I am most pleased and, in a way, I feel honored to write the Foreword for the book The Hanle Effect and Level-Crossing Spectroscopy, which covers such a very wide range of applications not only in the initial areas of atomic and molecular physics, but also in solid state physics, solar physics, laser physics, and gravitational metrology. To link these fields together in a coherent way has been the merit of the editors of the book, who attracted most distinguished authors for writing the chapters. In retrospect to Hanle's discovery of quantum mechanical coherence between two quantum states about 65 years ago, this book demonstrates the enormous impact and central importance the effect has had, and most vividly still has, on modern physics. On the other hand, the concept of quantum mechanical coherence, which is an outgrowth of the linear super position principle of quantum states, has been evident through a consider able number of experimental methods beyond the original Hanle effect; some of these methods were only recently discovered or applied and they have indeed revolutionized research fields such as atomic collision physics.

Keeping abreast of the latest techniques and applications, this new edition of the standard reference and graduate text on laser spectroscopy has been completely revised and expanded. While the general concept is unchanged, the new edition features a broad array of new material, e.g., ultrafast lasers (atto- and femto-second lasers), coherent matter waves, Doppler-free Fourier spectroscopy, interference spectroscopy, quantum optics and gravitational waves and still more applications in chemical analysis, medical diagnostics, and engineering.

W. HANLE and H. KLEINPOPPEN In 1919, in the first edition of Atombau and Spektrallinien, Sommerfeld referred to the immense amount of information which had been accumu lated during the first period of 60 years of spectroscopic practice. Sommer feld emphasized that the names of Planck and Bohr would be connected forever with the efforts that had been made to understand the physics and the theory of spectral lines. Another period of almost 60 years has elapsed since the first edition of Sommerfeld's famous monograph. As the editors of this monograph, Progress in Atomic Spectroscopy, we feel that the present period is best characterized by the large variety of new spec troscopic methods that have been invented in the last decades. Spectroscopy has always been involved in the field of research on atomic structure and the interaction of light and atoms. The development of new spectroscopic methods (i.e., new as compared to the traditional optical methods) has led to many outstanding achievements, which, together with the increase of activity over the last decades, appear as a kind of renaissance of atomic spectroscopy.

Keeping abreast of the latest techniques and applications, this new edition of the standard reference and graduate text on laser spectroscopy has been completely revised and expanded. While the general concept is unchanged, the new edition features a broad array of new material. This new edition has been completely revised, especially the chapters on non linear spectroscopy, ion trapping, ultra short laser pulses and new developments. Fifty new figures illustrate the newest developments and results. The author is one of the most renowned experts in this area and no other book with this broad scope is available.

Atomic physics and its underlying quantum theory are the point of departure for many modern areas of physics, astrophysics, chemistry, biology, and even electrical engineering. This textbook provides a careful and eminently readable introduction to the results and methods of empirical atomic physics. The student will acquire the tools of quantum physics and at the same time learn about the interplay between experiment and theory. A chapter on the quantum theory of the chemical bond provides the reader with an introduction to molecular physics. Plenty of problems are given to elucidate the material. The authors also discuss laser physics and nonlinear spectroscopy, incorporating latest experimental results and showing their relevance to basic research. Extra items in the second edition include solutions to the exercises, derivations of the relativistic Klein-Gordon and Dirac equations, a detailed theoretical derivation of the Lamb shift, a discussion of new developments in the spectroscopy of inner shells, and new applications of NMR spectroscopy, for instance tomography.

This fourth edition contains a few additional figures. Otherwise only typographical er rors have been removed. The final chapter on Fundamentals of the Quantum Theory of Chemical Bonding is continued in an extended way in the textbook Molecular Physics and Elements of Quantum Chemistry by the same authors. This book contains, in particular, a profound presentation of group theory as applied to atoms and molecules. Furthermore, the in teraction between atoms and molecules and light is treated in detail. We thank again Springer-Verlag, in particular Dr. H.1. Kblsch and Mr. C.-D. Bachem for their excellent cooperation as always, and Prof. W. D. Brewer for his con tinuous support in translating our German text. Stuttgart, February 1994 H. Haken H. C. Wolf Preface to the Third Edition The second edition of this book again enjoyed a very positive reception from both uni versity teachers and students. In this edition we have removed all of the typographical errors that came to our attention. In order to keep the book as current as possible, new developments in the direct observation of individual atoms in electromagnetic traps (Paul traps) and of atoms in molecules on solid surfaces using the scanning tunnel microscope have been added to this edition.

Combined with the other two volumes, this text is a comprehensive treatment of the key experimental methods of atomic, molecular, and optical physics, as well as an excellent experimental handbook for the field. Thewide availability of tunable lasers in the past several years has revolutionized the field and lead to the introduction of many new experimental methods that are covered in these volumes. Traditional methods are also included to ensure that the volumes will be a complete reference source for the field.

A wide-ranging review of modern spectroscopic techniques such as X-ray, photoelectron, optical and laser spectroscopy, and radiofrequency and microwave techniques. On the fundamental side the book focuses on physical principles and the impact of spectroscopy on our understanding of the building blocks of matter, while in the area of applications particular attention is given to those in chemical analysis, photochemistry, surface characterisation, environmental and medical diagnostics, remote sensing and astrophyscis. The Fourth Edition also provides the reader with an update on laser cooling and trapping, Bose-Einstein condensation, ultra-fast spectroscopy, high-power laser/matter interaction, satellite-based astronomy and spectroscopic aspects of laser medicine.

High Resolution Spectroscopy discusses the underlying concepts in the different branches of spectroscopy, especially in high resolution spectroscopy. The coverage of the book includes basic principles such as the quantization of energy, as well as the interaction of electromagnetic radiation with atoms and molecules; general experimental methods and features of instrumentation; and microwave, millimeter wave, and lamb dip spectroscopy. Also covered in the book are subjects such as the principles behind rotational spectroscopy; diatomic and polyatomic molecules in vibrational spectroscopy; and the electronic spectroscopy of atoms, as well as diatomic and polyatomic molecules. The text is recommended for engineers and physicists who would like to know more about the concepts, theories, methods, and instrumentation related to spectroscopy, particularly in the field of high resolution spectroscopy.