In der vorliegenden Arbeit wird der reaktive ITO-Abscheidprozess unter Verwendung metallischer In:Sn-Targets eingehend untersucht. Die Schichtabscheidung erfolgt am symmetrisch bipolar gepulstem Dual-Magnetron sowohl auf ruhende als auch bewegte Substrate. Die Arbeit umfasst zwei Teilgebiete. Einerseits wurde der dynamische ITO-Abscheideprozess an einer industrienahen Versuchsanlage umfassend charakterisiert und anhand seiner physikalischen Parameter erfolgreich an eine industrielle Beschichtungsanlage überführt. Andererseits fanden statische Beschichtungen statt. Diese ermöglichen die Analyse der lateralen Verteilung der funktionellen Schichteigenschaften. Dadurch konnte eine Korrelation zu den lateralen Verteilungen der gemessenen Plasmaparameter herausgearbeitet werden.

Many orchid species are seriously endangered at present. Reasons for their disappearing from natural habitats remain often unclear. Orchids depend on mycorrhizal symbiosis in nature, however only little is known about this symbiosis. Seeds of some species do not germinate in vitro, making their cultivation for scientific and rescue purposes impossible. We found that seed germination of one of such reluctant species, Pseudorchis albida, is strongly inhibited by nitrates even at extremely low concentrations. As this species prefers oligotrophic mountain meadows, nitrate-induced inhibition probably take place in natural conditions. Surprisingly, we found similar but slightly weaker inhibitory effect also in typical mesophillic species and even in slightly eutrophic ones. The sensitivity to nitrates correlates with trophy level of species canopy. This inhibitory effect of nitrates could be weakened by application of a range of growth regulators, including auxins, cytokinins and gibberellins, and also by mycorrhizal fungi. The action of nitratereductase is essential for this inhibitory effect of nitrates. Experiments with NO donors, scavengers, and NO quantification are pointing right at NO as compound which perhaps mediates nitrate inhibitory effect. Based on these results, the nitrate inhibitory...

Concentration of Ce3+ is one of the most important parameters that influence the reactivity of ceria based catalyst. In this work we examine different experimental approaches for controlling Ce3+ concentration in cerium oxide model catalyst systems such as: i) influencing the stoichiometry of ceria, ii) introducing high valence doping agent, and iii) growing ultra thin ceria films with a strong metal substrate interaction. Structure, morphology and chemical state of prepared reduced ceria based systems were examined by means of surface science techniques: scanning tunneling microscopy, low-energy electron diffraction and X-ray photoelectron spectroscopy. In the present work an original method of ceria film reduction was introduced that allows stepwise control on stoichiometry and degree of film reduction (i). Further we introduce preparation procedures for well-ordered tungsten doped ceria model system (ii) and for the high quality 2D ultrathin ceria system on Cu (1 1 1) (iii). Preparation methods and model systems introduced in this work incorporate different physicochemical principles of Ce3+ induction and provide a variety of model systems useful for examining different effects that diversely prepared Ce3+ ions have on the activity of the catalyst.

This work can be divided into two parts. In the first part, we examine possibilities of preparation of monocrystalline tungsten and tungsten oxide nanoclusters 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 aggre- gation 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 oxidation. 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. 1

Present doctoral thesis is focused on electron microscopy and spectroscopy investigation of novel metal-oxide anode catalyst for fuel cell application. Catalyst based on Pt- doped cerium oxide in form of thin layers prepared by simultaneous magnetron sputtering deposition on intermediate carbonaceous films grown on silicon substrate has been studied. The influence of catalyst support composition (a-C and CNx films), deposition time of CeOx layer and other deposition parameters, as deposition rate, composition of working atmosphere and Pt concentration on the morphology of Pt-CeOx layers has been investigated mainly by Transmission Electron Microscopy (TEM). The obtained results have shown that by suitable preparation conditions combination we are able to tune final morphology and composition of catalyst. Composition of carbonaceous films and Pt-CeOx layers was examined by complementary spectroscopy techniques - Energy Dispersive X-ray Spectroscopy (EDX), Electron Energy Loss Spectroscopy (EELS) and X-ray Photoelectron Spectroscopy (XPS). Such prepared porous structures of Pt-CeOx are of promising as anode catalytic material for real fuel cell application. Keywords: cerium oxide, platinum, fuel cell, magnetron sputtering, Transmission Electron Microscopy

