Radiative characteristics of a particle using a bump and pit sphere model

Using the particle superposition method, we constructed a bump and pit sphere model that randomly distributes bumps and pits onto the surface of a wavelength-sized host sphere to simulate a rough particle. We studied both the influence of the imaginary part of the refractive index and the number of dusted grains on the particle's radiative properties and found that the linear polarization and phase function of the particle were sensitive to these two parameters. Changes in the imaginary part of the refractive index caused a regular change in the linear polarization, which was reflected in the number of positive peaks and negative troughs. In addition, the number of dusted grains on the surface of the particle changed the absolute value of the linear polarization, because the linear polarization of a particle with many grains on its surface has a smaller absolute value than a particle with few grains. The backward-scattering region of the phase function became significantly smoother for non-dielectric particles than for dielectric particles. Finally, we analyzed the radiative characteristics of polydisperse compound particles. We found that the optical effects of the ratio of pit number to bump number on the polydisperse compound particles are rather weak, if not negligible.