QENS from "soft" systems: why use polarised neutrons?

In recent years, there has been increased research in soft condensed matter . More complex systems, such as polymers, exhibit interesting dynamics over a wide temperature range and a broad time scale. In order to reproduce thi s behaviour, a combination of model scattering laws and the best possible m easurements is necessary. By virtue of the experimental separation of the i ncoherent and coherent scattering parts, the use of polarised neutrons with spin polarisation analysis enables confident model fitting in such systems . This argument is illustrated by the examples of scattering from poly (met hyl methacrylate) and poly (ethylene oxide). (C) 2001 Elsevier Science B.V. All rights reserved.