The major topics discussed are the phosphorescence sensitization in the lanthanides via energy transfer and in the organics by heavy atom effects. The f-f transitions in lanthanides are parity forbidden and have weak molar extinction coefficients. Upon complexation with the ligand, ttrpy (4'-p-Tolyl-[2,2':6',2"]-terpyridine) the absorption takes place through the ligand and the excitation is transferred to the lanthanides, which in turn emit. This process is known as "sensitized luminescence." Bright red emission from europium and bright green emission from terbium complexes were observed. There is ongoing work on the making of OLEDs with neutral complexes of lanthanide hexafluoroacetyl acetonate/ttrpy, studied in this dissertation. Attempts to observe analogous energy transfer from the inorganic donor complexes of Au(I) thiocyanates were unsuccessful due to poor overlap of the emissions of these systems with the absorptions of Eu(III) and Tb(III). Photophysics of silver-aromatic complexes deals with the enhancement of phosphorescence in the aromatics. The heavy atom effect of the silver is responsible for this enhancement in phosphorescence. Aromatics such as naphthalene, perylene, anthracene and pyrene were involved in this study. Stern Volmer plots were studied by performing the quenching studies. The quenchers employed were both heavy metals such as silver and thallium and lighter metal like potassium. Dynamic quenching as the predominant phenomenon was noticed.

Selectins are key adhesion molecules responsible for initiating a multistep process that leads a cell out of the blood circulation and into a tissue or organ. The adhesion of cells (expressing ligands) to the endothelium (expressing the selectin i.e.,E-selectin) occurs through spatio-temporally regulated interactions that are mediated by multiple intra- and inter-cellular components. The mechanism of cell adhesion is investigated primarily using ensemble-based experiments, which provides indirect information about how individual molecules work in such a complex system. Recent developments in single-molecule (SM) fluorescence detection allow for the visualization of individual molecules with a good spatio-temporal resolution nanometer spatial resolution and millisecond time resolution). Furthermore, advanced SM fluorescence techniques such as Förster Resonance Energy Transfer (FRET) and super-resolution microscopy provide unique opportunities to obtain information about nanometer-scale conformational dynamics of proteins as well as nano-scale architectures of biological samples. Therefore, the state-of-the-art SM techniques are powerful tools for investigating complex biological system such as the mechanism of cell adhesion. In this project, several constructs of fluorescently labeled E-selectin will be used to study the conformational dynamics of E-selectin binding to its ligand(s) using SM-FRET and combination of SM-FRET and force microscopy. These studies will be beneficial to fully understand the mechanistic details of cell adhesion and migration of cells using the established model system of hematopoietic stem cells (HSCs) adhesion to the selectin expressing endothelial cells (such as the E-selectin expressing endothelial cells in the bone marrow).

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第21599号 / 理博第4506号 / 新制||理||1647(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 杉山 弘, 教授 秋山 芳展, 准教授 竹田 一旗 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第22876号 / 理博第4642号 / 新制||理||1667(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 寺西 利治, 教授 島川 祐一, 教授 長谷川 健 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

The thesis is aimed to the study of spiropyrane behavior in polymeric matrix of poly(N-vinylkarbazole) (PVK) and poly[2-methoxy-5-(3´,7´-dimethyloctyloxy)-1,4-fenylenvinylene)] (MDMO-PPV). The photochromic transformation of spiropyrane to its isomeric merocyanine form (SPMC) was studied by absorption and emission spectroscopy. It was found, that photochromic reaction is markedly dependent on the environment. In the PVK polymer, which don’t absorb in the visible region, a high yield of photochromic reaction was achieved. Both, absorption and emission spectrums were observed for this system. From the measurement of time dependencies of the fotochromic reaction, the activation energy of the reverse reaction was determined. A different behavior, particularly in emissive spectrums, was found for the MDMO-PPV polymer doped with spiropyrane. Instead of formation of new band of merocyanine, decrease of the polymer fluorescence was observed. Subsequently, we studied the interaction between the polymeric matrix and the photochromic spiropyrane using fluorescence quenching method. On the basis of energy transfer theory, a critical radius of the fluorescence quenching sphere in solution and in solid was determined.

