Development, characterization, and application of new analytical methodologies based on optical and mass spetrometry

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Our group is studying and developing atmospheric pressure ionization (API) sources for interfacing liquid chromatography (LC) with mass spectrometry (MS). In an effort to expand the range of compounds amenable to LC-MS, as well as to improve the sensitivity of LC-MS methods in general, a new ionization method, atmospheric pressure photoionization (APPI), has been recently developed. One of our ongoing research projects is aimed at elucidating the fundamental mechanisms responsible for the performance of the APPI source, to place APPI on a firm theoretical foundation through a systematic study of the photophysics and gas-phase chemistry in the ionization region. Future research projects will be undertaken to investigate improvements to the APPI source, as well as to develop novel API source enhancements.    Raman spectroscopy can be used to determine structural and environmental information concerning biomolecules, at relatively low concentration in aqueous solutions, which makes it a very powerful bioanalytical and biophysical technique. Ultraviolet resonance Raman spectroscopy (UVRRS) is being used for the study of the structure and properties of proteins, peptides, and DNA, and for the in-vivo detection and characterization of biomolecules.  The group will expand its arsenal of techniques for the study and characterization of biomolecular systems to include fs-coherent anti-Stokes Raman spectroscopy for structure and dynamics measurements.    In order to quantify the importance of atmospheric aerosols, we are developing an advanced single particle aerosol mass spectrometer that improves on current designs by combining thermal laser desorption and near threshold photoionization with ion trap mass spectrometry. The completed apparatus will be used to determine the size-resolved chemical composition of ambient aerosols, and the state of mixing of aerosol constituents. This type of information is critical for understanding the role of aerosols in the atmosphere.