Global ETD Search

11	Chiroptical molecular switches Schoevaars, Anne Marie. January 1991 (has links) Proefschrift Rijksuniversiteit Groningen. / Met lit.opg. - Met samenvatting in het Nederlands.
12	Studium kinetiky fotochemických reakcí v tenké tištěné polymerní vrstvě / Kinetic study of photochemical reactions in thin printed layer Rudická, Andrea January 2020 (has links) This diploma thesis deals with a study of kinetics of photochemical reactions in a thin printed polymer layer. The experimental part deals with the composition preparation and layers coating. The prepared layers were exposed and subsequently studied for their colour response to the light. The aim of this work was to prepare a photosensitive layer with a significant colour change between individual doses of radiation, to improve the mechanical resistance of the layers, to adjust the sensitivity of the compositions to UVB radiation and to study the kinetics of the photochemical reaction used.
13	Fosfan a oxid dusný jako falešně pozitivní biosignatury ve spektrech planet / Phosphine and nitrous oxide as false-positive biosignature gases in planetary spectra Kaiserová, Tereza January 2021 (has links) 5 Abstract This study is dedicated to evaluating the potential for a novel pathway of abiotic synthesis of phosphine (PH3) from phosphorus trioxide (P4O6) by a photocatalytic mechanism on aerosols. The mechanism might explain the recent possible detection of phosphine on Venus. This scenario has recently been suggested theoretically by our team based on an analogy with methane production form carbon dioxide on acidic photochemically-active surfaces of materials, which may account for a possible source of methane on Mars. Methane, just like phosphine, was suggested as an indicator of life on terrestrial planets, including Mars. The theoretical testing of photochemical phosphine generation suggests that even if this gas is present in the atmosphere of Venus it cannot be considered as an indicator of life until the suggested mechanism is excluded theoretically, or by experimental results, or direct evidence of life on Venus. This thesis will be followed by preparation of sophisticated experiments and intensive laboratory research addressing this. Furthermore, the role of nitrous oxide as another false positive biosignature was evaluated in this study. The presence of nitrous oxide can also be explained by processes other than biological, particularly on early planets. This study specifically demonstrates the...
14	Studium fotochlorace polyolefinů / The Study of Polyolefins Photochloration Kučera, Vladimír January 2014 (has links) This Master´s thesis deals with heterogeneous photochlorination of polyolefins and especially with the photochlorination of polypropylene itself. In the theoretical part the available information about properties, manufactory and application of chlorinated polyolefins, specifically polyethylene and polypropylene, is provided. The basic principles of the photochemistry are described, which are further applied to the issue of photochemistry chain reactions and photochemical halogenations, mainly photochlorinations. The practical part includes design and realization of few types of equipment for the heterogeneous photochlorination of polypropylene done at low temperatures (to 50° C) by gaseous chlorine in bulk or chlorine suspended in suspension of PP in CCl4. Series of chlorination was accomplished, which was varied in the type of PP, in the way of dosage Cl2 and in the period of high pressure mercury lamp irradiation (1–90 minutes). The chlorine content in prepared samples was determined by the gravimetry with ATR-FTIR spectroscopy, as well as by the Shöniger combustion method. Their accuracies were than compared. The chlorine content dependence on the period of chlorination and on the porosity of initial PP was established.
15	Pokročilé plazmonické materiály pro metapovrchy a fotochemii / Advanced plasmonic materials for metasurfaces and photochemistry Ligmajer, Filip January 2018 (has links) Plazmonika, tedy vědní obor zabývající se interakcí světla s kovovými materiály, nabízí ve spojení s nanotechnologiemi nezvyklé možnosti, jak světlo ovládat a využívat. Výsledkem tohoto spojení může být například zaostřování světla pod difrakční limit, zesilování emise nebo absorbce kvantových zářičů, či extrémně citlivá detekce molekul. Tato práce se zabývá zejména možnostmi využití plazmoniky pro vývoj plošných optických prvků, tzv. metapovrchů, a pro fotokatalytické aplikace založené na plazmonicky generovaných elektronech s vysokou energií, tzv. horkých elektronech. Nejprve jsou vysvětleny teoretické základy plazmoniky a je poskytnut přehled jejích nejvýznamnějších aplikací. Poté jsou představeny tři studie zabývající se využitím plazmonických nanostruktur pro ovládání fáze a polarizace světla, pro vytváření dynamicky laditelných metapovrchů, a pro foto-elektrochemii s horkými elektrony. Společným prvkem těchto studií je pak používání pokročilých, resp. v rámci těchto oblastí netradičních, materiálů, jako např. oxidu vanadičitého nebo dichalkogenidů přechodných kovů.
