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Towards lateral interactions within self-organized monomolecular layers
Staněk, Jan ; Baše, Tomáš (advisor) ; Bastl, Zdeněk (referee)
This work aimed at the utilization of chemical principles for stabilization of self-assembled monolayers (SAMs) of carboranethiol derivatives on a flat gold surface. Ideas employing surface confined coordination complex formation and dipole-dipole intermolecular interactions were outlined and the respective literature survey was compiled. Preliminary experiments were carried out to test for their feasibility and surfaces modified with self assembled monolayers proved very sensitive to reaction conditions ordinarily used for bulk synthesis. The chemical sensitivity of the studied surfaces, the necessity of using appropriate surface-sensitive analytical techniques and the depth of the problem initially defined made this task both advanced and challenging. The formation of intermolecular coordination complexes with ω-carboxylated SAMs of meta-carborane-9-thiol was chosen to answer those issues, extending the previous work of the author on carboxylated carboranethiol isomers presented in his bachelor thesis. Concepts different of those based on coordination chemistry are briefly discussed as well, but more as prospects for future work and to present this work in a broader context to which it belongs. Characterization of molecules assembled on a surface in a single layer requires surface sensitive...
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Modification of TiO2 electronic properties by means of chemical treatment (doping)
Zukalová, Markéta ; Lásková, Barbora ; Procházka, Jan ; Bastl, Zdeněk ; Havlíček, D. ; Kavan, Ladislav
The product of the reaction of nanofibrous anatase with ammonia in gas phase is nanofibrous cubic titanium oxynitride, c-TiO2N3. In contrary to the preparation of cubic titaniurn oxynitride from microcrystalline TiO2, requiring temperatures above 800°C, the conversion of nanofibrous TiO2 to TiO2N3 is completed at about 500°C due to its enhanced chemical reactivity. This conversion is fully reversible; the product of the back reaction is again nanofibrous Ti02. By the thermal treatment of nanofibrous anatase in H2 flow at 800°C for 2 hours the mixture of black disordered anatase, rutile and titanium suboxides was prepared. Evidently, particular phases can be synthesized simply by tuning the temperature of the treatment, which is a subject of the further research.
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Metal Nanoclusters in Zeolite Nanocages: Synthesis and Characterization by X-Ray Photoelectron Spectroscopy
Bastl, Zdeněk ; Spirovová, Ilona
Rhodium and palladium nanoparticles were prepared in zeolites X and Y from ion exchanged metal ammine complexes by thermal decomposition of the complexes. X-ray photoelectron spectroscopy was employed to characterize individual steps of decomposition and growth of metal nanoparticles. Substantial reduction of Pd-tetraammine complex in zeolites by X-ray irradiation leading to inward diffusion of Pd and production of highly dispersed metal has been observed. Autoreduction by heating up to 400 oC resulted in significant decrease of Rh surface concentration and less pronounced decrease of Pd surface concentration. The Pd metal autoreduction occured readily in Y zeolite yielding small nanoclusters of Pd. The shifts of the core level binding energy of metal 3d electrons observed for thermally reduced metals in zeolites were consistent with presence of highly dispersed Rh metal and/or Rh+ and indicated interaction of Pd nanoparticles with zeolite matrix.
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Characterization of Supported Nanoparticles by Photoelectron Spectroscopy Methods
Bastl, Zdeněk ; Spirovová, Ilona
The study of low-dimensional materials has taken a broad importance due to the fundamental as well as technological interests. Metal nanoparticles are objects that occupy a special place between free atoms and three-dimensional systems [1]. The electronic structure of nanoparticles and their physico-chemical properties are of primary importance in their applications in heterogeneous catalysis, gas sensors, magnetic devices, etc. In the case of supported nanoparticles the influence of the substrate can modify significantly their electronic structure and induce special structures, leading thus to changes of properties important for applications. Because of high surface to volume ratio surface chemistry is crucial to control many properties of nanoparticles.
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