This volume contains the invited papers and selected contributed papers presented at the biennial International Symposium on ELECTRON COLLISIONS WITH MOLECULES, CLUSTERS AND SURF ACES held at Royal Holloway, University of London from 29th to 30th July, 1993. This Symposium was a Satellite Meeting of the XVIII International Conference on the Physics of Electronic and Atomic Collisions (ICPEAC) and follows a 16 year tradition of Satellite Conferences in related areas of collisions held in association with previous ICPEAC's. In the past each of these electron -molecule symposia covered the broad field of electron-molecule scattering at rather low energies, but also included hot topics. This time as well as covering the whole field, well defined electron collisions with clusters and with particles in the complex potential of a surface were emphasized. Not many details are known about such collisions, although they become more and more important in surface characterisation, plasma-wall interactions, electron induced desorption and reorganisation of adsorbed particles. Recently, much work, theoretical and experimental, has been devoted to electron collisions with rather large carbon, silicon and halogen containing molecules. These problems are of relevance in plasma assisted thin film formation and etching of surfaces and can now be approached with advanced theoretical methods and experimental equipment.

This volume contains the Proceedings of the NATO Advanced Research Workshop (ARW) and Emil-Warburg-Symposium (EWS) "Nonlinear Coherent Structures in Phy sics and Biology" held at the University of Bayreuth from June 1 -4, 1993. Director of the ARW was K. H. Spatschek, while F.G. Mertens acted as the co-director, host, and organizer of the EWS. The other members of the scientific organizing committee were A.R. Bishop (Los Alamos), J.C. Eilbeck (Edinburgh), and M. Remoissenet (Dijon). This was the eighth meeting in a series of interdisciplinary workshops founded by our French colleagues who had organized all the previous workshops, e.g. 1989 in Montpel lier and 1991 in Dijon. We were asked to organize the meeting this time in Germany. Of course, we wanted to keep the character defined by the previous meetings, which were always characterized by an open and friendly atmosphere, being not too large in quantity, but high in quality. This time altogether 103 participants attended the workshop. During the past years most of the participants met several times and discussed problems connected with the generation of nonlinear coherent structures in physics and biology."

The Nato Advanced Study Institute "Phase Transitions in Liquid Crystals" was held May 2-12, 1991, in Erice, Sicily. This was the 16th conference organized by the International School of Quantum Electronics, under the auspices of the "Ettore Majorana" Centre for Scientific Culture. The subject of "Liquid Crystals" has made amazing progress since the last ISQE Course on this subject in 1985. The present Proceedings give a tutorial introduction to today's most important areas, as well as a review of current results by leading researchers. We have brought together some of the world's acknowledged experts in the field to summarize both the present state of their research and its background. Most of the lecturers attended all the lectures and devoted their spare hours to stimulating discussions. We would like to thank them all for their admirable contributions. The Institute also took advantage of a very active audience; most of the students were active researchers in the field and contributed with discussions and seminars. Some of these student seminars are also included in these Proceedings. We did not modify the original manuscripts in editing this book, but we did group them according to the following topics: 1) "Theoretical Foundations"; 2) "Thermotropic Liquid Crystals"; 3) "Ferroelectric Liquid Crystals"; 4) "Polymeric Liquid Crystals"; and 5) "Lyotropic Liquid Crystals".

The aim of this NATO Advanced Study Institute was to bring together scientists and students working in the field of laser matter interactions in order to review and stimulate developmentoffundamental science with ultra-short pulse lasers. New techniques of pulse compression and colliding-pulse mode-locking have made possible the construction of lasers with pulse lengths in the femtosecond range. Such lasers are now in operation at several research laboratories in Europe and the United States. These laser facilities present a new and exciting research direction with both pure and applied science components. In this ASI the emphasis is on fundamental processes occurring in the interaction of short laser pulses with atoms, molecules, solids, and plasmas. In the case of laser-atom (molecule) interactions, high power lasers provide the first access to extreme high-intensity conditions above 10'8 Watts/em', a new frontier for nonlinear interaction of photons with atoms and molecules. New phenomena observed include multiphoton ionization processes, atomic collisions in the presence of a strong laser field, Coulomb explosion following rapid ionization of a molecule and the production of high harmonics of the laser source. Another important topic reviewed in this ASI is the lasercooling ofatoms.

