Light absorption and scattering of core-shell aerosol particles

Area of Science:

• Atmospheric Chemistry
• Optical Physics
• Climate Science

Background:

• Atmospheric aerosol particles often have inhomogeneous chemical compositions, affecting their optical properties.
• Spherical core-shell particle models approximate these inhomogeneities for radiative forcing models.
• Understanding core-shell particle optics is crucial for aerosol research, including phase transitions and coagulation.

Purpose of the Study:

• To systematically investigate the influence of core and shell properties on light absorption and scattering by core-shell particles.
• To determine conditions under which core-shell particles' optical properties can be approximated by homogeneous particles.
• To provide guidelines for analyzing light scattering measurements and for climate modeling.

Main Methods:

• Systematic simulations of light absorption and scattering by core-shell particles.
• Analysis of the impact of core and shell volume and refractive indices (real and imaginary parts) on optical properties.
• Formulation of conditions for approximating core-shell particle optics with homogeneous equivalents.

Main Results:

• Absorption cross-sections are primarily dependent on the volume and imaginary part of the refractive index of the core and shell.
• Scattering cross-sections are highly sensitive to all particle properties (volume, real and imaginary refractive indices) and show significant variation.
• General trends and conditions for optical property similarity between core-shell and homogeneous particles are identified.

Conclusions:

• Core-shell particle optical properties are complex and depend on multiple factors, with scattering being more sensitive than absorption.
• Specific criteria are established to approximate core-shell particles as homogeneous ones, aiding model simplification.
• The findings offer practical guidance for interpreting light scattering data and improving radiative forcing and climate models.