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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
201

Plazmatické povrchové úpravy skleněných vláken na bázi organokřemičitanů / Plasma surface modification of glass fibers on a basis of organosilicones

Veteška, Jaromír January 2008 (has links)
This thesis is aimed at preparation of thin plasma-polymerized films deposited on glass fibers by Plasma-Enhanced Chemical Vapor Deposition (PE CVD) from a mixture of tetravinylsilane (TVS) and oxygen gas. Plasma-polymerized films which were deposited on silicon wafers were used to characterize chemical properties and optimization of deposition process with respect to reproducibility.
202

Samovolně seskupené vrstvy na bázi křemíku / Self-assembled layers based on silicon

Bábík, Adam January 2009 (has links)
Thin film deposition, characterization and properties of self-assembled monolayers based on silicon were studied with emphasis on the SA monolayers deposited from vinyltriethoxysilane and vinyltrichlorsilane. The thesis is aimed at basic properties of the SA monolayer and explanation of its growth. Methods and techniques used for analysis of the monolayer were described as well. Contact angle measurements and an evaluation of the surface free energy are depicted in details. The deposited SA layers were observed with respect to their chemical composition and surface morphology by X-ray photoelectron spectroscopy (XPS), ellipsometry and atomic force microscopy (AFM).
203

Tenké vrstvy připravené v RF doutnavém výboji a jejich fyzikálně-chemické vlastnosti / Thin films prepared in RF glow discharge and their physico-chemical properties

Bránecký, Martin January 2015 (has links)
Theoretical part of this master thesis was focused on literature recherché dealing with the formation of thin films, plasma, plasma analyses using mass spectrometry and plasma polymerization. Further, this section describes the analysis of thin films using optical methods such as spectroscopic ellipsometry and FT-IR spectrometry. Experimental part describes the materials which are used for the preparation of thin films as well as a description of the equipment for preparation of thin films using a technology of plasma-enhanced chemical vapor deposition (PE-CVD). Control of deposition conditions and monitoring of plasma with its products result in high reproducibility of thin films. The last part of the thesis describes the results of measurement of the first group of samples and their ellipsometric, mass spectrometry and FT-IR evaluation with respect to the deposition conditions.
204

Elipsometrie tenkých vrstev / Ellipsometry of Thin Films

Novotný, Zbyněk January 2010 (has links)
Diploma thesis deals with ageing process of thin films of Co and Cu on Si substrate, prepared by the IBAD method. The process of film ageing, which depends on time of exposition to the atmosphere at room conditions, was investigated with spectroscopic ellipsometry (VIS+UV) and atomic force microscopy. In case of thin Co films, approximately four days long incubation period was observed. During this time period, a change in the optical parameters of the film occurs without a measurable change of the film topography. Using non-contact atomic force microscopy, a growth of the transitional film in the island growth regime was observed. During the ageing of thin Cu films, two stages of growth of the transitional layer were observed - nucleation stage and growth stage. Both of these time periods of the transitional layer growth show direct logarithmic dependence. Using non-contact atomic force microscopy, the growth of the transitional film was observed. Using atomic force microscopy in non-contact regime, time dependent measurement was done and the process of forming of one monolayer of the transitional layer was documented. Within the diploma thesis, a series of experiments on ultra high vacuum system were performed in order to investigate phase transformation of thin Fe films (22 monolayers) on Cu(100) stabilized by CO absorption. The transformation from fcc phase to bcc phase was induced by Ar+ ion beam bombardment with the ion energy in the range (0.5-4) keV. The process of phase transformation was observed by surface magneto-optic Kerr effect, Auger electron spectroscopy and low energy electron diffraction.
205

Uspořádaná a neuspořádaná pole koloidních nanočástic a jejich využití pro detekci biomolekul / Ordered and disordered arrays of colloidal nanoparticles for biomolecule detection