The Institute for Amorphous Studies was founded in 1982 as the international center for the investigation of amorphous mate rials. It has since played an important role in promoting the und er standing of disordered matter in general. An Institute lecture series on "Fundamentals of Amorphous Materials and Devices" was held during 1982-83 with distinguished speakers from universities and industry. These events were free and open to the public, and were attended by many representatives of the scientific community. The lectures themselves were highly successful inasmuch as they provided not only formal instruction but also an opportunity for vigorous and stimulating debate. That last element could not be captured within the pages of a book I but the lectures concentrated on the latest advances in the field I which is why their essential contents are he re reproduced in collective form. Together they constitute an interdisciplinary status report of the field. The speakers brought many different viewpoints and a variety of back ground experiences io bear on the problems involved I but though language and conventions vary I the essential unity of the concerns is very clear I as indeed are the ultimate benefits of the many-sided approach."

of progress has been made in the development of In the last twenty years a great amount new magnetic materials. Permanent magnets have progressed from the AlNiCo's (with (BH)m-8 MGOe) to the strong rare-earth magnets of SmCo BH)m-20 MGOe), Sm2(Co, Fe, Cu, Zrh7 s BH)m-30 MGOe) and the recently discovered Nd-Fe-B super-magnets with (BH)m-50 MGOe. For years the magnetic storage industry has employed Fe0 and CrO for storage media and 2 3 z permalloys and ferrites for recording heads. The recent development of thin film heads, the demand of higher density of information storage and the emergence of completely new technologies, like magneto-optics, call for entirely new types of magnetic materials. Another area in which new techniques of materials preparation have made a dramatic impact is the epitaxial growth of magnetic films. Recent work has shown that this process can be controlled on the scale of atomic monolayers permitting the growth of totally artificial structures, such as artificial superlattices with a resolution on this scale. Epitaxial growth has also permitted the stabilization of metastable phases in thin film form. These new phases often possess striking properties, such as strong perpendicular anisotropies, which may prove useful for technological applications such as recording. Research on magnetic multilayers and superlattices is increasing at an accelerating pace. Complex couplings between different magnetic layers lead to new properties not seen in bulk materials.

In recent years, III-V devices, integrated circuits, and superconducting integrated circuits have emerged as leading contenders for high-frequency and ultrahigh speed applications. GaAs MESFETs have been applied in microwave systems as low-noise and high-power amplifiers since the early 1970s, replacing silicon devices. The heterojunction high-electron-mobility transistor (HEMT), invented in 1980, has become a key component for satellite broadcasting receiver systems, serving as the ultra-low-noise device at 12 GHz. Furthermore, the heterojunction bipolar transistor (HBT) has been considered as having the highest switching speed and cutoff frequency in the semiconductor device field. Initially most of these devices were used for analog high-frequency applications, but there is also a strong need to develop high-speed III-V digital devices for computer, telecom munication, and instrumentation systems, to replace silicon high-speed devices, because of the switching-speed and power-dissipation limitations of silicon. The potential high speed and low power dissipation of digital integrated circuits using GaAs MESFET, HEMT, HBT, and superconducting Josephson junction devices has evoked tremendous competition in the race to develop such technology. A technology review shows that Japanese research institutes and companies have taken the lead in the development of these devices, and some integrated circuits have already been applied to supercomputers in Japan. The activities of Japanese research institutes and companies in the III-V and superconducting device fields have been superior for three reasons. First, bulk crystal growth, epitaxial growth, process, and design technology were developed at the same time.

Photochromism is the reversible phototransformation of a chemical species between two forms having different absorption spectra. During the phototransformation not only the absorption spectra but also various physicochemical properties change, such as the refractive index, dielectric constant, oxidation/reduction potential, and geometrical structure. The property changes can be applied to photonic equipment such as erasable memory media, photo-optical switch components, and display devices. This book compiles the accomplishments of the research project titled "New Frontiers in Photochromism" supported by the Ministry of Education, Culture, Sports, Science and Technology of Japan. The project focused not only on the above-mentioned classical subjects in photochromism, such as color changes, optical memory, and optical switches, but also on fundamental physicochemical studies and unprecedented application fields that have not yet been explored in photochromism. The latter topics include light-driven mechanical motion, photocontrol of surface wettability, metal deposition on solid materials, photocontrol of chiral properties, ultrafast decoloration dyes, and femtosecond laser experiments, among others.

