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    Fundamental studies of atmospheric pressure electrical discharges for analytical spectrometry : towards the optimization of analytical ionization/excitation sources

    Author
    Molnar, Brian T.
    View/Open
    180646_Molnar_rpi_0185E_11859.pdf (4.593Mb)
    Other Contributors
    Shelley, Jacob T., 1984-; Korenowski, Gerald; Lakshmi, K. V.; Plawski, Joel;
    Date Issued
    2021-05
    Subject
    Chemistry
    Degree
    PhD;
    Terms of Use
    This electronic version is a licensed copy owned by Rensselaer Polytechnic Institute, Troy, NY. Copyright of original work retained by author.;
    Metadata
    Show full item record
    URI
    https://hdl.handle.net/20.500.13015/2716
    Abstract
    Electrical discharges have been critical to the advancement of analytical science for over a hundred years. Perhaps the most useful property of electrical discharges is that the resultant reactive species have exceptionally high potential energies (> 15 eV). These high energy reactive species are well suited for ionization (mass spectrometry, MS) and excitation (spectroscopy). Before 1973, many analytical electrical discharges, especially those used for molecular MS, were confined to high vacuum. High vacuum conditions are advantageous because a decrease the mean free path prevents an arc from forming, ambient gas flows and contamination do not affect the discharge, and there are no fluid dynamics to consider if mass transport is needed. Recently, numerous electrical discharges have been developed that operate at atmospheric pressure (AP) and are exposed to ambient conditions. Atmospheric pressure discharges are advantageous because they are less costly to build, sample compatibility is better, collisional cooling limits fragmentation of molecular species, and sample introduction is simpler. However, more work is needed to understand how AP ionization chemistry and mass transport at atmospheric pressure affect analytical results. In this work, chemical ionization processes were investigated for different types of electrical discharges and analytes with MS detection. Meanwhile, computational fluid dynamics and fluid flow visualization were used to better understand the role of mass transport from the ambient discharge source to the lower pressure MS inlet. Lastly, a variant of these electrical plasmas has been optimized for use as a source of vacuum ultraviolet radiation, for MS or optical spectroscopic detection. The results from these fundamental studies are used to suggest improvements that can be made in the design of ionization or excitation sources.;
    Description
    May 2021; School of Science
    Department
    Dept. of Chemistry and Chemical Biology;
    Publisher
    Rensselaer Polytechnic Institute, Troy, NY
    Relationships
    Rensselaer Theses and Dissertations Online Collection;
    Access
    Restricted to current Rensselaer faculty, staff and students. Access inquiries may be directed to the Rensselaer Libraries.;
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