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Emissions from the Earth's surfaces are a major source of trace gases in the atmosphere. Vice versa, vapors can be taken up by these surfaces, especially following chemical processing in the atmosphere – a process that can compete with uptake by aerosol. Online chemical ionization mass spectrometers (CIMS) have become a powerful tool for studying these air-surface exchange processes. I will present applications of CIMS to measure emissions of organic trace gases from wetlands and ammonia from agriculture, exploiting high sensitivities and fast time response for flux measurements via eddy covariance. The wetland emissions were surprisingly high and sensitive to temperature. Ammonia measurements were also made on an aircraft, with additional benefits but also challenges.
I will also present preliminary results of my current work in Boulder, where I am coupling a combined ion mobility-mass spectrometer (CI-IMS-MS) with the FIGAERO (filter inlet for gases and aerosols) thermal desorption inlet. The latter allows for determining the composition of a major fraction of organic aerosol on a molecular level, and also for assessing the molecules' volatility, a key property for understanding aerosol formation. Via IMS, we can additionally separate isomers. Supported by quantum chemistry-based calculations of ion adduct structures and mobilities, we can attempt to assign specific structures to the observed molecules.
Born in Austria, Sigi Schobesberger received a Master's degree in Physics from the University of Vienna in 2008 (advisor Paul Wagner), followed by a PhD from the University of Helsinki in 2014 (Markku Kulmala, Doug Worsnop). After a postdoctoral fellowship at the University of Washington (Joel Thornton), he joined the faculty in the Department of Technical Physics at the University of Eastern Finland in 2017, where he is currently a Professor. In September 2025, he started a 1-year Visiting Fellowship with CIRES at the University of Colorado Boulder (Department of Chemistry). His main research interests evolve around the formation and evolution of aerosol particles in the atmosphere, including the sources and sinks of aerosol-relevant trace gases. The primary research tools are online atmospheric mass spectrometers and fancy additional techniques, to make his life harder but also to make better sense of their measurements.
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