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Enhancement of detection limits in Laser-Induced Breakdown Spectroscopy (LIBS) using nanoparticles
Képeš, Erik ; Prochazka, David (referee) ; Sládková, Lucia (advisor)
This bachelor's thesis describes the options of ehnancing the detection limits of laser-induced breakdown spectroscopy (LIBS). It summarizes different modifications of the classical LIBS apparatus, which are used by methods double-pulsed LIBS (DPLIBS), Townsend effect plasma sectroscopy (TEPS), resonance enhanced LIBS (RELIBS), spark discharge LIBS (SDLIBS), flame-enhanced LIBS (FELIBS), and new ways of sample preparation, such as are used in the method nanoparticle enhanced LIBS (NELIBS). It briefly describes the mechanisms, which are used by each method to reduce the detection limit and it contains an overview of obtained enhancements against the classical method LIBS. It deals with the method nanoparticle enhanced LIBS in more detail and experimentally verifies and studies the effects of nanoparticles of different types and sizes on the emission spectrum of the method LIBS.
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Development of an Algorithm for Automatic Characterization of a Sample Based on the Data Received by Means of the Laser Induced Breakdown Spectroscopy (LIBS).
Klus, Jakub ; Černohorský,, Tomáš (referee) ; Veis,, Pavel (referee) ; Kaiser, Jozef (advisor)
Submitted work concerns with the theoretical and practical requirements for an automatic characterization of samples by means of Laser-Induced Breakdown Spectroscopy (LIBS). Theoretical aspects of laser-matter interaction, plasma expansion, and plasma emission are described theoretically within this work. The description of the plasma emission is enhanced with the spectral detection systems and statistical properties of the plasma. The principle of the automatic characterization is based on the multivariate data analysis theoretical background, which presents recent trend and fundamental approach for automatic spectra analysis in LIBS. Theoretical knowledge is manifested in six applications, which are presented as a comment to published manuscripts. These publications push the frontiers of automatic spectra processing in LIBS.
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Collection system design for multichannel spectrometer
Sovadina, Petr ; Buday, Jakub (referee) ; Novotný, Jan (advisor)
In laser-induced breakdown spectroscopy, the intensity of radiation that enters the spectrometer is crucial. Ideally, the collection of radiation is from a single point of plasma. The greater the intensity of radiation is, the more perspicuous the graph of wavelengths is. Therefore, it is necessary to have the best optimized optical collection system. The existing collection system was not designed for connection to a multichannel spectrometer. The use of the optical multifibre resulted in a collection of radiation from different spots in plasma. Therefore, there was a request for a new optical system designed to collect radiation from a single point of plasma and would be suited for the best collection of radiation. The designed and manufactured collection system was tested. During the test was discovered that the collection system can be calibrated well and allows collection from one point of plasma. The test is considered successful.
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Comparison of quantification strategies in Laser-Induced Breakdown Spectroscopy
Hošek, Martin ; Hrdlička, Aleš (referee) ; Prochazka, David (advisor)
The aim of the submitted work is a comparison of methods of quantitative analysis used in laser-induced breakdown spectroscopy (LIBS). The principles of LIBS method are explained at first, followed by a research of the most often used methods of quantitative analysis. The next part provides their description enabling a better comprehension and an eventual use of the methods in practice. Finally, the chosen methods are used to process data from the real experiment and the results are compared.
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Development of a device and methodology for Laser-Induced Breakdown Spectroscopy (LIBS)
Képeš, Erik ; Ferus,, Martin (referee) ; Lohninger, Hans (referee) ; Kaiser, Jozef (advisor)
Táto práca sa zaoberá prenosom analytických modelov medzi rôznymi systémami spektroskopie laserom indukovanej plazmy (LIBS) a porovnaním LIBS výsledkov získaných na rôznych systémoch. Instrumentácia LIBS aj spracovanie LIBS spektier sú vysoko flexibilné. Bohužiaľ, kvôli týmto flexibilitám sú výsledky získané na jednom LIBS systéme zriedka priamo porovnateľné s výsledkami získanými na inom systéme. Toto je ďalej komplikované rôznymi, často neznámymi, účinkami algoritmov spracovania LIBS spektier. V dôsledku toho sú modely analýzy spravidla špecifické pre systém (a parametre). Prenos analytických modelov medzi rôznými systémami by viedol k významnému zlepšeniu analytických schopností metódy LIBS a k miernemu zníženiu nákladov v priemyselných aplikáciách LIBS. Práca skúma vplyv rôznych stratégií merania metódou LIBS. Naďalej, práca skúma transformáciu získaných LIBS spektier prostredníctvom spracovávania údajov. Práca sa napokon zaoberá prenosom analytických modelov medzi rôznymi LIBS systémami.
