2. Reflectometry. Surface profiles

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)