Structural correlations and dependent scattering mechanism on the radiative properties of random media

Abstract

The dependent scattering mechanism is known to have a significant impact on the radiative properties of random media containing discrete scatterers. Here we theoretically demonstrate the role of dependent scattering on the radiative properties of disordered media composed of nonabsorbing, dual-dipolar particles. Based on our theoretical formulas for the radiative properties for such media, we investigate the dependent scattering effects, including the effect of modification of the electric and magnetic dipole excitations and the far-field interference effect, both induced and influenced by the structural correlations. We study in detail how the structural correlations play a role in the dependent scattering mechanism by using two types of particle system, i.e., the hard-sphere system and the sticky-hard-sphere system. We show that the inverse stickiness parameter, which controls the interparticle adhesive force and thus the particle correlations, can tune the radiative properties significantly. Particularly, increasing the surface stickiness can result in a higher scattering coefficient and a larger asymmetry factor. The results also imply that in the present system, the far-field interference effect plays a dominant role in the radiative properties while the effect of modification of the electric and magnetic dipole excitations is more subtle. Our study is promising in understanding and manipulating the radiative properties of dual-dipolar random media.

The dependent scattering effect on radiative properties of micro/nanoscale discrete disordered media

“…For other DDM with more complicated micro/nanostructures, it is still difficult to do so. On the basis of previous works on direct numerical simula-tions, we can summarize the implementation procedure of this method to derive radiative properties, which is described as follows [323].…”

Rigorous Accounting for Dependent Scattering in Thick and Concentrated Nanoemulsions

“…Previously, researchers have noted the larger transmittance and related it to the effect of osmotic compressibility on the structure factor. , The structure factor has been used to explain qualitatively the reduction in turbidity, i.e. , the increase in transmittance in colloids with increasing volume fraction. − However, the structure factor correction accounts for dependent scattering only by using a far-field approximation to modify the independent scattering solution of the scattering coefficient but does not account for near-field effects. − ,− However, the latter can affect the appearance of nanoemulsions, which is an important consideration in food and cosmetics applications, for example.…”

“…For example, Mishchenko , utilized the static structure factor as a correction in the asymmetry factor and scattering coefficient of soil particles and planetary regoliths. Though the static structure factor does not account for near-field effects and does not alter the absorption cross-section calculated by the Lorenz–Mie theory, it has been widely used to account for dependent scattering included in colloidal suspensions. − …”

“…Many studies have analyzed the effect of the structure factor of the optical behavior of colloidal suspensions. − For example, Wang and Zhao studied numerically the effect of the structure factor on the scattering coefficient and asymmetry factor of charged colloidal suspensions of TiO 2 or polystyrene nanoparticles in water with volume fraction f v ranging between 1 and 30%. The authors used the Yukawa hard sphere formulation to determine the correlated positions of each scatterer in the medium and the corresponding static structure factor.…”

“…Though the static structure factor does not account for near-field effects and does not alter the absorption cross-section calculated by the Lorenz–Mie theory, it has been widely used to account for dependent scattering included in colloidal suspensions. 20 − 22 …”