National Repository of Grey Literature 7 records found  Search took 0.00 seconds. 
Optical characterization of advanced nanomaterials with a high lateral resolution
Liška, Petr ; Münz, Filip (referee) ; Dvořák, Petr (advisor)
Advanced nanomaterials show a significant improvement in certain physical or functional properties compared to conventional materials. Such advanced materials are, for example, lead halide perovskites (LHP). It is a group of hybrid organic-inorganic materials with a direct bandgap exhibiting unique optical properties. The high quantum efficiency of photoluminescence makes nanocrystals or thin films of LHP suitable candidates for the production of light-emitting diodes, solar cells and LCD displays. Their inexpensive and simple fabrication together with their unique optical properties makes LHP one of the most developed materials of the last decade. This diploma thesis aims to study the optical properties of CsPbBr3 perovskite nanocrystals using high lateral resolution methods. CsPbBr3 perovskite nanocrystals show intense anti-Stokes photoluminescence. These nanocrystals can emit light with a lower wavelength than that of the light that causes their photoluminescence. The nanocrystals are prepared in two different ways: by evaporation or by crystallization of the precursor in a solution of dimethylformamide. The morphology, photoluminescence properties and chemical composition of individual nanocrystals are studied. Each nanocrystal is studied individually and its size, shape, photoluminescence properties and chemical compounds are determined, which leads to a deeper understanding of the anti-Stokes photoluminescence of perovskite nanocrystals.
Fourier transform infrared spectroscopy on nanostructures
Halabuková, Hana ; Münz, Filip (referee) ; Kolíbal, Miroslav (advisor)
This master’s thesis deals with the plasmon resonance of the nanostructures of several selected tungsten oxides using Fourier transform infrared spectroscopy (FTIR spectroscopy). The physical principles of the plasmonics, the characteristics of the materials used, as well as the principle of operating and measuring on the FTIR spectrometer, are described in the first part of this thesis. The second part is focused on the preparation of samples and performing measurements on the FTIR spectrometer. This part ends by representing the final spectra and the results obtained.
Statistical Analysis of the Observable Data of Gamma-Ray Bursts
Řípa, Jakub ; Mészáros, Attila (advisor) ; Münz, Filip (referee) ; Ramirez-Ruiz, Enrico Jorge (referee)
Gamma-ray bursts are still not fully understood events. However, their exploration could pro- vide a useful tool for a better understanding of the early Universe because they belong to the most distant and violent objects that astronomers know. This thesis tries to bring more information about a so-called group of intermediate-duration bursts claimed by different authors employing dif- ferent data samples. Firstly, duration and spectral hardness properties of bursts from the Reuven Ramaty High-Energy Solar Spectroscopic Imager are statistically analysed. The obtained results bring a suspicion that these intermediate bursts gather into a separate group. Secondly, these bursts are investigated in more detail with respect to their spectral lags, peak count rates, red- shifts, supernova observations, and so forth. Thirdly, long-duration bursts with known redshifts and with derived pseudo-redshifts detected by The Burst and Transient Source Experiment, Swift and Fermi bursts with known redshifts, are used to study the cosmological effects on the observed flux and fluence distributions.
Optical characterization of advanced nanomaterials with a high lateral resolution
Liška, Petr ; Münz, Filip (referee) ; Dvořák, Petr (advisor)
Advanced nanomaterials show a significant improvement in certain physical or functional properties compared to conventional materials. Such advanced materials are, for example, lead halide perovskites (LHP). It is a group of hybrid organic-inorganic materials with a direct bandgap exhibiting unique optical properties. The high quantum efficiency of photoluminescence makes nanocrystals or thin films of LHP suitable candidates for the production of light-emitting diodes, solar cells and LCD displays. Their inexpensive and simple fabrication together with their unique optical properties makes LHP one of the most developed materials of the last decade. This diploma thesis aims to study the optical properties of CsPbBr3 perovskite nanocrystals using high lateral resolution methods. CsPbBr3 perovskite nanocrystals show intense anti-Stokes photoluminescence. These nanocrystals can emit light with a lower wavelength than that of the light that causes their photoluminescence. The nanocrystals are prepared in two different ways: by evaporation or by crystallization of the precursor in a solution of dimethylformamide. The morphology, photoluminescence properties and chemical composition of individual nanocrystals are studied. Each nanocrystal is studied individually and its size, shape, photoluminescence properties and chemical compounds are determined, which leads to a deeper understanding of the anti-Stokes photoluminescence of perovskite nanocrystals.
Multi-spectral analysis of a gamma-ray burst
Maleňáková, Alžběta ; Jelínek, Martin (advisor) ; Münz, Filip (referee)
Gamma-ray bursts are fascinating high energy phenomena, related with supernovas and black holes, which were discovered by accident in the second half of the 20. century. The goal of this thesis is to perform a multi-spectral analysis of the GRB 190919B after becoming familiar with the elementary knowledge about this phenomena. The images of an optical afterglow from robotic telescopes FRAM and BOOTES enabled us to construct the photometric light curve of the given burst. Together with the publicly available data from other spectral fields, the spectral energy distribution could be created. Afterwards, we fitted both obtained graphs with several functions with different choices of constraining parameters. Through analysis of the acquired values, we obtained several variants of the scenario of the observed event. By determining the value of initial Lorentz factors, we confirmed that all the options lie within the boundaries of typical values for the model of relativistic fireball. 1
Fourier transform infrared spectroscopy on nanostructures
Halabuková, Hana ; Münz, Filip (referee) ; Kolíbal, Miroslav (advisor)
This master’s thesis deals with the plasmon resonance of the nanostructures of several selected tungsten oxides using Fourier transform infrared spectroscopy (FTIR spectroscopy). The physical principles of the plasmonics, the characteristics of the materials used, as well as the principle of operating and measuring on the FTIR spectrometer, are described in the first part of this thesis. The second part is focused on the preparation of samples and performing measurements on the FTIR spectrometer. This part ends by representing the final spectra and the results obtained.
Statistical Analysis of the Observable Data of Gamma-Ray Bursts
Řípa, Jakub ; Mészáros, Attila (advisor) ; Münz, Filip (referee) ; Ramirez-Ruiz, Enrico Jorge (referee)
Gamma-ray bursts are still not fully understood events. However, their exploration could pro- vide a useful tool for a better understanding of the early Universe because they belong to the most distant and violent objects that astronomers know. This thesis tries to bring more information about a so-called group of intermediate-duration bursts claimed by different authors employing dif- ferent data samples. Firstly, duration and spectral hardness properties of bursts from the Reuven Ramaty High-Energy Solar Spectroscopic Imager are statistically analysed. The obtained results bring a suspicion that these intermediate bursts gather into a separate group. Secondly, these bursts are investigated in more detail with respect to their spectral lags, peak count rates, red- shifts, supernova observations, and so forth. Thirdly, long-duration bursts with known redshifts and with derived pseudo-redshifts detected by The Burst and Transient Source Experiment, Swift and Fermi bursts with known redshifts, are used to study the cosmological effects on the observed flux and fluence distributions.

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