Analytical solutions to radiative absorption and scattering by the large multilayer concentric-sphere particle

This study develops the ray-tracing method based on geometric optics approximation to quantify analytically radiative absorption and scattering by the large multilayer concentric-sphere particle with specular or diffuse interfaces. Analytical expressions of the absorptance and scattering albedo of the multilayer particle are presented and the contribution of each layer to the total absorption of the multilayer particle is analytically provided as well. These analytical results are validated by the Monte Carlo method and Lorenz-Mie theory. The absorptance of the multilayer particle with either specular or diffuse interfaces increases with increasing size parameter. The contribution of each layer to the total absorption of the multilayer particle depends on the model of interfaces (specular or diffuse) and varies slightly with increasing size parameter. Moreover, refractive index of each layer has slight effects on the absorptance for specular interfaces, while it increases the later for diffuse interfaces. The absorptance increases with increasing absorption index of each layer, especially with increasing absorption index of the layer with larger volume fraction.