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Stabilita a vlastnosti kombinovaných nápojů a ovocných koncentrátů
Klatová, Kamila ; Vítová, Eva (oponent) ; Vespalcová, Milena (vedoucí práce)
Tato diplomová práce se zabývá stabilitou a základními vlastnostmi kombinovaných nápojů a ovocných koncentrátů. V teoretické části byla popsána výroba a využití ovocných koncentrátů. Dále se práce zabývala anthokyanovými pigmenty a fenolickými látkami. Byl popsán princip a instrumentace kapalinové chromatografie a elektronové paramagnetické rezonance. V další podkapitole byly popsány metody stanovení celkových anthokyanů a fenolických látek. V experimentální části práce bylo popsáno stanovení rozpustné sušiny, viskozity a antioxidační aktivity. Metodou podle Folin-Ciocalteua byl stanoven celkový obsah fenolických látek a pHdiferenciální metodou celkový obsah anthokyanů. Pomocí kapalinové chromatografie byl ve vzorcích stanoven obsah kyanidin-3-glukosidu a kyanidin-3-galaktosidu.
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Semianalytical approach to simulations in nanophotonics
Hrtoň, Martin ; Hohenester, Ulrich (oponent) ; Aizpurua, Javier (oponent) ; Šikola, Tomáš (vedoucí práce)
Numerical simulations have become an indispensable part of the design process in nanophotonics, which inevitably led to the development of specialized software dedicated to this task. Although there is a number of capable and commercially available options that can serve that purpose, many applications require data analysis that goes beyond the standardly offered analysis tools. The data post-processing lies at the focus of this thesis, with emphasis on the development of semianalytical models that are tailored specifically to each type of experiment, providing better insight into its physical background and improved agreement between theory and measurements. A major part of the thesis is dedicated to the plasmon enhanced electron paramagnetic resonance (PE EPR), a novel technique employing metallic antennas for enhancing the interaction between light and materials exhibiting magnetic spin transitions. Fundamental principles of this effect are laid down and a model facilitating rapid optimization of antenna arrays for thin film PE EPR spectroscopy is presented. Particular attention is paid to the current distribution and to advantages it offers when dealing with far-field projections and electromagnetic interaction between objects. This is further demonstrated on several applications, namely the phase imaging of metasurfaces using coherence controlled holographic microscope, the design of a metasurface-based fan-out element, and the multipolar analysis of far-fields generated by objects embedded within stratified media.
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Nízkoenergetická excitace v orientovaném grafitu pomocí THz magnetooptické spektroskopie
Dubský, Jan ; Kunc, Jan (oponent) ; Vrba, Radimír (vedoucí práce)
Tato diplomová práce se zabývá modelováním elektronických vlastností krystalu grafitu, které jsou měřitelné za užití spektrometru určeného pro vysokofrekvenční elektronově paramagnetickou rezonanci (anglicky high frequency electron paramagnetic resonance, zkráceně HFEPR) nacházejícího se v laboratořích CEITEC VUT. Jedná se zejména o pásovou strukturu grafitu a jeho Landauovy hladiny. V teoretické části práce jsou popsány stěžejní jevy a souvislosti z kvantové mechaniky a definice významných pojmů z fyziky pevných látek, s jejichž pomocí je možné popsat krystalickou strukturu grafitu a jeho elektronické vlastnosti. Dále je v práci popsán HFEPR spektrometr a jeho funkční princip. V praktické části se nacházejí numerické modely pásové struktury grafitu, modely jeho Landauových hladin a popis přípravy vzorku grafitu pro měření. Na konci praktické části je analýza výsledků měření, konkrétně cyklotronové rezonance a Shubnikových-de Haasových oscilací, díky níž je možné určit fyzikální parametry vzorku, jako např. efektivní hmotnost nosičů náboje a fundamentální frekvenci.
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Design of the far-infrared spectrometer coupling to a superconductive magnet and magneto-optical measurements in the far-infrared region
Dubnická Midlíková, Jana ; Slageren, Joris van (oponent) ; Neugebauer, Petr (vedoucí práce)
The thesis deals with the development of the far-infrared (FIR) spectroscopy in the high magnetic field. The combination of the FIR spectroscopy and high magnetic field is a very important tool in the characterization of materials such as Single-Molecule Magnets (SMMs). It also presents an ideal experimental technique that can probe and elucidate properties of novel 2D materials. The FIR spectroscopy in the magnetic field also allows studying Electron Paramagnetic Resonance (EPR) of SMMs with very large zero-field splitting, mainly based on transition metal complexes or lanthanides, in which commonly used EPR systems do not provide experimental access to the magnetic resonance transitions. In the thesis, two setups of the FIR spectrometers coupled to the superconductive magnets are described in detail. The first described setup, located at the University of Stuttgart, is already assembled and its performance is discussed. The magneto-optical measurements of SMMs performed on this setup are presented. The second magneto-optical setup draws on the experiences gained in the first setup and is designed for CEITEC.
