Chapter 1. Neutron Applications in Earth, Energy and Environmental Sciences.

Abstract Neutron-based studies permit the determination of the structural details and the dynamics of atomic arrangements in materials from simple measurements of scattering and absorption processes. Neutrons are scattered by atomic nuclei, are sensitive to the atomic magnetic moment, and have scattering and absorption cross-sections independent of atomic number and mass. They therefore have a complementary role to X-rays, scattered by the electrons in atoms. A prominent aspect of this lies in the sensitivity of neutrons to light elements, in particular hydrogen, a ubiquitous component of organic and inorganic matter and a key component of Earth, energy, and environment-related materials. Furthermore, thanks to the low absorption of neutrons by most substances, neutron scattering allows good quality data to be obtained over a wide range of non-ambient environments. This permits studies of transformations and fundamental properties of materials in situ, while they are still subject to the physical–chemical conditions in the diverse environments in which they normally exist and function, from the Earth’s surface to its deep interior, and to laboratory conditions of one’s choice. The limitations traditionally connected with modest neutron flux, and consequent need for relatively large samples, are being overcome by current advances in neutron sources and instrumentation. As a result, the potential of neutron-based methods in the examination of materials in Earth, energy, and environmental studies has gained momentum and opened up diverse new possibilities in these fields of scientific and technological research.