Polarized neutron scattering

Coppens, P.; Su, Z.; Becker, P. J.

doi:10.1107/97809553602060000615

International
Tables for
Crystallography
Volume C
Mathematical, physical and chemical tables
Edited by E. Prince

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International Tables for Crystallography (2006). Vol. C. ch. 8.7, p. 728

Section 8.7.4.4.3. Polarized neutron scattering

P. Coppens,^a Z. Su^b and P. J. Becker^c

^a 732 NSM Building, Department of Chemistry, State University of New York at Buffalo, Buffalo, NY 14260-3000, USA,^bDigital Equipment Co., 129 Parker Street, PKO1/C22, Maynard, MA 01754-2122, USA, and ^cEcole Centrale Paris, Centre de Recherche, Grand Voie des Vignes, F-92295 Châtenay Malabry CEDEX, France

8.7.4.4.3. Polarized neutron scattering

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It is generally possible to polarize the incident beam by using as a monochromator a ferromagnetic alloy, for which at a given Bragg angle $[I_\downarrow{\rm (monochromator)}=0]$ , because of a cancellation of nuclear and magnetic scattering components. The scattered-beam intensity is thus $[I_\uparrow]$ . By using a radio-frequency (r.f.) coil tuned to the Larmor frequency of the neutron, the neutron spin can be flipped into the $[(\downarrow)]$ state for which the scattered beam intensity is $[I_\downarrow]$ . This allows measurement of the `flipping ratio' R(h): $[R({\bf h}) = {I_\uparrow({\bf h}) \over I_\downarrow ({\bf h})}. \eqno (8.7.4.42)]$ As the two measurements are made under similar conditions, most systematic effects are eliminated by this technique, which is only applicable to cases where both [F_N] and [F_M] occur at the same scattering vectors. This excludes any antiferromagnetic type of ordering.

The experimental set-up is discussed by Forsyth (1980).

References

Forsyth, J. B. (1980). In Electron and magnetization densities in molecules and solids, edited by P. Becker. New York/London: Plenum.Google Scholar

International Tables for Crystallography (2006). Vol. C. ch. 8.7, p. 728