Optical properties and kappa factors of aerosol particles are necessary for improving current climate models. The kappa factors for both subsaturated and supersaturated aerosol particles should theoretically be the same. There are deviations between the two which are not well understood. This work investigates optical properties and particle growth of four glass-forming sugars (sucrose, raffinose, trehalose, and levoglucosan).  Optical growth factors and refractive indices are determined by use of Cavity Ring-Down spectroscopy (CRDS), wherein the extinction cross-sections of both the dry and humidified aerosol particles are determined. Subsequently the growth factors of each compound were calculated using Mie scattering theory and kappa factors were calculated using Kohler theory. The subsaturated kappa factors obtained form CRDS are compared to supersaturated kappa factors. We have found no effect of viscosity on the water uptake behavior of these systems for nanoscale particles using CRDS. These results are important to help us understand the water uptake behavior of aerosol particles, which can impact haze formation and visibility.<br/>

Subsaturated kappa factor determination and comparison for model systems

2019 Fall National Meeting

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