Title:     Hydrated Semi-Volatile Organic Compounds of Atmospheric Relevance: Rotational Spectroscopy and Electronic Structure Calculations

Time:     2024-05-27 10:00

Lecturer:  Prof. Wolfgang Jäger

  University of Alberta

Venue:    Room 202, Lecture Hall, Lu-Jiaxi Building

Abstract：

Volatile organic compounds (VOCs) of both biogenic and anthropogenic origin play important roles in atmospheric chemistry. They can be oxidized by OH radical to form compounds of lower volatility which can partition from the gas into the condensed phase to form secondary organic aerosol (SOA). SOAs can affect our climate by absorbing and scattering solar radiation which leads to heating or cooling depending on the composition and morphology of the particles. SOAs also affect human health as small particles with diameter less than 2.5 μm (PM2.5) can enter deep into the lungs and can transport toxic substances into our blood stream.

The initial phases of aerosol particle formation involve hydrogen-bonded complexes and clusters that are thought to contain oxidized organic substances, water molecules, sulfuric acid, and ammonia. In this presentation, I will describe several substances of atmospheric relevance, such as α-pinene, vanillic acid, oxalic acid, and 4-methylcatechol, and their stepwise micro-solvation by water molecules. From the rotational spectra of these hydrogen-bonded complexes and clusters information about their structures, conformers, and intra-and inter-molecular dynamics can be extracted. Electronic structure calculations are indispensable for assignments of the experimental spectra and analyses of electron density distributions from those calculations are used to gain further insights into the inter-molecular interactions.

Bio of Prof. Wolfgang Jäger：

Wolfgang Jäger received his PhD degree in Chemistry from the Christian-Albrechts University in Kiel, Germany, in 1989. He joined the Department of Chemistry at the University of Alberta, Edmonton, Canada, in 1995 after spending time as postdoctoral fellow and research associate at the University of British Columbia, Vancouver, Canada. He was promoted to Associate Professor in 2001 and to the rank of Full Professor in 2003.

Professor Jäger’s research includes fundamental studies of intermolecular interactions using spectroscopic investigations of weakly bound complexes and clusters, development of atmospheric trace gas sensing techniques that utilize solid state infrared diode lasers, photoreaction chamber studies of aerosol formation, and design and fabrication of external cavity lasers using MEMS technology. His work has resulted in more than 200 publications and numerous presentations at national and international meetings.

For his scientific achievements, Professor Jäger was awarded the NSERC Steacie Memorial Fellowship in 2002, in 2004 he became a Tier I Canada Research Chair in Cluster Science which was renewed in 2011, and in 2008 he was elected Fellow of the Royal Society of Canada. From 2009 to 2010, he spent a sabbatical year at the Fritz Haber Institute of the Max Planck Society in Berlin, Germany, which was funded by a Humboldt Fellowship.