Determining the presence of an analyte of interest, and finding the enantiomeric purity of chiral molecules are challenging tasks. This work in molecular recognition is carried out routinely by many different researchers, including both academic as well as industrial research groups. The following dissertation presents original research directed toward two different areas of interest to the molecular recognition community: enantioselective sensing in solution, and sensing at a defined interfacial environment. This work begins with a review of the non-chromatographic ways that the enantiomeric purity of chiral carboxylic acids is determined, presented in Chapter 1. Carboxylic acids are important functional groups, both for organic synthesis as well as pharmaceutical drug development. Chapter 2 presents efforts that have been made to rapidly assess both the enantiomeric purity and identity of chiral carboxylic acids, utilizing the technique of exciton-coupled circular dichroism (ECCD). A twist is imparted on a complex, and can be correlated with the absolute configuration of the stereocenter. The enantiomeric composition can be rapidly determined. After creating the assay, the focus of the work shifted toward applying this system to new classes of analytes. Chapter 3 covers chemo- and enantioselective differentiation of [mathematical symbol]-amino acids, and continues to discuss the expansion to [mathematical symbol]-homoamino acids. Then a synthetic substrates was tested, and a series of reactions screened to determine if any enantioselectivity had been imparted by a Baeyer-Villiger oxidation. Finally, the enantiomeric composition of a biaryl atropisomer, a compound lacking a stereocenter, was determined. The signal produced from this assay is at a relatively short wavelength, and efforts were undertaken to push this signal to longer wavelength. Chapter 4 is a compendium of the lessons that were learned upon attempting to create a self-assembled sensing system. The final chapter details work that was done in collaboration with Professor Katsuhiko Ariga at the National Institute of Materials Science in Tsukuba, Japan. In this chapter, an indicator displacement assay was carried out for the first time at the air-water interface. This contribution opens the door for sensing to be carried out at defined regions, rather than free in bulk solution. / text

Recent experiments show evidence for long-lived electronic coherence in several photosynthetic complexes, for example in the Fenna-Matthews-Olson complex of green sulfur bacteria. The experiments raise questions about the microscopic reasons for this quantum coherence and its role to the functioning of these highly evolved biological systems. The present thesis addresses both questions. We find that an interplay of electronic coherence and the fluctuating phonon environment is responsible for the high exciton transport efficiency in these complexes and generalize this idea to the concept of environment-assisted quantum transport (ENAQT). In addition, we quantify the contribution of coherent dynamics to the efficiency and thus to the biological functioning. We determine the effect of temporal (non-Markovian) and spatial correlations and develop an ab initio propagation method based on atomistic detail which predicts the long-lived coherence. The research in photosynthetic energy transfer can inspire new designs for the control of excitons in engineered systems. We develop a method for computing the Forster coupling between semiconductor nanoparticle quantum dots. The focus is on the size and shape dependence and the presence of a spatially varying dielectric environment and metallic gates. A separation of the wavefunction into slowly and fast varying part provides the basis for an efficient computation on a real-space grid. Finally, the simulation of structured models of photosynthetic energy transfer is a challenging task using conventional computing resources. To this end, we propose a special-purpose superconducting device based on flux quantum bits and quantum LC resonators and show that parameters can be engineered such that this simulation becomes possible. / Chemistry and Chemical Biology

Le travail de recherche qui est rapporté dans ce manuscrit porte sur les couches minces de pérovskites et leur utilisation dans le cadre de la problématique des microcavités en régime de couplage fort. L'arrangement cristallin des pérovskites forme une structure en multi-puits quantiques dans laquelle les états excitoniques présentent une grande force d'oscillateur et une énergie de liaison importante (quelques 100 meV), en raison des effets de confinements quantique et diélectrique. Un premier axe de ce travail a consisté à collecter des informations sur les propriétés excitoniques de ces matériaux. Sur une pérovskite particulière (PEPI), nous avons notamment effectué des mesures de photoluminescence sous excitation impulsionnelle et des mesures pompe-sonde qui semblent suggérer l'existence, sous forte densité d'excitation, d'un processus de recombinaison Auger des excitons. Un deuxième axe de recherche fut de mettre en cavité des couches de certaines pérovskites. Avec les pérovskites PEPI et PEPC, nous avons montré que la réalisation de microcavités présentant un facteur de qualité de l'ordre de la dizaine suffit à obtenir, à température ambiante, le régime de couplage fort en absorption et en émission avec des dédoublements de Rabi pouvant atteindre 220 meV. Un goulet d'étranglement dans la relaxation des polaritons a été clairement mis en évidence pour la microcavité PEPI. Nous avons d'autre part montré que les pérovskites pouvaient également être associées à des semi-conducteurs inorganiques dans des microcavités dites "hybrides". Selon Agranovich et al., ces dernières pourraient, dans le cadre de la problématique du laser à polaritons, constituer une alternative à l'augmentation du facteur de qualité des microcavités. Dans cette optique, le couple ZnO/MFMPB semble particulièrement prometteur.

