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Optical properties of protective emulsions
Valasová, Denisa ; Veselý, Michal (referee) ; Zmeškal, Oldřich (advisor)
This bachelor´s thesis is aimed to the study of optical properties of protective commercially available emulsions. Chosen emulsions should be responsible for sun protection. They also may be used in cosmetic industry. In the beginning of the thesis, there are defined theoretical features of emulsions and their interaction with UV radiation. Methods which are used to describe optical properties could be found in this section too. The optical properties were measured in thin layer films, in order to simulate emulsions applied on the human skin. UV-VIS spectrophotometry was mainly used to study the optical properties. The obtained results could serve, purely hypothetically, like sun protective tests of chosen emulsions.
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Study of optical properties of perovskites and their precursors thin films
Blahut, Jan ; Pospíšil, Jan (referee) ; Zmeškal, Oldřich (advisor)
The thesis is focused on the study of the optical properties of thin films of perovskites and their precursors. The first two chapters of the theoretical part are theoretical introduction to the studied problems, they discuss the basics of electromagnetic radiation and its interaction with matter and basic informations about perovskite materials, especially their semiconductor structure. The remaining two chapters deal with specific principles and practical uses of methods and procedures for the preparation of thin films, as well as the instrumentál characteristics of thin films in terms of their optical properties. The experimental part is focused on the preparation of solutions of perovskites and their precursors, where the replication and optimization of published procedures took place, the preparation of thin layers of these solutions by the spin coating method and their ellipsometric characterization using the Tauc plot method, modeling and fitting of the experimentally determined data, which led to the determination of the index refraction, absorption coefficient and band gap width of individual materials.
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Spectroscopic studies of new generation of optical and magneto-optical materials
Butková, Eva ; Veis, Martin (advisor) ; Chlan, Vojtěch (referee) ; Zemen, Jan (referee)
Title: Spectroscopic studies of new generation of optical and magneto-optical materials Author: Eva Butková Department / Institute: Institute of Physics of Charles University. Department of Materials Science and Technology of Nagaoka University of Technology. Supervisors of the doctoral thesis: RNDr. Martin Veis, Ph.D., Division of Magneto-optics, Institute of Physics of Charles University Dr. Takayuki Ishibashi, Ph.D., Department of Materials Science and Technology, Nagaoka University of Technology Abstract: In recent years, novel optical and magneto-optical devices have been proposed. This ranges from integrated photonic devices such as 3D holographic displays to magnetic recording, non- reciprocal photonic devices such as optical isolators and circulators or high-energy X-ray/gamma ray detectors. These devices, however, require suitable materials with tunable optical and magneto-optical properties. Presented thesis aims to systematically study such materials, namely GdxFe(100-x), magnetic garnets (Y3-xBixFe5O12, Nd2BiFe(5-x)GaxO12, Nd0.5Bi2.5Fe(5-x)GaxO12) and Ce(0.95-x)HfxCo0.05O(2-δ). Systematic study is carried out by the combination of experimental methods of spectroscopic ellipsometry, magneto-optical Kerr effect spectroscopy and Faraday effect spectroscopy. Experimental data are confronted to...
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Characterization of ultra-thin polymer films on solid substrates using different physical techniques
Pop-Georgievski, Ognen ; Rypáček, František (advisor) ; Adam, Pavel (referee) ; Werner, Carsten (referee)
The presented doctoral research was aimed at preparation and characterization of ultra thin polymer films on solid substrates using different physical techniques. Each of these physical techniques probes selectively different characteristics of the films. While some of the techniques are strong in the predetermination of some unique properties of the layers, they might be limited and give no specific/conclusive information about some other important characteristics. Therefore, only the combination of the techniques provides a profound picture of the thickness, architecture, composition and functionality of the films/layers. This combined characterization approach elucidates in details the physical characteristics and the mechanisms responsible for the unique behavior of different polymer films/layers in the application that they are intended for. In the thesis, of particular interest were films of high biomedical, biotechnological and tissue engineering importance, such as: 1. poly(lactide) films formed by grafting "from-" a silanized alacrite thin films (L605 Co-based super alloy), 2. polydopamine (PDA) films that could serve as substrate independent mod- ification platform for further surface modification steps, 3. poly(ethylene oxide)films formed by "grafting to-" PDA modified surfaces, 4....
