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Ultrafast laser spectroscopy of semiconductor nanostructures
Neudert, Karel ; Trojánek, František (advisor) ; Nikl, Martin (referee) ; Herynková, Kateřina (referee)
This doctoral thesis deals with analysis of carrier dynamics in semiconductor nanocrystals and nanostructures by methods of ultrafast laser spectroscopy. In three chapters silicon, InAs/GaAs, InAs/AlAs and CdSSe materials are studied. Silicon nanocrystals prepared by sol-gel method were measured by time-resolved luminescence method with various time resolutions, two-photon absorption and Z-scan method. A model describing findings was suggested. InAs was well measured by upconversion method and gained knowledge appeared to be fully consistent with quantum model. CdSe material was examined in two basic forms - thin films of nanocrystals prepared by chemical deposition and nanocrystals in comercial filters. In both cases all questions regarding influencing optical properties of nanocrystals by modification of their growth were answered.
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Luminescence properties of phosphors for highpower LED applications
Rejman, Martin ; Nikl, Martin (advisor) ; Mareš, Jiří A. (referee) ; Nejezchleb, Karel (referee)
For selected YAG:Ce sample the temperature dependent absorbtion and emission spectra were measured and used to simulate white LED behavior. Various CIE-xy dependencies were observed. Sample surface scaterring parameters were calibrated using a custom-made automated goniospektrometer, which provided measured data with fine accuracy. Finally, the measured data were used to construct a Geant4 simulation to optimize two light devices for output intensity and target CIE-xy coordinates. Powered by TCPDF (www.tcpdf.org)
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Fast scintillation materials based on tailored monocrystalline perovskites and garnets
Pokorný, Martin ; Nikl, Martin (advisor) ; Bryknar, Zdeněk (referee) ; Šulc, Miroslav (referee)
1 Title: Fast scintillation materials based on tailored monocrystalline perovskites and garnets Author: Martin Pokorný University: Charles University Faculty: Faculty of Mathematics and Physics Department: Department of Chemical Physics and Optics Supervisor: doc. Ing. Martin Nikl, CSc., Institute of Physics of the Czech Academy of Sciences, Cukrovarnická 10, 162 00 Prague 6 Abstract: This dissertation thesis is focused on the possibilities of speeding-up the main decay component of selected monocrystalline bulk scintillator via energy transfer toward the acceptor. In the beginning it summarizes the main scintillator characteristics together with their respective measurement methods, as well as several growth methods used for the preparation of the crystals for all the samples characterized further in this thesis. In particular, one chapter is focused on the detailed description of the scintillation decay measurement, because this particular method was much improved during the work on this thesis. The main part is focused on the photoluminescent and scintillation characteristics of codoped YAG:Ce and LuAP:Ce bulk scintillators. For these compositions we theoretically described the energy transfers according to the Förster-Dexter model and calculated its microscopic parameters. Moreover for the (Lu,Gd)AP:Ce...
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Luminescence properties of phosphors for highpower LED applications
Rejman, Martin ; Nikl, Martin (advisor) ; Mareš, Jiří A. (referee) ; Nejezchleb, Karel (referee)
For selected YAG:Ce sample the temperature dependent absorbtion and emission spectra were measured and used to simulate white LED behavior. Various CIE-xy dependencies were observed. Sample surface scaterring parameters were calibrated using a custom-made automated goniospektrometer, which provided measured data with fine accuracy. Finally, the measured data were used to construct a Geant4 simulation to optimize two light devices for output intensity and target CIE-xy coordinates. Powered by TCPDF (www.tcpdf.org)
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Ultrafast laser spectroscopy of semiconductor nanostructures
Neudert, Karel ; Trojánek, František (advisor) ; Nikl, Martin (referee) ; Herynková, Kateřina (referee)
This doctoral thesis deals with analysis of carrier dynamics in semiconductor nanocrystals and nanostructures by methods of ultrafast laser spectroscopy. In three chapters silicon, InAs/GaAs, InAs/AlAs and CdSSe materials are studied. Silicon nanocrystals prepared by sol-gel method were measured by time-resolved luminescence method with various time resolutions, two-photon absorption and Z-scan method. A model describing findings was suggested. InAs was well measured by upconversion method and gained knowledge appeared to be fully consistent with quantum model. CdSe material was examined in two basic forms - thin films of nanocrystals prepared by chemical deposition and nanocrystals in comercial filters. In both cases all questions regarding influencing optical properties of nanocrystals by modification of their growth were answered.
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Deployment of corporate audio-video technology
Nikl, Martin ; Havránek, Martin (advisor) ; Matyáš, Matyáš (referee)
This thesis deals with the possibility of connecting, automating and controlling audio/video hardware. In the theoretical part the author deals with input and output A/V devices, A/V interfaces communication interfaces, possibility of connecting automation elements and a room control. It explains terms relating to the audio/video topic.
The practical part suggests a complete design and implementation of a showroom to present the portfolio of Colsys company, which demonstrates functions of the control system Crestron, such as controlling projectors, video matrices, sound equipment and building automation (lights, air conditioning, blinds, etc.). First part of this section deals with defining the requirements for individual devices. The next step was the selection of suitable components based on fulfilling the set criteria and the budget. After that a check of compatibility was performed and room layout was designed, which contained electrical layout and a room blueprint. Final step of this section was designing the user interface and its realization in order to create the control unit program.
Based on the theoretical part the author created a chapter titled Recommendation, which is verified in the practical part by creating a fully functional showroom for Colsys company, which also serves as a meeting room.
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