Controlling the quantum states of charge (excitons) or spin-polarized carriers in semiconductor quantum dots (QDs) has been the focus of a considerable research effort in recent years due to the strong promise of using this approach to develop solid state quantum computing hardware. The long-term scalability of this type of quantum computing architecture is enhanced by the use of QDs emitting in the telecom band, which would exploit the established photonic infrastructure. This thesis reports the use of all optical infrared experimental techniques to control exciton dynamics in two different QD samples consisting of InAs/GaAs QDs and InAs/InP QDs within a planar microcavity. An infrared quantum control apparatus was developed and used to apply optimized shaping masks to ultrafast pulses from an optical parametric oscillator. Pulse shaping protocols designed to execute a two-qubit controlled-rotation operation on an individual semiconductor QD were demonstrated and characterized. The quantum control apparatus was then implemented in simultaneous single qubit rotations using two uncoupled, distant InAs/GaAs QDs. These optimal control experiments demonstrated high fidelity optical manipulation of exciton states in the two QDs using a single broadband laser pulse, representing a step forward on the path to a scalable QD architecture and showcasing the power of pulse shaping techniques for quantum control on solid state qubits. As an alternative to single QDs, which have very low optical signals, subsets of QDs within an ensemble can be used in quantum computing applications. To investigate the mediation of inhomogeneities in a QD ensemble, pump-probe experiments were performed on InAs/InP QDs within a dielectric Bragg stack microcavity. Two different excitation geometries showed that the angle dependence of the microcavity transmission allowed for the spectral selection of QD subsets with transition energies resonant with the cavity mode. The microcavity mitigated inhomogeneities in the ensemble while providing a basis for addressing QD subsets which could be used as distinguishable quantum bits. This thesis work shows significant advances towards an optical computing architecture using quantum states in semiconductor QDs.

Due to their unique properties organic semiconductors may be used for various applications in organic optoelectronic devices: light emitting devices, lasers, field-effect transistors, photovoltaic cells and etc. Despite high perspectives of organic semiconductors they are still upstaged by their inorganic counterparts. Development of organic electronics requires better understanding of electrooptical properties of organic semiconductors and relationships between their structure and functions. The main goal of this thesis is a detailed investigation of ultrafast exciton and charge carrier processes in pure organic semiconductors and their blends with fullerene derivatives. Investigated organic or silicon organic semiconductors were poly-di-n-hexylsilane (PDHS), polyfluorenes F8BT and PSF-BT, merocyanine MD376. C60 fullerene and its derivative PCBM were used in blends. Ultrafast transient absorption, fluorescence, and integral mode photocurrent measurements were used for investigations. The investigation of PDHS nanocomposites revealed that PDHS incorporation into nanopores can be used for improvement of fluorescence properties. Formation of intramolecular charge transfer state was proposed for PSF-BT neat films. Charge transfer scheme of the formation of long-lived charge pair state in PSF-BT/PCBM blend was presented. The charge pair and free charge carrier generation scheme in merocyanine blends with fullerene derivatives were discussed in detail. Analysis of measurement... [to full text] / Dėl savo unikalių savybių organiniai puslaidininkiai gali būti plačiai pritaikyti įvairiuose optoelektroniniuose prietaisuose: organiniuose šviestukuose, organiniuose lazeriuose, organiniuose tranzistoriuose ir organiniuose šviesos elementuose. Visi šie pritaikymai yra galimi dėl organinių molekulių laidumo. Nepaisant didelių organinių puslaidininkių perspektyvų, jie vis dar yra nukonkuruojami neorganinių puslaidininkių. Pagrindinis šių tezių tikslas yra detaliai ištirti eksitonų ir krūvininkų dinamikos procesus grynuose organiniuose puslaidininkiuose ir jų mišiniuose su fulereno dariniais. Buvo matuoti organiniai ir silicio organiniai puslaidininkiai: poli-di-n-heksilsilanas (PDHS), polifluoreno dariniai F8BT ir PSF-BT, merocianinas MD376. Mišiniuose naudoti fulerenai buvo C60 ir jo darinys PCBM. Tyrimams buvo naudoti ultraspartūs skirtuminės sugerties, fluorescencijos ir integralinės fotosrovės matavimai. PDHS tyrimai atskleidė, kad neorganinės matricos sumažina nespindulinį relaksacijos kanalą. PDHS nanokompozitai gali būti naudojami polimero fluorescencijos savybių: stabilumo, kvantinio našumo pagerinimui. Polifluorenų F8BT ir PSF-BT grynų plėvelių tyrimų metu nustatyti eksitonų-eksitonų anihiliacijos ir eksitonų migracijos skirtumai. Vidumolekulinės krūvio pernašos būsenos formavimasis buvo pasiūlytas PSF-BT grynoms plėvelėms. Pristatyta ilgi gyvuojančių krūvininkų porų formavimosi schema PSF-BT/PCBM mišiniuose. Krūvio pernašos būsenų formavimasis buvo ištirtas... [toliau žr. visą tekstą]

