Neutron reflectometry is a nondestructive technique used to determine the structure, composition, and magnetism of thin films and buried interfaces with sub-nanometer depth resolution over length scales of approximately 0.5–350 nm. By measuring the reflection of cold neutrons from a surface, the technique provides depth profiles of scattering length density that reveal layer thicknesses, interfacial roughness, composition, and, when applicable, magnetic structure. Because neutrons are highly sensitive to hydrogen and its isotopes, as well as magnetic moments, neutron reflectometry is uniquely suited for studying soft matter, energy materials, magnetic thin films, and other complex layered systems.
ORNL's reflectometry suite includes two complementary instruments. The Liquids Reflectometer (LIQREF) is optimized for studies of free liquid surfaces and buried solid–liquid interfaces, enabling in situ and operando investigations of electrochemical, biological, and other dynamic interfacial processes. The Magnetism Reflectometer (MAGREF) employs polarized neutron beams to probe the depth-dependent magnetic structure of thin films and multilayers while simultaneously determining their chemical structure. Typical samples have surface roughness less than 1 nm (RMS), thickness uniformity better than 5% over the illuminated area, and a surface area greater than approximately 1 cm².
