Neutron scattering
Neutron scattering, the irregular dispersal of free neutrons by matter, can refer to either the naturally occurring physical process itself or to the man-made experimental techniques that use the natural process for investigating materials.
They can be scattered by condensed matter—nuclei having kinetic energies far below 1 eV—as a valid experimental approximation of an elastic collision with a particle at rest.
And with each collision, the "fast" neutron is slowed until it reaches thermal equilibrium with the material in which it is scattered.
Important elements like carbon and oxygen are quite visible in neutron scattering—this is in marked contrast to X-ray scattering where cross sections systematically increase with atomic number.
Thus neutrons can be used to analyze materials with low atomic numbers, including proteins and surfactants.
Depending on the research question, most measurements concentrate on either elastic or inelastic scattering.
Such single-energy beams are termed 'monochromatic', and monochromaticity is achieved either with a crystal monochromator or with a time of flight (TOF) spectrometer.
The neutron has a net electric charge of zero, but has a significant magnetic moment, although only about 0.1% of that of the electron.
[2] Inelastic neutron scattering is an experimental technique commonly used in condensed matter research to study atomic and molecular motion as well as magnetic and crystal field excitations.
Results are generally communicated as the dynamic structure factor (also called inelastic scattering law)
, they can often be interpreted in the same way as spectra obtained by conventional spectroscopic techniques; insofar as inelastic neutron scattering can be seen as a special spectroscopy.
The development culminated in the high-flux reactor of the Institut Laue-Langevin (in operation since 1972) that achieved the highest neutron flux to this date.
Because of the low count rates involved in neutron scattering experiments, relatively long periods of beam time (on the order of days) are usually required for usable data sets.
