Ever look up the sky and wonder how the particles are formed in the atmosphere and how we can mimic and investigate the process in the laboratory? The Aerosol Interaction and Dynamics in the Atmosphere (AIDA) chamber (KIT - IMK-AAF - Competences - AIDA facilities - AIDAc Facility) is one of the facilities that we can use to simulate reactions in atmospheric clouds, aerosols, and trace gases and their further impact on climate, weather, and air pollution.

In September 2023 and January 2024, two chamber simulation campaigns were conducted in the AIDA chamber at Karlsruhe Institute of Technology, Germany. The objective of the two campaigns is to simulate secondary organic aerosol formation pathways from the oxidation of various organic precursors, especially under a high relative humidity condition, i.e. under the presence of aqueous phase chemical reactions, and a presence of reactive nitrogen. By controlling the reaction conditions we try to simulate typical Dutch spring-time atmosphere when the humidity is high and a high concentration of nitrogen-containing pollutants are detected. Different precursors were injected, oxidized, mixed with the existing salt droplets and further irradiated with the potential participation of aqueous phase reactions.

In order to characterize the physical and chemical properties of the products in the chamber, various instruments were deployed, including particle counters and sizers, mass spectrometers in both high resolution and unit mass resolution, a cloud condensation nuclei counter and an aethalometer. In addition to real-time measurement, filters were also collected for further chemical compounds characterization in particle phase using thermal desorption methods connected respectively to a chemical ionization mass spectrometer (CIMS) and a proton transfer reaction mass spectrometer (PTR-MS).

In addition to the CAINA project, the campaigns are also funded by European Union via the ATMO-ACCESS project.