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Implementation of a Multipurpose Measurement System for (Sub)Terahertz Electron Spin Resonance Spectroscopy
Šedivý, Matúš ; Malik, Aamir Saeed (referee) ; Epel, Boris (referee) ; Vrba, Radimír (advisor)
Spektroskopie elektronové spinové rezonance (také nazývaná elektronová paramagnetická rezonance nebo jen EPR) zahrnuje metody, které zkoumají hmotu prostřednictvím nepárových elektronů. Jednou z progresivních metod EPR je rychlé skenování, které umožňuje pozorovat kinetiku chemických reakcí. Kromě toho nedávný vývoj vysokofrekvenčních součástkách rozšířil použití vysokofrekvenční EPR (HFEPR), které využívají sub-terahertzové až terahertzové vlny. Tato práce se zabývá propojením obou cest do HFEPR spektrometru s rychlým skenováním frekvencí (FRaScan), který byl nedávno vyvinut na CEITEC VUT. Na začátku je stručně uvedena základní teorie k EPR, následovaný přehledem přístrojového vybavení pro HFEPR. V praktické části je popsáno technické řešení spektrometru. Důraz je kladen na implementaci softwaru, pomocí kterého je spektrometr ovládán a měření jsou automatizována. Následně jsou ukázány příklady z měření pevných látek, konkrétně karbidu křemíku dopovaného vanadem (SiC:V), ftalocyaninu líthia (LiPc) a krystalu 1,3-bisdifenylen-2-fenylallylu (BDPA). Příklady demonstrují schopnosti spektrometru získat multifrekvenční vlnově spojitá EPR spektra a frekvenčně rozmítaná spektra v závislosti na teplotě a orientaci vzorku, a taky spektra pomocí rychlého skenování frekvencí
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Optimization of the experimental NQR spectrometer
Segiňák, Ján ; Král, Bohumil (referee) ; Steinbauer, Miloslav (advisor)
The thesis deals with the NQR spectroscopy, which is one of the modern non-destructive measurement and diagnostic methods for the characterization of various materials. It is using a quadrupole moment - a property of atomic nuclei of certain isotopes. A method of nuclear quadrupole resonance (NQR) is in principle very similar to nuclear magnetic resonance (NMR). Thesis in the theoretical part analyse the principles of NMR and NQR, describes the possible use of this method to detect for example explosives, drugs, and other chemicals. In the following chapters are analysed the key parameters of NQR spectrometer and the principle of the chosen measurement method. The practical part deals with the individual components of NQR spectrometer, the design of possible improvements and programming of the measuring sequence. In the final chapter are processed the measurements of the submitted samples.
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Automatic sample tilt compensation for chemical mapping by LIBS
Stříbrná, Klára ; Pořízka, Pavel (referee) ; Prochazka, David (advisor)
This thesis deals with designing an algorithm for slope compensation of a sample examined using the LIBS (Laser-induced breakdown spectroscopy) method. It mainly fucuses on the purpose of elemental mapping. The sample slope noticeably affects the result quality and therefore a demand for a simple and inexpensive solution to this problem appeared that would also be applicable for commercial uses of LIBS.
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High frequency electron spin resonance spectroscopy
Hrubý, Jakub ; Perfetti, Mauro (referee) ; ShangDa, Jiang (referee) ; Neugebauer, Petr (advisor)
Elektronová spinová rezonance (ESR) je neinvazivní spektroskopická technika založená na magnetické rezonanci. Používá se v mnoha vědních oborech jako biologie, chemie a fyzika pro zkoumání systémů s nepárovými elektrony. Tato dizertační práce se věnuje spektroskopii vysokofrekvenční rezonance spinů elektronů (HF-ESR) a jejímu použití na paramagnetické koordinační sloučeniny. V první části je představen teoretický základ s rešerší literatury v této oblasti a jsou představeny aplikace HF-ESR. Dále jsou představeny metody použité ke studování těchto systémů. Zde jsou popsány doplňující metody (XPS, RS, UV-VIS, AFM, SEM) pro zkoumání vzorků a je představen návrh nové sublimační komory vysokého vakua, která byla sestavena pro tvorbu tenkých vrstech koordinačních sloučenin na površích. Následují výsledky dosažené pomocí HF-ESR na molekulárních kvantových bitech [Cu(dbm)2], jednomolekulárních magnetech [CoX2(dppf)], [Co(4MeO-L)2Cl2] a je nastíněna vize bolometrů na bázi grafenu pro detekci této třídy sloučenin. Výsledky jsou diskutovány a jejich implikace jsou shrnuty v závěru. Reference a autorské výstupy pak uzavírají celou tuto práci.
