Techniques and Applications in Characterizing Atmospheric Particles through Chemical Imaging

The physical and chemical characterization of atmospheric aerosol particles proves challenging due to the nature and complexity of these particles in the atmosphere. The properties of aerosol particles are dependent on a multitude of factors including, but not limited to, the aerosol properties, such as source, morphology, and mixing state, as well as atmospheric influences, such as reactions, transport, and ambient temperature and humidity. Chemical imaging provides the means to elucidate both physical and chemical properties of aerosol particles by capturing the structure and distribution of constituents within individual particles.¹ By utilizing techniques such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM) and secondary ion mass spectrometry (SIMS), chemical imaging allows for the study of particle transformations, mixing states, morphologies, hygroscopic growth, and surface chemical composition as a means to classify and characterize aerosol particles.^2-6 One of the greatest advantages of chemical imaging techniques is the ability to perform studies of a single aerosol particle which common bulk chemical analysis methods cannot. With an improved understanding of aerosol properties obtained through the chemical imaging of single particles, the climate and health effects of aerosol particles can be better constrained.

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6. Li, W. J. et al., TOF-SIMS surface analysis of chemical components of size-fractioned urban aerosols in a typical heavy air pollution event in Beijing. Journal of Environmental Sciences 2018, 69, 61-76.