Proteinogenic amino acids are the basic structural building units of proteins. Their analysis is important in many fields, especially in medicine. This thesis deals with one of the methods of derivatization of amino acids in order to increase their absorption in the UV - the post-column derivatization using copper (II) oxide. It is quick, robust and easy-to-use method. Following the nowadays trend in the analysis of free amino acids, this thesis is focused on the HILIC mode separation environment.

Title: Model systems with the use of CeO2 for bioapplication Author: Sofiia Bercha Department: Department of Surface and Plasma Science Supervisor: Ing. Nataliya Tsud Ph.D., Department of Surface and Plasma Science Abstract: This thesis is focused on the investigation of model systems for bioapplications. Interfaces between biomolecules and inorganic materials were studied by means of advanced surface science techniques with emphasis on the molecular electronic structure and bonding geometry as a function of material morphology and/or molecular deposition method. For the histidine/cerium oxide system it is demonstrated that the morphology of the oxide determines the mechanism of the molecular adsorption. The presence of an aqueous medium does not alter the histidine interaction with the nanostructured cerium oxide. For the adenine/cerium oxide system we have shown that the adenine molecule chemisorbs on CeO2 intact via nitrogen atoms, independent of the oxide morphology and deposition technique. The adenine molecule was found to decompose on a reduced surface of the cerium oxide. Combining experimental and theoretical methods two distinct phases of adenine on CeO2 were found. For adenine/Cu(111) system it was shown that the strong interaction with the surface keeps the molecule intact on the surface till...

