Reflectometry. Surface profiles
Neutron beams - Understanding and characterizing matter

A neutron beam is reflected by a surface at grazing incidence (figure 19). Reflection is total as long as the angle remains below a critical angle, characteristic of the surface.

When the angle of incidence is greater than the critical angle, only a fraction of the neutrons are reflected. The curve of reflected intensity as a function of angle of incidence (Figure 20) provides unambiguous information on compositions, thicknesses and roughness (or inter-layer interdiffusion distances) [14].