There is no paucity of books on high pressure. Beginning with P. W. Bridgman's The Physics of High Pressure, books of general interest include the two-volume Physics and Chemistry of High Pressure, edited by R. S. Bradley, and the series, Advances in High Pressure Research, as well as the report on the Lake George Conference in 1960. Solid state physics is well represented by Solids Under Pressure, edited by Paul and Warschauer, by Physics of Solids at High Pressure, edited by Tomizuka and Emrick, and by Properties Physiques des Solides sous Pression, edited by Bloch, as well as by chapters in Volumes 6, 13, 17, and 19 of Solid State Physics, edited by Seitz, Turnbull, and Ehrenreich. Chemistry in gases and liquids is covered in Weale's Chemical Reactions at High Pressure, and Hamann's Physico-chemical Effects of Pressure. In addition to the coverage of techniques and calibrations in the above volumes, Modern Very High Pressure Techniques, edited by Wentorf, High Pressure Methods in Solid State Research, by C. C. Bradley, The Accurate Characterization of the High Pressure Environment, edited by E. C. Lloyd, and a chapter in Volume 11 of Solid State Physics are devoted entirely to this facet of high pressure research. It is not our plan either to supersede or extend these approaches. It is our purpose here to discuss the effect of high pressure on the electronic properties of solids.

This series of books, which is published at the rate of about one per year, addresses fundamental problems in materials science. The contents cover a broad range of topics from small clusters of atoms to engineering materials and involve chemistry, physics, materials science, and engineering, with length scales ranging from Angstroms up to millimeters. The emphasis is on basic science rather than on applications. Each book focuses on a single area of current interest and brings together leading experts to give an up-to-date discussion of their work and the work of others. Each article contains enough references that the interested reader can access the relevant literature. Thanks are given to the Center for Fundamental Materials Research at Michigan State University for supporting this series. M.F. Thorpe, Series Editor E-mail: [email protected] East Lansing, Michigan, November 200 I v PREFACE The study of the atomic structure of crystalline materials began at the beginning of the twentieth century with the discovery by Max von Laue and by W.H. and W.L. Bragg that crystals diffract x-rays. At that time, even the existence of atoms was controversial.

"Ionic liquids will never find application in industry", "I don't understand this fad for ionic liquids" and "there is no widespread interest in these systems" are just three of quotes from the reports of referees for research proposals that I have received over the years. I wonder what these people think today. There are currently at least nine large-scale industrial uses of ionic liquids, including, we now rec- nise, the production of ?-Caprolactam (a monomer for the production of nylon-6) [1]. There has been a steady increase in the interest in ionic liquids for well over a decade and last year the number of papers and patents including ionic liquids was counted in the thousands. This remarkable achievement has been built on the hard work and enthusiasm, first of a small band of devotees, but now of huge numbers of scientists all over the world who do not see themselves as specialists in ionic liquids. The ionic liquids field continues to develop at an incredible rate. No sooner do I think that I am on top of the literature than it turns out that a whole new area of work has emerged without me noticing. Things that were once supposedly impos- 1 sible in ionic liquids, such as measuring the H NMR of solutes, are now widely applicable (see Chapter 8). Hence, collected volumes such as this are very w- come.

This is a textbook of what is often called magnetochemistry. We take the point of view that magnetic phenomena are interesting because of what they tell us about chemical systems. Yet, we believe it is no longer tenable to write only about such subjects as distinguishing stereochemistry from the measurement of a magnetic susceptibility over a restricted temper ature region; that is, paramagnetism is so well-understood that little remains to explore which is of fundamental interest. The major purpose of this book is to direct chemists to some of the recent work of physicists, and in particular to a lengthy exposition of magnetic ordering phenomena. Chemists have long been interested in magnetic interactions in clusters, but many have shied away from long-range ordering phenomena. Now however more people are investigating magnetic behavior at temperatures in the liquid helium region, where ordering phenomena can scarcely be avoided. The emphasis is on complexes of the iron-series ions, for this is where most of the recent work, both experimental and theoretical, has been done. The discussion therefore is limited to insulating crystals; the nature of magnetism in metals and such materials as semiconductors is sufficiently different that a discussion of these substances is beyond our purposes. The book is directed more at the practical experimentalist than at the theoretician."

