Utilizing an electrical low-pressure impactor to indirectly probe water uptake via particle bounce measurements

Abstract. Secondary organic aerosol (SOA), formed through oxidation of volatile compounds (VOCs), displays complex viscosity and phase behaviors influenced by temperature, relative humidity (RH), chemical composition. Here, the efficacy a multi-stage electrical low-pressure impactor (ELPI) for indirect water uptake measurements was studied ammonium sulfate (AS) aerosol, sucrose ?-pinene-derived SOA. All three systems were subjected to greater than 90 % chamber humidity, with subsequent analysis indicating persistence particle bounce 70 nm (initial dry diameter) SOA number geometric mean diameters between 39 136 diameter). On other hand, 190 AS down exhibited no at elevated RH. Partial drying within lower diameter ELPI impaction stages, where inherent significant RH reductions occur, is proposed as one explanation persistence.