The combined electronic, optic and magnetic properties of transition metal (TM) implanted ferromagnetic TiO2 is of interest for spintronic applications. The nature of the observed abundant ferromagnetism in such materials has been investigated for more than one and a half decades, yet still no clear explanation for its appearance can be given. In this thesis, the origin of the ferromagnetic order in TM:TiO2 systems is studied by investigating the interplay between structural order, defects and incorporation of implanted ions within the host lattice. The defect properties of the host TiO2 are altered by preparing different microstructures of TiO2 (e.g. amorphous, polycrystalline anatase and epitaxial anatase). The difference in microstructure is also found to influence the incorporation of the implanted ions with the host lattice. The crystallographic incorporation of the implanted TM atoms is found only in crystalline films. Moreover, it is observed that the suppression of the dopant related secondary phases can also be achieved by changing the microstructure. The obtained experimental results are compared with the existing theoretical frameworks, while the most relevant one describing our findings is elucidated. Based on this discussion, we propose an ideal microstructural candidate for a dilute magnetic oxide material based on our results.:1 Introduction 2 1.1 Spintronics 2 1.2 Dilute magnetic oxides 5 2 Fundamentals 13 2.1 Introduction 13 2.2 Magnetism in diluted magnetic oxides 13 2.2.1 Possible locations of dopant 3d ions in an oxide matrix 14 2.2.2 Mean field model 15 2.2.3 Bound magnetic polaron model 16 2.2.4 Charge transfer model 17 2.2.5 Ferromagnetism in undoped oxides 19 2.2.6 Extrinsic sources of ferromagnetism 20 2.3 Motivation 21 3 Experimental 24 3.1 Sample preparation 24 3.1.1 DC magnetron sputtering 24 3.1.2 Ion implantation 27 3.2 X-ray methods 29 3.2.1 X-ray diffraction 29 3.2.2 X-ray absorption 31 3.2.2.1 Synchrotron radiation 31 3.2.2.2 Physics of X-ray absorption 31 3.3 SQUID magnetometry 35 3.3.1 Avoiding magnetic contamination 37 3.4 Positron annihilation spectroscopy 38 4 TM Implantation into Different TiO2 Structures (TM = Co, Mn, V) 43 4.1 Experiments 43 4.2 Co+ implantation: from diluted paramagnetism to superparamagnetic clusters 45 4.2.1 Cluster-free Co+-implanted TiO2 thin films 45 4.2.1.1 Experiments 45 4.2.1.2 Structural properties 46 4.2.1.3 Implantation-induced structural defects 47 4.2.1.4 Magnetic properties 50 4.2.1.5 Local environment of implanted Co atoms 51 4.2.1.6 Summary 52 4.2.2 Revealing nano-clusters within Co+-implanted TiO2 thin films 54 4.2.2.1 Experiments 54 4.2.2.2 Structural properties 54 4.2.2.3 Magnetic properties 57 4.2.2.4 Local environment of implanted Co atoms 59 4.2.2.5 Summary 61 4.3 Mn+ implantation: from a non-magnet to a ferromagnet 63 4.3.1 Experiments 63 4.3.2 Relation between lattice damage and defects 64 4.3.3 Electrical transport properties 65 4.3.4 Local environment of implanted Mn atoms 66 4.3.5 Magnetic properties 67 4.3.6 Summary 69 4.4 V+-implanted TiO2 thin films 71 4.4.1 Experiments 71 4.4.2 Magnetic properties 71 4.4.3 Summary 74 5 The effect of the open volume defects on the magnetic properties of V:TiO2 films prepared by doping during deposition 76 5.1 Experiments 76 5.2 Structural Properties 77 5.3 Investigation of the open volume defects 78 5.4 Magnetic, optical and electrical properties 79 5.5 Summary 81 6 Conclusions 84 6.1 Defects in TiO2 84 6.2 Formation of secondary phases 85 6.3 Evolution of the ferromagnetism in different microstructures of TiO2 87 7 Acknowledgments 91 / Die kombinierten elektrischen, optischen und