Small-angle scattering of X rays and neutrons is a widely used diffraction method for studying the structure of matter. This method of elastic scattering is used in various branches of science and technology, includ ing condensed matter physics, molecular biology and biophysics, polymer science, and metallurgy. Many small-angle scattering studies are of value for pure science and practical applications. It is well known that the most general and informative method for investigating the spatial structure of matter is based on wave-diffraction phenomena. In diffraction experiments a primary beam of radiation influences a studied object, and the scattering pattern is analyzed. In principle, this analysis allows one to obtain information on the structure of a substance with a spatial resolution determined by the wavelength of the radiation. Diffraction methods are used for studying matter on all scales, from elementary particles to macro-objects. The use of X rays, neutrons, and electron beams, with wavelengths of about 1 A, permits the study of the condensed state of matter, solids and liquids, down to atomic resolution. Determination of the atomic structure of crystals, i.e., the arrangement of atoms in a unit cell, is an important example of this line of investigation.

to the Fundamental and Applied Catalysis Series Catalysis is important academically and industrially. It plays an essential role in the manufacture of a wide range of products, from gasoline and plastics to fertilizers and herbicides, which would otherwise be unobtainable or prohibitive ly expensive. There are few chemical-or oil-based material items in modern society that do not depend in some way on a catalytic stage in their manufacture. Apart from manufacturing processes, catalysis is finding other important and over-increasing uses; for example, successful applications of catalysis in the control ofpollution and its use in environmental control are certain to in crease in the future. The commercial import an ce of catalysis and the diverse intellectual challenges of catalytic phenomena have stimulated study by a broad spectrum of scientists including chemists, physicists, chemical engineers, and material scientists. Increasing research activity over the years has brought deeper levels of understanding, and these have been associated with a continually growing amount of published material. As recentlyas sixty years ago, Rideal and Taylor could still treat the subject comprehensively in a single volume, but by the 19 50s Emmett required six volumes, and no conventional multivolume text could now cover the whole of catalysis in any depth.

This 2-volume set includes extensive discussions of scattering techniques (light, neutron and X-ray) and related fluctuation and grating techniques that are at the forefront of this field. Most of the scattering techniques are Fourier space techniques. Recent advances have seen the development of powerful direct imaging methods such as atomic force microscopy and scanning probe microscopy. In addition, techniques that can be used to manipulate soft matter on the nanometer scale are also in rapid development. These include the scanning probe microscopy technique mentioned above as well as optical and magnetic tweezers.

The technique of smal1-angle soattering (SAS) is now about sixty years o1d. Soon after the first observations of, a continuous, intense X-ray scattering near the primary beam from samp1es such as canbo:tt,bla:cks, it was recognized that this scattering arose from e1ectron density heterogeneities on a scale of severa! tens to severa! hundred times the wave1ength of the radiation used. By the time the classic monograph of Guinier and Foumet appeared in 1955, much of the basic theory and instrumentation had been developed, and applications to colloidal suspensions, macromolecular solutions inc1uding proteins and viruses, fibers, porous and finely divided solids, metallic alloys etc. numbered in the hundreds. Following severa! specialized meetings, the first international conference on small-ang1e X-ray scattering was helditi, Syracuse in 1965, marked by the presentation of new scattering theory for polydisperse systems, polymer coils and filaments, new instrumentation (the Bonse-Hart camera), and new applications to polymeric, biologica!, and metallic systems, to critica! phenomena and to catalysts. The second conference (Graz, 1970) no longer dealt exclusively with X ray scattering, but also inc1uded neutron small-angle scattering (SANS). SANS applications developed rapidly during this period, especially for studying synthetic and biologica! macromolecules, when the possibilities of exploiting scattering Iength density differences, created by selective deuteration, were recognized.

Reasoned and based on the difference between discovery and invention, according to the traditional conception, science can be distinguished between basic science and applied science. Nevertheless, we know that the sciences are inseparable. A century or more ago, Louis Pasteur said "there is no applied science, there are applications of science." With this assertion, he establishes the logic of complementarity between them. Science certainly goes beyond its own material application and brings us to issues that have intrigued humanity for a long time. During the many years that we have been working with techniques of material characterization, we observed that this complementarity was not always understood by the researchers. In line with the reasoning that the technique joined with science generates technology, the application of techniques that use x-ray and neutron sources seems to us of fundamental importance for the development of technology. In this way, we present in this book how the existing technology of material characterization can contribute to science and applied technology. The authors who contributed with this book sought to show the importance of applying the existing techniques in the development of their works.

This book provides a clear, comprehensible and up-to-date description of how Small Angle Scattering (SAS) can help structural biology researchers. SAS is an efficient technique that offers structural information on how biological macromolecules behave in solution. SAS provides distinct and complementary data for integrative structural biology approaches in combination with other widely used probes, such as X-ray crystallography, Nuclear magnetic resonance, Mass spectrometry and Cryo-electron Microscopy. The development of brilliant synchrotron small-angle X-ray scattering (SAXS) beam lines has increased the number of researchers interested in solution scattering. SAS is especially useful for studying conformational changes in proteins, highly flexible proteins, and intrinsically disordered proteins. Small-angle neutron scattering (SANS) with neutron contrast variation is ideally suited for studying multi-component assemblies as well as membrane proteins that are stabilized in surfactant micelles or vesicles. SAS is also used for studying dynamic processes of protein fibrillation in amyloid diseases, and pharmaceutical drug delivery. The combination with size-exclusion chromatography further increases the range of SAS applications. The book is written by leading experts in solution SAS methodologies. The principles and theoretical background of various SAS techniques are included, along with practical aspects that range from sample preparation to data presentation for publication. Topics covered include techniques for improving data quality and analysis, as well as different scientific applications of SAS. With abundant illustrations and practical tips, we hope the clear explanations of the principles and the reviews on the latest progresses will serve as a guide through all aspects of biological solution SAS. The scope of this book is particularly relevant for structural biology researchers who are new to SAS. Advanced users of the technique will find it helpful for exploring the diversity of solution SAS methods and applications. Chapter 3 of this book is available open access under a CC BY 4.0 license at link.springer.com.