In the atmospheric community, the mechanism of ice nucleation continues to be a topic of debate. For heterogeneous ice nucleation, the composition and surface features of an aerosol particle can have a large impact on the ice nucleation activity. Because of the complexity of atmospheric aerosol particles, it is difficult to determine which properties contribute to its ice nucleation efficiency. In this study, a metal oxide model system, aluminum oxide, was used to study the effect of crystallinity and crystal structure on ice nucleation. The aluminum oxides were characterized, and then, immersion ice nucleation experiments were run in an environmental chamber. From X-ray diffraction studies, the aluminum oxides showed varying amounts of crystallinity that were correlated with the ice nucleation activity. The samples with higher crystallinity had higher ice nucleation activity, while those with more amorphous content had lower activity. In addition, among the crystalline samples, a hexagonal crystal structure was shown to improve ice nucleation activity. As a follow up study, iron oxides were studied and gave further insight on the effect of surface features on ice nucleation. Overall, the use of model systems to study aerosol properties such as crystallinity and crystal structure can further unravel the complexity of atmospheric particles by systematically investigating the effect that specific properties have on ice nucleation activity.

Using model metal oxide systems to study ice nucleation activity

2019 Fall National Meeting

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