NMR is better suited than any other experimental technique for the characterization of supramolecular systems in solution. The presentations included here can be broadly divided into three classes. The first class illustrates the state of the art in the design of supramolecular systems and includes examples of different classes of supramolecular complexes: catenanes, rotaxanes, hydrogen-bonded rosettes, tubes, capsules, dendrimers, and metal-containing hosts. The second class comprises contributions to NMR methods that can be applied to address the main structural problems that arise in supramolecular chemistry. The third class includes biological supramolecular systems studied by state-of-the-art NMR techniques.

217 2. COPOLYMERIZATION OF PROPENE OR HIGHER I-ALKENES WITH 218 CARBON MONOXIDE 2. 1. Ligands and polymerization conditions 218 2. 2. Spiroketal formation 221 2. 3. Enantioselectivity 222 2. 4. Higher I-Alkenes 226 3. COPOLYMERIZATION OF STYRENE OR ITS DERIVATIVES WITH 226 CARBON MONOXIDE 4. COPOLYMERIZATION OF OTHER OLEANS WITH CARBON MONOXIDE 230 5. ASYMMETRIC TERPOLYMERIZATION OF MORE THAN Two KINDS OF 232 OLEFINS WITH CARBON MONOXIDE 6. POLYKETONE CONFORMATION 233 7. CONCLUSION 234 Chapter 8. Chain Propagation Mechanisms 237 Ayusman Sen 1. INTRODUCTION 237 2. PALLADIUM (II) BASED SYSTEMS 238 3. NICKEL (II) BASED SYSTEMS 256 4. RHODIUM (I) BASED SYSTEMS 257 5. CONCLUSION 261 Chapter 9. Theoretical Studies on Copolymerization of Polar Monomers 265 Peter Margl, Artur Michalak, and Tom Ziegler 1. INTRODUCTION 265 2. COPOLYMERIZATION OF CARBON MONOXIDE WITH ETHYLENE 267 2. 1. Experimental and calculated rates for the insertion processes for 267 copolymerization catalysed by Pd(II) systems. 2. 2. A more detailed look at the productive and unproductive cycles 270 in copolymerization catalysed by Pd(II) complexes. 2. 2. 1. The productive cycle 270 2. 2. 2. C2H4 misinsertion into an ethylene terminated polyketone 275 chain 2. 3. Experimental and calculated rates for the insertion processes for 277 alternating copolymerization catalyzed by Ni(II) systems 3. COPOLYMERIZATION OF OLEFINS WITH POLAR MONOMERS OTHER 280 THAN CO 3. 1. Preferred binding mode of oxygen containing monomers 282 3. 2. Preferred binding mode of nitrogen containing monomers 285 3. 3.

"Meditationis est perscrutari occulta; contemplationis est admirari perspicua . . . Admiratio generat qurestionem, qurestio investigationem, investigatio inventionem" once wrote HUGO DE S. VICTORE and possibly described best the life span of the rare earths since the Swedish Army Lieutenant, C. A. ARRHENIDS' discovery of an unusual black mineral at Ytterby in 1787. Since then the rare earths have passed through the machinery of various phases of physical science. Europium as a member of the rare earth family shows characteristics of the series as a whole as well as some typical behaviour of its own due to the presence of its six f electrons i. e. , one less than the half-filled shell. This present volume attempts to provide an understanding of the various aspects of its chemical and physical behaviour. In doing so, it is hoped to provide the reader with more than just a list of the complete bibliography on the subject, and I have tried to review the literature for it's interesting features, balancing the experimental facts with the help of the minimum amount of theory as far as possible. Experience has shown us that the trend of inorganic research has changed during the past years and one frequently needs some understanding of chemical spectroscopy and quantum mechanics to be able to appreciate the developments in this field and to interpret the wealth of experimental data. The reader is referred to B. G. WYBOURNE'S book: Spectroscopic Properties of Rare Earths (ref. [488]), and B. R.

A lively demonstration of the great vitality and the multidisciplinary character of cluster research and of the usefulness of synthesizing its various aspects was given at this symposium. This volume covers all aspects of the physical and chemical properties of free and supported clusters or small particles: static, dynamical, electronic, magnetic and optical properties, adsorption and chemical phenomena. It thus gives a complete overview of the status of the field and its development.

