The presented diploma thesis is focused on finding conditions suitable for the study of surface reactions, especially Suzuki-Miyaura cross-coupling reaction (SMCR), by the surface- enhanced Raman scattering (SERS) method. The first part of the work deals with the optimization of the conditions of individual reactions using the classical synthetic Schlenk technique. Traditional, published, conditions for SMCR were gradually modified during the work so that the reactions could be performed in aqueous media and at room temperature, i.e., under conditions suitable for SERS spectroscopy. The following catalysts were tested: (i) PEPPSI - the traditional SMCR catalyst; (ii) palladium ions; (iii) Pd colloids; (iv) bimetallic colloids of Pd and plasmonic metal (Ag, Au) in the form of core-shell and alloy; (v) Ag and Au colloids with additions of palladium salt or N- heterocyclic carbenes (NHC-catalysts). Two groups of substrates were used: substrates with functional groups with high affinity for the surfaces of metal nanoparticles (NPs) and substrates without these anchoring functional groups. Substrates without the anchoring functional groups can be expected to enter the SMCR reaction from solution. In the second part of this diploma thesis selected reaction mixtures for SMCR were performed in septum...

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Ce travail a pour but l’étude comparative de trois systèmes d’intérêt pour des applications en optique non linéaire, TeO2-TiO2-ZnO (TTZ), TeO2-TiO2-Nb2O5 (TTN) and TeO2-GeO2-ZnO (TGZ). L’objectif étant de mettre en évidence une corrélation entre la structure et les propriétés mécaniques de ces verres à température ambiante mais surtout en fonction de la température et notamment autour de la température de transition vitreuse (Tg). L’étude structurale des verres a montré que dans le système TTZ, le zinc avait une coordination et donc un comportement différent au sein de la matrice tellurite en fonction de la concentration. Ces résultats ont été corrélés aux propriétés élastiques de ces verres, le module d’Young, le module de cisaillement et le coefficient de Poisson, qui présentent des évolutions non linéaires en fonction de la concentration en ZnO. Dans le système TGZ, contrairement au système TTZ, ces évolutions singulières n’ont pas été remarquées. Il a été supposé que l’oxyde de germanium empêche cette modification du polyèdre de Zinc. Pour les verres du système TTN aucun changement structural majeur en fonction de la concentration n’a été observé ce qui se traduit par des évolutions linéaires des propriétés élastiques. Les études en fonctions de la température ont montré qu’avant la température de transition vitreuse (Tg), l’évolution de la fréquence du pic Boson (spectroscopie Raman) et des propriétés élastiques sont en accord avec l’idée d’une relaxation du réseau vitreux. Après Tg, les évolutions structurales et mécaniques a montré l’existence d’une transition vers l’état de liquide en surfusion. Enfin il a aussi été possible de mettre en évidence une corrélation après Tg de l’évolution de la fréquence du pic Boson et des propriétés élastiques, permettant ainsi de prédire l’évolution des propriétés mécaniques grâce à l’étude vibrationnelle basses fréquences des verres tellurites. Ces informations sont des paramètres clés pour aider à la maitrise de la mise en forme de ce type de verre. / This work aims to comparatively study three systems aimed at nonlinear optical application, TeO2-TiO2-ZnO (TTZ); TeO2-TiO2-Nb2O5 (TTN) and TeO2-GeO2-ZnO (TGZ). The goal is to highlight correlations between structural and mechanical properties of the studied glasses at room temperature but also as a function of temperature, and in particular around the glass transition temperature (Tg). The structural study of the glasses showed that in the TTZ system, the zinc had a coordination and hence a behavior change in the tellurite matrix as a function of the concentration. Those results were correlated to the elastic properties of the glasses, the Young modulus, the shear modulus and the Poisson ratio, who presented nonlinear evolutions as a function of the ZnO concentration. In the TGZ system, in contrary to the TTZ system, these singular evolutions were not highlighted. It was hypothesized that the germanium oxide is preventing the change in comportment of the zinc polyhedra. For the TTN system, no major structural changes were observed as a function of niobium oxide concentration, which was translated with a linear increase of the elastic properties of those glasses. The temperature dependent studies showed that before the glass transition temperature (Tg), the Boson peak frequency (Raman spectroscopy) and the elastic properties evolutions are in accordance with the vitreous network relaxation idea. After Tg, the structural and mechanical evolution showed a transition toward a viscous liquid state. At last, it was possible to evidence a correlation after Tg of the evolution of the Boson peak frequency and the elastic properties, thus allowing a prediction of the mechanical properties thanks to the low frequency vibrational study in tellurite glasses. These information are key parameters needed to help the glass shaping mastery of these types of glasses.

