Many Body Effects in the Structure of Simple Fluids

Classical radiation scattering experiments are related, via the first Born approximation, to the pair correlation function only. However statistical physics provides many inter-relationships between g(r) and higher correlation functions which can be exploited to study these functions. Some examples will be given and the limitations of this approach discussed. Many physical phenomena which involve higher correlation functions also involve higher order forces.Thus a study to unravel the role of the higher correlation functions usually involves a study of higher order forces too. Because the theory of these forces is unsatisfactory, it is important that new experiments are attempted which highlight the principal features of these forces. Recent progress in this area will be reviewed. The examples used in this review will be taken from the work of the author and his colleagues over the past 10 to 15 years.