Particle Scattering, X-ray Diffraction, and Microstructure of Solids and Liquids

The investigation of the microstructure of solids using particle scattering techniques is a fairly mature field where both the experimental techniques and theoretical models have now reached a significant degree of sophistication. The set of lectures given at the 157th WE-Heraeus Seminar on 'Particle Scattering, X-ray Diffraction, and Microstructure of Solids and Liquids', edited by M L Ristig and K A Gernoth and published by Springer Verlag, gives a powerful introduction to the current state of theoretical methods and experimental techniques developed in the field. The lectures cover a broad range of advanced topics ranging from the 'zoological garden' of defects and excitations of condensed isotopes of helium to a fairly difficult treatment of diffraction and diffuse scattering associated with double-beam experiments. There are a number of specific points that I am sure will attract the attention of an interested reader. The last chapter of the book (by G Eckold) gives a nearly ideal introduction to the field of neutron scattering. Not only does it cover in just a few pages all the main points that a non-expert needs to know about inelastic neutron scattering, but it also directs the reader to a number of significant recent publications. The chapter on diffuse scattering by disorder and quasicrystals deserves special mention. It is very well written and the expertise of the author (F Frey) is illustrated by the quality of explanations of some fairly difficult concepts including, for example, the use of projection from higher-dimensional space in the treatment of scattering by quasicrystals (see e.g. figures 10 and 11). The reader will probably enjoy seeing a curious misprint in the definition of the Fourier transform in the very first equation of the chapter. The treatment of one- and two-body densities and their relation to Bragg and diffuse scattering given in the chapter written by K Gernoth is very powerful technically but could be made more readable if a discussion of relevant experimental observations as well as the treatment of effects of partial coherence had been included in the list of topics that he addresses in the chapter. A real jewel in the book is the chapter on simulation and theory of inhomogeneous liquid crystals written by M Allen. It is very rarely that one finds such an outstandingly brilliant and comprehensive description of some fairly difficult theoretical topics related to methods and concepts underlying our current level of understanding of the symmetry properties and dynamics of liquid crystals. It is unquestionably one of the best introductions to the subject available in the current literature. Unfortunately I found the chapter addressing the problem of diffuse scattering and molecular dynamics studies of silica somewhat disappointing and too technical. Some of the points described by the author (M Muser) are debatable and a potential reader would have benefited from the presentation of possible alternative points of view. For example, when discussing the fact that there is still room for improvements of classical potentials describing SiO2 the author does not mention the extreme difficulties associated with attempting to derive the potentials from density functional calculations. The presentation of material in the book would have benefited from the inclusion of a chapter on electron diffraction and scattering, particularly given that the most recent developments in that field (related to fluctuation microscopy) now offer the possibility of studying four-body correlations in condensed matter. Still, my overall impression is that it is an excellent and very useful book and I am delighted to have it as a reference on my desk.