This book contains the papers and discussions from the sympo , ium on "The Catalytic Chemistry of Nitrogen Oxides" held at the General Motors Research Laboratories on October 7-8, 1974. This symposium is the eighteenth in the annual series presented by the Research Laboratories. The topics for these symposiums have covered a broad range. Each topic was selected to be of intense current interest and of significant technical importance. There is no question that the subject of the 1974 Symposium satisfies these two criteria. The control of automotive nitrogen oxides has been perhaps the most difficult and controversial area of automotive emissions both in terms of what is necessary and in terms of what is technically feasible. This area has been a source of considerable discussion not only in the technical community but also in governments both in the U. S. and abroad. This meeting brought together scientists working in surface chemistry with engineers working on system design. It also brought together representatives of government, academia and industry. We feel that an important side benefit of the meeting was the improved understanding that was developed between these groups. Participants came from Europe and Japan as well as Canada and the United States. The technical papers spanned the range from fundamental interactions of NO on surfaces through bench scale kinetic and mechanistic studies and ended with catalytic applications. Although the emphasis was on automotive NO removal, stack gas NO x x control was also covered.

It is now some sixteen years since the author's first series of books on the analysis of organometallic compounds. Many developments in the subject have occurred since that time and a new book on the subject is now overdue. The present book aims to provide a comprehensive review of the subject. It covers not only all aspects of the analysis of organometallic compounds but also contains two additional chapters, dealing with environmental analysis and the use of chelates of metals in the determination of very low concentrations of organic metals. Whilst reviewing the literature for the present book, it was observed that whereas papers published prior to 1973 dealt almost exclusively with various forms of analysis, a high proportion of those published during the past ten years were concerned with the application of proven or newly developed methods to the determination of organometallic compounds in environmental samples such as water, air, soil, river and ocean sediments, fish life and biota samples. An increasing range of elements including mercury, lead, arsenic, tin, antimony, selenium and manganese are now being found in organically bound forms in the environment, some resulting from pollution, others formed in nature by bacterial processes. As many of these substances have appreciable implications to human and animal health and the ecosystem as a whole, it was considered that it would be timely to include a separate chapter in the book devoted entirely to this subject.

In every generation the achievements in science have served mankind. The progress accomplished by one generation stimulates the next generation to even greater achievements, which may take the form of increasing, crystallizing, or detailing existing theo- ries. Other forms, generally resulting from persistence and enlight- ened fortune, open new areas of investigation previously unimagined and have an impact that may be felt for many years. An example of this latter form of achievement was the prepara- tion and elucidation of the structures of dicyclopentadienyliron (ferrocene, reported in 1951) dibenzenechromium iodide, triphenyl- chromium tristetrahydrofuranate, and numerous olefin-metal -com- plexes which provided an introduction to new types of chemical bonds- the sigma carbon-transition metal bond and the metal -complex bond. Initial progress in the field of organotransition-metal chemis- try followed the lines of interest generated separately by organic and inorganic chemistry. However, it is becoming increasingly clear that organotransit10n-metal chemistry is not only bridging these two fields, but also crosslinking many other fields of science.

The three natural streams of present-day chemistry are Structure, Dynamics and Synthesis and all these three elements are essential for the study of materials, particularly in the solid state. The solid state provides challenging opportunities for illustrating and applying principles of chemistry to systems of academic interest and technological importance. There are several practising solid state chemists in universities and research laboratories, but the subject has not yet become part of the formal training program in chemistry. Being one of the new frontiers of chemistry, Solid State Chemistry has a tremendous future and undoubtedly demands the active involvement of many more chemists. A Winter School in Solid State Chemistry was organized at the Indian Institute of Technology, Kanpur, to promote this area and to develop curricular material. Solid State Chemistry being lighly interdisciplinary in nature, the lecturers and participants at the Winter School had widely different backgrounds and interests. It was my great desire that the lecture material from the Winter School should become available to a larger body of students, teachers and research workers interested in the solid state and hence this volume.

During the course of far-infrared investigations of inorganic and coordina tion compounds at Argonne National Laboratory in the years 1962-1966, it became apparent that no suitable book existed which correlated and dis cussed the important vibrations occurring in this region for these molecules. Early in 1967 the initial steps were taken to write such a book. Then, in 1968, an excellent text by Professor David M. Adams entitled Metal-Ligand and Related Vibrations was published. At this point serious consideration was given to discontinuing work on this book. However, upon examination of Adams' book, it became clear that the references covered only the period to 1966. This field of research is accelerating so tremendously, and the period 1966-1969 has seen so many new studies, that upon reconsideration it was decided to continue writing this text. The references in this book, particularly in the last several chapters, include many papers published in 1969. However, the proliferation of the far-infrared literature has made it impossible to present all the published material that has any bearing on the subject. Many titles do not pertain primarily to the far-infrared region as such, and some of this research has been omitted for this reason. Organometallic compounds have been neglected since the author feels that adequate reviews of that subject are available. Other studies may be missing simply because, owing to space limitations, only the more important researches could be considered. Of course, "importance" may, in this case, reflect the author's interest and prejudices."

