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Investigating the evolution of laser induced plasmas by complementary optical and spectroscopic methods
Buday, Jakub ; Novotný, Karel (oponent) ; Pouzar, Miroslav (oponent) ; Kaiser, Jozef (vedoucí práce)
Laser-Induced Breakdown Spectroscopy (LIBS) is a method of analytical chemistry that provides a qualitative and quantitative sample analysis. As this method has been implemented in more and more applications, certain limitations and drawbacks have been raised from this progress. Some of these limitations are connected to the fact, that the ablation process of a~sample is fast and dynamic and the changes of the plasma plume in time and space are a question of a few microseconds. As this can cause certain limitations in the analysis process, there has been a question of how to minimize or eliminate these problems. For this purpose, supplementary methods have been more and more implemented in the LIBS experiments. The goal is simple, acquire more information from the complex process of the ablation and improve the analytical performance of LIBS, be it in the scope of qualitative or quantitative analysis. Here lies the main motivation of this dissertation thesis. Goal of this thesis was to research, implement and utilize supplementary methods, that could be used in combination with the existing LIBS experimental setup. As a result, direct plasma imaging, shadowgraphy and sound analysis systems have been implemented and streamlined into the typical analytical process. Each of these methods brings certain additional information. For direct plasma imaging, it can be the spacious-temporal morphology of the plasma plume, or the distribution of individual elements within its volume. The Shadowgraphy method can be used to calculate the energy spent on the ablation itself, pointing at the thermal properties of the analyzed sample. Lastly, the sound information from the generated shock wave is connected to the amount of ablated mass. Within this thesis, all of the mentioned supplementary methods were examined, and utilized. Insight into these methods together with the LIBS analysis was done individually for each method as well as from the point of their mutual combination. The theoretical information as well as their background is described and discussed. Moreover, the technical information is discussed and analyzed, be it the implementation of the LIBS experiment, or the actual data analysis process. This work will serve as a foundation for further research in this area, where a selection of these methods will be used in several applications that are already using LIBS but suffer from certain limitations. These methods will be used to mitigate the limitation and to elevate the potential use of the LIBS in certain areas and applications.
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