At the outlet of the chamber, SOA material was collected onto fluorinated glass slides (12 mm slides; coated with CYTONIX, FluoroPel 800) using either a multi-orifice single stage impactor (MSP Corporation) or a slit impactor (Sioutas Cascade Impactor, SKC Inc.). Each sample was collected continuously for ~7-24 h. During this time, the individual SOA particles coagulated on the glass slide forming larger SOA particles with diameters of ~30-200 µm. At the end of the collection, the sample slide was taken out of the impactor, sealed, and stored at -18 °C until the viscosity measurements.