This volume contains the papers presented at the NATO Advanced Research Workshop on "Magnetism and Structure in Systems of Reduced Dimension," held at l'Institut d'Etudes Scientifiques de Cargese - U.M.S. - C.N.R.S. - Universite de Corte Universite de Nice Sophia - Antipolis during June 15-19, 1992. The ordering of papers in the volume reflects the sequence of papers presented at the workshop. The aim was not to segregate the papers into rigidly defmed areas but to group the papers into small clusters, each cluster having a common theme. In this way the parallel, rather than serial, development of areas such as preparation of films, magnetic and structural characterization was highlighted. Indeed the success of the field depends on such parallel development and is assisted by workshops of this nature and the international collaborations which they foster. The organizers and participants of the NATO workshop express their thanks to Mme. Marie-France Hanseier and the staff at l'Institut d'Etudes Scientifiques de Cargese U.M.S. - C.N.R.S. - Universite de Corte - Universite de Nice Sophia - Antipolis for making the workshop and local arrangements a memorable success. Warm thanks are also expressed to Varadachari Sadagopan and Pascal Stefanou for their encouragement and help in making the workshop a reality. We are also grateful to Kristl Hathaway, Larry Cooper and Gary Prinz for advice in developing the workshop program."

Covering both theory and applications, this important work provides a comprehensive introduction to the modern theory of X-ray and electronic spectra of free atoms. Romas Karazija discusses methods of angular momenta, irreducible tensorial operators, and coefficients of fractional parentage and their use in determining cross sections and probabilities of elementary processes. In addition, Karazija addresses the structure of electronic shells with inner vacancies and many-body effects.

The textbook we offer to the reader is based on a two-term course of lec tures, "Electromagnetic Response of Material Media," that the authors gave for a number of years to the final-year students of the Physics Depart ment of Moscow University. This course built on courses in quantum electronics, nonlinear optics and theoretical fundamentals of quantum radiophysics; students are as sumed to have mastered the fundamentals of quantum mechanics, laser physics and nonlinear optics. The essential core of the course, and hence of the book, is the current general theory of electromagnetic response of a nonrelativistic medium. The main aspects are presented in Chapters 1 and 2. The second part is devoted to more traditional topics which students learn in this course of lectures and also in the course "Condensed Matter Physics" for students who choose to major in radiophysics and laser physics; this course is also taught by the authors at the Physics Department. This volume was intended as a text for students and, as such, does not cite original publications. We decided to provide a list of additional recommended literature, mostly of well known, easily accessible textbooks.

At first glance, the articles in this book may appear to have nothing in common. They cover such seemingly disparate subjects as the properties of small metallic clusters and the behavior of superfluid He3, nuclear physics and organic materials, copper oxides and mag netic resonance. Why have they been brought together, particUlarly in our time of narrow spe cialization? In fact, the properties and effects described in this book touch upon one and the same fundamental phenomenon: pair correlation. Introduced in the theory of superconductivity by J. Bardeen, L. Cooper, and J. Schrieffer (BCS), this effect plays a key role in various Fermi systems. The book consists of several sections. The first chapter is concerned with conven tional and high Tc superconductors. The second chapter describes two relatively young fami lies of superconductors: organics and fullerenes. Chapter III addresses the superfluidity of 3 He * The discovery of this phenomenon in 1971 was a big event in physics and last year was acknowledged by a Nobel prize. This book contains the text of the Nobel lecture. Chapters IV and V are devoted to correlations in finite Fermi systems such as small metallic clusters, C 60 anions, and atomic nuclei. The book thus covers a broad range of problems, illuminating the close ties between various areas of physics.

The NATO Advanced Study Institute on "Scale Invariance, Interfaces and Non Equilibrium Dynamics" was held at the Isaac Newton Institute for Mathematical Sciences in Cambridge, UK from 20-30 June 1994. The topics discussed at the Institute were all concerned with the origin and nature of complex structures found far from equilibrium. Examples ranged from reaction diffusion systems and hydrodynamics through to surface growth due to deposition. A common theme was that of scale invariance due to the self-similarity of the underly ing structures. The topics that were covered can be broadly classified as pattern for mation (theoretical, computational and experimental aspects), the non-equilibrium dynamics of the growth of interfaces and other manifolds, coarsening phenomena, generic scale invariance in driven systems and the concept of self-organized critical ity. The main feature of the Institute was the four one-hour-Iong lectures given each day by invited speakers. In addition to thirty-seven of these lectures, two contributed lectures were also given. The many questions that were asked after the lectures attested to the excitement and interest that the lecturers succeeded in generating amongst the students. In addition to the discussions initiated by lectures, an im portant component of the meeting were the poster sessions, where participants were able to present their own work, which took place on three of the afternoons. The list of titles given at the end of these proceedings gives some idea of the range and scope of these posters."

