The research of unitary concepts in solid state and molecular chemistry is of current interest for both chemist and physicist communities. It is clear that due to their relative simplicity, low dimensional materials have attracted most of the attention. Thus, many non-trivial problems were solved in chain systems, giving some insight into the behavior of real systems which would otherwise be untractable. The NATO Advanced Research Workshop on "Organic and Inorganic Low-Dimensional Crystalline Materials" was organized to review the most striking electronic properties exhibited by organic and inorganic sytems whose space dimensionality ranges from zero (Od) to one (1d), and to discuss related scientific and technological potentials. The initial objectives of this Workshop were, respectively: i) To research unitary concepts in solid state physics, in particular for one dimensional compounds, ii) To reinforce, through a close coupling between theory and experiment, the interplay between organic and inorganic chemistry, on the one hand, and solid state physics on the other, iii) To get a salient understanding of new low-dimensional materials showing "exotic" physical properties, in conjunction with structural features.

This volume represents the written account of the NATO Advanced Study Institute "Lower-Dimensional Systems and Molecular Electronics" held at Hotel Spetses, Spetses Island, Greece from 12 June to 23 June 1989. The goal of the Institute was to demonstrate the breadth of chemical and physical knowledge that has been acquired in the last 20 years in inorganic and organic crystals, polymers, and thin films, which exhibit phenomena of reduced dimensionality. The interest in these systems started in the late 1960's with lower-dimensional inorganic conductors, in the early 1970's with quasi-one-dimensional crystalline organic conductors. which by 1979 led to the first organic superconductors, and, in 1977, to the fITSt conducting polymers. The study of monolayer films (Langmuir-Blodgett films) had progressed since the 1930's, but reached a great upsurge in . the early 1980's. The pursuit of non-linear optical phenomena became increasingly popular in the early 1980's, as the attention turned from inorganic crystals to organic films and polymers. And in the last few years the term "moleculw' electronics" has gained ever-increasing acceptance, although it is used in several contexts. We now have organic superconductors with critical temperatures in excess of 10 K, conducting polymers that are soluble and processable, and used commercially; we have films of a few monolayers that have high in-plane electrical conductivity, and polymers that show great promise in photonics; we even have a few devices that function almost at the molecular level.

This edited work contains eight extensive, review-type contributions by leading scientists in the field of synthetic metals. The authors were invited by the organisers of the International Conference on Science and Technology of Synthetic Metals '98 (ICSM'98) to review the progress of research in the past two decades in a unifying and pedagogical manner. The present work highlights the state-of-the-art of the field and assesses the prospects for future research.

One of the major challenges of science in the last few years of the second millennium is learning how to design materials which can fulfill specific tasks. Ambitious as it may be, the possibilities of success are not ne~li~ble provided that all the different expertises merge to overcome the limits of eXIsting disciplines and forming new paradigms science. The NATO Advanced Research Workshop on "Magnetic Molecular Materials" was organized with the above considerations in mind in order to determine which are the most appropriate synthetic strategies, experimental techniques of investigation, and theoretical models which are needed in order to develop new classes of magnetic materials which are based on molecules rather than on metallic or ionic lattices. Why molecules? The answer may be obvious: molecular chemistry in principle fine can tune the structures and the properties of complex aggregates, and nature already provides a large number of molecular aggregates which can perform the most disparate functions. The contributions collected in this book provide a rather complete view of the current research accomplishments of magnetic molecular materials. There are several different synthetic approaches which are followed ranging from purely organic to inorganic materials. Some encouraging successes have already been achieved, even if the critical temperatures below which magnetic order is observed still are in the range requiring liquid helium.

The latest addition to this series covers a field which is commonly referred to as charge density wave dynamics.The most thoroughly investigated materials are inorganic linear chain compounds with highly anisotropic electronic properties. The volume opens with an examination of their structural properties and the essential features which allow charge density waves to develop.The behaviour of the charge density waves, where interesting phenomena are observed, is treated both from a theoretical and an experimental standpoint. The role of impurities in statics and dynamics is considered and an examination of the possible role of solitons in incommensurate charge density wave systems is given. A number of ways to describe charge density waves theoretically, using computer simulations as well as microscopical models, are presented by a truely international board of authors.

