Douglas Worsnop

worsnop Mass Spectrometry of Atmospheric Aerosol: 1 nanometer to 1 micron

About the Presenter:

Doug Worsnop is a leading expert in the chemistry and heterogeneous reactions of atmospheric aerosols. He has pioneered the development of laboratory and field measurement techniques for investigating chemical interactions between atmospheric trace gases and aerosols, including water droplets. His expertise extends to the mechanisms of the formation of polar stratospheric clouds, and to measurements of the chemical composition of atmospheric aerosols. Dr. Worsnop is a recipient of the 2004 Benjamin Y. H. Liu Award (American Association for Aerosol Research) for his achievements in atmospheric composition measurement with the Aerodyne mass spectrometer system (AMS). He received the 2010 Yoram Kaufman (AGU Atmospheric Sciences) for Unselfish Cooperation in Research and is a Fellow of AAAS and AGU.

Full Presentation:


Despite much effort in the past decades, uncertainties in both climate impacts and health effects of atmospheric aerosols remain large. During the last ten years, aerosol mass spectrometry (AMS) has enabled size resolved measurement of sub-micron aerosol, showing that chemical composition is roughly 50:50 inorganic and organic worldwide. Elemental analysis (C, H, O, N, S; via time-of-flight mass spectrometry, ToFMS) has separated primary and secondary aerosol and shown that organics become highly oxidized on a time scale of days, with low volatility oxidized organic dominating remote aerosol organic loading. Global aerosol loading is dominated by photochemical production of inorganic and organic components. Parallel application of ToFMS to directly sample atmospheric ions has provided the first observation of molecular cluster ions involved in atmospheric nucleation. Chemical ionization mass spectrometry (CIMS), based on high pressure TOFMS, has extended detection to neutral molecules and clusters, detecting highly oxidized multifunctional organics in the gas phase. Ambient sampling and photochemical chamber experiments (Hyytiälä, Finland, and Cosmics Leaving OUtdoor Droplets (CLOUD) at CERN, respectively) have resolved the interaction of H2SO4 and low volatility organic vapors in nanoparticle particle nucleation and growth.