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Optimization of the operational temperature of photoluminescence sensor field for detection of linear alcohols
Pokorný, Matěj ; Dian, Juraj (advisor) ; Červený, Václav (referee)
Chemical sensors are used to detect the presence of chemical substances using various physical quantities. Porous silicon, prepared by electrochemically etching the surface of crystalline silicon with a mixture of hydrofluoric acid and ethanol under appropriate conditions, is a porous material that contains nanocrystalline forms of silicon. Nanocrystalline silicon exhibits intense photoluminescence properties at room temperature, which strongly depend on the presence of chemical substances in its surroundings. The photoluminescence intensity of porous silicon is generally quenched in the presence of the analyte. The photoluminescence sensor response to the substances to be determined depends mainly on the concentration of the substance in question, but also on the operating conditions. Most critical is the operating temperature, which fundamentally affects the intensity of photoluminescence and the rate of sensor response when the analyte is added or removed from the system. The aim of this bachelor thesis was the preparation of porous silicon samples and their characterization by infrared (FTIR) and photoluminescence spectroscopy. These samples were tested as sensor elements of a photoluminescence sensor array for the detection of ethanol linear alcohol vapor. The main objective of the bachelor...
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Photoluminescence sensor field applied for detection of chemical compounds in gas mixtures
Liška, Jiří ; Dian, Juraj (advisor) ; Broncová, Gabriela (referee)
Title: Photoluminescence sensor field applied for detection of chemical compounds in gas mixtures Author: Jiří Liška Department: Department of Analytical Chemistry Supervisor: doc. RNDr. Juraj Dian, CSc. Abstract Porous silicon is a nanostructured material that can be prepared by galvanic etching of silicon in the presence of hydrofluoric acid. The properties of this material can be influenced by way of preparation or by the chemical modification of the surface. Porous silicon has many extraordinary properties as compared to macrocrystalline silicon; the most important one for chemical sensing is the visible photoluminescence at room temperature. In the presence of organic and inorganic analytes in the gas phase, the photoluminescence of the material is quenched. This phenomenon can be used for chemical sensors of chemical compounds in the gas phase. These sensors are very sensitive and give reasonable results for organic compounds. Photoluminescence sensor field uses for measurement several sensor elements with the modified surface. It is possible to use this method for the identification and determination of gaseous organic compounds. The aim of this thesis was: 1. the preparation of porous silicon samples, 2. the modification of surface with different methods, 3. the characterization of samples with FTIR...
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Novel fluorosensors based on naphthalimide derivatives
Garbárová, Veronika ; Dian, Juraj (advisor) ; Hraníček, Jakub (referee)
The aim of the diploma thesis was to prepare and characterize fluorescence sensor systems based on fluorophores and supramolecular components - cyclodextrins - attached to solid supports. In this work, functionalized 75 µm glass beads and two types of Nafion membranes were used as negatively charged solid surfaces. Derivatives of naphthalimide with a positively charged part allowing the attachment to surfaces were synthesized. The positively charged naphthalimide derivative was then attached on negatively charged surfaces via electrostatic interactions and the binding to the solid supports was examined using UV-VIS spectroscopy. Alternatively, the positively charged β-cyclodextrin derivative was also attached to the surface in an equimolar ratio with PNI-HEMPDA. The focus of the work were measurements of fluorescence sensor responses in the gas and liquid phase to linear alcohols - methanol to n-hexanol - for all sensor systems. For the studied sensor systems, the selected sensor parameters were determined - sensitivity, the limit of detection, linear dynamic range and a sensor response time constant. A practical application of the novel sensor system for the detection of ethanol in gasoline was examined. Fluorescence sensor response measurements of the prepared systems based on naphthalimide and...
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