The aim of this book is to present a coherent introductory account of the theory of vibrational spectroscopy and of its application to the study of synthetic organic polymers. The level of presentation is intended to be suitable for the research student who has previously obtained a degree in either physics or chemistry and who is embarking on research in this area. Such a student would, we hope, read the book in its entirety and then be equipped with sufficient background knowledge and understanding to tackle the specialised literature of the subject with some confidence. We hope that in addition the book will fulfil a similar function for any research worker new to the subject and that parts of it may also be found useful by undergraduate students studying either vibrational spectroscopy or polymer science. To make the book accessible to those new to the study of polymers we have given a brief introduction to the subject in chapter 1. This chapter also contains a brief description of experimental methods in vibrational spectroscopy which is intended to give the reader the minimum amount of information required to follow the rest of the book and to feel that his feet are firmly on the ground. Although we regard the book primarily as one to be read rather than simply referred to, we have provided detailed indexes, since the nature of the subject is such that the spectroscopist needs to master a large number of ideas and facts and easy reference to these is vital if that mastery is to be quickly obtained.