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Low energy excitations in oriented graphite by THz magneto-optical spectroscopy
Dubský, Jan ; Kunc, Jan (referee) ; Vrba, Radimír (advisor)
This master’s thesis deals with the modelling of electronic properties of graphite crystal, which are measurable using a spectrometer based on high frequency electron paramagnetic resonance (HFEPR for short) located in laboratories of CEITEC BUT. This is especially the band structure of graphite and its Landau levels. The theoretical part of the thesis describes key effects and connections from quantum mechanics and definitions of important terms from solid state physics, which are used to describe the crystalline structure of graphite and its electronic properties. Furthermore, the project describes the HFEPR spectrometer and its functional principle. In the practical part of the thesis, there are numerical models of the band structure of graphite and of its Landau levels and description of the preparation of a graphite sample for measurement. At the end of the practical part there is the analysis of measurements results, namely the cyclotron resonance and Shubnikov-de Haas oscillations, thanks to which it is possible to determine physical parameters of the sample, such as effective mass of charge carriers and fundamental frequency.
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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 (referee) ; Neugebauer, Petr (advisor)
Práca sa zaoberá vývojom ďalekej infračervenej spektroskopie v silnom magnetickom poli. Kombinácia ďalekej infračervenej spektroskopie a silného magnetického poľa je veľmi dôležitým nástrojom pri charakterizácii materiálov, ako sú jedno-molekulové magnety. Predstavuje tiež ideálnu experimentálnu techniku, ktorá dokáže skúmať a objasniť vlastnosti nových 2D materiálov. Ďaleká infračervená spektroskopia v magnetickom poli taktiež umožňuje študovať elektrónovú paramagnetickú rezonanciu (EPR) jedno-molekulových magnetov s veľmi veľkým delením pri nulovom poli, hlavne na báze komplexov prechodných kovov alebo lantanoidov, v ktorých bežne používané EPR systémy neposkytujú experimentálny prístup k magnetickým rezonančným prechodom. V práci sú podrobne popísané dve zostavy ďaleko infračervených spektrometrov pripojené k supravodivým magnetom. Prvá opísaná zostava, ktoré sa nachádza na univerzite v Stuttgarte, je už zmontovaná a jej výkon je diskutovaný. Magneto-optické merania jedno-molekulových magnetov vykonané na tejto zostave sú predstavené. Druhá magneto-optická zostava čerpá zo skúseností získaných pri prvej zostave a je určená pre CEITEC.
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Stability and properties of combined beverages and fruit concentrates
Klatová, Kamila ; Vítová, Eva (referee) ; Vespalcová, Milena (advisor)
This diploma thesis deals with the stability and basic properties of combined beverages and fruit concentrates. The theoretical part describes the production and use of fruit concentrates. Furthermore, the work deals with anthocyanic pigments and phenolic substances. The principle and instrumentation of liquid chromatography and electron paramagnetic resonance were described. In the next subchapter, the methods of determination of total anthocyanins and phenolic substances were described. The experimental part of the thesis described the determination of soluble solids, viscosity and antioxidant activity. The total content of phenolic compounds were determined by the Folin-Ciocalteua method and the total anthocyanins were determined by the pH-differential method. In the samples were determined cyanidine-3-glucoside and cyanidin-3-galactoside by liquid chromatography.
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