Tracking Water Sorption in Glassy Aerosol Particles using Morphology-Dependent Resonances

Area of Science:

• Atmospheric chemistry and physics
• Optical properties of aerosols
• Spectroscopy

Background:

• Morphology-dependent resonances (MDRs) are sensitive to microsphere size and composition.
• Analyzing MDRs in complex aerosol particles is challenging.
• Water sorption in ultraviscous and glassy aerosols creates a propagating concentration front.

Purpose of the Study:

• To investigate the applicability of a core-shell model for analyzing MDRs in water-sorbing aerosol particles.
• To simplify the analysis of MDRs during water uptake in high-viscosity aerosols.
• To assess the limitations of the core-shell model for tracking water sorption.

Main Methods:

• Simulating MDR positions for aerosol particles with sharp water concentration fronts.
• Comparing simulated MDRs to those predicted by a spherical core-shell model.
• Analyzing experimental MDR data from single aerosol particles during water sorption.

Main Results:

• MDR positions for sharp water concentration fronts closely resemble those of a core-shell profile.
• The core-shell model effectively simplifies the analysis of MDRs during water sorption.
• The radial position of the diffusion front can be readily determined using MDRs.

Conclusions:

• The core-shell model provides a faster and less error-prone method for analyzing MDRs in water-sorbing aerosols.
• This approach simplifies the characterization of water sorption dynamics in high-viscosity particles.
• Methods for calculating MDRs in core-shell particles are discussed, enhancing analytical capabilities.