Light scattering from irregular tetrahedral aggregates

We examine the light scattering from spheres aggregated into tetrahedral structures and the changes that occur when the internal structure of the system is modified by filling the central portion of the tetrahedron with an index-matching solution. Several effects are noticed in the scattering signals. The scattering phase function of aggregates is quite sensitive to changes in the internal structure within the aggregate. The positions and relative intensities of the maxima and minima of an aggregate tend to have a stronger dependence on orientation and internal structure than for a sphere containing an inclusion. As the area of the interfaces increases, the backscatter intensity increases, resulting in a decrease in the asymmetry parameter. Specular reflections also occur due to the constructive interference of rays reflecting off the different lattice sites. (C) 1998 Elsevier Science B.V. All rights reserved.