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Analysis of Nanostructures by ToF-LEIS
Duda, Radek ; Král, Jaroslav (referee) ; Mašek, Karel (referee) ; Dub, Petr (advisor)
The presented thesis deals with the utilization of TOF-LEIS analytical method in the area of nanostructure analysis. A new procedure for depth profiling of the elemental composition of the sample, based on the alternate measurement with the DSIMS method, was established. The TOF-LEIS method is able to detect the interface between the layers before its mixing by the ion beam of the DSIMS method. Furthermore, a procedure of TOF-LEIS spektra modification was established to obtain the actual concentration of elements in the sample by reduction of a multiple collision contribution. By comparison of TOF-LEIS spectra with the results received by the DSIMS method the ratio of molybdenum and silicon ion yields was obtained. In the next section advantages of the TOF-LEIS method in combination with XPS during analysis of thermal stability of gold nanoparticles are presented. The mutual complementarity of both methods is shown and final conclusions are supported by electron microscopy images. The final section deals with a newly assembled apparatus for the TOF-SARS analytical method and shows its possibilities regarding the detection of hydrogen on the graphene.
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Study of physical and chemical properties of tin dioxide-based systems
Leiko, Oleksandr ; Mašek, Karel (advisor) ; Korotcenkov, Ghenadii (referee) ; Pihosh, Yuriy (referee)
Title: Study of physical and chemical properties of tin dioxide-based systems Author: Oleksandr Leiko Department: Department of Surface and Plasma Science Supervisor: doc. RNDr. Karel Mašek, Dr. Abstract: In the presented work, we studied the tin dioxide-based systems and their interaction with methanol and the influence of palladium doping on such interaction. Epitaxial tin dioxide model systems were prepared on the copper and rutile single-crystal surface by evaporation in the reactive atomic oxygen flux or in the elevated pressures of molecular oxygen. More complex polycrystalline tin dioxide layers were prepared by magnetron sputtering. Studies of the methanol decomposition on pure and palladium loaded tin dioxide systems were performed by the photoelectron spectroscopy technique under near-ambient pressure or in ultra-high vacuum conditions using synchrotron radiation. The studies revealed that methanol decomposes through C-H and C-O scission reactions. The C-O scission reaction intensity can be enhanced via palladium loading. Keywords: model systems, tin dioxide, photoelectron spectroscopy, methanol, palladium.
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Structural study of metal-CeO2/Cu(111) model systems by RHEED
Beran, Jan ; Mašek, Karel (advisor) ; Jiříček, Petr (referee)
The cerium oxide was deposited by reactive vacuum evaporation on the (111) surface of copper single-crystal in oxygen atmosphere at constant substrate temperatures of 25řC, 300řC and 450řC and at increasing temperature from 25řC to 450řC. In each case, the cerium oxide grew epitaxially with the (111) plane parallel to the substrate. The lattice parameter of the oxide increased up to the value of 5,28 during the deposition. At increasing temperature the growth of additional three-dimensional domains with tetrafold symmetry and (100) plane parallel to the surface was observed. Lattice parameter of these domains exhibited the value of 5,36 in the direction parallel to the surface. These domains were also observed by STM. The palladium grew on the cerium oxide surface in form of epitaxial islands having (111) epitaxial plane parallel to the substrate surface. The palladium deposition resulted in the partial reduction of the oxide layer. The reduction was caused by the interaction of the palladium and oxygen atoms leading to the formation of PdO phase. This feature became more pronounced during annealing at 300řC. Annealing at higher temperatures led to coalescence of the palladium islands and thermal induced decomposition of the palladium oxide.
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Interoperability between component-based and service-oriented systems
Mašek, Karel
The component-based and service-oriented development have become commonly used techniques for building high quality, evolvable, large systems in a timely and affordable manner. In this setting, interoperability is one the essential issues, since it enables the composition of heterogeneous components and services. The aim of the thesis is to analyze possibilities of interoperability between the SOFA2 component system and the OSGi Service Platform, and based on that propose and implement a solution for mutual collaboration. The actual integration is based on the use of aspects and annotations. The issues connected with the runtime service management (e.g. binding/unbinding services) are handled by the control part of components using the aspects. While, the annotations serve for specifying service-enabled SOFA2 components in a declarative way. The OSGi support is incorporated in both the SOFA2 runtime environment and the tool for developing SOFA2 components. Furthermore, the outlined approach is general and can be easily reused for integrating other SOA-based systems as well.
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Study of physical and chemical properties of surface-modified tungsten oxide
Polášek, Jan ; Mašek, Karel (advisor)
Title: Study of physical and chemical properties of surface-modified tungsten oxide Author: Jan Polášek Department: Department of Surface and Plasma Science Supervisor: Doc. RNDr. Karel Mašek, Dr., Department of Surface and Plasma Science Abstract: This work can be divided into two parts. In the first part, we examine possibilities of preparation of monocrystalline tungsten and tungsten oxide na- noclusters by means of magnetron sputtering with gas aggregation. Clusters are prepared in the non-reactive (Ar) and reactive (Ar + O2) atmosphere and heated after the deposition or during the flight by IR radiation. Influence of oxygen in the aggregation process was described and possibilities of generating crystalline tungsten and tungsten oxide clusters were found. In the second part, we study reactivity of tungsten oxide layers, pure and doped with rare metals (Pt, Au), deposited on the silicon wafer and etched carbon, towards partial methanol oxi- dation. Influence of carbon substrate and metal doppants on reactivity was found and described, along with mofrological and chemical changes that occurs in the sample during the proces. Keywords: catalysis, tungsten oxide, clusters, partial oxidation of methanol, etched carbon 1
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