This thesis investigates the transitions from one electronically excited state to another. Such processes - the fastest of events in chemistry - can be studied with femtosecond resolution, and Thomas S. Kuhlman approaches the question both with experimental and theoretical methods. His approach contributes to explain processes of high importance to all scientific fields concerned with the interaction between light and matter: the deactivation of the electronically excited states after excitation. Thomas S. Kuhlman concludes in this thesis that the electronic transition proceeds before the entire set of available degrees of freedom are active - 'It is as simple as that' !

In this unique textbook and reference source, the authors integrate theoretical and applied research from a host of disciplines, including materials science, plasma physics, and advanced transport phenomena. Volume 1, the first of two, covers the fundamentals of plasma physics and gaseous electronics, thermodynamics, and transport properties of plasma.

This volume contains a sequence of reviews presented at the NATO Advanced Study Institute on 'Low Dimensional Structures in Semiconductors ... from Basic Physics to Applications.' This was part of the International School of Materials Science and 1990 at the Ettore Majorana Centre in Sicily. Technology held in July Only a few years ago, Low Dimensional Structures was an esoteric concept, but now it is apparent they are likely to playa major role in the next generation of electronic devices. The theme of the School acknowledged this rapidly developing maturity.' The contributions to the volume consider not only the essential physics, but take a wider view of the topic, starting from material growth and processing, then prog ressing right through to applications with some discussion of the likely use of low dimensional devices in systems. The papers are arranged into four sections, the first of which deals with basic con cepts of semiconductor and low dimensional systems. The second section is on growth and fabrication, reviewing MBE and MOVPE methods and discussing the achievements and limitations of techniques to reduce structures into the realms of one and zero dimensions. The third section covers the crucial issue of interfaces while the final section deals with devices and device physics."

Since the publication in 1950 of Vol. I, Spectra of Diatomic Molecules of Molecular Spectra and Molecular Structure, much progress has been made in the field. While there have been some important refinements in the theory of diatomic molecular spectra, most of the advances have been in the further exploration of individual spectra. Not only has the number of molecules about which some spectroscopic data are available been increased by a factor of 2 to 3, but also the spectroscopic information about the molecules known in 1950 has been vastly extended. This is due to the observation of new elec tronic states (about three times as many as known before), the enormous improvements in the accuracy of the constants of the states known in 1950, and the determination of higher order constants. In view of the increasing use of spectroscopic information on diatomic molecules in other fields of physics, in chemistry, and in astrophysics, it appeared desirable to prepare an up-to-date version of the table of molecular constants in the appendix of Vol. I. This updating proved to be far more time-consuming than originally anticipated, and it is only now, 10 years that we are able to present such a table, which, instead after its initiation, of the original 80 pages (plus 30 pages of bibliography), now fills a volume of 700 pages. In the interest of economy, and unlike the original version, the new table has been produced by photo-offset from the final manuscript."

"You, 0 Sun, are the eye of the world You are the soul of all embodied beings You are the source of all creatures You are the discipline of all engaged in work" - Translated from Mahabharata 3rd Century BC Today, energy is the lifeline and status symbol of "civilized" societies. All nations have therefore embarked upon Research and Development pro grams of varying magnitudes to explore and effectively utilize renewable sources of energy. Albeit a low-grade energy with large temporal and spatial variations, solar energy is abundant, cheap, clean, and renewable, and thus presents a very attractive alternative source. The direct conver sion of solar energy to electricity (photovoltaic effect) via devices called solar cells has already become an established frontier area of science and technology. Born out of necessity for remote area applications, the first commercially manufactured solar cells - single-crystal silicon and thin film CdS/Cu2S - were available well over 20 years ago. Indeed, all space vehicles today are powered by silicon solar cells. But large-scale terrestrial applications of solar cells still await major breakthroughs in terms of discovering new and radical concepts in solar cell device structures, utilizing relatively more abundant, cheap, and even exotic materials, and inventing simpler and less energy intensive fabrication processes. No doubt, this extraordinary challenge in R/D has led to a virtual explosion of activities in the field of photovoltaics in the last several years."

