2016 Volume 16 Issue 11 Pages 535-540
Neutron reflectometry (NR) is an essential experimental technique for structural analysis on material interfaces and thin films, because it can probe the structures along the depth direction with a high resolution of a sub-nm scale in a non-destructive manner utilizing optical reflection property of neutron at flat interfaces. The neutron is capable of distinguishing between isotopes, and especially there is the large difference in coherent scattering length between isotopes of hydrogen: light hydrogen (H) and deuterium (D), which is one of major elements constituting soft matters such as polymers, surfactants, lipids, etc. The neutron contrast can be introduced in soft matters without significant change in their physical properties by replacing all or part of H with D in the samples (deuterium labeling). Also, the neutron exhibits high transmissivity for materials, so that NR can examine deeply-buried interfaces in materials in a non-destructive manner. Here, the advantages of NR for structural analysis on soft interfaces are explained by introducing the experimental examples of polymer thin films prepared on silicon substrates, though NR can be adopted for various material interfaces including free interfaces such as liquid surface.
