Academic literature on the topic 'Luminiscenční spektroskopie'

Time-resolved spectroscopy is a modern method enabling the analysis of the dynamics of quantum luminescence transitions. This method uses ultra-fast light pulses to study materials, which makes it possible to observe the time evolution of luminescence quenching and thus provides additional information for static absorption and emission spectroscopy. This diploma thesis deals with the automation of the optical setup used in the Optical and Plasmonic Laboratory at Ceitec Nano for performing time-resolved spectroscopy. As part of the work, an application was created enabling communication with 13 devices used in the laboratory. The application automates already performed measurements, and in addition enables the scanning of samples, which was not possible due to time constraints due to the manual control of the stage movement. At the end of the work, test measurements are performed, with a discussion of their effectiveness and time savings for the user.

This diploma thesis deals with evaluation of toxicity and bioaccumulation of photon-upconversion nanoparticles (UCNPs) in model plant maize (Zea mays). Lanthanide-doped UCNPs with different composition and size were tested in three different concentrations in this work. The exposure took place for 168 hours. Toxicity was assessed based on four macroscopic toxicological endpoints (mortality, the length of belowground part of the plants, the length of aboveground part of the plants and whole plants length). Spatial distribution of elements yttrium, ytterbium, erbium and gadolinium in model plants was determined using laser induced breakdown spectroscopy with spatial resolution of 100 m and 26 m. Distribution of UCNPs in plants was further studied with photon-upconversion microscanning with spatial resolution of 40 m. Stability of UCNPs during and after the plant exposure was also discussed in this thesis.

Title: Study of semiconductors by methods of time resolved laser spectroscopy: Luminescence spectroscopy of nanocrystalline diamond Author: Branislav Dzurňák Department: Department of Chemical Physics and Optics Supervisor: doc. RNDr. František Trojánek, Ph.D. Abstract: The PhD thesis is focused on optical properties of nanocrystalline diamond prepared by chemical vapour deposition method. Photoluminescence of nanocrystalline diamond samples and effects of ambient temperature, pressure, pH and UV irradiation on it are studied by laser spectroscopy. Results suggest the keyrole of water and air adsorbates which affect the energy states in the sub-bandgap region of diamond. Photoluminescence decay of samples of different surface termination and structure and its dependency on ambient pressure and temperature is studied by methods of ultrafast (picosecond and nanosecond scale) laser spectroscopy. Results are analysed by power-law decay function which fits well the luminescence decay curves and also describes the dynamics of charge carriers in states localised within the bandgap. The model of interaction of nanocrystalline diamond with air adsorbates is proposed. Non-linear optical properties of nanocrystalline diamond are also studied, namely the generation of second and third harmonic frequency. The thesis...

The aim of this work is the study of photoluminescence properties of GaAs/Al0.33Ga0.67As double quantum well. Low-temperature luminescence spectra of this sample are measured in dependence on electric and magnetic eld and dierent excitation power. The temperature dependencies of photoluminescence especially of the indirect excitons in in-plane magnetic eld are gauged as well. The simple model of localized indirect excitons is discussed to explain the discrepancy concerning the damping of indirect exciton photoluminescence in in-plane magnetic eld. The eective g-factors of indirect, neutral and charged excitons are calculated from observed Zeeman splitting. Few simple models are proposed to explain the behavior of eective g-factors. The possible agreement or contradiction with other published experimental data is discussed.

In the present work we studied the dependence on concentration gallium ion in single crystal LGAG: Pr a LuAG: Pr, prepared by ,,micro-pulling down,, method (-PD) at Tohoku University in Sendai, Japan. -PD method allows growing a single crystal using small amount of row material, typically less than 1 g, in time period of one day because of very high growth speed up to 20mm/min. Scintillation materials are necessary for a number of applications (e.g. medicine), in which high spatial resolution is required. The aim of this work was to measure luminescence and scintillation characteristics of the Pr3+ doped -PD grown Lu3Al5O12 single crystal host. The absorption, photo- and radioluminescence spectra and both photoluminescence and scintillation decay curves were measured. The photoluminescence decay curves was single-exponetial characterized by a lifetime around 17ns. Slow components were present in the scintillation decay curves. This is a consequence of retrapping of the charge carriers on electron traps connected with the anti-site defects, which are generally present in Czochralski od -PD grown aluminium garnets. On the other hand, they are completely supressed in the liquid-phase-epitaxy grown single crystalline films due to lower growth temperature. Excitation spectra of the 5d-4f luminescence completely...