Absorption and scattering of light by polydisperse aggregates

Area of Science:

• Physical Chemistry
• Materials Science
• Optical Physics

Background:

• Optical properties of aggregates are essential for understanding light-matter interactions.
• Fractal aggregates, formed via cluster-cluster aggregation, are prevalent in various scientific and industrial contexts.
• Accurate modeling of optical properties requires consideration of aggregate structure and size distribution.

Purpose of the Study:

• To present absorption, scattering, and differential scattering cross sections for polydisperse fractal aggregates.
• To formulate these optical properties based on primary particle size, size distribution moments, and radius of gyration.
• To compare results with existing theories and simulations for validation.

Main Methods:

• Theoretical formulation of optical properties for polydisperse aggregates.
• Utilizing fractal dimension and primary particle size as key parameters.
• Comparison with Rayleigh theory for small sizes and computational simulations for larger aggregates.

Main Results:

• Formulated optical properties in terms of primary particle diameter, size distribution moments, and mean-square radius of gyration.
• Absorption and scattering cross sections align with Rayleigh theory in the small size limit.
• Differential scattering cross sections are described by Guinier's law and a power-law for larger sizes.

Conclusions:

• The presented cross sections accurately describe polydisperse fractal aggregates.
• The findings are applicable to fractallike aggregates relevant to laboratory experiments and industrial processes.
• The study provides a robust framework for predicting optical behavior of complex aggregate structures.