V. I. MATKOVICH During the meeting of the International Symposium on Boron held in October, 1972 in Tbilisi, U.S.S.R., the idea was proposed to assemble a review of boron and refractory borides by the specialists present. The advantages of such a work were immediately apparent. Such diverse applications of borides as in protective armor, nuclear reactors, coat ings, reinforcement, etc. can hardly all be presented in sufficient detail by a single author. On the other hand it was also recognized that with so much specialization, some areas of interest may not be covered. Within the last decade or two a number of areas have been developed in which the use of refractory borides is growing and improvements are being actively explored. Thus, a number of borides have considerable potential as reinforcing material for plastics or light metals, though only boron fibers have been firmly established up to the present. Ap plication of flakes and films for two-dimensional reinforcement appears attractive, although the high cost of materials and development repre sents a considerable barrier. A number of borides have been used to manufacture lightweight protec tive armor. In this area relatively fast changes seem to be taking place as improvements in performance and weight are made. Boron carbide has found considerable use in this application and new developments exploit the light weight of beryllium borides."

Recent developments in various areas of chemistry have been decisively influenced by the principles of structure and mechanism and by the ideas of coordination chemistry, in particular by the donor-acceptor approach, A unified view of almost all kinds of molecular forces is provided by quantum mechanics, and for practical purposes have been classified according to model assumptions, namely, dispersion, polarization, electrostatic, and short-range forces. The latter are divided into two- and three-center covalent chemical bonds, metallic bonds, and exchange-repulsion forces. This approach allows statements of principle and systematic analysis. However, quantitative predictions on concrete large systems are virtually impossible, and there are no general rules that account for structural and chemical changes due to intermolecular interactions. Chemists are therefore left with qualitative descriptions in which the changes in electron densities are considered. Such models as the MO theory or the resonance concept unrealistically assume that the nuclei remain in fixed positions. Further difficulties are encountered in the attempted description on the "nature" of the chemical bond, e.g., the forces involved. In order to avoid these difficulties an extension of the donor-acceptor concept, characterized by the comparison between equilibrium structures in different molecular environments, will be presented in this book. In this way, changes in the positions of the nuclei can be taken into account and the question of the nature of the molecular forces is no longer important.

Humans have been "manually" extracting patterns from data for centuries, but the increasing volume of data in modern times has called for more automatic approaches. Early methods of identifying patterns in data include Bayes' theorem (1700s) and Regression analysis (1800s). The proliferation, ubiquity and incre- ing power of computer technology has increased data collection and storage. As data sets have grown in size and complexity, direct hands-on data analysis has - creasingly been augmented with indirect, automatic data processing. Data mining has been developed as the tool for extracting hidden patterns from data, by using computing power and applying new techniques and methodologies for knowledge discovery. This has been aided by other discoveries in computer science, such as Neural networks, Clustering, Genetic algorithms (1950s), Decision trees (1960s) and Support vector machines (1980s). Data mining commonlyinvolves four classes of tasks: * Classi cation: Arranges the data into prede ned groups. For example, an e-mail program might attempt to classify an e-mail as legitimate or spam. Common algorithmsinclude Nearest neighbor,Naive Bayes classi er and Neural network. * Clustering: Is like classi cation but the groups are not prede ned, so the algorithm will try to group similar items together. * Regression: Attempts to nd a function which models the data with the least error. A common method is to use Genetic Programming. * Association rule learning: Searches for relationships between variables. For example, a supermarket might gather data of what each customer buys.

When this book was first conceived as a project the expanding interest in the clinical use of platinum and gold complexes made a survey of the relevant biological properties of metal complexes timely and appropriate. This timeliness has not diminished during the gestation and final publica tion of the manuscript. The introduction contains an explanation of the layout and approach to the book, which I wrote as an overall survey of the wide variety of biological properties of metal complexes. Hopefully, the reader will see the parallels in mechanisms and behavior, even in different organisms. The writing was considerably helped by the enthusiasm and confidence (totally unearned on my part) in the project of Professor Brian James and lowe him my special thanks. I also owe a great debt of gratitude to my colleagues, and especially to Eucler Paniago, of the Universidade Federal de Minas Gerais, for their comprehension and for the initial leave of absence which allowed me to begin the project. To those who read some or all of the manuscript and made suggestions, Bernhard Lippert, Kirsten Skov, and Tom Tritton, as well as the editor's reviewer I am also grateful. As usual, the final responsibility for errors or otherwise rests with the author."

