Effects of Anisotropy in Light Scattering by Anisotropic Layer Around a Spherical Particle in Uniaxial Medium.

摘要

We have used a Mie-type theory to study the light scattering from an annular anisotropic layer around a spherical colloidal particle. We have derived an exact solution of the scattering problem in the case when the distribution of the optical axes around the particles posses some special transformation properties under rotation and, outside of the layer, the ambient medium is isotropic. We have then calculated the dependence of the scattering cross- section on particle size, anisotropy parameter, and layer thickness for different optical axis distributions. We find that the scattering cross-section is strongly affected by the type of anisotropy. The presence of disclinations enhances scattering efficiency. We determine the region of validity of Rayleigh- Gans approximation by comparing approximate values of the scattering cross- section with the results computed from the exact solution. As an additional effect specific to anisotropic scatterer, it is found that for structures with broken central symmetry there is the phase shift proportional to the logarithm of layer thickness that enters the scattering amplitudes. In order to study the case of anisotropic ambient medium, approximate theory has been developed. The phase shift is found to affect the scattering amplitudes even if the central symmetry is unbroken.