Ligmajer, Filip January 2013 (has links)
This thesis deals with guided self-assembly of gold nanoparticles from their colloidal solutions onto silicon substrates and possible employment of nanoparticles for detection of biomolecules. It was found that by adjustment of solution pH and surface chemistry modification by means of electron beam irradiation it is possible to facilitate nanoparticle deposition to patterns with almost single particle precision. Spectroscopic ellipsometry was then employed in analysis of self-assembled layers of nanoparticles and its combination with a theory of effective medium approximation has proven the ability to assess nanoparticle dimensions and volume fractions. By experiments with thiolated oligonucleotides it has been shown that using ellipsometry one can detect even with very subtle changes in nanoparticle environment caused by biomolecules, thus promising its possible use in the field of biodetection.
206

Élaboration par ablation laser en milieu liquide de nanoparticules métalliques : caractérisation et modélisation des réponses plasmoniques des nanoparticules d’or et d’argent / Generation of metallic nanoparticles by Pulsed-Laser Ablation in Liquids : Characterization and modelling of the plasmonics responses of gold and silver nanoparticles

Resano-Garcia, Amandine 30 November 2016 (has links)
Les nanoparticules métalliques (NPs) présentent des propriétés optiques (PO) uniques provenant de l’oscillation collective de leurs électrons. Cet effet se traduit par l'émergence d'une bande plasmon dont les caractéristiques peuvent être modulées par la taille, la forme, la nature des NPs et le milieu hôte. Il existe de nombreuses méthodes pour la préparation de ces NPs, l'une d'entre elles est l'ablation laser en milieu liquide (ALML). Cette technique offre certains avantages comme la simplicité, l’adaptabilité et des NPs dépourvues de contamination. Ses principaux inconvénients sont la productivité et le contrôle de la taille et de la forme des NPs. Ce travail est consacré à l'élaboration de NPs d’Ag par l’ALML et à l'étude théorique de leurs PO. Nous donnons dans ce manuscrit, les résultats de l'optimisation des paramètres d'élaboration conduisant à l'obtention de distributions en NPs reproductibles et contrôlées. Les PO de ces NPs sont mesurées et comparées à des modèles physiques spécifiques basés sur la théorie des milieux effectifs (EMT). L'EMT, telle que le modèle de Maxwell-Garnett, permet de décrire les PO de NPs monodisperses. Cependant, les voies de préparation classiques conduisent inévitablement vers des NPs montrant une distribution de forme et de taille qui induit des changements drastiques sur leurs PO. Le modèle SDEMT est proposée pour le calcul de la fonction diélectrique effective et du coefficient d'absorption de solutions colloïdales de NPs métalliques. Contrairement à Maxwell-Garnett, ce modèle donne une meilleure description des spectres d'absorption et d’ellipsométrie mesurés sur des échantillons contenant des NPs d’Ag et d’Au / Metal nanoparticles (NPs) exhibit unique optical properties (OP) coming from the collective oscillations of their electrons. This effect is translated by the emergence of a band of plasmon, the characteristics which can be modulated by the size, the shape and the nature of the NPs as well as by the environment of the host. There are many methods for the preparation of NPs, and one of them is the pulsed-laser ablation in liquid (PLAL). This technique offers some advantages such as simplicity, versatility and surface NP without contamination (reducing agent residues and/or stabilizers). Its main drawbacks are the lacks of productivity and control of the NP size and shape. This work is devoted to elaboration of Ag NPs by PLAL and theoretical investigation of their OP. We give here the results about the optimization of elaboration parameters leading to obtaining reproducible and controlled distributions of Ag NPs. The OP of these NPs are measured and compared to specific physical models based on the effective medium theory (EMT). Classical EMT such as Maxwell Garnett approximation allows describing the OP of monodisperse NPs. However, conventional preparation routes unavoidably conduct to NPs showing a shape and a size distribution which induces drastic changes in the OP. A SDEMT model which considers the shape dispersion is proposed for the calculation of the effective dielectric function and absorption coefficient of colloidal solution of metal NPs in water. Contrary to the conventional theory, this model gives a better description of the measured absorption and ellispometry spectra of sample containing Ag and Au NPs
207

Fyzika rozhraní v magnetických nanostrukturách / Physics of interfaces in magnetic nano structures

