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Zobrazování deformace kovových materiálů pomalými elektrony
Piňos, Jakub ; Kolíbal, Miroslav (oponent) ; Kasl, Josef (oponent) ; Frank, Luděk (vedoucí práce)
Rastrovací elektronová mikroskopie patří k běžným technikám analýzy moderních strojírenských materiálů. Rozvoj různých zobrazovacích technik umožňuje volit vhodný způsob pozorování pro získání nových informací o vzorku. Tato práce se zabývá přímým zobrazením deformace v kovových vzorcích pomocí rastrovací mikroskopie pomalými elektrony v průběhu in-situ tahové zkoušky. Experimenty byly provedeny na vzorcích z čisté mědi. V průběhu zkoušek byly získány snímky umožňující sledovat vývoj vlivu deformace na mikrostrukturu materiálu od jeho prvních projevů ve struktuře při intenzitách plastické deformace 3-4% až po extrémní plastickou deformaci na čele trhliny.
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Thermal desorption spectroscopy in prototype furnace for chemical vapor deposition
Průcha, Lukáš ; Daniel, Benjamin ; Piňos, Jakub ; Mikmeková, Eliška
Cleaning of the sample surfaces is crucial for scanning electron microscopy, especially for\nlow energy electron microscopy or for the deposition of thin layers, such as graphene,\nwhere surface has to be well prepared. In the best case, every unwanted particle should be\ncleaned from the sample surface for best low energy electron microscopy observation or thin\nfilm deposition. Unfortunately, the standard cleaning procedures can leave residues on the\nsample surface. This work is focused on thermal desorption spectroscopy (TDS). TDS is a method of observing desorbed molecules from a sample surface during the increase of\ntemperature of the sample. The aim of this study was to determine optimum conditions:\ntemperature and time, to achieve clean surfaces in the shortest time.
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Real time observation of strain in the SEM sample
Piňos, Jakub ; Frank, Luděk
The SEM with various detector arrangements and analytical attachments represents an\nirreplaceable tool in material research. One of the techniques available in most contemporary\nmicroscopes is the scanning low energy electron microscopy (SLEEM) with biased specimen, marketed as the beam deceleration mode, gentle beam and others. The SLEEM allows\ncontrolling the information depth of the backscatter electron (BSE) imaging within a wide\nrange by altering the landing energy of electrons.
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Very low energy electron transmission spectromicroscopy
Daniel, Benjamin ; Radlička, Tomáš ; Piňos, Jakub ; Mikmeková, Šárka ; Konvalina, Ivo ; Frank, Luděk ; Müllerová, Ilona
For more than 25 years, Scanning Low Energy Electron Microscopy (SLEEM) has been\ndeveloped at the Institute of Scientific Instruments (ISI), with several commercially available SEMs adapted with a cathode lens for SLEEM use, as well as a dedicated self-built UHVSLEEM setup.\nFor a better understanding of contrast formation at low energies, especially at very low energies below 50 eV, where the local density of states plays an important role, more general knowledge about the interaction of (very) low energy electrons with solids is required. This will be achieved using a newly developed ultra-high vacuum (UHV SLEEM) setup which includes several enhancements compared to other available machines. Data processing is presented in, and processed data will be further used and tested with the Monte Carlosimulation package BRUCE, which is being developed by Werner et al. at TU Vienna.
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The information depth of backscattered electron imaging
Piňos, Jakub ; Mikmeková, Šárka ; Frank, Luděk
Of the conventional imaging signals in the scanning electron microscope (SEM), the secondary electrons generally reflect surface properties of the sample, while the backscattered electrons (BSE) are capable of providing information about complex properties of the target down to a certain subsurface depth. Contrast mechanisms are combined according to the energy of incident electrons and energy and angular acceptance of BSE detection. In all cases, a question arises concerning the information depth of this mode. No applicable answer provides a definition declaring this depth as that from which we still obtain useful information about the object. We can employ software simulating the electron scattering in solids,\nwhile experimental approaches are also possible. Moreover, two analytic formulas can be found in the literature.
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Very low energy STEM/TOF system
Daniel, Benjamin ; Radlička, Tomáš ; Piňos, Jakub ; Frank, Luděk ; Müllerová, Ilona
Scanning low energy electron microscopes (SLEEMs) have been built at ISI for over 20 years, either by modification of commercially available SEMs with a cathode lens or completely self-built in case of a dedicated ultra-high vacuum scanning low energy electron microscope (UHV SLEEM). Recently, the range of detection methods has been extended\nby a detector for electrons transmitted through ultrathin films and 2D crystals like graphene. For a better understanding of interaction between low energy electrons and solids in general, and the image contrast mechanism in particular, it was considered useful to measure the energy of transmitted electrons. This allows a better comparison with simulations, which suffer from increasing complexity due to a stronger interaction of electrons with the density of states at low energies.
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