The first edition of this book was written in 1961 when I was Morris Loeb Lecturer in Physics at Harvard. In the preface I wrote: "The problem faced by a beginner today is enormous. If he attempts to read a current article, he often finds that the first paragraph refers to an earlier paper on which the whole article is based, and with which the author naturally assumes familiarity. That reference in turn is based on another, so the hapless student finds himself in a seemingly endless retreat. I have felt that graduate students or others beginning research in magnetic resonance needed a book which really went into the details of calculations, yet was aimed at the beginner rather than the expert. " The original goal was to treat only those topics that are essential to an understanding of the literature. Thus the goal was to be selective rather than comprehensive. With the passage of time, important new concepts were becoming so all-pervasive that I felt the need to add them. That led to the second edition, which Dr. Lotsch, Physics Editor of Springer-Verlag, encouraged me to write and which helped launch the Springer Series in Solid-State Sciences. Now, ten years later, that book (and its 1980 revised printing) is no longer available. Meanwhile, workers in magnetic resonance have continued to develop startling new insights.

Modem materials science is exploiting novel tools of solid-state physics and chemistry to obtain an unprecedented understanding of the structure of matter at the atomic level. The direct outcome of this understanding is the ability to design and fabricate new materials whose properties are tailored to a given device ap­ plication. Although applications of materials science can range from low weight, high strength composites for the automobile and aviation industry to biocompat­ ible polymers, in no other field has progress been more strikingly rapid than in that of electronic materials. In this area, it is now possible to predict from first principles the properties of hypothetical materials and to construct artificially structured materials with layer-by-Iayer control of composition and microstruc­ ture. The resulting superlattices, multiple quantum wells, and high temperature superconductors, among others, will dominate our technological future. A large fraction of the current undergraduate and graduate students in science and engi­ neering will be directly involved in furthering the revolution in electronic mate­ rials. With this book, we want to welcome such students to electronic materials research and provide them with an introduction to this exciting and rapidly de­ veloping area of study. A second purpose of this volume is to provide experts in other fields of solid­ state physics and chemistry with an overview of contemporary research within the field of electronic materials.

The study of quantum fluids, stimulated by the discovery of superfluidity in liquid helium, has experienced renewed interest after the observation of Bose-Einstein condensation (BEC) in ultra-cold atomic gases and the observation a new type of quantum fluid with specific characteristics derived from its intrinsic out-of-equilibrium nature.