ferromagnetischen Eigenschaften von TiO2, welches mit einem Übergangsmetall (TM) dotiert wurde, sind für Anwendungen in der Spintronik von hoher Bedeutung. Obwohl dieses Material seit mehr als anderthalb Jahrzehnten untersucht wird, kann derzeit noch keine eindeutige Erklärung für den beobachteten Ferromagnetismus gegeben werden. In dieser Arbeit wird die Ursache für die ferromagnetische Ordnung in TM:TiO2-Systemen untersucht, indem der Zusammenhang von struktureller Ordnung, Defekten und der Einlagerung der implantierten Ionen im Wirtsgitter analysiert wird. Durch die Verwendung unterschiedlicher Mikrostrukturen (z.B. amorphes, polykristalliner Anatas und epitaktischer Anatas) wurden auch die Defekteigenschaften des Wirts-Titanoxid variiert. Dabei zeigte sich ein Einfluss der unterschiedlichen Mikrostrukturen auf die Einlagerung der implantierten Atome in das Wirtsgitter. So konnte die Substitution von Ti-Atomen durch Atome des dotierten Übergangsmetalls nur in kristallinen Filmen beobachtet werden. Weiterhin wurde herausgefunden, dass die vom Dotanden hervorgerufenen Sekundärphasen durch die initiale Mikrostruktur unterdrückt werden können. Die experimentellen Ergebnisse wurden mit aktuellen Theorien verglichen. Zusammenfassend wird ein Überblick über die wichtigsten Ergebnisse gegeben, auf Basis welcher eine optimale Mikrostruktur für ein verdünntes magnetisches Oxid vorgeschlagen wird.:1 Introduction 2 1.1 Spintronics 2 1.2 Dilute magnetic oxides 5 2 Fundamentals 13 2.1 Introduction 13 2.2 Magnetism in diluted magnetic oxides 13 2.2.1 Possible locations of dopant 3d ions in an oxide matrix 14 2.2.2 Mean field model 15 2.2.3 Bound magnetic polaron model 16 2.2.4 Charge transfer model 17 2.2.5 Ferromagnetism in undoped oxides 19 2.2.6 Extrinsic sources of ferromagnetism 20 2.3 Motivation 21 3 Experimental 24 3.1 Sample preparation 24 3.1.1 DC magnetron sputtering 24 3.1.2 Ion implantation 27 3.2 X-ray methods 29 3.2.1 X-ray diffraction 29 3.2.2 X-ray absorption 31 3.2.2.1 Synchrotron radiation 31 3.2.2.2 Physics of X-ray absorption 31 3.3 SQUID magnetometry 35 3.3.1 Avoiding magnetic contamination 37 3.4 Positron annihilation spectroscopy 38 4 TM Implantation into Different TiO2 Structures (TM = Co, Mn, V) 43 4.1 Experiments 43 4.2 Co+ implantation: from diluted paramagnetism to superparamagnetic clusters 45 4.2.1 Cluster-free Co+-implanted TiO2 thin films 45 4.2.1.1 Experiments 45 4.2.1.2 Structural properties 46 4.2.1.3 Implantation-induced structural defects 47 4.2.1.4 Magnetic properties 50 4.2.1.5 Local environment of implanted Co atoms 51 4.2.1.6 Summary 52 4.2.2 Revealing nano-clusters within Co+-implanted TiO2 thin films 54 4.2.2.1 Experiments 54 4.2.2.2 Structural properties 54 4.2.2.3 Magnetic properties 57 4.2.2.4 Local environment of implanted Co atoms 59 4.2.2.5 Summary 61 4.3 Mn+ implantation: from a non-magnet to a ferromagnet 63 4.3.1 Experiments 63 4.3.2 Relation between lattice damage and defects 64 4.3.3 Electrical transport properties 65 4.3.4 Local environment of implanted Mn atoms 66 4.3.5 Magnetic properties 67 4.3.6 Summary 69 4.4 V+-implanted TiO2 thin films 71 4.4.1 Experiments 71 4.4.2 Magnetic properties 71 4.4.3 Summary 74 5 The effect of the open volume defects on the magnetic properties of V:TiO2 films prepared by doping during deposition 76 5.1 Experiments 76 5.2 Structural Properties 77 5.3 Investigation of the open volume defects 78 5.4 Magnetic, optical and electrical properties 79 5.5 Summary 81 6 Conclusions 84 6.1 Defects in TiO2 84 6.2 Formation of secondary phases 85 6.3 Evolution of the ferromagnetism in different microstructures of TiO2 87 7 Acknowledgments 91

