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Implementation of a Multipurpose Measurement System for (Sub)Terahertz Electron Spin Resonance Spectroscopy
Šedivý, Matúš ; Malik, Aamir Saeed (referee) ; Epel, Boris (referee) ; Vrba, Radimír (advisor)
Spektroskopie elektronové spinové rezonance (také nazývaná elektronová paramagnetická rezonance nebo jen EPR) zahrnuje metody, které zkoumají hmotu prostřednictvím nepárových elektronů. Jednou z progresivních metod EPR je rychlé skenování, které umožňuje pozorovat kinetiku chemických reakcí. Kromě toho nedávný vývoj vysokofrekvenčních součástkách rozšířil použití vysokofrekvenční EPR (HFEPR), které využívají sub-terahertzové až terahertzové vlny. Tato práce se zabývá propojením obou cest do HFEPR spektrometru s rychlým skenováním frekvencí (FRaScan), který byl nedávno vyvinut na CEITEC VUT. Na začátku je stručně uvedena základní teorie k EPR, následovaný přehledem přístrojového vybavení pro HFEPR. V praktické části je popsáno technické řešení spektrometru. Důraz je kladen na implementaci softwaru, pomocí kterého je spektrometr ovládán a měření jsou automatizována. Následně jsou ukázány příklady z měření pevných látek, konkrétně karbidu křemíku dopovaného vanadem (SiC:V), ftalocyaninu líthia (LiPc) a krystalu 1,3-bisdifenylen-2-fenylallylu (BDPA). Příklady demonstrují schopnosti spektrometru získat multifrekvenční vlnově spojitá EPR spektra a frekvenčně rozmítaná spektra v závislosti na teplotě a orientaci vzorku, a taky spektra pomocí rychlého skenování frekvencí
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Investigation of high voltage influence on different materials in high and low vacuum
Šedivý, Matúš ; Šandera, Josef (referee) ; Hejátková, Edita (advisor)
The beginning of this thesis contains an overview of properties of the insulators, and description of insulators that were used for in depth research of surface breakdown in vacuum. Furthermore, this work focuses on mechanisms of an electric breakdown initiation at the interface of the solid insulator and surrounding low pressure gas. Multiple methods for measurements of dielectric strength are examined. The experimental part describes the measurements performed in the vacuum chamber. The results of these measurements are then analysed. In conclusion, used insulators are compared and suggestions for further work are given.
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Semiconductive gas sensors for detection of organic gases and vapours
Šedivý, Matúš ; Gablech, Evelína (referee) ; Gablech, Imrich (advisor)
This bachelor thesis is focused on gas sensors. Basic characteristics of sensors are discussed in the first part. Next part contains an overview of the most used types of gas sensors based on different physical principles. The main aim of thesis outlines last chapter where process of making gas sensors with different semiconductive metal oxides active layers is described. This thesis also describes measuring of their characteristics and characteristics of commercial gas sensor TGS 822 made by Figaro. Measured data are processed in graphs and tables and then were used for comparison with created sensors. In conclusion, there are discussed possibilities of improving selectivity of gas detection by using sensors with different active layer.
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Tracking Resistance Of
Various Materials In Vacuum
Šedivý, Matúš
Many vacuum instruments used in industry and scientific research apply high voltage components. Vacuum performs as an insulator with theoretically infinite breakdown voltage. Surface of dielectrics between two electrodes inside a vacuum chamber is the weakest link for a possible electrical breakdown (tracking). This paper focuses on examination of a vacuum pressure influence to the surface breakdown voltage of a various materials. Results were compared and led to determination of an appropriate materials for a design of internal connectors in electron microscopes produced by the company Thermo Fisher Scientific.
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Investigation of high voltage influence on different materials in high and low vacuum
Šedivý, Matúš ; Šandera, Josef (referee) ; Hejátková, Edita (advisor)
The beginning of this thesis contains an overview of properties of the insulators, and description of insulators that were used for in depth research of surface breakdown in vacuum. Furthermore, this work focuses on mechanisms of an electric breakdown initiation at the interface of the solid insulator and surrounding low pressure gas. Multiple methods for measurements of dielectric strength are examined. The experimental part describes the measurements performed in the vacuum chamber. The results of these measurements are then analysed. In conclusion, used insulators are compared and suggestions for further work are given.
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Semiconductive gas sensors for detection of organic gases and vapours
Šedivý, Matúš ; Gablech, Evelína (referee) ; Gablech, Imrich (advisor)
This bachelor thesis is focused on gas sensors. Basic characteristics of sensors are discussed in the first part. Next part contains an overview of the most used types of gas sensors based on different physical principles. The main aim of thesis outlines last chapter where process of making gas sensors with different semiconductive metal oxides active layers is described. This thesis also describes measuring of their characteristics and characteristics of commercial gas sensor TGS 822 made by Figaro. Measured data are processed in graphs and tables and then were used for comparison with created sensors. In conclusion, there are discussed possibilities of improving selectivity of gas detection by using sensors with different active layer.
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