The central subject of this volume is the atomic and molecular physics of heavy par ticles as investigated with charged particle accelerators. The natural division be tween atomic structure and ion-atom collision studies, and the similar division be tween the theoretical and experimental branches of these subjects, are reflected in a parallel subdivision into corresponding chapters. In addition, one chapter is de voted to the important interface between atomic and molecular physics with condensed matter physics. A principal aim of the present volume is to provide a compact de scription of a number of current interests and trends within the heavy particle structure and collisions field in a sufficiently general, non-specialized way that interested scientists who wish to become acquainted with such interests and trends can do so without becoming bogged down in excessive archival detail. It is, therefore, hoped that the book will be of some use to advanced students who seek a general in troduction to these subjects. Numerous, more specialized, archival review articles are frequently referred to in each chapter for the benefit of those who seek more detailed knowledge about particular topics discussed. The editor wishes to acknowledge the support of two U. S. government agencies: the Office of Naval Research and the National Science Foundation, during the preparation of this volume. Sincere thanks are due Mrs. Betty Thoe for her excellent editorial work on the various manuscripts and Mrs."

Stanley Bashkin Beam-foil spectroscopy has enjoyed a rapid growth since the publication of KAY's first experiment [I.1J and my own first formal discussion of the possibilities inherent in a foil-excited particle beam [1.2J. In addition to fulfilling a number of the impor tant promises, the beam-foil source has been found to hold substantial surprises, the unearthing of which has contributed to our knowledge of basic atomic physics. Since the early days, major extensions have been made in the range of wavelength and par ticle energies which have been used, but only the bare beginnings have been made in exploiting the potential of the beam-foil source. Since there are many people who would like to turn their accelerator facilities to beam-foil problems or apply their theoretical techniques to calculations which bear on the beam-foil field, it seemed appropriate to assemble a discussion of the present status of beam-foil spectroscopy. The present volume attempts to summarize what has been learned and outlines a number of studies which remain to be made.