Atmospheric aerosols are important to the environment, climate, and human health. The aerosol droplets contain both inorganic salt and organic compounds. Nitrate and sulfur make up the urban aerosols from plants and human activities. On the other hand, marine aerosols from sea salt water mainly contain sodium chloride. Among all kinds of organic compounds, water-soluble surfactant molecules exist at the interface of the aqueous bulk and the non-soluble organic shell, which play an important role in the growth of aerosol droplets. In our experiments, we mimic marine aerosols with sodium chloride solution and urban aerosols with ammonium sulfate solution. We used surfactant dye molecules to mimic soluble surfactant molecules in atmospheric aerosols. With the second harmonic scattering technique, only the surface dye molecules contributed to the signal. We plotted a Langmuir isotherm and used fitting parameters to calculate the surfactant molecules partition at the aerosol surface. The marine aerosols with NaCl have more surfactant than urban aerosols with (NH4)2SO4, the free energy of the equilibrium of the dye molecules between the bulk and surface is higher in urban aerosols with (NH4)2SO4. Our results showed that the surface properties of marine aerosols and urban aerosols are different due to the inorganic salt composition.

Marine aerosols and urban aerosols are different in surface properties -- using second harmonic scattering to observe the organic sufactant partition at the aerosol surface

Where thousands of chemistry professionals meet to share ideas and advance scientific and technical knowledge. Spring 2023 abstracts, posters, and presentations will launch at the end of March.

ACS Spring 2023

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.