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Master's Thesis
Author of thesis: Ing. Mojmír Komora
Acad. year: 2017/2018
Supervisor: prof. Ing. Jan Čechal, Ph.D.
Reviewer: doc. Mgr. Adam Dubroka, Ph.D.
This thesis deals with study of alpha-Fe2O3(012) exposed to water environment. The up to date knowledge of different oxides with focus on alpha-Fe2O3 and its R-cut (012) non polar surface is briefly reviewed. The experimental part of this work start with the description of the state of the art ultra high vacuum compatible experimental setup for dosing liquid water onto single crystal surfaces. Individual features of the system are thoroughly discussed and the tests of the system were performed on silver foil and on Fe3O4(001) single crystal surface. The chemical composition and surface morphology of the crystal after liquid water experiment is discussed. The proposed setup was used to study interaction of water with known (1x1) and (2x1) surface reconstruction of alpha-Fe2O3(012). The experimental data shows that water binds to both reconstruction disociatively with some molecular water bound to adsorbed hydroxyls. The (1x1) reconstruction appears to survive exposure to different pressures of water vapor, while the (2x1) seems to change into (1x1) after exposures to higher pressures or by exposing it to electron beam. Further, this thesis presents the first real time study of (1x1)-to-(2x1) transition by Low Energy Electron Microscopy. These results show iniciation of the transition at atomic step edges and defects, which then continues to the centers of terraces at lower temperatures. Onservation of gradual transition at higher temperatures suggets creation of numerous nucleation centers from which then (2x1) spread. The beam damage is believed to also play role in the transformation as documented in the thesis.
Condensation liquid water doser, cold finger, drop maker, oxides, iron oxides, Hematite, $\alpha$-Fe$_2$O$_3$(012), STM, LEEM, XPS, LEED, LEIS
Date of defence
18.06.2018
Result of the defence
Defended (thesis was successfully defended)
Grading
A
Process of defence
XPS je povrchově citlivá metoda. Na vzorku se nachází 30 % nějaké sloučeniny, ale v XPS spektru není příliš zastoupena. Jak je to možné? Bylo by možné pro studium povrchu použít i metodu LEIS? Bývá zvykem v difraktogramech stopy indexovat. Proč to neděláte?
Language of thesis
English
Faculty
Fakulta strojního inženýrství
Department
Institute of Physical Engineering
Study programme
Applied Sciences in Engineering (M2A-P)
Field of study
Physical Engineering and Nanotechnology (M-FIN)
Composition of Committee
prof. RNDr. Tomáš Šikola, CSc. (předseda) prof. RNDr. Miroslav Liška, DrSc. (místopředseda) prof. RNDr. Bohumila Lencová, CSc. (člen) prof. RNDr. Jiří Komrska, CSc. (člen) prof. RNDr. Petr Dub, CSc. (člen) prof. RNDr. Radim Chmelík, Ph.D. (člen) prof. RNDr. Jiří Spousta, Ph.D. (člen) prof. RNDr. Eduard Schmidt, CSc. (člen) prof. RNDr. Pavel Zemánek, Ph.D. (člen) RNDr. Antonín Fejfar, CSc. (člen) doc. Ing. Radek Kalousek, Ph.D. (člen)
Supervisor’s reportprof. Ing. Jan Čechal, Ph.D.
Grade proposed by supervisor: A
Reviewer’s reportdoc. Mgr. Adam Dubroka, Ph.D.
Grade proposed by reviewer: A
Responsibility: Mgr. et Mgr. Hana Odstrčilová