Scattering from Isolated Particles

Abstract

This chapter describes scattering from an optically isotropic particle with a well-defined geometrical shape based on the model approach. The scattering from the following particles is presented: sphere, cylinder, and ellipsoid of revolution with perfect orientation and random orientation, infinitesimally thin rod and disk with random orientation, and Gaussian polymer chain. The asymptotic behavior at q → 0 (Guinier law) and that at q → ∞ (Porod law) are discussed in scattering from each particle, and the importance of the principle of the reciprocal phenomena is also pointed out in each case. The particles with a large aspect ratio, i.e., with large anisotropy in shape, such as long cylinder and thin disk, are presented to exhibit crossover behaviors in the q-dependence of the scattering intensity at the crossover lengths or q’s relevant to the radius of gyration of the while particle and that of the cross-section of the particle. The Lorentz factor is also described as a factor necessary for analyzing the scattering intensity distribution from those particles described above oriented in 3D space.