For a long time, the properties of transition metal and rare earth compounds have fascinated chemists and physicists from a scientific view-point, and more recently also their enormous potential as new materials has been explored. Applications in different fields have already been realized or are under c- rent investigation, for example, new laser materials, IR to visible upconversion systems, compounds for photolithographic processes, systems involving pho- redox processes for solar energy conversion, new photovoltaic devices, chemical sensors, biosensors, electroluminescent devices (OLEDs) for flat panel display systems, supramolecular devices with wide-range definable photophysical properties, materials for energy harvesting, optical information and storage systems, etc. Metal complexes are also highly important in biology and me- cine. Most of the applications mentioned are directly related to the properties of the electronic ground state and the lower-lying excited states. Metal complexes with organic ligands or organometallic compounds exhibit outstanding features as compared to purely organic molecules. For instance, metal compounds can often be prepared and applied in different oxidation states. Furthermore, various types of low-lying electronic excitations can be induced by a suitable choice of ligands, for example, such as metal-centered transitions (MC, e. g. d-d* tran- tion), ligand-centered (LC, e. g. n-n*), metal-to-ligand-charge transfer (MLCT, e. g. d-7r*), intra-ligand-charge-transfer (ILCT) transitions, etc. In particular, the orbitals involved in the resulting lowest excited states determine the photoph- ical and photochemical properties and thus the specific use of the compoun

The activation of carbon dioxide by transition metal complexes has been extensively studied. both experimentally and theoretically. 1 Central reactions in this chemistry are the insertion of C02 into M-X bonds. where X = H. C. 0. and N. (eq. 1-4). We are presently investigating the mechanistic aspects of these reaction processes and will herein deSCribe our current level of understanding. Comparisons of the pathway of the carbon-carbon bond fonning process in transition metal chemistry with the well known analogous chemistry involving organolithium reagents will be presented. Furthermore. the role of these reaction types in both homogeneous and heterogenous catalytic processes leading to useful chemicals will be elaborated. _OM> (1) lMt-H + ~ lMlopi _OM> (2) [Mt-R + C0. 2 [M]0. 2CR _OM> (3) [Mt-OR+ ~ [M]0. 2COR _OM> (4) [Mt-NR2 + C0. 2 [M]~CNR2 Insertion of C02 into the Metal-Hydride Bond. The reaction of anionic group 6 (Cr. Mo. W) transition metal hydrides with carbon dioxide to afford metalloformates occurs readlly at ambient temperature and 2 reduced pressures of carbon dioxide. This insertion process is referred to the normal pathway (Scheme 1). There are no documented cases of C02 insertion into the metal hydride bond to provide the alternative. metallocarboxylic acid. isomer (referred in Scheme 1 as abnormal). 3 Recent theoretical studies ascribe this preference to an unfavorable electrostatic interaction and poorer orbital overlap in the latter pro 4 cess. Nevertheless.

Explanation of the structure-property relationship of a given molecule is generally simple because the characteristics of the atomic groups and chemical bonds and the effects emerging from their interaction have long been known, both from theore- cal studies and numerous experimental results. In contrast, it is often difficult to analyze, estimate, and account for the structure-properties relationship in sup- molecules. The characteristics of supramolecules are governed both by the nature of the constituent molecules and by their configuration while the characteristics of the constituent molecules are usually evident as mentioned above; their configu- tions are difficult to control, predict, and accurately estimate because of insufficient knowledge regarding the intermolecular forces. Moreover, since most of the int- molecular forces constructing supramolecules are weak, the supramolecular str- ture may vary depending on various factors, such as modification of the molecular structure, auxiliaries, and experimental conditions. Thus, in order to obtain supramolecules with the desired structures and properties, theoretical investigations on the intermolecular forces and accumulation of experimental studies on the re- tionship between the supramolecular structure and properties are both important.