Wir untersuchen die Phasenbildung von Festkörperlösungen von (InxGa1-x)2O3 experimentell mittels Transmissionselektronenmikroskopie und stützen uns bei der Modellierung auf die Clusterexpansion. Epitaktische (InxGa1-x)2O3 Schichten auf kristallinen Substrate sind durch ausgeprägte Ordnung auf den Kationenuntergittern gekennzeichnet, bei welchem In und Ga sich auf Gitterplätze einbauen auf denen sie die energetisch günstigste Koordination zum Sauerstoff einnehmen. Ausgehend von diesem Befund, modifizieren wir das Modells der idealen Mischung so dass wir die Konfigurationsentropie auf den kationischen Untergittern mit spezifischer Koordinations getrennt betrachten um diese realistisch zu berechnen. Das resultierende Phasendiagramm ist durch enge thermodynamisch Stabilitätsbereiche für die jeweiligen Phasen gekennzeichnet, weil sich gleichzeitig große metastabile Zusammensetzungsbereiche ergeben bei Temperaturen die typisch für epitaktisches Wachstum sind: so ist die monokline Phase im Zusammensetzungsbereich x<0.5 metastabil, die hexagonale Phase für 0.55<x<0.7 und die kubische Bixbyit-Phase für x>0.91. Wird amorphes (InxGa1-x)2O3 kristallisiert in-situ im TEM, bildet sich im Zusammensetzungbereich bis x<0.22 die Spinellphase, die als ungeordnete Variante der monoklinen Phase beschrieben wird. Oberhalb dieser Zusammensetzung ist die kubische Phase stabil. Ursache hierfür ist der Einfluss der maximale Menge an Konfiguartionsentropie auf die Bildungsenthalpie in Strukturen mit vielfältigem Koordinationsumgebungen der Kationen. Der letzte Teil der Arbeit befasst sich mit dem Einflusses der Gitterordnung auf den Materialkontrast bei der Abbildung mittels HAADF (High Angle Annular Dark Field) STEM. Hier wird gezeigt, dass die Anregung des 2s-Bloch-Wellen-Zustands zu langperiodsichen Kontrastoszillationen führt, die die quantitaive Bestimmung der Zusammensetzung mittels Z-Kontrast erschwert es aber erlaubt den Ordnungsparameter bei bekaannter Zusammensetzung zu messen. / We investigate the phase formation in (InxGa1-x)2O3 solid solutions experimentally by means of transmission electron microscopy (TEM) and with computational support using cluster expansion. In the case of epitaxial growth on crystalline substrates, we find strong ordering on the cation sublattices of (InxGa1-x)2O3, energetically driven by the tendency of In and Ga to each assume their preferred coordination environment. Based on this experimental finding, we modify the model of the ideal mixture by considering the configurational entropy on the respective cation sublattices with different coordination separately in order to calculate it realistically. The resulting phase diagram is characterized by narrow thermodynamically stable ranges for each phase, while wide composition ranges of metastable compounds are predicted, which can be achieved at temperatures typical for epitaxy: the monoclinic phase is metastable in the composition range x<0.5, the hexagonal phase for 0.55<x<0.7, and the cubic bixbyite phase for x>0.91. If amorphous (InxGa1-x)2O3 is crystallized in-situ in the TEM, the spinel phase, which is described as a disordered variant of the monoclinic phase, is formed in the composition range up to x<0.22, while above this composition, the bixbyite phase is stable. This shift in stability is explained by the maximum amount of configurational entropy present during crystallization, which strongly influences the formation enthalpy in structures with diverse coordination environments of the cations. The last part of the work deals with the influence of the lattice order on the material contrast when imaging by HAADF (High Angle Annular Dark Field) STEM. It is shown that the excitation of the 2s-Bloch wave state leads to long-period contrast oscillations, which complicate the quantitative determination of the composition by Z-contrast but allows to quantify the order parameter for a given composition.

Title: Study of cerium oxide thin films for biosensing applications Author: Yuliia Kosto Department: Department of Surface and Plasma Science Supervisor: Prof. RNDr. Vladimír Matolín, DrSc. Abstract: The presented scientific work was conducted in two main directions. The first one is an investigation of the simple biomolecules (glycine and sarcosine) bonding to cerium oxide model films by surface science techniques: photoelectron and near-edge X-ray absorption spectroscopies. Adsorption chemistry and thermal stability of the molecules on the oxides were studied in relation to the oxidation state of ceria cations, film morphology, and molecular deposition method. The oxygen vacancies in the oxide were shown to affect the adsorption geometry of glycine and stimulate molecular decomposition. The polycrystalline oxide morphology provided stabilizing effect on the glycine adlayer. Sarcosine deposited in vacuum formed densely packed adlayer with the molecules directed outwards. Interestingly, the results revealed that molecular film deposited from the aqueous solution, in contrast to deposition in vacuum, induces continuous reduction of the cerium oxide during thermal annealing. The second part is a study of polycrystalline cerium oxide thin films as an electrode for electrochemical and electrochemiluminescent...