Dėl savo unikalių savybių organiniai puslaidininkiai gali būti plačiai pritaikyti įvairiuose optoelektroniniuose prietaisuose: organiniuose šviestukuose, organiniuose lazeriuose, organiniuose tranzistoriuose ir organiniuose šviesos elementuose. Visi šie pritaikymai yra galimi dėl organinių molekulių laidumo. Nepaisant didelių organinių puslaidininkių perspektyvų, jie vis dar yra nukonkuruojami neorganinių puslaidininkių. Pagrindinis šių tezių tikslas yra detaliai ištirti eksitonų ir krūvininkų dinamikos procesus grynuose organiniuose puslaidininkiuose ir jų mišiniuose su fulereno dariniais. Buvo matuoti organiniai ir silicio organiniai puslaidininkiai: poli-di-n-heksilsilanas (PDHS), polifluoreno dariniai F8BT ir PSF-BT, merocianinas MD376. Mišiniuose naudoti fulerenai buvo C60 ir jo darinys PCBM. Tyrimams buvo naudoti ultraspartūs skirtuminės sugerties, fluorescencijos ir integralinės fotosrovės matavimai. PDHS tyrimai atskleidė, kad neorganinės matricos sumažina nespindulinį relaksacijos kanalą. PDHS nanokompozitai gali būti naudojami polimero fluorescencijos savybių: stabilumo, kvantinio našumo pagerinimui. Polifluorenų F8BT ir PSF-BT grynų plėvelių tyrimų metu nustatyti eksitonų-eksitonų anihiliacijos ir eksitonų migracijos skirtumai. Vidumolekulinės krūvio pernašos būsenos formavimasis buvo pasiūlytas PSF-BT grynoms plėvelėms. Pristatyta ilgi gyvuojančių krūvininkų porų formavimosi schema PSF-BT/PCBM mišiniuose. Krūvio pernašos būsenų formavimasis buvo ištirtas... [toliau žr. visą tekstą] / Due to their unique properties organic semiconductors may be used for various applications in organic optoelectronic devices: light emitting devices, lasers, field-effect transistors and photovoltaic cells and etc. Despite high perspectives of organic semiconductors they are still upstaged by their inorganic counterpart. The efficiency of electrooptical properties of organic semiconductors is tried to increase. The main goal of this thesis is a detailed investigation of ultrafast exciton and charge carrier processes in pure organic semiconductors and their blends with fullerene derivatives. Measured organic or silicon organic semiconductors were poly-di-n-hexylsilane (PDHS), polyfluorenes F8BT and PSF-BT, merocyanine MD376. Fullerenes used in blends were C60 and its derivative PCBM. Ultrafast transient absorption, fluorescence, and integral mode photocurrent measurements were used for investigations. The investigation of PDHS revealed that PDHS nanocomposites can be used for improvement of neat PDHS films fluorescence properties. The formation of intramolecular charge transfer state was proposed for PSF-BT neat films. Charge transfer scheme of the formation of long-lived charge pair state in PSF-BT/PCBM blend was presented. The formation of charge transfer states was explored in neat merocyanine films and blends with fullerene derivatives. The scheme of generation of charge pairs and free charge carriers in merocyanine blends with fullerene derivatives was discussed in... [to full text]

