Current sucrose film experiments follow up on past experiments focused on water diffusion through a thin-film model for secondary organic aerosols (SOAs). Using FTIR-ATR instrumentation and thin films of a methylglyoxal-glycine brown carbon laboratory produced model, we found anomalous water diffusion behavior. This non-Fickian behavior was either because of the hydration of unreacted carbonyl groups in the film or, because the water diffusion constant substantially changes with water content of the film. To further investigate these two scenarios, a new way of manufacturing highly viscous glassy films was developed using sucrose to eliminate the possibility of diffusion reactions and focus on water content. Multiple methods were tested to make glassy non-crystalline films for use in our FTIR-ATR instrument. The glassy state is an important factor to our research as it allows for the sucrose to act as a model for SOAs. Film composition is then assessed gravimetrically and spectroscopically allowing us to calculate thickness as well as sucrose by weight. Ideally using these new sucrose films, we will develop a model for water diffusion through a system that changes as more water diffuses into it. Ultimately, the goal is to model water uptake in brown carbon aerosols so as to better understand their role in climate models and impact on human health.

Standardization of sucrose films as a model for water diffusion in brown carbon mimics

2019 Spring National Meeting

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