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Advanced SPM techniques for measuring electrical properties of materials
Kramář, Jan ; Konečný, Martin (referee) ; Pavera, Michal (advisor)
This bachelor thesis is concerned about development of local electric properties characterization technique of sample in contact mode of Atomic Force Microscopy. The research part describes the most expanded techniques of characterization of local electric properties using Scanning Probe Microscopy. For realization was chosen Scanning Spreading Resistance Microscopy. Important part of this technique is current amplifier. For that reason, operational amplifiers, circuits with them and implementation of new amplifier on microscop are described. Last chapter is dedicated to description of samples, which were used to test functionality of the amplifier and technique.
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Nonlinear phenomena in optical fibers
Burian, Radek ; Horváth, Tomáš (referee) ; Münster, Petr (advisor)
The subject of this thesis is to describe nonlinear phenomena in the optic fiber. The theoretical part describes a principle of transmission in optical fibers. Optics modules, fibers and their parameters are described marginally. Except nonlinear phenomena, there is also described linear phenomena such as attenuation, dispersion, scattering. In terms of nonlinear phenomena there is described second order phenomena such as Second harmonic generation (SHG), Sum and difference harmonic generation (SFG and DFG) and third order phenomena, such as Kerr effect, Third harmonic generation (THG), Four-wave mixing (FWM) and Cross phase modulation (XPM). There are also described nonlinear scattering, such as Raman´s and Brillouin´s scattering. The Four-wave mixing is simulated in the first half of the practical part. Four-wave mixing occurs in DWMD systems, where can invoke cross-talks between channels. In the second half of the practical part is measured this nonlinear phenomenon. The aim of the measurement is to understand the behaviour of the FWM and find the way how to eliminate its power. The Four-wave mixing measurement is based on the simulation. Second measurement is designed for Brillouin scattering. The conclusion from simulated and laboratory part from both measurements are compared with theoretical knowledge.
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Multifunctional SNOM probes of new generation for correlative SEM/SPM measurements
Zezulka, Lukáš ; Kolíbal, Miroslav (referee) ; Spousta, Jiří (advisor)
Práce se věnuje návrhu multifunkční SNOM sondy pro korelativní SEM/SPM měření využívající dutého optického vlákna s plným jádrem. V rešerši jsou prozkoumány možné způsoby výroby SNOM hrotů na dutém optickém vlákně, využití dutých kapilár pro přívod pracovních tekutin ke vzorku a možnosti přívodu potenciálového rozdílu ke vzorku pomocí kapilár vyplněných vodivým materiálem. Dále je v práci prezentován vyvinutý způsob výroby unikátních SNOM hrotů a celý koncept je ověřen provedenými korelativními měřeními. Následně jsou diskutované problémy spojené s výrobou a měřeními.
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Correlated probe and electron microscopy for the study of modern magnetic nanomaterials
Novotný, Ondřej ; Flajšman, Lukáš (referee) ; Pavera, Michal (advisor)
High pressure on the development of new magnetic materials and their miniaturization also emphasizes the development of new analytical techniques. This diploma thesis deals with the development and demonstration of correlated magnetic force and electron microscopy, which is a promising tool for the characterization of magnetic nanomaterials. The first part of this thesis describes the fundamental physics of micromagnetism with a focus on cylindrical nanofibers. The following pages describe optic, probe, electron, and synchrotron methods for mapping the magnetic properties of materials. The next part describes magnetic domain wall motion in cylindrical nanowires performed as a part of a more extensive material study. The last part of the thesis describes the development of correlated magnetic force and electron microscopy on LiteScope device. A production of magnetic probes was designed and successfully tested. Probes were fabricated by focused electron beam-induced deposition from the Co2(CO)8 precursor. Further, the developed correlated microscopy is demonstrated on a multilayer PtCo sample, magnetic cylindrical nanofibers, NiFe vortex structures, and FeRh metamagnetic nano-islands.
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Processing of MREG MRI data
Lampert, Frederik ; Mikl, Michal (referee) ; Gajdoš, Martin (advisor)
MR-encephalography (MREG) is an innovative method of ultrafast magnetic resonance imaging. Most of the publications about this method are concerning about acquisition and reconstruction of raw data. Studies dedicated to standardization of preprocessing MREG data have not been published yet, which led to motivation of creating this bachelor thesis. The main goal of this thesis is to set an optimal way of preprocessing MREG data, which could be advised for future studies utilizing this method. The main goal of this work was divided into several subgoals, consisting of making a literary review, implementation of general method for data preprocessing and suggesting an alternative ways of data preprocessing and their implementation into MATLAB programming language. Suggested ways of data preprocessing were evaluated by created criteria, described in this work. Results of the evaluation were discussed and interpreted by graphs. Based on the results of the evaluation, an optimal way for preprocessing data was set. It consists of movement and geometric distortion correction accomplished by SPM Realign & UNWARP function, spatial normalisation to EPI MNI template and spatial smoothing by Gaussian kernel.
