Evaporation of mixed citric acid/(NH)SO/HO particles: Volatility of organic aerosol by using optical tweezers.

The condensation and evaporation processes of semi-volatile organic compounds (SVOCs) in atmospheric aerosols can induce significant evolutions of their chemical and physical properties. Hence, for interpreting and predicting composition changes of atmospheric aerosols, it is indispensable to provide insight into the partitioning behaviors of SVOCs between condensed and gas phases. In this research, optical tweezers coupled with cavity-enhanced Raman spectroscopy were employed to observe the volatility of internally mixed citric acid (CA)/(NH)SO (AS) particles, and the effect of AS on the gas/particle partitioning behaviors of atmospheric organic acids was investigated.

Investigation of gel formation and volatilization of acetate acid in magnesium acetate droplets by the optical tweezers.

Hygroscopicity and volatility of single magnesium acetate (MgAc) aerosol particles at various relative humidities (RHs) are studied by a single-beam optical tweezers, and refractive indices (RIs) and morphology are characterized by cavity enhanced Raman spectroscopy. Gel formation and volatilization of acetate acid (HAc) in MgAc droplets are observed. Due to the formation of amorphous gel structure, water transposition in droplets at RH < 50% is significantly impeded on a time scale of 140,000 s.