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DESIGN OF FIBER-OPTIC BIOSENSOR WITH NEAR-INFRARED SPECTRAL ANALYSIS
Křepelka, Pavel ; Jakubec,, Martin (referee) ; Skládal, Petr (referee) ; Mikulka, Jan (advisor)
This thesis deals with a measurement and interpretation of NIR spectra of bacterial cells and design of biosensor using this analytical technique. In the first chapter, there is introduction of current state of knowledge in the field of NIR spectroscopy in microbiology and technology of fiber optic biosensors. The summary of this chapter shows that NIR is a suitable technique for direct molecular analysis of bacteria, but it suffers from low sensitivity and insufficient interpretation of bacterial spectra. In the next part of the thesis, there is a theoretical background of spectral analysis techniques and technology of fiber optic sensors. In the practical part of this work, there is suggested the elimination of disadvantages of NIR spectroscopy in microbiology by a series of experiments used for interpretation of NIR spectra of bacteria and design of fiber optic sensor to increase sensitivity of this technique. In this work, spectral regions important for the identification of bacterial strains were determined and partially interpreted and the sensor for bacterial analysis capable of classifying strains based on 105 captured cells was designed. Therefore, the objectives of this work were fulfilled.
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Numerical optimization of absorption of mid-infrared plasmonic structures
Kulič, Martin ; Křápek, Vlastimil (referee) ; Kvapil, Michal (advisor)
Plasmonic nanostructures have a long and rich history in spectroscopy and sensing. First, we look at the history and applications of plasmonic structures and we discuss the parameters that influence the enhancement of various methods. Then the influence of plasmonic nanostructures on energy absorption in a thin layer of silicon oxide, silicon nitride and silicon-rich oxynitride of varying thickness is probed using Lumerical FDTD Solutions software. The last part of this thesis focuses on numerical demonstration of application of plasmonic antennas in spectroscopy.
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Optimization of thin films of metal oxide materials
Vítek, Jiří ; Šimonová, Lucie (referee) ; Šubarda, Jiří (advisor)
This thesis is focused on the description of the method of reactive sputtering of thin films. Currently, there are many ways how to create thin films and there are many applications of thin films in various industrial sectors. In this paper at the first are listed the issue of thin films, followed by an overview of the deposition techniques and of the chemical analysis of deposited thin films. It also describes the four-point measurement method of sheet resistance, mechanical test of adhesion and optical properties. At the end of the theoretical part are described the material composition of the deposited films. The goal of the practical part is to optimize the deposition process of the mixed layer of indium tin oxide (In2O3: SnO2) and contribute to the overall understanding of the influence of annealing on the layer. There were created six series of samples with that applied layers. First, the work focused on examining of the influence of annealing on the throughput in the whole measuring range, and then comparing the series due to the transmittance in the visible light spectrum. Furthermore were compared the value of sheet resistance of unannealed and subsequently annealed samples.
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Fluorine detection by means of Laser-Induced Breakdown Spectroscopy
Jaworková, Magdalena ; Pořízka, Pavel (referee) ; Prochazka, David (advisor)
This work concerns the Laser Induced Break-down Spectroscopy LIBS and it´s usage in detection of fluorine in specimens. This method and the particular methods of measurements suitable for fluorine detection are analysed in theoretical part. The sensitivity of particular methods such as usage of buffer gases (He), change of ambient pressure, usage of double laser pulse (DP–LIBS) or detection of molecular bands are compared in experimental part.
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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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Geometry of protein moleculs
Novotný, Jan ; Maděránková, Denisa (referee) ; Škutková, Helena (advisor)
Objective of this work was to study the spatial arrangement of protein molecules, with their extraction, notations and variables used in the course descriptions. Prediction of protein structures is very important for determining the future function of proteins. Another objective was to create a function in MATLAB that will graphically represent the spatial arrangement of the backbone structure of the protein by form Ramachandran plot. Along with this function create another function to render the side-chains of amino acids and function to calculate the stereochemical quality. Finally, create a program for a complete assessment of the spatial arrangement of the protein molecules and calculating the stereochemical quality of and test program for protein structures from public databases RSCB PDB.
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