The thesis is focused on the design of antennas for wireless power transfer inside a car near the frequency of 8 GHz. In the last century, a number of scientists dealt with wireless transmission of energy with high power and long distances. Currently, attention is given to methods capable of transmitting energy with good effectively over a distance of meters for charging mobile devices, wireless sensors and other devices with low power consumption.

This dissertation investigates the chemical ingenuity into the development of various photoactive supramolecular donor – acceptor systems to produce clean and carbon free energy for the next generation. The process is inspired by the principles learned from nature’s approach where the solar energy is converted into the chemical energy through the natural photosynthesis process. Owing to the importance and complexity of natural photosynthesis process, we have designed ideal donor-acceptor systems to investigate their light energy harvesting properties. This process involves two major steps: the first step is the absorption of light energy by antenna or donor systems to promote them to an excited electronic state. The second step involves, the transfer of excitation energy to the reaction center, which triggers an electron transfer process within the system. Based on this principle, the research is focused into the development of artificial photosynthesis systems to investigate dynamics of photo induced energy and electron transfer events. The derivatives of Porphyrins, Phthalocyanines, BODIPY, and SubPhthalocyanines etc have been widely used as the primary building blocks for designing photoactive and electroactive ensembles in this area because of their excellent and unique photophysical and photochemical properties. Meanwhile, the fullerene, mainly its readily available version C60 is typicaly used as an electron acceptor component because of its unique redox potential, symmetrical shape and low reorganization energy appropriate for improved charge separation behavior. The primary research motivation of the study is to achieve fast charge separation and slow charge recombination of the system by stabilizing the radical ion pairs which are formed from photo excitation, for maximum utility of solar energy. Besides Fullerene C60, this dissertation has also investigated the potential application of carbon nanomaterials (Carbon nanotubes and graphene) as primary building blocks for the study of the artificial photosynthesis process.

In radiotherapy, a quantity asked for by clinics when calculating a treatment plan, along withdose, is linear energy transfer. Linear energy transfer is defined as the absorbed energy intissue per particle track length and has been shown to increase with relative biologicaleffectiveness untill the overkilling effect. In this master thesis the dose averaged linear energytransfer from proton and carbon ion beams was simulated using the FLUKA multi purposeMonte Carlo code. The simulated distributions have been compared to algorithms fromRaySearch Laboratories AB in order to investigate the agreement between the computationmethods. For the proton computation algorithm improvements to the current scoring algorithmwere also implemented. A first version of the linear energy transfer validation code was alsoconstructed. Scoring of linear energy transfer in the RaySearch algorithm was done with theproton Monte Carlo dose engine and the carbon pencil beam dose engine. The results indicatedthat the dose averaged linear energy transfer from RaySearch Laboratories agreed well for lowenergies for both proton and carbon beams. For higher energies shape differences were notedwhen using both a small and large field size. The protons, the RaySearch algorithm initiallyoverestimates the linear energy transfer which could result from fluence differences in FLUKAcompared to the RaySearch algorithm. For carbon ions, the difference could stem from someloss of information in the tables used to calculate the linear energy transfer in the RaySearchalgorithm. From validation γ-tests the proton linear energy transfer passed for (3%/3mm) and(1%/1mm) with no voxels out of tolerance. γ-tests for the carbon linear energy transfer passedwith no voxels out of tolerance for (5%/5mm) and a fail rate of 2.92% for (3%/3mm).

