Neutron-Scattering Measurements of “Soft Matter”

Abstract

Neutron scattering had its origin in 1932, the year that marked the discovery of the neutron by Chadwick, and the first nuclear reactors were successfully operated in Chicago and Oak Ridge, Tenn., in the early 1940s. During its initial stages, neutron scattering was used mainly for the study of “hard” crystalline materials. For example, Shull and Wollan's pioneering research, which led to the 1994 Nobel Prize in physics, began with studies of iron, chromium, and iridium, and was followed by the development of polarization analysis to determine the structure of magnetic materials. Such studies continue to yield important structural information (see the articles on magnetism by Aeppli and Hayden and on crystallography by Radaelli and Jorgensen in this issue of MRS Bulletin), although during the last two decades, the technique has been increasingly used by scientists from other disciplines (chemistry, biology, polymer science), and many of these newer applications have involved “soft” matter such as polymers, colloids, and gels. By definition, these substances are “plastic” or “squishy,” and easy to mold into different shapes; because of this flexibility, they have become some of the most practical and widely used materials today.