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........ published in NEWSLETTER # 65
LIGHT SCATTERING AND PHOTON CORRELATION SPECTROSCOPY
by Professor E.R. Pike, FRS, King's College, London (U.K.)
Following the earliest developments in laser scattering by dilute macromolecular suspensions, in which particle sizing was the main aim, and also by flowing and turbulent fluids for velocimetry, which took place in the 1970s, significant advances have been made in recent years in many other areas. These are reflected in the topics covered in this book (NATO ASI SERIES 3-40), which contains the lectures presented at a NATO Advanced Research Workshop held in Krakow, Poland, in August 1996. They include experimental techniques, statistics and data reducltion, colloids and aggregation, polymers, gels, liquid crystals, protein solutions, critical phenomena, dense media, phase transitions in the microgravity environment provided by the space-shuttle missions, quantum cryptography and the application of the technique at x-ray wavelengths. The book includes a number of contributions from the CP countries, which were expertly co-ordinated by Dr. Igor Yudin, of the Oil and Gas Research Institute of the Russian Academy of Sciences.
Several chapters will update the reader on the continuously evolving experimental techniques, which are taking advantage of the miniaturisation and performance improvements provided by solid-state lasers, fibre optics and avalanche photodiode detectors and on the powerful new techniques of analysis from the lively field of inverse problems which are being applied to data analysis. Much progress is being made in the study of dense media using index-matching techniques, two-colour systems and the theory of photon diffusion and relationships between structural relaxation and viscosity in hard-sphere colloids and the complex process of crystallisation of colloid solutions through the liquid-solid phase transition are investigated by these methods.
A new bulk relaxation, characteristic of binary polymer blends near the macrophase separation temperature, has been found and layer-height fluctuations at the surface have been studied by evanescent-wave dynamical light scattering. A universal function describing the concentration and temperature dependence of the static and dynamic properties of binary separating mixtures is also given.
Two contributions describe microgravity research on board the space shuttle, namely, experiments in 1995 on colloidal crystals in which light scattering was used to probe both static structure and particle dynamics and the Zeno instrument, developed to measure the density fluctuation decay times of a liquid-vapour critical fluid.
X-ray photon correlation spectroscopy using synchrotron sources, and the range of its possible applications to problems in condensed matter systems, including complex fluids, glasses and metallic alloys is the subject of another chapter.
The basic theory and techniques of the subject of photon correlation spectorscopy for the measurement of sub-micron particle size and for the measurement of fluid flow and turbulence were laid down in two previous NATO ASI Series volumes ("Photon Correlation and Light-Beating Spectroscopy", B-3, 1974 and "Photon Correlation Spectroscopy and Velocimetry", B-23, 1977, both published by Plenum Press and both edited by H.Z. Cummins and E.R. Pike). Although there have been some 15 International Conferences on Photo Correlation Spectroscopy between these and the present volume, it is interesting to note that these two original NATO publications are still widely used for reference and introduction to the field.
Reference books: 3-40, A59, B3, B23, B273
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