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Classification of metals by means of Laser-induced Breakdown Spectroscopy and chemometric methods
Képeš, Erik ; Hrdlička, Aleš (referee) ; Novotný, Jan (advisor)
Táto diplomová práca sa zaoberá klasifikáciou kovov pomocou spektroskopie laserom indukovanej plazmy (LIBS) a chemometrických metód. Práca poskytuje prehľad o štúdiách na danú tému. Sú vybrané tri široko používané chemometrické klasifikačné metódy: "Soft Independent Modeling of Class Analogy" (SIMCA), "Partial Least Squares Discriminant Analysis" (PLS-DA) a variácia umelých neurónových sietí (ANN), "Feedforward Multilayer Perceptron". Rôzne prístupy k prieskumovej analýze su tiež preskúmané. Metódy sú stručne opísané. Následne sú klasifikátory experimentálne porovnané.
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Development of universal software interface for detection units in optical spectroscopy
Belica, Martin ; Pořízka, Pavel (referee) ; Žalud, Luděk (advisor)
This master's thesis deals with the design and implementation of universal user interface for detection devices used in Laser-induced breakdown spectroscopy. The design and implementation are based on analysis of current state of instrumentation used in laser spectroscopy. The user interface should be able to work with high repetition frequency of measurement. Acquired spectra should be visualised to user and it is also necessary to save this data on hard drive. The resulting application must be universal. It means the application must support various types and vendors of detection devices.
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Impact of the atmosphere on laser ablation of matters
Černá, Svatava ; Hrdlička, Aleš (referee) ; Pořízka, Pavel (advisor)
This thesis deals with a general overview of laser-induced breakdown spectroscopy - ablation of material and plasma formation when a change of the surrounding environment occurs. The aim is to establish ideal conditions for improving detection, which is difficult for some elements when the measurement takes place in the ambient atmosphere. This is the reason why we change the ambient conditions, the gas (air, helium, argon) and its pressure. Buffer gases (helium, argon) influence the development of the material ablation and quality of generated plasma. That is why we inspect the changes in the signal according to particular atmospheres (signal change in buffer gases compared to the ambient atmosphere). The first part of the thesis presents the principle and physical nature of laser ablation with a brief search of experiments performed so far for similar purposes. Based on this search we determine conclusions about the influence of buffer gasses and pressure on the detection used gasses. In the second part of the work, the controlled experiment is presented, which consisted of the detection of spectral lines of fluorine and potassium, see chapter 5.6 and molecular transitions of calcium fluoride, see chapter 5.10. In a controlled experiment, we established two assumptions. The first assumption is the influence of the inert gas atmosphere, which should significantly improve the detection of fluorine and potassium compared to the air atmosphere. We confirmed this finding only for the argon atmosphere. In contrast, in the helium atmosphere, the detection of none of the elements improved. The second assumption is the effect of reducing the ambient pressure, which in combination with an inert gas should allow the detection of fluorine even at low concentrations in the sample. We consider the measured glass disk in chapter 5.7 to be such a sample. This assumption is not confirmed, as the increased intensity of the fluorine spectral line does not manifest itself in any way when the pressure in the vacuum chamber decreases. Finally, in chapter 7 from the results of individual parts of the experiment, the most suitable conditions for the future detection of the measured substances were proposed: fluorine, potassium and calcium fluoride molecules.
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Analysis of biotic matrices by Laser-Induced Breakdown Spectroscopy
Střítežská, Sára ; Karel,, Novotný (referee) ; Modlitbová, Pavlína (advisor)
This bachelor thesis discusses the possibility of using Laser-induced breakdown spectroscopy (LIBS) for biological application. The LIBS method was used to determine spatial distribution of a chosen element, cadmium, in selected model plant, white mustard (Sinapis Alba L.) The exposure took place in hydroponic conditions and lasted for 72 hours, therefore it was an acute toxicity test. Three different sources of cadmium were tested, mercaptopropionic acid stabilized quantum dots (CdTe QDs), silica coated quantum dots (CdTe/SiO2 QDs), and cadmium chloride, which was used as a positive control. After the exposure and before determination of the spatial distribution of cadmium in plants, a significant portion of the thesis was devoted to optimization of selected parameters of LIBS measurement (laser energy and gate delay). Subsequently, the cadmium distribution was determined and the obtained results were discussed with regards to the tested substance, its stability and its tendency to aggregate/agglomerate in water medium in contact with testing organism during exposure. In the final part of the work, the suitability of the LIBS method for the determination of spatial distribution of chosen contaminants was evaluated.
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Detection of heavy metals in hard tissues by laser-induced breakdown spectroscopy
Konečná, Anna ; Novotný, Karel (referee) ; Pořízka, Pavel (advisor)
This master thesis deals with the detection of heavy metals bioaccumulated in hard tissues by laser-induced breakdown spectroscopy (LIBS). As model samples, murine mandibles and femurs of animals exposed to lead oxide or cadmium oxide nanoparticles were used. The exposure of animals lasted for 6 or 7 weeks. Control group of animals was exposed only to air for a reference. The distribution of biogenic elements and contaminants was determined by mapping the samples' surface using LIBS with a spatial resolution of 30 and 100 µm. The second part of the work focused on the possibility of using the method LIBS for quantitative analysis. Samples of hydroxyapatite standards were prepared as reference material. By their analysis a calibration curve was constructed, and the limits of detection and quantification were determined. Furthermore, a model for prediction of heavy metal concentration by calculation from the calibration curve was presented.
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