This volume contains a series of papers originally presented at the Symposium on Polymer Gels organized and sponsored by the Research Group on Polymer Gels, The Society of Polymer Science of Japan and co-sponsored by the Science and Technology Agency (ST A) and MIT , Japan. The Symposium took place at Tsukuba Science City on 18th and 19th September, 1989. Recognized experts in their fields were invited to speak and there was a strong attendance from government, academic and industrial research centers. The purpose of the Symposium was to review the state of the art and to present and discuss recent progress in the understanding of the behavioral properties of polymer gels and their application to biomedical, environmental and robotic fields. Most of the papers and related discussions concentrated on the swelling behavior of hydrogels and chemomechanical systems, both artificial and naturally occurring, in which external stimuli of a physical or chemical nature control energy transformation or signal transduction. The recent great interest in chemomechanical systems based on polymer gels has stimulated considerable effort towards the development of new sensors and actuators, controllable membrane separation processes, and delivery systems in which the functions of sensing, processing and actuation are all built into the polymeric network device. Artificial chemomechanical systems, through the use of environmentally sensitive polymer gels, are emerging as interesting materials for mimicking basic processes previously only confined to the biological world, and commercially viable applications are also foreseen in the not-too-distant future

Metal-Ligand Interactions - Structure and Reactivity emphasizes the experimental determination of structure and dynamics, supported by the theoretical and computational approaches needed to establish the concepts and guide the experiments. Leading experts present masterly surveys of: clusters, inorganic complexes, surfaces, catalysis, ab initio theory, density functional theory, semiempirical methods, and dynamics. Besides the presentations of the fields of study themselves, the papers also bring out those aspects that impinge on, or could benefit from, progress in other disciplines. Refined in the fire of an interactive and stimulating conference, the papers presented here represent the state of the art of current research.

Since the discovery of high temperature superconductivity, a tidal wave of res earch into the newly found phenomena took off in several directions. The theor ists began to examine BSC and its implications. Mostly everyone was syn thesizing materials.The experimentalists were studying relations among electri cal and magnetic properties while the pure materials scientists began to exam ine the microstructures, and the relations of processing to one or two measurab le parameters. The engineering and systems community were preparing real conductors and designing the needed components. Each of the communities was holding between two and three annual meetings to discuss most recent re sults. As work progressed, and promised applications did not materialize, it became apparent to us that the physics and materials science communities needed to establish solid communication lines. This NATO Advanced Study Institute was thus conceived and organized. This was a two week summer school, which 15 internationally acclaimed physicists and material scientists were invited to par ticipate in the capacity of Lecturers. Eighty students, from 12 different countries, also attended."

The intrinsic properties of a solid, i. e. , the properties that result from its specific structure, can be largely modified by crystallographic and chem ical defects. The formation of these defects is governed by the heat and mass transfer conditions which prevail on and near a crystal-nutrient in terface during crystallization. Hence, both the growth of highly perfect crystals and the preparation of samples having predetermined defect-induced (extrinsic) properties require a thorough understanding of the reaction and transport mechanisms that govern crystallization from vapors, solutions and melts. Crystal growth, as a science, is therefore mostly concerned with the chemistry and physics of heat and mass transport in these fluid-solid phase transitions. Solid-solid transitions are, at this time, not widely employed for high quality single-crystal production. Transport concepts are largely built upon equilibrium considerations, i. e. , on thermodynamic and phase equilibrium concepts. Hence to supply a "workable" foundation for the succeeding discussions, this text begins in Chapter 2 with a concise treatment of thermodynamics which emphasizes applications to mate rials preparation. After working through this chapter, the reader should feel at ease with often (particularly among physicists) unfamiliar entities such as chemical potentials, fugacities, activities. etc. Special sections on ther mochemical calculations (and their pitfalls) and compilations of thermochemi cal data conclude the second chapter. Crystal growth can be called. in a wide sense, the science and technology of controlling phase transitions that lead to (single crystalline) solids.

Radiationless transitions comprise an important class of physical phenomena occurring in the excited states of molecules. They affect the lifetimes of the ex cited states and govern primary photochemical and photophysical processes. Much effort has been devoted to the understanding of radiationless transi tions. Still, owing to recent advances, the field continues to attract attention. The demand for a book on the theory of these processes naturally arises in at tempting to comprehend a large body of literature, as the famous review article by K. F. Freed and the book by R. Englman do not encompass some issues of current interest. Our intent is to highlight the underlying physical principles and methods in such a way that the book both in its content and its presentation is instruc tive for a wide audience. The basic ideas are treated in simple mathematical terms intelligible to ex perimentalists and to readers unfamiliar with the field. Complicated theoret ical methods are always expounded from first principles, so that a knowledge of quantum mechanics and mathematics at the graduate-student level will enable the reader to easily follow the derivations. Experts will find efficient methods of calculating the transition rates, as well as new applications of quasiclassical methods and fresh treatments of standard problems. Details of measurements are not discussed, and experimental data are only invoked to illustrate the theory."