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Properties of point defects in CdTe at temperatures of 300 - 600 K
Korcsmáros, Gabriel ; Moravec, Pavel (advisor) ; Šikula, Josef (referee) ; Toušková, Jana (referee)
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
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Properties of point defects in CdTe at temperatures of 300 - 600 K
Korcsmáros, Gabriel ; Moravec, Pavel (advisor) ; Šikula, Josef (referee) ; Toušková, Jana (referee)
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
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Morphology study of ultra thin layers by XPS analysis of multiple peaks of a single element
Pokorný, David ; Šik, Ondřej (referee) ; Polčák, Josef (advisor)
This diploma thesis deals with methodology of thin film thickness determination using X-ray radiation of silver anode which provides radiation with energy of 2984,3 eV. This energy is twice as high as the standard aluminium radiation which allows a measurement of new photoelectron lines with higher bonding energy and it also provides thanks to the higher photoelectron energy greater information depth. In order to get the right results it was necessary to calibrate the spectrometer Kratos Axis Supra in the silver anode mode first and found out the form of the transmission function. The determination of the thickness of the thin layer was demonstrated by the comparation of the ratio of different photoelectron lines intensities with the theoretical model. For that purpose was specifically used the Si 1s and Si 2p peak bound in the substrate in the Si-Si bonding or in the thin oxid layer in the Si-O bonding. The results show that for thin SiO2/Si film thickness determination is the best to use the intensity ratio of only one photoelectron line. A silver anode however provides greater information depth.
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Temperature changes in thin films of nanoparticles
Krtouš, Zdeněk ; Kousal, Jaroslav (advisor) ; Hanuš, Jan (referee)
Many properties of nanoparticles are different from general bulk properties. This work is focused on coalescence of nanoparticles depending on temperature.Coalsescence was experimentaly measuered on gold nanoparticles, copper nanoparticles and silver nano- islands.The samples were characterised by SEM, AFM and in-situ ellipsometry in range between 20řC and 350 řC. In the theoretical part was analyzed existing semi-analytical model of coalescence and then it was created a new model based on previous one. In the end, the comparison between experimental data and model was done. New model predicts greater coalescence of nanoparticles, what corresponds to experimental data.
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Optical characterization of thin oxide layers
Statelov, Martin ; Franc, Jan (advisor) ; Moravec, Pavel (referee)
Performance of CdZnTe-based detectors is highly related to the surface quality. Mechanical polishing, chemical etching and passivation are routinely employed for this purpose. The dynamics and properties of CdZnTe surface oxide layers, created by etching-only and passivation by KOH and NH4F/H2O2 solutions, were studied by optical ellipsometry. Effective medium approximation model was used to evaluate ellipsometric spectra. Thickness and formation rate of the surface oxide layers differed in each of the passivation method. Leakage currents were measured simultaneously and were compared with the surface oxide layer properties. NH4F/H2O2 passivation showed to be method with most desirable properties of the surface oxide layer; thick oxide layer and low leakage currents.
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Characterization of ultra-thin polymer films on solid substrates using different physical techniques
Pop-Georgievski, Ognen ; Rypáček, František (advisor) ; Adam, Pavel (referee) ; Werner, Carsten (referee)
The presented doctoral research was aimed at preparation and characterization of ultra thin polymer films on solid substrates using different physical techniques. Each of these physical techniques probes selectively different characteristics of the films. While some of the techniques are strong in the predetermination of some unique properties of the layers, they might be limited and give no specific/conclusive information about some other important characteristics. Therefore, only the combination of the techniques provides a profound picture of the thickness, architecture, composition and functionality of the films/layers. This combined characterization approach elucidates in details the physical characteristics and the mechanisms responsible for the unique behavior of different polymer films/layers in the application that they are intended for. In the thesis, of particular interest were films of high biomedical, biotechnological and tissue engineering importance, such as: 1. poly(lactide) films formed by grafting "from-" a silanized alacrite thin films (L605 Co-based super alloy), 2. polydopamine (PDA) films that could serve as substrate independent mod- ification platform for further surface modification steps, 3. poly(ethylene oxide)films formed by "grafting to-" PDA modified surfaces, 4....
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