Die vorliegende Arbeit befasst sich mit der Untersuchung von weitbandlückigen Halbleitern mittels Raman-Spektroskopie. Diese wurde vorwiegend unter Verwendung von Licht einer Wellenlänge von 325 nm im ultravioletten Spektralbereich angeregt. Damit konnten zum einen aufgrund eines erhöhten Streuquerschnittes Messungen zur Probencharakterisierung durchgeführt werden, die mit Anregung im sichtbaren Spektralbereich nicht möglich gewesen wären. Zum anderen wurden bei dieser Anregungswellenlänge auftretende Resonanzeffekte untersucht. Dabei werden zwei verschiedene Materialsysteme behandelt: zum einen Kristalle mit Wurtzitstruktur und zum anderen binäre und ternäre Sesquioxide mit Metallionen der III. Hauptgruppe. An den Kristallen mit Wurtzitstruktur wurde die Streuung des Anregungslichts mit Energie oberhalb der Bandlücke an longitudinal-optischen (LO) Phononen untersucht. Die Streuung an einzelnen LO-Phononen wird unter diesen Anregungsbedingungen von einem Prozess dominiert, der eine elastische Streuung beinhaltet, durch die die Impulserhaltung verletzt wird. Es wurde ein Modell aufgestellt, dass zwischen einer elastischen Streuung an der Oberfläche und an Punktdefekten unterscheidet, und mit Hilfe von Experimenten verifiziert. Weiterhin wurde der Einfluss von Ladungsträgern auf die Energie der LO-Phononen untersucht und es wird eine Anwendung dieser Erkenntnisse zur Charakterisierung der Oberfläche von Zinkoxid vorgestellt. An den binären Oxiden des Galliums und Indiums wurden die Energien der Phononenmoden ermittelt und die resonante Verstärkung bei der verwendeten Anregungswellenlänge untersucht. Für das Galliumoxid wurde dabei insbesondere die Anisotropie des Materials berücksichtigt. Für das Indiumoxid wird dargestellt, dass durch die resonante Anregung alle Phononenmoden beobachtet werden können, was insbesondere auch die Bestimmung der Phononenmoden von Dünnschichtproben ermöglicht. Weiterhin waren Mischkristalle des Galliumoxids Untersuchungsgegenstand, in denen das Gallium teilweise durch Indium oder Aluminium ersetzt wurde. Die Phononenenergien wurden in Abhängigkeit der Zusammensetzung ermittelt und der Einfluss von strukturellen Eigenschaften darauf sowie das Auftreten von Phasenübergängen untersucht.

Title: Optical Responses of Biomolecules on Regular Metal Plasmonic Nanostructures Author: Martin Šubr Department: Institute of Physics of Charles University Supervisor of the doctoral thesis: prof. RNDr. Marek Procházka, Dr., Institute of Physics of Charles University Abstract: Adsorption of molecules on metal plasmonic nanostructures leads to significant enhancement of many optical processes, such as Raman scattering (surface-enhanced Raman scattering - SERS) or fluorescence (surface-enhanced fluorescence - SEF). Two groups of substrates were tested within this thesis: (i) Silver nanorods prepared by oblique angle vapor deposition, and (ii) silver and gold nanoislands growing on magnetron-sputtered polytetrafluoroethylene film. Step-by- step optimization process was performed on the nanoislands in order to obtain optimum SERS sensitivity and reproducibility. Detailed SERS intensity profiles were obtained using gradient nanostructures with the localized surface plasmon resonance (LSPR) condition varying across the sample and three different excitation wavelengths. It was also found that spectral position and height of the LSPR band can be controlled simultaneously using mixed gold/silver nanoislands. Detailed investigation of polarization- and angular- dependences of anisotropic silver nanorods was...

1 Nucleotides are organic molecules that have a wide range of functions in living organisms. They participate in cell signaling, serve as cofactors of enzymatic reactions, play a central role in cellular metabolism, and are the basic monomeric units of nucleic acid polymers. Nucleotides consist of three subunit molecules - nitrogen nucleobase, a five-carbon sugar (ribose or 2'-deoxyribose), and a phosphate group containing one to three phosphates. The subject of this master thesis is the study of various nucleotides and their self-assemblies in water by means of vibrational spectroscopy - Raman scattering and its chirally sensitive variant Raman optical activity (ROA). ROA has the potential to provide new information about the structural arrangement, dynamics, and interactions of nucleotides, as it supposes to be much more sensitive to vibrations of its sugar part containing three to four chiral carbons, compared to Raman scattering. We study spectral manifestations associated with chemical modifications (difference between ribo- and deoxyribonucleotides, the influence of different phosphate positions) and the change of physical conditions (various charge states according to the set pH, effect of concentration, influence of ions). A substantial amount of work is devoted to studying the self-association of...

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<p> </p> <p>High-speed flows are important for defense, national security, and transportation applications and generate harsh environments where simplifying assumptions such as the ideal gas law are not valid due to nonequilibrium and chemistry effects. These flows are difficult and expensive to replicate experimentally, so the development and improvement of high-speed vehicles often relies on high-fidelity computational fluid dynamics (CFD) models. The successful modeling of complicated phenomena, such as heat transfer in a turbulent boundary layer, relies on validation by experimental data taken with high spatiotemporal resolution, precision, and accuracy. Precise experimental measurement of temperature, an important thermodynamic property for CFD models, is difficult with physical probes which are typically slow and perturb the flow. Instead, hybrid femtosecond/picosecond (fs/ps) coherent anti-Stokes Raman scattering (CARS) allows for non-intrusive, spatially-resolved, collision-free thermometry at kHz repetition rates with high precision and accuracy. </p> <p>The goal of this thesis is to advance hybrid fs/ps CARS for extension to high-speed flows, with particular improvements to the spatial extent, probe characteristics, and precision of the technique. A novel method for multipoint measurements in a simple and effective optical arrangement is demonstrated, enabling single-shot and averaged measurements of temperature and O₂/N₂ concentration along a linear array of probe volumes. The generation of a variable-pulsewidth probe beam by a ps slicer, electro-optic modulator, fiber amplifier, and custom narrowband amplifier system is used for improved signal-to-noise ratios at low pressure. Simultaneous CARS thermometry and femtosecond laser electronic excitation tagging (FLEET) velocimetry are performed in the freestream of Mach 3 and Mach 4 nitrogen flows. These measurements reveal the need to quantify and establish the ultimate precision of the hybrid fs/ps CARS technique. Sources of uncertainty in hybrid fs/ps CARS thermometry are determined through a theoretical uncertainty analysis and the predicted precision of the technique is confirmed experimentally in room temperature nitrogen. Benchtop measurements in a supersonic nozzle are used to indicate spatial and temporal simultaneity between FLEET and CARS measurements and hybrid fs/ps CARS thermometry is performed in a high-speed, low temperature flow.</p>