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Development of Fourier Transform InfraRed Spectroscopy in High Magnetic Fields
Dubnická Midlíková, Jana ; Marsik, Přemysl (oponent) ; Schnegg, Alexander (oponent) ; Neugebauer, Petr (vedoucí práce)
Fourier-transform infrared (FTIR) spectroscopy in high magnetic fields, concisely FTIR magneto-spectroscopy, is a powerful spectroscopic technique used to investigate many important effects in materials, e.g., electron paramagnetic resonance, cyclotron resonance, and transitions between Landau levels. Despite their enormous potential in solid-state physics, infrared magneto-spectrometers are still relatively rare and custom-made since such systems generally require complex infrastructure. This doctoral thesis describes in detail the design and implementation of a versatile FTIR magneto-spectroscopic setup operating in the range of 50 – 10 000 cm-1, high magnetic field up to 16 T and temperatures between 2 – 320 K located at the Central European Institute of Technology of Brno University of Technology. This setup allows us to perform a variety of magneto-optical measurements spanning the range from THz/far-infrared (FIR) to near-infrared (NIR). It consists of a commercial FTIR spectrometer coupled to a 16 T cryogen-free superconductive magnet by the custom-designed optical coupling and transmission probes designed for experiments with multiple detectors and samples in Faraday geometry. The novelty of the setup lies in the usage of a cryogen-free superconducting magnet. We have optimized and tested the performance of the FTIR magneto-spectroscopic setup for various configurations and determined a workable setup range. The functionality of the FTIR magneto-spectroscopic setup was demonstrated by the magneto-optical measurements of the zero-field splitting in cobalt(II)-based single ion magnet in the FIR region, indirect inter-band transitions between Landau levels (LLs) in germanium in the NIR region, and inter-band transitions between LLs in graphene in the FIR region. Moreover, we measured the I-V characteristics of graphene bolometer devices.
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Development of a Novel Terahertz Magnetic Resonance Spectrometer for Spin Dynamics Investigations
Sojka, Antonín ; Smith, Graham Murray (oponent) ; Tseytlin, Mark (oponent) ; Neugebauer, Petr (vedoucí práce)
During the last decades, the method called High Frequency/Field Electron Paramagnetic Resonance (HF-EPR) spectroscopy experienced a boom in chemistry, biology, material science, and physics. Still, HF-EPR spectrometers operating at sub-THz frequencies are mostly custom-made with non-standard solutions. The thesis aims to develop a novel broadband EPR spectrometer capable of operating in the field and frequency domain and performing frequency domain rapid scan to study relaxation times. The spectrometer operates at high magnetic fields up to 16\,T, broad frequency range from 90 to 1100 GHz, and temperature ranges of 4 –- 400\,K. Furthermore, The work describes the design and development of six different exchangeable sample holders with a proof-of functionality measurement and unique fast-loading flange for the sample holder. The capability of the spectrometer to perform Rapid Scan measurement is demonstrated in the measurements of the LiPc single crystal and the DPPH sample dissolved in toluene.
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Magneto optical studies of solid states materials
Solodovnyk, Artur ; Malissa, Hans (oponent) ; Tol, Johan van (oponent) ; Neugebauer, Petr (vedoucí práce)
Electrically detected magnetic resonance (EDMR) is a sensitive and powerful technique for the determination of fundamental intrinsic properties of semiconductive solid-state materials. This work describes the fundamental theory of electron paramagnetic resonance and EDMR spectroscopy, in particular, several models of spin-dependent recombination are reviewed. The instrumental and software parts are presented, as well as the development of a new sample holder specific for EDMR. We intend to bring EDMR investigations to a new level, by developing a setup, which will operate at frequencies up to 1.1 THz and external magnetic field up to 16 T. Taking into account the possibilities of a home-built THz Frequency-Domain Rapid Scan (THz FraScan) spectrometer located in CEITEC BUT, samples will be characterized using both magnetic field and frequency sweeps. Thus, compared to the conventional continuous wave (CW) EDMR, this will allow obtaining not only the dependence of the voltage change on the external magnetic field at a given microwave frequency but also measuring frequency-field maps.
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Development of a Novel Terahertz Magnetic Resonance Spectrometer for Spin Dynamics Investigations
Sojka, Antonín ; Smith, Graham Murray (oponent) ; Tseytlin, Mark (oponent) ; Neugebauer, Petr (vedoucí práce)
During the last decades, the method called High Frequency/Field Electron Paramagnetic Resonance (HF-EPR) spectroscopy experienced a boom in chemistry, biology, material science, and physics. Still, HF-EPR spectrometers operating at sub-THz frequencies are mostly custom-made with non-standard solutions. The thesis aims to develop a novel broadband EPR spectrometer capable of operating in the field and frequency domain and performing frequency domain rapid scan to study relaxation times. The spectrometer operates at high magnetic fields up to 16\,T, broad frequency range from 90 to 1100 GHz, and temperature ranges of 4 –- 400\,K. Furthermore, The work describes the design and development of six different exchangeable sample holders with a proof-of functionality measurement and unique fast-loading flange for the sample holder. The capability of the spectrometer to perform Rapid Scan measurement is demonstrated in the measurements of the LiPc single crystal and the DPPH sample dissolved in toluene.
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Semianalytical approach to simulations in nanophotonics
Hrtoň, Martin ; Hohenester, Ulrich (oponent) ; Aizpurua, Javier (oponent) ; Šikola, Tomáš (vedoucí práce)
Numerical simulations have become an indispensable part of the design process in nanophotonics, which inevitably led to the development of specialized software dedicated to this task. Although there is a number of capable and commercially available options that can serve that purpose, many applications require data analysis that goes beyond the standardly offered analysis tools. The data post-processing lies at the focus of this thesis, with emphasis on the development of semianalytical models that are tailored specifically to each type of experiment, providing better insight into its physical background and improved agreement between theory and measurements. A major part of the thesis is dedicated to the plasmon enhanced electron paramagnetic resonance (PE EPR), a novel technique employing metallic antennas for enhancing the interaction between light and materials exhibiting magnetic spin transitions. Fundamental principles of this effect are laid down and a model facilitating rapid optimization of antenna arrays for thin film PE EPR spectroscopy is presented. Particular attention is paid to the current distribution and to advantages it offers when dealing with far-field projections and electromagnetic interaction between objects. This is further demonstrated on several applications, namely the phase imaging of metasurfaces using coherence controlled holographic microscope, the design of a metasurface-based fan-out element, and the multipolar analysis of far-fields generated by objects embedded within stratified media.
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