Within the scope of the OCEANET-Project (autonomous measurement platforms for energy and material exchange between ocean and atmosphere) on board of the research vessel (RV) Polarstern clouds have been investigated over the Atlantic Ocean under different atmospheric conditions and climate zones by active and passive remote sensing. An existing measurement platform, including lidar, microwave radiometer, all sky camera and broadband radiation sensors, has been extended by spectral radiation measurements with the COmpact RAdiation measurements System (CORAS). CORAS measures spectral downward radiances and irradiances in the visible to near-infrared wavelength region. The data were corrected to consider the movements of the ship and with it the misalignment of the sensor plane from earth’s horizon. Using observed and modeled spectral transmitted radiances cloud properties such as cloud optical thickness (tau ) and effective radius (reff) were retrieved. The vertical cloud structure with limitations for thick clouds is obtained from lidar and microwave radiometer measurements. The all sky camera provides information on the horizontal cloud variability. Cloud optical thickness and effective radius, will be retrieved by using a plane parallel radiative transfer model and a new spectral 3D retrieval method. / Im Rahmen des OCEANET-Projektes (autonome Messplattform zur Bestimmung des Material- und Energieaustauschs zwischen Ozean und Atmosphäre) wurden Wolken über dem Atlantischen Ozean unter verschiedenen atmosphärischen Bedingungen und Klimazonen an Bord des Forschungsschiffes Polarstern durch aktive und passive Fernerkundung untersucht. Die bereits existierende Messplattform (Lidar, Mikrowellenradiometer, Vollhimmels-Kamera, Standardmeteorologie und breitbandige Strahlung) wurde mit einem Spektrometersystem (CORAS) erweitert. CORAS misst spektrale abwärtsgerichtete Irradianzen und Radianzen im Wellenlängenbereich 350-2000 nm. Die Daten werden in Bezug auf die Schiffsbewegungen, sowie die horizontale Abweichung der Sensorebene lagekorrigiert. Mit beobachteten und modellierten Radianzen werden Wolkenparameter, wie die optische Dicke (tau) und der effektiveRadius (reff) abgeleitet. Die vertikale Wolkenstruktur (mit Beschränkungen für dicke Wolken) wird von Lidar- und Mikrowellenradiometer erhalten. Die Vollhimmelskamera liefert Informationen über die horizontale Wolkenverteilung. Die Wolkenparameter werden mit einem plan-parallelem Strahlungstransfermodell in Kombination mit einem neuen spektralen 3D Retrieval abgeleitet.

L'objectif de cette thèse est la mise en place et l'étude d'un transfert d'énergie électronique réversible (REET), à la suite d’une excitation lumineuse, entre des sous-composants moléculaires au sein d’architectures nanométriques de type rotaxane. Dans un système bichromophorique, lorsque les états excités du chromophore les plus bas sont quasi-isoénergétiques et que la cinétique du transfert interchromophore est rapide, le REET peut être instillé en modifiant les propriétés de l'état excité. Des dérivés du pyrène et du tris(bipyridine)ruthénium(II) ont été choisis comme chromophores appariés. La formation de rotaxane a été catalysée par du cuivre (réactions de Huisgen et Cadiot-Chodkiewicz) au sein d’un macrocycle doté de pyrène, couplant des demi-fils moléculaires comprenant des groupements terminaux volumineux - dont Ru(bpy)32+. Des durées de vie de luminescence prolongée (jusqu'à 14 μs), comparées au parent Ru(bpy)32+, indiquent que des processus de transfert d'énergie électroniques réversibles ont été établis dans une série de rotaxanes de structure variable, sont étudiés par spectroscopies stationnaire et résolue dans le temps. / The focus of this thesis is the establishment and study of reversible electronic energy transfer (REET), following light excitation, between molecular subcomponents within ring-on-thread rotaxane nanometric architectures. When the lowest-lying chromophore excited states are quasi-isoenergetic and kinetics of interchromophore transfer are rapid, REET can be instilled - changing excited-state properties. Pyrene and ruthenium(II) tris(bipyridine) derivatives were chosen as matched chromophores. Rotaxane formation was based on active template copper catalysis (Huisgen and Cadiot-Chodkiewicz reactions) within a pyrene-decorated macrocycle, coupling half threads comprising bulky stopper groups - one of which being Ru(bpy)32+. Prolonged luminescence lifetimes (up to 14 μs), compared to parent Ru(bpy)32+, indicated that reversible electronic energy transfer processes were instilled in a series of rotaxanes of varying structure, which were studied by state-state and time-resolved spectroscopies.