Ohnoutek, Lukáš January 2017 (has links)
Modification of interfaces in nanostructures can significantly influence their overall properties. Magneto-optical spectroscopy and spectroscopic ellipsometry are ideal for studying these phenomena thanks to their in-depth sensitivity and contactless measurements. Two methods of nonreversible modification of magnetic properties, especially the magnetic anisotropy, are investigated. The measured spectral dependence of magneto-optical Kerr effect is compared to a theoretical calculation in order to determine the profile of the samples for different levels and methods of modification. In addition to this, ellipsometric measurements are performed on a device whose optical properties change by voltage application.
208

Vlastnosti bodových defektů v CdTe při teplotách 300 - 600 K / Properties of point defects in CdTe at temperatures of 300 - 600 K

Korcsmáros, Gabriel January 2019 (has links)
The thermal stability of p-type CdTe crystals by using conductivity and Hall-effect measurements have been studied at room and slightly increased temperatures. It was observed that thermal changes often implicate an anomalous behavior of the hole density characterized by reversible decrease/increase in a heating/cooling regime. This anomaly was explained by a transfer of fast diffusing donors between Te inclusions and the bulk of the sample. Sodium and potassium were determined by the Secondary Ion Mass Spectroscopy (SIMS) as the most probable diffusing species. To verify this behavior samples were also treated in saturated NaCl solution for different time intervals in order to examine the influence of the oxide layer and sodium on the surface of the sample. To determine the structure of the surface the sample was characterized by ellipsometric and X-ray photoelectron spectroscopy (XPS) and SIMS. Very low determined diffusion coefficient of Na was explained by trapping of Na in Cd sublattice
209

Wechselwirkung von dünnen Schichten aus HVZ Polyestern im wässrigen Medium mit Modellproteinen

Mikhaylova, Yulia 11 May 2006 (has links)
The dissertation work focuses on the whole route of material development starting from the investigations of properties of the initial (raw) HBPs to their applications. Each research step is given in a separate chapter to enhance attention to various aspects of the aim of the work. Thus, every chapter is started with an introduction. After that, the methods applied and experimental procedure are described. Next part tries to give the comprehensive description of the results obtained. At the end of the chapter, the main points are summarized. The Chapter 1 gives the theoretical description of the main experimental techniques used in this work. In Chapter 2 the chemical (chemical composition, purity, typical structure elements) and physical (glass transition temperature, the temperature of the maximum decomposition, the thermal stability at the high temperatures, molar mass, polydispersity and possible aggregation in solution) properties examined by different techniques of polymer analysis are described. The Chapter 3 is divided into three separate parts: In Chapter 3.1 the description of the formation and modification of inter- and intramolecular hydrogen bonds of hydroxyl terminated HBP is presented to reveal the information of hydroxyl groups re- and/or association due to the high temperatures applied. In Chapter 3.2 the nature of the solid-liquid interface of HBP thin films have been studied by different surface sensitive techniques with respect to further protein adsorption investigations. In Chapter 3.3 the strategy for the fabrication of surface attached carboxyl terminated HBP using "grafting to" technique is developed. The Chapter 4 consists of two parts: The first (theoretic) part outlines the basic principles of protein chemistry, factors influencing on the protein molecule stability in aqueous medium, the mechanism of protein adsorption and forces involved in the adsorption process. In the second part the combination of different in situ techniques was applied to obtain a comprehensive description of complex adsorption processes of protein molecules on different polymer surfaces.
210

Einfluss der Verzweigung, Terminierung und Immobilisierung auf die Eigenschaften dünner Polyesterschichten

Reichelt, Senta 26 September 2008 (has links)
Die vorliegende Arbeit liefert einen Beitrag zum Verständnis der komplexen Struktur-/Eigenschaftsbeziehungen dünner Schichten hochverzweigter Polyester. Für die umfassende Charakterisierung wurde eine Vielzahl analytischer Methoden kombiniert. Des Weiteren wurde das Anwendungspotential dieser Schichten hinsichtlich möglicher Sensoranwendung anhand der Adsorption von Modellproteinen gewichtet. Dazu war es notwendig verschieden Methoden zur Stabilisierung dieser Schichten zu entwickeln.

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