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Preparation of plasmonic nanoparticles in non-aqueous environments and in water using chemical way and by laser ablation and their testing
Hochmann, Lukáš ; Šmejkal, Petr (advisor) ; Procházka, Marek (referee)
Příprava nanočástic (N) se stala význačnou oblastí chemie díky unikátním vlastnostem, které tyto částice mají a které vedou k širokému okruhu možných aplikací. N se běžně používají v katalýze, elektronice, fotonice a nachází se i v mnoha předmětech běžné denní potřeby. Navíc, vzhledem ke svým plasmonickým vlastnostem, se N ušlechtilých kov· hojně používají ve spektroskopii, kupříkladu při povrchově zesíleném Ramanově rozptylu (SERS). V závislosti na plánovaném použití N lze k jejich přípravě použít více cest. V pří- padě přípravy N v kapalinách (koloid·) lze použít r·zné metody chemické redukce. Tyto metody jsou dobře zavedené postupy, obzvláště ve vodném prostředí. Pro určité aplikace by však byly příhodnější koloidy v jiných rozpouštědlech. Proto je hlavním cílem této práce zhodnotit možnosti přípravy koloid· chemickou redukcí a laserovou ablací ve vodě a organick- ých rozpouštědlech. Dalším cílem je charakterizace připravených částic a zhodnocení jejich potenciálu pro SERS. Zlaté koloidy ve vodě a alkoholech byly připraveny redukcí kyseliny tetracholoro zlatité tetrahydridoboritanem sodným. K přípravě stabilních sol· v alkoholech byl dále nutný pří- davek polyvinylpyrrolidonu (PVP) jako stabilizátoru, protože přímá příprava koloid· chemickou redukcí v alkoholech vedla k jejich kolapsu. Dále...
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Use and limitations of laser ablation ICP-MS in geoscience applications
Míková, Jitka ; Košler, Jan (advisor) ; Kanický, Viktor (referee) ; Anczkiewicz, Robert (referee)
This dissertation contributes to applications of laser ablation plasma source mass spectrometry (LA ICP-MS) in Earth sciences. The primary goal of the thesis is to address some of the fundamental processes related to laser ablation of solid samples that result in decoupling of elements during laser ablation ICP-MS analysis. Better understanding of mechanisms that cause the elemental fractionation and matrix effects is necessary before the accuracy and precision of laser ablation ICP-MS analyses can be improved. The chemical and phase compositions of particles produced by laser ablation (266 nm Nd:YAG) of silicate NIST glasses and zircon were studied by SIMS and HR-TEM techniques with a particular focus on Pb/U fractionation. This is of great importance in geology as the Pb/U elemental fractionation hampered the precision and accuracy of the measured accessory mineral ages. The data suggest that chemical composition and mineralogy of particles produced at the ablation site during laser ablation differs from the original sample and varies with their size. This can result in elemental fractionation (non-stochiometric sampling) in material delivered to the ICP-MS for quantitative analysis. Evidence of the element fractionation is preserved in chemically zoned ejecta deposited around the ablation pit....
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Properties of Aerosol, Produced by Laser Ablation of Standard Materials for ICP-MS Analysis.
Holá, M. ; Nováková, H. ; Ondráček, Jakub ; Vojtíšek, M. ; Kanický, V.
Laser ablation (LA), together with inductively coupled plasma mass spectrometry (ICP-MS) as a detection system, has become a routine method for the direct analysis of various solid samples. The product of laser ablation contains a mixture of vapour, droplets and solid particles. All components are finally transported to a plasma by a carrier gas as a dry aerosol including mainly agglomerates of primary nanoparticles. In general, characterisation of aerosols by their particle size distribution (PSD) represents indispensable tool for fundamental studies of the interaction of laser radiation with various materials. The particle size distribution of dry aerosol originating from laser ablation of standard material was monitored by two aerosol spectrometers – Fast Mobility Particle Sizer (EEPS) and Scanning Mobility Particle Sizer (SMPS) simultaneously with laser ablation - ICP-MS analysis.\n
Fulltext: content.csg -  PDF
Plný tet: SKMBT_C22016102412241 - PDF
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THE APPLICATION OF NANOMATERIALS FOR LEAD FREE SOLDERS DEVELOPMENT
Pešina, Zbyněk ; Pinkas, Jiří (referee) ; Spousta, Jiří (referee) ; Sopoušek, Jiří (advisor)
The present dissertation is motivated by the search for alternatives of lead-free soldering by nanoparticles of metals and their alloys. The research focuses on the possibility of replacing lead-free solders by nanoparticles. This issue is currently being addressed by the use of lead-free solders but their properties are not entirely equivalent to properties of lead-tin based alloys. The theoretical part of the dissertation first summarizes up-to date knowledge on the development of lead-free alloys currently used for soldering in the electronics. The work compares these lead-free solder candidates with previously used Pb-Sn alloys. The second section of the theoretical part is devoted to nanotechnology that offers possible solutions of problems associated with the use of lead-free solders. The text contains a description of the properties of nanocrystalline materials in comparison with those of compact alloys having the same chemical composition. The possibility of preparation of nanoparticles and potential problems associated with small particle sizes are also presented. Introduction of the experimental part focuses on the preparation of nanoparticles of pure metals and alloys by chemical and physical ways as well as on an instrumentation for characterisation and analysis. Attention is focused on the silver in nanoparticle form that exhibits the low temperature sintering effect, which is thermally activated by decomposition of oxide envelope covering the Ag nanoparticles. This factor is critical for low-temperature sintering and thus also for possible future applications. The thermal effects of the low sintering process were studied by methods of thermal analysis. The preparation of the Cu / Ag nano / Cu joints was carried out in-situ in inert atmosphere and under the action of atmospheric oxygen. In both cases varying conditions of thermal treatment were used. The cross sections of the prepared joints were then used for the metallographic analysis of the local mechanical properties of the resulting silver layer, for the chemical composition evaluation of the resulting layers of the joint, and for the microstructure study. Strength characteristics are represented by testing shear strength of individual joints.
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