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Influence of decreasing surface temperature of Si(100) on metal growth morphology at low coverage
Doležal, Jiří ; Ošťádal, Ivan (advisor) ; Matvija, Peter (referee)
The thesis is focused on study of growth of tin chains on Si(100) surface deposited by vacuum evaporation at temperatures below room temperature. Scanning tunneling microscopy (STM) was used for surface imaging and growth characteristics were determined from the data. Comparison of the characteristics for different deposition temperatures and two different coverages shows a dominant role of the same growth mechanism in all cases. An influence of heating toward room temperature on chain length distribution of structures prepared at low temperatures is described and discussed. A role of Cdefects at the chain growth and a corresponding influence on shape of a scaling function of the chain length distribution is discussed as well. Properties of the STM system with liquid nitrogen cooling were successfully tested together with developed pumping of nitrogen into a container inside the STM vacuum chamber.
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Electronics and adsorption properties of model catalytic systems contains cerium
Cabala, Miloš ; Veltruská, Kateřina (advisor) ; Jiříček, Petr (referee) ; Polčík, Martin (referee)
Title: Electronics and adsorption properties of model catalytic systems contains cerium Author: Miloš Cabala Department: Department of Surface and Plasma Science, Supervisor: RNDr. Kateřina Veltruská, Department of Surface and Plasma Science, Abstract: The doctoral thesis contains the study of model catalyst systems based on cerium and ceria. The thesis deals with model systems of CeAg, CeO2/Cu(111), Ni- CeO2/Cu(111) a Ni-Sn-CeO2/Cu(111). We have studied these systems using photoelectron spectroscopy, ion scattering spectroscopy and low energy electron diffraction. Model systems were prepared under strictly defined conditions. The strong bimetallic interaction was observed on the CeAg layers. Molecular adsorption of carbon monoxide on CeAg was demonstrated. We also observed intensive reaction of these layers with oxygen. By measurements in different directions of surface Brillouin zone, we managed to reconstruct the band structure of the prepared CeO2/Cu(111) layer. We have shown that the Cu substrate interacts weakly with deposited CeO2 layer. This interaction results in a charge transfer from Cu into CeO2. Overall, in the valence spectrum we have identified three main electron bands corresponding to O 2p state bound in CeO2. It has been proven that the deposition of Ni on CeO2 layers leads to partial...
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Study of the structure and of interaction with gas molecules of Rh-Sn and Rh-SnO2
Janeček, Petr ; Nehasil, Václav (advisor) ; Jirka, Ivan (referee) ; Bartoš, Igor (referee)
In this work we present the results of the analysis of the surface structures and absorption properties with respect to the CO and O2 molecules of the Sn/Rh and Rh/SnO2 model systems. In the part dedicated to the Sn structures on Rh surfaces with two different orientations - Rh(110) and Rh(111) - we have investigated the development of the core electron levels and valence band during the development of surface reconstructions and absorption of CO molecules. The surface reconstructions of the Sn/Rh(110) systems were studied for the first time. Difference in behaviour w.r.t. Sn/Rh(111) was observed and explanation offered. Finally, on in-situ prepared epitaxial SnO2 layers, the surface reconstruction (4×1) was observed. The CO adsorp- tion properties of Rh on polycrystalline and epitaxial SnO2 layers were also studied and difference in behaviour explained.
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