16	Direct observation and characterisation of 3-azido-2H-azirines: postulated, but highly elusive intermediates Weigand, Kevin, Singh, Neeraj, Hagedorn, Manfred, Banert, Klaus 29 March 2017 (has links) (PDF) For the first time, successful synthesis of an unknown class of compounds, 3-azido-2H-azirines, which are implicated as highly reactive intermediates in the thermolysis of the corresponding 1,1-diazidoethenes, has been performed. These elusive heterocycles have been detected and characterised by low-temperature NMR and in situ IR spectroscopy. Even the parent compound, 3-azido-2H-azirine, has been observed via low-temperature photolysis of 1,1-diazidoethene, as a highly reactive species with a half-life period of only 12 min at −40 °C. / Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich. Azide Cycloadditionsreaktionen heterocyclische Verbindungen Infrarot-Spektroskopie Kernmagnetische Resonanzspektroskopie kurzlebige Intermediate Photochemie Ringspannung azides cycloaddition reactions heterocyclic compounds IR spectroscopy NMR spectroscopy photochemistry ring strain short-lived intermediates ddc:547 Azide Heterocyclische Verbindungen Infrarotspektroskopie NMR-Spektroskopie Fotochemie Ringspannung
17	Propojení atmosferické chemie/aerosolů s regionálními klimatickými modely / Coupling atmospheric chemistry/aerosols to regional climate models Huszár, Peter January 2010 (has links) Title: Coupling atmospheric chemistry/aerosols to regional climate models Author: Peter Huszár Department: Department of Meteorology and Environment Protection Supervisor: doc. RNDr. Tomáš Halenka, CSc. Supervisor's e-mail address: tomas.halenka@mff.cuni.cz Abstract: In this thesis, the connections between air quality and climate are studied. For this purpose, regional climate model RegCM3 and chemistry transport model CAMx has been coupled offline with one- and two-way interaction. Our work represents a first attempt to connect RegCM3 not only with CAMx, but with any other chemistry transport model. As a first step, an offline one way couple of RegCM3 and CAMx has been developed, meaning that the climate model drives the transport, emission, chemical transformation and deposition of species while the radiative feedbacks of gases and aerosols are not considered. A meteorological interface has been developed at our department in order to convert the meteorological data generated by RegCM3 to fields required by CAMx. For those parameters that are essential for CAMx but the regional climate model does not supply them, diagnostic methods were implemented into this interface. Further, it is used to calculate biogenic emissions. Regarding anthropogenic emissions, a simple utility has been developed to...
18	Direct observation and characterisation of 3-azido-2H-azirines: postulated, but highly elusive intermediates Weigand, Kevin, Singh, Neeraj, Hagedorn, Manfred, Banert, Klaus 29 March 2017 (has links) For the first time, successful synthesis of an unknown class of compounds, 3-azido-2H-azirines, which are implicated as highly reactive intermediates in the thermolysis of the corresponding 1,1-diazidoethenes, has been performed. These elusive heterocycles have been detected and characterised by low-temperature NMR and in situ IR spectroscopy. Even the parent compound, 3-azido-2H-azirine, has been observed via low-temperature photolysis of 1,1-diazidoethene, as a highly reactive species with a half-life period of only 12 min at −40 °C. / Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich. info:eu-repo/classification/ddc/547 ddc:547

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