Fluid Interfaces Grazing Angles ReflectOmeter

Neutron reflectometry examines the way in which surfaces or interfaces reflect neutrons in order to provide information on their organization, thickness, composition and roughness. Surface stacking can be studied on a depth of 1 to 300 nm (5 to 1500 atomic layers).
If the incident angle is lower than the critical angle, the material acts like a mirror and reflects all neutrons. If it is wider, only a part of neutrons are reflected. Measuring the proportion of reflected neutrons for a reflection angle equal to the incident angle makes it possible to explore the sample in a direction perpendicular to its surface. If measurement is made for different incident and reflecting angles, the sample is explored in its surface plane.

Reflection on a plane surface (the interface between two materials)

To make the illustration clearer, angles are greatly exagerated from their actual values for cold neutrons.