicate a possible composite structure of the c-quark and clearly physics beyond the Standard Model (SM). So far, no experimental measurements of this value of baryons with heavy flavoured quarks have been carried out due to a short decay length of these particles (about 60 um). The proposal made in this thesis is to produce charm baryons by a strong interaction of the extracted proton beam (using a first bent crystal) impinging onto a target followed by the second large angle bent crystal (of several mrad) to channel the baryons and to rotate their polarization vector. This configuration is called a double-crystal setup and the experiment is proposed to take place at the LHC. In this thesis, I concentrate mainly on all the tests and validation needed at the SPS prior to the implementation at the LHC. A possible experimental configuration for the MDM measurements at the SPS is also proposed with an estimation of the absolute error of the measured g-factor value for the LambdaC+ baryon.

Protein electrical properties have been studied using dielectric relaxation measurements throughout the past century. These measurements have advanced both the theory and practice of liquid dielectric spectroscopy and have contributed to understanding of protein structure and function. In this dissertation, the relationship between permittivity measurements and underlying molecular mechanisms is explored. Also presented is a method to take molecular structures from the Protein Data Bank and subsequently estimate the charge distribution and dielectric relaxation properties of the proteins in solution. This process enables screening of target compounds for analysis by dielectric spectroscopy as well as better interpretation of protein relaxation data. For charge estimation, the shifted pKa values for amino acid residues are calculated using Poisson-Boltzmann solutions of the protein electrostatics over varying pH conditions. The estimated internal permittivity and estimated dipole moments through shifted pKa values are then calculated. Molecular dynamics simulations are additionally used to refine and approximate the solution-state conformation of the proteins. These calculations and simulations are verified with laboratory experiments over a large pH and frequency range (40 Hz to 110 MHz). The measurement apparatus is improved over previous designs by controlling temperature and limiting the electrode polarization effect through electrode surface preparation and adjustment of the cell's physical dimensions. The techniques developed in this dissertation can be used to analyze a wide variety of molecular phenomena experimentally and computationally, as demonstrated through various interactions amongst avidin, biotin, biotin-labeled and unlabeled bovine serum albumin, beta-lactoglobulin, and hen-lysozyme.

The electrical properties of proteins in solution are important for their structure and function. Computational biophysics studies of proteins need accurate parameters to ensure that numerical simulations match physical reality. Past work in this eld has compared the electrical properties of proteins obtained from dielectric spectroscopy to numerical simulations of proteins in water with adjustment of pKa values to try to capture the inevitable changes in electrical conformation that will occur in a complex structure such as a folded protein. However, fundamental veri cation of the charge parameters of the amino acid building blocks in common molecular dynamics software packages with electrical experiments needs to be performed to have increased con dence in the results from numerical simulations. The aim of this thesis is to start from a fundamental building block, the single amino acid alanine, and to compare numerical simulations of this amino acid in water using parameters from commonly used charge structures in CHARMM, GROMOS, and OPLS, with electrical parameters obtained from dielectric spectroscopy experiments in the GHz range. To this end, multiple molecular dynamics simulations were performed to accurately determine how these different charge structures yield different dielectric increments. Additionally, a commercial RF dielectric measurement probe was modi ed to perform measurements on solutions containing alanine at different concentrations. Using regression, the dielectric increment of alanine is readily determined and compared with the numerical simulations. The results indicate that the CHARMM and OPLS parameters seem to adequately capture the charge con guration of alanine in solution, while the GROMOS parameters produce a dielectric increment but do not seem to adequately capture the charge con guration of alanine in solution. These studies lay the foundation for future studies of additional amino acids in solution as well as a stepping stone for larger simulations of the electrical properties of fully solvated proteins in solution.

This thesis is devoted to optical properties of Aharonov-Bohm quantum rings in external electromagnetic fields. It contains two problems. The first problem deals with a single-electron Aharonov-Bohm quantum ring pierced by a magnetic flux and subjected to an in-plane (lateral) electric field. We predict magneto-oscillations of the ring electric dipole moment. These oscillations are accompanied by periodic changes in the selection rules for inter-level optical transitions in the ring allowing control of polarization properties of the associated terahertz radiation. The second problem treats a single-mode microcavity with an embedded Aharonov-Bohm quantum ring, which is pierced by a magnetic flux and subjected to a lateral electric field. We show that external electric and magnetic fields provide additional means of control of the emission spectrum of the system. In particular, when the magnetic flux through the quantum ring is equal to a half-integer number of the magnetic flux quantum, a small change in the lateral electric field allows tuning of the energy levels of the quantum ring into resonance with the microcavity mode, providing an efficient way to control the quantum ring-microcavity coupling strength. Emission spectra of the system are calculated for several combinations of the applied magnetic and electric fields.

