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Ionization detector of secondary electrons for environmental scanning electron microscope
Dušek, Petr ; Zimáková, Jana (referee) ; Čudek, Pavel (advisor)
This thesis deals with problematics of a detection of secondary electrons by ionization detector for environmental scanning electron microscope. In this thesis is described the difference between scanning electron microscope and environmental scanning electron microscope. Further there is described emission and detection of the choosen signals that arise while primary electrons are interacting with a specimen in scanning electron microscope. A special emphasis is placed on a description, sorting and on the form of detection of secondary electrons. In thesis there is described principle of a function of ionization a scintilation detectors. Experimental part of thesis describes design of 3 different elctrode systems of a tabular ionization detector, which will be intended to be placed in environmental scanning electron microscope. Based on measuring with the detectors, with experimental design, there is chosen one with the highest quality of signal detection.
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Scintillation SE detector for ESEM
Odehnal, Adam ; Špinka, Jiří (referee) ; Jirák, Josef (advisor)
Thesis deals with theoretical knowledge about scanning electron microscopy and environmental scanning electron microscopy. It describes principle of operation, signals generated by interaction between primary electron beam and specimen and means of detection of secondary electron signal in environmental conditions using scintillation detector. Furthermore, thesis focuses on optimization of detection od secondary electrons by adjusting electrode system of scintillation detector. Computer program Simion is used for modelling signal electron trajectories for proper adjustments. Simulation were starting-point for adjusting the design of the detector. Detection efficiency of adjusted detector was determined by evaluating signal magnitude from captured images, secondary electron detection capability from voltage contrast and quality of the captured images from signal/noise ratio.
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Detection of signal electrons in ESEM
Šváb, Martin ; Špinka, Jiří (referee) ; Jirák, Josef (advisor)
This bachelor's thesis deals with problems of environmental scanning electron microscopy and with detection of signal electrons at higher pressure in working chamber. In this thesis I will focus on comparison of detected signal level achieved under different working conditions.
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Scintillation Secondary Electrons Detector for ESEM
Čudek, Pavel ; Kadlec, Jaromír (referee) ; Rek, Antonín (referee) ; Jirák, Josef (advisor)
The thesis deals with the scintillation secondary electron detector for environmental scanning electron microscope, its design and construction. The starting point was numerical simulation of electrostatic fields and electron trajectories in the electrode system of the detector and simulation of pressure distribution and flow of gases in different parts of the detector. On the basis of modeling and simulation, construction changes of the detector were gradually implemented. Detection efficiency of each version of the detector was determined by the method described in the work. This method enables to evaluate signal level from the captured images of the specimen, quality of images was stated from signal to noise ratio. The thesis describes the whole process of the detector improvement from initial state, when the detector operated with lower efficiency in the pressure range from 300 to 900 Pa, to final version that enables usage of the detector in the range from vacuum up to 1000 Pa of water vapors in the specimen chamber of the microscope.
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Thermal stability of sputtered yttrium oxide layers
Kršňák, Jiří ; Boušek, Jaroslav (referee) ; Hégr, Ondřej (advisor)
This work deals with behavior of deposited yttrium oxide thin film after heat stress. Within solution thin yttrium oxide films were deposited at silicon substrates, which were exposed to various cycles of heat stress. Tested structures were investigated before and after heat stress in term of surface topography stability with the hepl of electron microscopy.
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Image analysis for correction of electron microscopes
Smital, Petr ; Schwarz, Daniel (referee) ; Kolář, Radim (advisor)
This thesis describes the physical nature of corrections of an electron microscope and mathematical methods of image processing required for their complete automation. The corrections include different types of focusing, astigmatism correction, electron beam centring, and image stabilisation. The mathematical methods described in this thesis include various methods of measuring focus and astigmatism, with and without using the Fourier transform, edge detection, histogram operations, and image registration, i.e. detection of spatial transformations in images. This thesis includes detailed descriptions of the mathematical methods, their evaluation using an “offline” application, descriptions of the algorithms of their implementation into an actual electron microscope and results of their testing on the actual electron microscope, in the form of a video footage grabbed from its control computer’s screen.
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Elemental composition analysis of inorganic materials
Szmek, Václav ; Richtera, Lukáš (referee) ; Zmrzlý, Martin (advisor)
This work deals with elemental analysis of inorganic materials, that are presented by blast furnace slag and geopolymeric material containing fly-ashes. In the theoretical part there are explained principles of elemental analysis of inorganic materials. Ways of dissolution of samples, optical emission spectroscopy and electron microscopy with energy dispersive x-ray analysis are commented. In experimental part the ICP analysis of oxide standards is described. The standards were used for estimation of EDS-correction factors. Then follow the preparation, proving and use of standards in analysis of blast furnace slag. The work is finished by exact analysis of concentration profiles of elements in interface of phases in geopolymeric material.
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Cellulose Nanofibers and Aerogel Materials
Salajková, Michaela ; Kalfus, Jan (referee) ; Jančář, Josef (advisor)
Tato diplomová práce se zabývá přípravou nových kompozitů na bázi mikrofibrilované celulozy a multi-walls carbon nanotubes (MFC/MWCNTs). Tři různé metody byly použity pro modifikaci MWCNTs. Byl zkoumán vliv použitých modifikací na kvalitu MWCNTs suspense. Dále byly připraveny kompozity obsahující MFC a MWCNTs a vliv MWCNTs na mechanické a elektrické vlastnosti a morfologii byl zkoumán. MWCNTs suspense byly charakterizovány za použití UV-VIS spektrofotometrie, Rastrovacího elektronového mikroskopu (SEM) a Termogravimetrické analýzy (TGA). Elektrické vlastnosti byly měřeny pomocí Keithly Electrometer/High Resistivity Meter. Mechanické vlastnosti v tahu byly měřeny za použití Miniature Materials Tester a pro studium morfologie byl použit SEM. Žádný významný vliv MWCNTs na mechanické vlastnosti nebyl pozorován. Hodnoty získané z měření rezistivity vykazují typický perkolační trend a výrazného snížení rezistivity bylo dosaženo přidáním 1 – 2 wt.% MWCNTs. Nicméně hodnoty se velice liší pro horní a spodní stranu téhož vzorku. Ze získaných výsledků vyplývá, že klíčovým krokem ke zdokonalení vlastností materiálu jsou dobrá suspense MWCNTs a také dosažení vzájemné kompatibility obou složek.
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Morphology study of organic molecular compounds thin films
Schön, Martin ; Vala, Martin (referee) ; Salyk, Ota (advisor)
This thesis deals with morphology study of organic molecular thin film compounds. The vapour deposition was used for thin films preparation. There are described used vacuum technology and measuring instruments in the theoretical part. In the second part is then described the experiment. The characteristics and morphology of thin films have been analyzed by scanning electron microscope (SEM). Influence of deposition temperature and distance between substrate holder and evaporator boat on film morphology have been analyzed. Diketopyrrolopyrrole (DPP) thin films have interesting chemical and physical properties, expecting wide range of applications, especially in electronics industry.
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