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Laser-assisted Spectrometry and Spectroscopy for Open-air and in Situ Analyses
Many areas, such as medical diagnosis, forensic analysis, and environmental supervision require advanced analytical techniques. These techniques serve as our eyes and help us see what we cannot see. Conventional analytical methods require tedious procedures, such as liquid chromatography, which take time. However, in some cases, such as post-detonation analysis, simple, fast, open-air, and in situ analytical screening approaches are in urgent demand. In this dissertation, we focused on two advanced analytical techniques which support simple, fast, open-air and in situ applications: 1) laser-assisted mass spectrometry for open-air and in situ analysis; and 2) nonlinear optical microscopy for label-free visualization. Laser-assisted mass spectrometry (LAMS) has been one of the most powerful analytical techniques for atomic and molecular analyses. However, the conventional mass spectrometer systems operate either in a vacuum chamber or a sealed container with a controlled environment, which largely limits the applications. To extend the applications of LAMS and make it fit for open-air and in situ applications, we developed an open-air operated LAMS which is suitable for simple and fast analysis. Many techniques, such as magnetic field were investigated and applied to improve the sensitivity of the system. Nonlinear optical microscopy images the intrinsic properties of the sample which eliminates the tedious labeling processes and avoids unexpected distortions. As a label-free technique, nonlinear optical microscopy provides molecular information about the sample and has high potential to be used in biomedical analysis, especially for endoscopy. In this dissertation, nonlinear optical microscopy was investigated for cancer diagnosis and plant characterization. This dissertation investigates: 1) development of open-air, laser-assisted mass spectrometry (OA-LAMS) and its capabilities, 2) the isotopic signatures obtained from OA-LAMS, 3) improvement of the sensitivity of the OA-LAMS system by incorporating different external techniques: magnetic field, postresonant excitation, and direct analysis in real time (DART) ion source, and 4) nonlinear optical imaging techniques and their corresponding applications for cancer diagnosis and plant characterization. As a result of the work of this dissertation, the two analytical techniques, open-air, laser-assisted mass spectrometry and nonlinear optical microscopy, show great potential for use in simple, fast, open-air and in situ applications.
Lu, Yao, "Laser-assisted Spectrometry and Spectroscopy for Open-air and in Situ Analyses" (2018). ETD collection for University of Nebraska - Lincoln. AAI10845796.