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.

<p> </p><p>The interaction between light and organometallic chromophores has been investigated theoretically in a strive for fast optical filters. The main emphasis is on two-photon absorption and excited state absorption as illustrated in the Jablonski diagram. We stress the need for relativistic calculations and have developed methods to address this issue. Furthermore, we present how quantum chemical calculations can be combined with Maxwell's equations in order to simulate propagation of laser pulses through a materials doped with chromophores with high two-photon absorption cross sections. Finally, we also discuss how fast agile filters using spin-transition materials can be modeled in order to accomplish theoretical material design.</p> / Report code: LIU-TEK-LIC-2006:55. On the day of the defence date the status on article III was Manuscript, article IV was Accepted and article V was Submitted.

The interaction between light and organometallic chromophores has been investigated theoretically in a strive for fast optical filters. The main emphasis is on two-photon absorption and excited state absorption as illustrated in the Jablonski diagram. We stress the need for relativistic calculations and have developed methods to address this issue. Furthermore, we present how quantum chemical calculations can be combined with Maxwell's equations in order to simulate propagation of laser pulses through a materials doped with chromophores with high two-photon absorption cross sections. Finally, we also discuss how fast agile filters using spin-transition materials can be modeled in order to accomplish theoretical material design. / <p>Report code: LIU-TEK-LIC-2006:55. On the day of the defence date the status on article III was Manuscript, article IV was Accepted and article V was Submitted.</p>

Un moment dipolaire électrique permanent (EDM) est une propriété fondamentale des systèmes simples comme par exemple l'électron, les atomes/molécules ou le neutron dont l'existence est prédite par le Modèle Standard de la physique des particules (MS) mais qui n'a pas pour l'heure jamais été observée. Cette observable violant la symétrie CP offre la possibilité de relier la physique des particules à l'énigme cosmologique fondamentale de l'asymétrie baryonique de l'Univers observée de nos jours. Produire une telle asymétrie requiert de nouvelles sources/de nouveaux mécanismes de violation de CP, hors MS, qui peuvent être sondés de façon privilégiée par les recherches d'EDM. La sensibilité des expériences EDM actuelles se trouve des ordres de grandeurs au-dessus des prédictions du secteur faible du MS. L'absence de signal, après 60 ans de quête, détermine la limite supérieure la plus forte sur la violation de CP dans le secteur fort du MS et contraint l'espace des phases des modèles de nouvelle physique. A contrario, la mesure d'un EDM non nul dans les années à venir pourra s'interpréter comme le signal d'une physique au-delà du MS évoluant à l'échelle multi-TeV. Dans cette perspective envoûtante, de nombreux nouveaux projets de mesures des EDM ont vu le jour ces dernières années et d'importants efforts sont poursuivis auprès du neutron notamment. Ce manuscrit présente la recherche de l'EDM du neutron menée auprès de l'expérience la plus sensible à ce jour basée à l'Institut Paul Scherrer en Suisse. / A permanent electric dipole moment (EDM) is a fundamental property of simple systems such as the electron, atoms/molecules or the neutron whose amplitude is expected to be non-zero within the Standard Model of particles physics (SM) but which has never been observed so far. This observable violating the CP symmetry offers the opportunity to link particle physics to the fundamental cosmological enigma of the observed baryon asymmetry of the Universe. Such an asymmetry requires new CP violation sources/mechanism beyond the SM, which can be best probed by EDM searches. The current EDM experiments sensitivity is order of magnitude above the weak SM sector predictions. Measuring a null EDM, after a 60 years quest, set the strongest upper limit on the CP violation in the strong SM sector and constrains the new physics models phase space. On the contrary, measuring a non-zero EDM in the coming years can be understood as a signal from physics beyond the SM evolving at a multi-TeV scale. In this haunting perspective, many new EDM projects raised in the last years and important efforts are pursued near the neutron in particular. This manuscript present the neutron EDM search near the most sensitive experiment running at the Paul Scherrer Institute in Switzerland.