Small-angle neutron scattering (SANS) is a well-established characterization method for microstructure investigations, spanning length scales from A to micron sizes. Within the SANS approximation, Q simplifies to Q = 2я0/А The SANS Q range is typically from 0.001 to 0.45 A-1. For example, scattering from a simple spherical system in a solvent yields a SANS coherent macroscopic neutron-scattering cross section (scattering intensity in an absolute scale) of:

^dX(Q) = NVpAq2P(Q)S: (Q) (1.2)

where (N/V) is the number density of particles, VP is the particle volume, Др2 the contrast factor, P(Q) is the single particle form factor, and SI(Q) is the inter-particle structure factor. SI(Q) has a peak corresponding to the average particle inter­distance.