Tasso Springer - Böcker

The Institut Max-von-Laue-Paul Langevin (ILL) in Grenoble regularly organ­ ises workshops that deal with the various applications of neutrons in physics, chemistry, biology and also in nuclear physics. The workshop" Atomic Trans­ port and Defects in Metals by Neutron Scattering", jointly organised by the Institut Laue-Langevin and the Institut fiir Festkorperforschung of the KFA­ Jiilich, was held in October 1985 in Jiilich. The study of problems in metal physics and in physical metallurgy is a traditional field of neutron scattering. The most commonly used methods are diffuse elastic, small-angle and inelastic scattering of neutrons. A number of problems can be identified where neutrons yield information that is supple­ mentary to that from other methods such as x-ray diffraction, synchrotron radiation or electron microscopy. In certain fields, for example spectroscopy for the investigation of atomic motions or for the investigation of magnetic properties, neutron scattering is a unique method. The facilities at the High Flux Reactor of the ILL, and also at the Jiilich and at other medium flux research reactors, have contributed numerous re­ sults in these fields. It was the aim of this workshop to give a survey of the present state of neutron scattering in metal physics.

The Institut Max von Laue-Paul Langevin (ILL) in Grenoble regularly orga­ nizes workshops that deal with various applications of neutrons in physics, chemistry, biology and materials science. The workshop "Quantum Aspects of Molecular Motions in Solids" was jointly organized by the Institut Laue­ Langevin and the Institut fiir Festkorperforschung at the Kernforschungsan­ lage Jiilich and took place in September 1986 in Grenoble. Tunneling phenomena in molecular crystals were first observed with macro­ scopic methods like specific heat experiments and later also with NMR. Fi­ nally, the development of high resolution neutron scattering techniques like neutron backscattering led to direct spectroscopic observation of the tunnel split ground state. This breakthrough was achieved in 1975 at Jiilich. Since then the large variety of high-resolution techniques available in combination with high neutron flux have turned ILL into the leading laboratory in the field of tunneling spectroscopy. Since 1980 regular meetings of scientists involved in this topic have been organized every two years (Jiilich, Braunschweig, Nottingham) and have led to an intense exchange of ideas and experimental results. The present workshop is the fourth of this series and the first with published proceedings presenting the state of the art in this field. The eight review articles introduce scientists not involved in the subject to the actual discussion. Sessions on translational tunneling of light interstitials in metals as well as on tunneling phenomena in amorphous substances provide bridges to adjacent fields.

The nine review articles and roughly 30 contributed papers contained in this volume survey the present understanding of the molecular motion of polymers in concentrated solutions, melts and the amorphous state. Although the main emphasis is on results from neutron scattering experiments, about half of the contributions relate to complementary techniques such as light scattering and NMR. The book highlights three areas of active reseach that have received increasing attention in recent years. First, work on polymer relaxation near the glass transition and in glassy systems has shown that the application of different experimental techniques is indispensable due to the broad range of time scales over which these phenomena occur on a molecular level. Second, it is reported that the internal Brownian motion of long chain molecules and their diffusion in an entangled environment still does not have a generally accepted physical picture, although detailed insights into the microscopic motion have been obtained. Third, important progress has been made in unravelling the characteristics of phase separation of polymer blends, in which modifications to the ordinary laws of diffusion are of particular interest.