2P-55 PDF
Measurement of the hygroscopic growth factor distributions of urban aerosol particles and the mass spectra of single particles
Hygroscopicity (water uptake ability) is a property that relates to the polarity, chemical reactivity, and lifetime of aerosols by water removal process in the atmosphere. Some previous studies using the well-known model particles in the laboratory had reported that the amount of water retained by the particles as a function of relative humidity (RH) is governed by the phase state and chemical composition. However, there have been few reports for atmospheric aerosol particles. In this study, hygroscopic growth factor (g) distributions of atmospheric aerosol particles and mass spectra of single particles selected by the growth factors were measured using a combination of hygroscopicity tandem differential mobility analyzer (HTDMA) and a high resolution time-of-flight aerosol mass spectrometer (AMS). The 349 mass spectra of single particles with specific g were extracted from the obtained data. Particles were categorized by the hygroscopic modes, chemical composition and RH conditions and results suggested the presence of metastable-state aqueous solutions in the particles.