Národní úložiště šedé literatury Nalezeno 17 záznamů.  1 - 10další  přejít na záznam: Hledání trvalo 0.01 vteřin. 
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.
Single-Molecule Magnets with Trigonal Symmetry of the Coordination Polyhedron: Structure, Magnetic Properties and Deposition on Surfaces
Havlíček, Lubomír ; Pinkas,, Jiří (oponent) ; Čižmár,, Erik (oponent) ; Neugebauer, Petr (vedoucí práce)
This thesis focusses on synthesis, structure and magnetization study of Single Ion Magnets with trigonal symmetry and their deposition on surfaces. The first part outlines the introduction into State of the art of the Single Molecule magnets. Followed by description of methods used to perform all discussed characterizations and theoretical background of these methods. In the next part are discussed all the obtained results and it is concluded by discussion about the achieved aims of this thesis. The last part of this thesis provides references and author’s published results.
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.
High frequency electron spin resonance spectroscopy
Hrubý, Jakub ; Perfetti, Mauro (oponent) ; ShangDa, Jiang (oponent) ; Neugebauer, Petr (vedoucí práce)
Electron spin resonance (ESR) is a non-invasive magnetic-resonance-based spectroscopic technique. It is used in many scientific fields such as biology, chemistry, and physics to investigate systems with unpaired electrons. This doctoral thesis deals with high-frequency electron spin resonance (HF-ESR) spectroscopy and its use on paramagnetic coordination compounds. The first part outlines theoretical basics with literature research in this field and shows the HF-ESR applications. Afterwards, methods used to study systems of interest are presented. Herein, the complementary spectroscopic methods (XPS, RS, UV-VIS, AFM, SEM) are described, and the design of a newly built high-vacuum (HV) sublimation chamber was developed for the preparation of thin films of coordination compounds on surfaces. The next part deals with results obtained by HF-ESR on molecular quantum bits [Cu(dbm)2], single-molecule magnets [CoX2(dppf)], [Co(4MeO-L)2Cl2], and vision of graphene-based bolometers for detection of this class of compounds is outlined. The results are further discussed, and their implications are summarised in conclusions. Finally, references and the author's outputs make up the final chapters of this work.
Design of mobile vacuum chamber for loading samples into high-frequency electron paramagnetic resonance spectrometer
Láznička, Tomáš ; Slageren, Joris van (oponent) ; Neugebauer, Petr (vedoucí práce)
In order to be able to characterize atmosphere sensitive samples in high-frequency electron paramagnetic resonance spectrometer (HF-EPR), a system of vacuum transportation is needed. The scope of this thesis is to design and develop a vacuum transport system which will allow this transportation. The vacuum system, which consists of a mobile vacuum suitcase, palette holder and airlock, was designed, assembled and tested. The pressure of 4.3 10^{-10} mbar was achieved, which will ensure inert condition for sample transportation. The transport of the sample from an ultra-high vacuum (UHV) cluster to the HF-EPR spectrometer was performed. The contamination of the test samples was characterized using x-ray photoelectron spectroscopy. It was found that there is no detectable contamination if the sample is in the vacuum system for less than 16 hours. The extension for transportation of the samples from a glove box and sample palette for graphene were proposed, but their production has not been performed yet. The developed vacuum system is fully functional and provides the alternative to commercially available products, thus it will be further used in the investigation of an atmosphere sensitive samples in CEITEC Nano laboratories.
Design of a Non-Resonant General Purpose Sample Holder for Terahertz Electron Paramagnetic Resonance Spectroscopy
Martínek, Tomáš ; Sojka, Zbigniew (oponent) ; Neugebauer, Petr (vedoucí práce)
The aim of this diploma thesis is to design dedicated sample holders for a high-frequency electron paramagnetic resonance spectroscopy. The main task deals with the development of a user-friendly and fast locking system for connection between microwave waveguide and a sample holder. Two types of sample holders are designed one for loading multiple samples and one for single crystal rotation. Thanks to loading up to 6 samples the overall measurement time is estimated to be reduced more than twice. In the case of the single crystal rotator based on the precise piezoelectric rotator with resistive encoder a milliradian, precision is provided. Both sample holders are designed in such a way that the full automatization can be applied in the measurement.
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.
Frequency-swept rapid-scan EPR on organic radicals
Tuček, Marek ; Marko, Andriy (oponent) ; Neugebauer, Petr (vedoucí práce)
This thesis describes a historically first multi-frequency rapid-scan EPR. While introducing microwave radiation at 200 GHz range with subsequent sinusoidal modulation, the frequency sweep rates up to 61 500 THz/s were achieved and the rapid passage distortion known as ”wiggles” was observed in the spectra of both studied organic radicals samples – BDPA in a polystyrene matrix and LiPc. This thesis presents a flexible method of conducting rapid-scan EPR experiments, using a voltage controlled oscillator (VCO) and zero-bias detector (ZBD) as a source and detector, respectively, and thus opening the possibility to advance further into high field / high frequency range. Furthermore, the method of extracting the steady-state absorption spectra from the rapid-scan results, known as Fourier deconvolution, is described and subsequently, the spin dephasing times of the samples are determined from the comparison of the spectra with the results of numerically solved Bloch equations. The resulting values are 50 ns for BDPA and 12 ns for LiPc.
Faktory ovlivňující rozhodování na finančních trzích
Neugebauer, Petr ; Votava, Libor (vedoucí práce) ; Fujcik, Lukáš (oponent)
Mezi různými školami probíhá nekončící diskuse na téma efektivity finančních trhů. Mnoho provedených studií otevřelo prostor k posunu paradigmatu v otázce racio-nálního myšlení. V této práci je řešena problematika asymetrické intepretace informací při změněných stavech myšlení. Účelem studie je zjistit, jak v praxi použí-vaný nástroj v podobě obchodního plánu ovlivňuje chování aktérů. Pokud obchodníci podléhají iracionalitě, pravděpodobně dělají rozhodnutí, která snižují jejich potenciál. Proto byl sestaven experiment s účastníky z řad studentů FM VŠE. Byly sledovány proměnné během obchodování bez přípravy a následně s přípravou. Doplňující data mapují osobní kontext z pohledu řízení duševní pohody a sebere-flexe. Závěry naznačují výhodu používání obchodního plánu pro ovlivňování faktorů, které mohou negativně působit na kvalitu rozhodování.
Národní stereotypy: příklad Čechů v 19. století
Neugebauer, Petr ; Rak, Jiří (vedoucí práce) ; Konrád, Ota (oponent)
Hlavním cílem práce je popsat vznik, využívání a zánik národních stereotypů na příkladu Čechů v 19. století, s důrazem na formování českého autostereotypu. Využívá k tomu kombinaci klasického rozboru odborné literatury zabývající se daným tématem s odkazy na karikaturu. První kapitola se věnuje teoretickému ukotvení pojmů a vytváří tak teoretický základ práce. S využitím především sociologických poznatků definuje národ, stereotyp a národní stereotyp. Dále blíže zkoumá fungování národních stereotypů především vztah auto- a heterostereotypu. Druhá kapitola se věnuje českým národním stereotypům v 19. století. První podkapitola představí vývoj českého národního hnutí a následně zkoumá české národní stereotypy vycházející z historických mýtů. Mezi hlavní témata patří vztah k náboženství: katolické církvi a protestantismu (především husitství), odmítnutí šlechty a sakralizaci plebejství a také heterostereotypům Němců, Slovanů a Habsburské monarchie. Druhá podkapitola se soustředí na české národní stereotypy ve vypjatých 90. letech z pohledu mladočechů, realistů a sociálních demokratů.

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