As its name suggests, the 1988 workshop on "Interacting Electrons in Reduced Dimen the wide variety of physical effects that are associated with (possibly sions" focused on strongly) correlated electrons interacting in quasi-one- and quasi-two-dimensional mate rials. Among the phenomena discussed were superconductivity, magnetic ordering, the metal-insulator transition, localization, the fractional Quantum Hall effect (QHE), Peierls and spin-Peierls transitions, conductance fluctuations and sliding charge-density (CDW) and spin-density (SDW) waves. That these effects appear most pronounced in systems of reduced dimensionality was amply demonstrated at the meeting. Indeed, when concrete illustrations were presented, they typically involved chain-like materials such as conjugated polymers, inorganic CDW systems and organie conductors, or layered materials such as high-temperature copper-oxide superconductors, certain of the organic superconductors, and the QHE samples, or devices where the electrons are confined to a restricted region of sample, e. g. , the depletion layer of a MOSFET. To enable this broad subject to be covered in thirty-five lectures (and ab out half as many posters), the workshop was deliberately focused on theoretical models for these phenomena and on methods for describing as faithfully as possible the "true" behav ior of these models. This latter emphasis was especially important, since the inherently many-body nature of problems involving interacting electrons renders conventional effec tive single-particle/mean-field methods (e. g. , Hartree-Fock or the local-density approxi mation in density-functional theory) highly suspect. Again, this is particularly true in reduced dimensions, where strong quantum fluctuations can invalidate mean-field results.

This book is a printed edition of the Special Issue "Advances in Organic Conductors and Superconductors" that was published in Crystals

Nuclear magnetic resonance (NMR), nuclear quadrupole resonance (NQR), time differential perturbed angular correlations (TDPAC), and the Mössbauer effect (ME) have been applied to the study of charge density wave (CDW) systems. These hyperfine techniques provide unique tools to probe the structure and symmetry of commensurate CDWs, give a clear fingerprint of incommensurate CDWs, and are ideally suited for CDW dynamics. This book represents a new attempt in the series `Physics and Chemistry of Materials with Low-dimensional Structures' to bring together a consistent group of scientific results obtained by nuclear spectroscopy related to CDW phenomena in pseudo-one- and two-dimensional systems. The individual chapters contain: the theory of CDWs in chain-like transition metal tetrachalcogenides; NMR, NQR, TDPAC, and ME investigations of layered transition metal dichalcogenides; NMR studies of CDW-transport in chain-like NbSe3 and molybdenum bronzes; multinuclear NMR of KCP; high resolution NMR of organic conductors. This book is of interest to graduate students and all scientists who want to acquire a broader knowledge of nuclear spectroscopy techniques applied to CDW systems.

The last few years have ~een rapid improvements in semiconductor growth techniques which have produced an expanding range of high quality heterostructures for new semiconductor devises. As the dimensions of such structures approach the nanometer level, it becomes increasingly important to characterise materials properties such as composition uniformity, strain, interface sharpness and roughness and the nature of defects, as well as their influence on electrical and optical properties. Much of this information is being obtained by electron microscopy and this is also an area of rapid progress. There have been advances for thin film studies across a wide range of techniques, including, for example, convergent beam electron diffraction, X-ray and electron energy loss microanalysis and high spatial resolution cathodoluminescence as well as by conventional and high resolution methods. Important develop ments have also occurred in the study of surfaces and film growth phenomena by both microscopy and diffraction techniques. With these developments in mind, an application was made to the NATO Science Committee in late summer 1987 to fund an Advanced Research Work shop to review the electron microscopy of advanced semiconductors. This was subsequently accepted for the 1988 programme and became the "NATO Advanced Research Workshop on the Evaluation of Advanced Semiconductor Materials by Electron Microscopy". The Workshop took place in the pleasant and intimate surroundings of Wills Hall, Bristol, UK, during the week 11-17 September 1988 and was attended by fifty-five participants from fourteen countries.