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Correlative measurement of cathodoluminescence using SEM and SPM techniques
Černek, Ondrej ; Knápek, Alexandr (referee) ; Spousta, Jiří (advisor)
The diploma thesis deals with the combined use of SEM and SPM techniques using optical fiber, which is used to collect the cathodoluminescent signal in close proximity to the sample. The thesis also includes a research section, which lists description of CPEM technique, the techniques used to modify the optical fiber, theoretical introduction to cathodoluminescence and techniques used to measure it. The practical part discusses the obtained measurement results and the problems that occurred in the process of modification of the optical fiber, its use as an SPM probe and in the measurement of cathodoluminescence active materials.
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Noise and artifact suppression in fMRI data based on multi-echo data and independent component analysis
Pospíšil, Jan ; Gajdoš, Martin (referee) ; Mikl, Michal (advisor)
The main task of this work is to design an algorithm for suppressing unwanted noise and artifacts in fMRI data using the analysis of independent components and multi-echo data. The theoretical part deals with the basic principles of magnetic resonance, including construction and image data processing. The practical part presents a pilot design of a method inspired by a professional publication in the Matlab software environment, where this design is subsequently tested on real fMRI data provided by the Laboratory of Multimodal and Functional Imaging, CEITEC MU.
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Formation, Functionalization and Characterization of 2D Materials on Crystalline Supports
López-Roso Redondo, Jesús Rubén ; Švec, Martin (advisor) ; Gonzáles Pascual, César (referee) ; Mysliveček, Josef (referee)
In this thesis, the growth of 2D materials, in particular graphene and FeO2 on crystalline supports, is studied by a multitude of surface-sensitive techniques. The mechanisms of graphene growth in ultra-high vacuum and high Ar pressure are explored, and a simple device for the manufacturing of high-quality, monocrystalline graphene on SiC is described. The electronic and chemical properties of B and N dopants on graphene are characterized by means of STM/AFM with CO-functionalized tips and supported by DFT calculations. The chemical interaction of a probe molecule (FePc) with doped graphene is also investigated. The long-standing controversy of the so-called "biphase" reconstruction of α - Fe2O3(0001) is resolved by the discovery of a complete FeO2 overlayer in this phase. The structure of this overlayer is investigated by means of STM, LEEM and DFT calculations. A thorough description of the routes to obtain single phases over the whole surface of α - Fe2O3(0001) is provided.
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Use of a special optical fiber in an electron microscope chamber
Černek, Ondrej ; Konečný, Martin (referee) ; Pavera, Michal (advisor)
This bachelor thesis is concerned about the modification of vacuum chamber of the Scanning Electron Microscope VEGA developed by TESCAN Brno s.r.o. in order to implementation of Scanning Probe Microscope. Moreover, it is dedicated to development of apparatus for using hollow optical fiber allowing the guidance of light and various gases on the sample surface placed in the vacuum of electron microscope. By using the hollow optical fiber as a probe of Scanning Probe Microscope, it is possible to work with a tip with specific properties. A brief introduction to Scanning Electron Microscopy and Atomic Force Microscopy is presented in the theoretical part. Furthermore, there is a technique of using optical fibers in Scanning Near-field Optical Microscopy described. Also a problem of vacuum systems, gas flow through the pipe and technique of Gas Injection System is introduced. In the construction part, there are initiated steps in the development of the vacuum chamber and the apparatus allowing the guidance of hollow optical fiber into the chamber of microscope. The experimental part presents the result of measurements obtained by probe of Scanning Probe Microscope with modified optical fiber and gas transmissivity of hollow optical fiber.
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Mechanical excitation of self sensing SPM probes
Novotný, Ondřej ; Piastek, Jakub (referee) ; Pavera, Michal (advisor)
This bachelor thesis deals with the development of the SPM microscope probe holder which is designed for mechanical excitation of the probes. The first part of the thesis focuses on the description of physical theory, such as the principle of atomic force microscopy, the function of piezoceramics and the description of used quartz tunning fork based probes. The second part describes the gradual development and design of the new probe holder. Testing of the designed probe holder and comparison of mechanical and electric excitation is depicted at the end of this work. The designed probe holder was manufactured, the assembly procedure was described, and the drawings of the individual parts were created.
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