This thesis presents a theoretical study of the collective effects of a large number of photon emitters coupled to optical cavities. The ensemble effects are accounted for by considering both the light emitting and scattering by the photon emitters. It suggests that, to correctly estimate the emitters ensemble coupled cavity mode, it is necessary to consider the existence of the excited excitons ensemble and optical pumps. This thesis shows that optical pumps can excite more excitons and scattering channels as pumping power increases. The change in exciton population can lead to comprehensive spectral behaviors by changing the cavity spectral shapes, bandwidth and resonance positions, through the inhomogeneous broadening and frequencies repulsion effects of collective emissions. The existence of the exciton ensemble can also enhance optical coupling effects between target excitons and the cavity mode. The target exciton, which has a relatively large coupling strength and is close to the cavity peak, can affect the properties of the background dipoles and their coupling to the cavity. All these collective effects are sensitive to the number, the resonances distribution, and the optical properties of the background excitons in the frequency domain and the property of the target exciton, if any. This study provides a perspective on the control of the optical properties of cavities and individual excitons through collective excitation. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2012-07-30 14:51:15.914

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Impurity trapped excitons (ITEs) occurring in divalent ytterbium doped calcium and strontium fluoride crystals have been investigated by exploiting the radically different radiative decay rates of the lowest exciton state and higher excited states, utilizing a novel two-colour transient photoluminescence enhancement experiment. The ITE energy levels have been directly measured with the observation of sharp transitions occurring from the changes of states of the localized hole and broad bands associated with changes of state of the delocalized electrons. The dynamic behaviour under excitation by time delayed ultra-violet (UV) and infrared (IR) pulses has been observed allowing for the identification of excitation and decay pathways between the ITE states. The position and transition intensities of the sharp lines within the IR excitation spectrum have been successfully matched using a semi-empirical effective Hamiltonian crystal field model. In CaCaF₂:Yb²⁺ the lines occurring at 249 and 1145 cm⁻¹ were matched with the crystal field parameter B4 = 800 cm⁻¹ and the exchange parameter G3(fs) = 5900 cm⁻¹. In SrCaF₂:Yb²⁺ these lines were observed at 178 and 1284 cm⁻¹ and matched with B4 = 600 cm⁻¹ and G3(fs) = 7278 cm⁻¹. Local heating and direct absorption by intra-excitonic transitions are found to be the causes of the broad band observed in the spectrum and have been deconvolved by studying the dynamic behaviour of the monitored emission at different IR excitation frequencies. Through this modeling, higher lying ITE states have been identified occurring at 785 cm⁻¹ in SrCaF₂:Yb²⁺ and in between 740 - 820 cm⁻¹ in CaCaF₂:Yb²⁺. The dynamic model developed successfully simulates the temporal behaviour of the emission under IR excitation under a variety of parameters including IR fluence, excitation frequency, sample temperature and UV - IR pulse delay. Examination of the SrCaF₂:Yb²⁺ dynamic behaviour over a time scale of 100 ms shows UV driven trap population at a rate of approximately 3% per pulse, which are liberated and recycled to the Yb²⁺ ground state by the IR pulse. The two-colour technique is applied to MgCaF₂:Yb²⁺, a candidate for possible ITE emission. Temperature dependent emission spectra obtained under UV excitation indicates the possibility of an ITE state, independently populated from the 5d level of the Yb²⁺. Typical 5d emission is also observed from this system. Under IR excitation, liberation of shallow traps and possible local heating is observed. No ITE emission is conclusively found with IR probing.

Les interactions entre les électrons et les photons sont au cœur des recherches liées à l'information quantique, nées en particulier d'échanges croissants entre deux domaines de la physique : l'opto-électronique, qui s'intéresse aux dispositifs d'émission, de détection et de conversion de lumière à base de matériaux semiconducteurs, et l'optique quantique, historiquement centrée sur l'étude des interactions entre atome et rayonnement électromagnétique. Dans ce mémoire, nous explorons les configurations originales de couplage entre les excitations électroniques (les excitons) et les modes photoniques façonnés au sein de nanostructures semiconductrices. Ces travaux ont été développés sur les matériaux semiconducteurs " à grand gap ", GaN et ZnO, dont les excitons sont robustes jusqu'à température ambiante et les propriétés quantiques d'interaction avec la lumière sont les plus fortes parmi les matériaux semiconducteurs. Le premier chapitre est consacrée à l'étude de l'exciton confiné dans une boîte quantique unique GaN. Dans le second chapitre, nous discuterons l'insertion de telles boîtes quantiques dans des cavités photoniques destinées à réaliser des nanolasers à boîtes quantiques. Enfin, dans le troisième chapitre consacré aux microcavités planaires à base de ZnO, nous montrons comment les polaritons, particules hybrides exciton-photon, forment à forte densité des condensats de Bose (des états macroscopiques cohérents) appelés lasers à polaritons, jusqu'à température ambiante. Les perspectives de développement d'optique quantique en cavité dans ces nouveaux systèmes sont enfin présentées.