Neutron Diffraction

Abstract

Although the neutron is stable when incorporated into a nuclide, a free neutron is unstable and decays into an electron, a proton, and an antineutrino with a half-life of 13 minutes. as a consequence, neutron diffraction experiments must be carried out with neutrons from either a nuclear reactor or a spallation source. in either case the high kinetic energy of the neutrons that result from the nuclear fission or spallation must be reduced, i.e., the neutrons must be thermalized, through collisions with a moderator such as light or heavy water. the resulting thermal neutrons have an energy of ca. 10-1 to 10-3 eV or a wavelength, as derived from the de Broglie equivalence, of ca. 1–5 Å. Thus thermal neutrons have wavelengths appropriate for diffraction by an atomic or molecular lattice. as a consequence, neutron diffraction is closely related to X-ray diffraction, and typically neutron diffraction studies are preceded by X-ray diffraction structural studies. Neutron diffraction does, however, have certain advantages over X-ray diffraction, advantages which will be discussed herein. the neutron is a neutral particle that has a nuclear spin of 1=2 and hence a magnetic moment, μ, of -1.913 μN, where μN = eh/2mp = 5.051 x 10-27 J T-1 is the nuclear Bohr magneton. a comparison of the fundamental properties of neutrons and X-rays is given in Table 1.

Department(s)

Chemistry

International Standard Book Number (ISBN)

978-008043748-4

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2024 Elsevier, All rights reserved.

Publication Date

01 Jun 2004

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