Structure of Organic and Inorganic Mixed Aerosol Particles

Aerosols are defined a suspension of liquid or solid particles in gas. In nature, most aerosol particles are composites, made up of both inorganic and organic matter. While the identities of common components for the mixed aerosol particles are known, the structure of the particles is not. The structure of these mixed aerosol particles can alter its behavior in the presence of water due to different hygroscopic tendencies of the individual components. This study examined morphologies and structure of mixed particles, organic and inorganic, using Scanning Electron Microscopy. The higher volatility of the organic compounds under high voltages in the SEM allowed for the burning away of the organic compound and revealed the structure of the inorganic compound. An organic acid was mixed with NaCl, in varying concentrations, and the particles were then imaged. The particles were then placed into the SEM at a high electron beam at a tilted angle. The particles were then imaged before the burning process, and then kept under the beam for an allotted time, and the volatile organic was burned away. After the burning process the particles were then imaged again. Three different acids and NaCl combinations were explored. The three acids were adipic, glutaric, and succinic acid, all of which are dicarboxylic acids that react with ozone. The overall goal of this study was to examine the structure of composite particles to better understand cloud formation and modeling of global climate change.