Quasielastic neutron scattering (QENS) designates a limiting case of

inelastic 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. Th ...

, characterized by energy transfers being small compared to the incident energy of the scattered particles. In a more strict meaning, it denotes scattering processes where dynamics in the sample (such as diffusive dynamics) lead to a broadening of the incident neutron spectrum, in contrast to, e.g., the scattering from a diffusionless crystal, where the scattered neutron energy spectrum consists of an elastic line (corresponding to no energy transfer with the sample) and a number of well-separated inelastic lines due to the creation or annihilation of phonons with specific energies. The term

quasielastic scattering In physics, quasielastic scattering designates a limiting case of inelastic scattering, characterized by energy transfers being small compared to the incident energy of the scattered particles. The term was originally coined in nuclear physics. I ...

was originally coined in nuclear physics. It was applied to thermal

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. Th ...

since the early 1960s, notably in an article by

Leon van Hove Leon, Léon (French) or León (Spanish) may refer to: Places Europe * León, Spain, capital city of the Province of León * Province of León, Spain * Kingdom of León, an independent state in the Iberian Peninsula from 910 to 1230 and again f ...

and in a highly cited one by

Pierre Gilles de Gennes Pierre-Gilles de Gennes (; 24 October 1932 – 18 May 2007) was a French physicist and the Nobel Prize laureate in physics in 1991. Education and early life He was born in Paris, France, and was home-schooled to the age of 12. By the age of ...

. QENS is typically investigated on high-resolution spectrometers (

neutron backscattering Neutron backscattering is one of several inelastic neutron scattering techniques. Backscattering from monochromator and analyzer crystals is used to achieve an energy resolution in the order of μeV. Neutron backscattering experiments are performed ...

neutron time-of-flight scattering The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons beha ...

neutron spin echo Neutron spin echo spectroscopy is an inelastic neutron scattering technique invented by Ferenc Mezei in the 1970s, and developed in collaboration with John Hayter. In recognition of his work and in other areas, Mezei was awarded the first Walte ...

). It is used to investigate topics like * solid-state diffusion (e.g. hydrogen in metals) * slow modes in crystals (e.g.

methyl group rotation In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula . In formulas, the group is often abbreviated as Me. This hydrocarbon group occurs in ma ...

) * relaxation of viscous liquids

Conference Series

Starting in 1992, there is a conference series entitled QENS. Since 2012, it is being held together with the Workshop on Inelastic Neutron Spectrometry (WINS).

Textbooks

* M. Beé, ''Quasielastic Neutron Scattering'', Adam Hilger: Bristol (1988). * R. Hempelmann, ''Quasielastic Neutron Scattering and Solid State Diffusion'', Clarendon Press: Oxford (2000).

References

{{Reflist Neutron scattering