The study of the formation and molecular chemical composition of SOA is critical because of their influence on climate through cloud formation and the radiative forcing of SOA. An understanding of SOA composition is beneficial for the improvement of air quality models, given that SOA are a major component of fine particulate matter (PM2.5). Furthermore, changes in VOC emissions resulting from expected future increase in biomass burning events and shifts in energy production and usage also alter the composition and pathways of SOA formation. Consequently, it is important to understand these dynamics in order to accurately predict their impact on air quality, climate, and human health (e.g. respiratory and cardiovascular diseases).

In our studies, we employ a range of advanced analytical techniques, including High-Resolution Time-of-Flight Aerosol Mass Spectrometry (HR-ToF-AMS) and Extractive Electrospray Ionization Long-Time-of-Flight Chemical Ionization Mass Spectrometry (EESI-LToF-CIMS). HR-ToF-AMS is employed to provide real-time, high-resolution data on the bulk chemical composition of aerosols including elemental ratios and oxidation states. EESI-LToF-CIMS provides an additional capability by enabling the sensitive detection of highly oxygenated organic molecules and low-volatile compounds directly online from the gas and particle phases without the necessity for extensive sample preparation or alteration. This allows a more complete picture of the complex chemical composition of SOA to be captured. Another measurement method we use is the combination instrument CPC and SMPS.

These analytical techniques are employed within controlled simulation environments, including the atmosphere simulation chamber SAPHIR, the Plant Unit for Simulation coupled to SAPHIR (SAPHIR-PLUS), and the Stirred Atmospheric Flow Reactor (SAPHIR-STAR). The SAPHIR chamber allows for the study of photochemical reactions and atmospheric processes under near-real atmospheric conditions, while SAPHIR-PLUS is specifically designed to study real biogenic emissions offering a unique opportunity to assess how plant-derived VOCs contribute to SOA formation under varying environmental conditions, including constitutive emissions, and emissions due to e.g. heat, drought or ozone stress. The SAPHIR-STAR chamber permits the investigation of SOA formation and gas-particle partitioning in a highly controlled environment and under steady-state conditions which is essential to understand critical chemical processes that drive and contribute to SOA formation. These investigations are carried out in close collaboration with the "Heterogeneous Reactions" group.

Current cooperations

Aerosol mass spectrometers and Chemical ionization mass spectrometers from Aerodyne Research Inc. are employed for online analysis of the chemical composition of aerosols within the ICE-3 simulation chambers (SAPHIR, SAPHIR-PLUS, SAPHIR*) and in the field (Beijing winter fine particulate Study – Oxidation, Nucleation, and light Extinctions (BEST-ONE), JUelich Atmospheric Chemistry study (JULIAC tower, see SAPHIR), aeroHEALTH). The group participates in the ongoing Zeppelin activities at the ICE-3 and to preparations for longer term ambient measurements at the FZJ Meteorological Tower.

The German-Israeli Helmholtz International Laboratory aeroHEALTH strives to understand the biological and health effects of atmospheric aerosols. In this combined effort information and characterization on primary emissions as well as secondary organic aerosols and ambient aerosols are combined. Atmospheric processing (“ageing”) under atmospheric relevant conditions of biogenic and anthropogenic emissions are simulated on short- and long-term scales to connect laboratory observations with the observed health impacts from field experiments. The aeroHEALTH consortium consists of leading groups of two Helmholtz institutes in Germany and the Weizmann Institute for Science in Israel with associated international partners from the academic and commercial sector, combining complementary expertise and cutting-edge technology. The work of the aeroHEALTH consortium is reflected in joined extensive measurements campaigns studying the complex primary and aged emissions of combustion processes (jet engine emissions, shipping emissions, gasoline car emissions, and biomass burning emissions from wood stoves) and the subsequent formation of gas phase products and secondary organic aerosol (SOA) formation and contribution after aging in oxidation flow reactors (OFR). The Aerosol Chemistry group of the ICE-3 participates in the aeroHEALTH campaigns and studies in close collaboration with all partners, providing essential analysis and insights into OA formation and SOA chemical characterization.

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