Grazing-incidence small-angle scattering
Grazing-incidence small-angle scattering (GISAS) is a diffraction technique used to study nanostructured surfaces and thin films. The scattered probe is either photons (grazing-incidence small-angle X-ray scattering, GISAXS) or neutrons (grazing-incidence small-angle neutron scattering, GISANS).
Source: Wikipedia — Grazing-incidence small-angle scattering (CC BY-SA 4.0)