During the past decade the theoretical physics community has learned how to evaluate accurately polarizabilities and susceptibilities for many-electron systems such as atoms, solids, and liquids. The most accurate numerical technique employs a method often called the Time-Dependent Local Density Approximation, which is abbreviated TDLDA. The present volume is a review of recent research on the theory of po larizabilities and susceptibilities. Both authors have been doing these cal culations. However, this review surveys the entire field, summarizing the research of many contributors. The application of an external field, either ac or de, will induce a dipole moment which can be calculated and compared with experiment. For mod erately strong fields, both linear and nonlinear processes contribute to the moment. We cover topics such as polarizability, hyperpolarizability, pho toionization, phonons, and piezoelectricity. Density functional theory in the Local Density Approximation (LDA) has been shown to be a very accurate method for calculating ground state prop erties of electronic system. For static external fields, the induced moments are properties of the ground state. Then the calculation of the polarizability . is very accurate. For ac fields, the moment is not part of the ground state. However, the TDLDA methods are still very accurate."

The main objective of this book is to systematically describe the basic principles of the most widely used techniques for the analysis of physical, structural, and compositional properties of solids with a spatial resolution of approxi mately 1 ~m or less. Many books and reviews on a wide variety of microanalysis techniques have appeared in recent years, and the purpose of this book is not to replace them. Rather, the motivation for combining the descriptions of various mi croanalysis techniques in one comprehensive volume is the need for a reference source to help identify microanalysis techniques, and their capabilities, for obtaining particular information on solid-state materials. In principle, there are several possible ways to group the various micro analysis techniques. They can be distinguished by the means of excitation, or the emitted species, or whether they are surface or bulk-sensitive techniques, or on the basis of the information obtained. We have chosen to group them according to the means of excitation. Thus, the major parts of the book are: Electron Beam Techniques, Ion Beam Techniques, Photon Beam Techniques, Acoustic Wave Excitation, and Tunneling of Electrons and Scanning Probe Microscopies. We hope that this book will be useful to students (final year undergrad uates and graduates) and researchers, such as physicists, material scientists, electrical engineers, and chemists, working in a wide variety of fields in solid state sciences.

Many and ever more mobile users wish to enjoy a variety of multimedia services, in very diverse geographical environments. The growing number of communication options within and across wireless standards is accommodating the growing volume and heterogeneity in wireless wishes. On the other hand, advancement in radio technologies opening much more flexibility, a.o. through Software Defined Radios, opens up the possibility to realize mobile devices featuring multi-mode options at low cost and interesting form factors.

It is crucial to manage the new degrees of freedom opened up in radios and standards in a smart way, such that the required service is offered at satisfactory quality as efficiently as possible. Efficiency in energy consumption is clearly primordial for battery powered mobile terminals specifically, and in the context of growing ecological concerns in a broader context. Moreover, efficient usage of the spectrum is a growing prerequisite for wireless systems, and coexistence of different standards puts overall throughput at risk.

The management of flexibility risks bringing about intolerable complexity and hamper the desired agility. A systematic approach, consisting of anticipative preparing for smooth operation, allows mastering this challenge. Case studies show that already today, this approach enables smart operation of radios realizing impressive efficiency gains without hampering Quality-of-Service. In the future wireless communication scenes will be able to profit form the opening of the spectrum. Even smarter and cognitive behavior will become possible and essential.

The development of linear-scaling density functional theory (LS-DFT) has made ab initio calculations on systems containing thousands of atoms possible. These systems range from nanostructures to biomolecules. These methods rely on the use of localized basis sets, which are optimised for the representation of occupied Kohn-Sham states but do not guarantee an accurate representation of the unoccupied states. This is problematic if one wishes to combine the power of LS-DFT with that of theoretical spectroscopy, which provides a direct link between simulation and experiment. In this work a new method is presented for optimizing localized functions to accurately represent the unoccupied states, thus allowing theoretical spectroscopy of large systems. Results are presented for optical absorption spectra calculated using the ONETEP code, but the method is equally applicable to other spectroscopies and LS formulations. Other topics covered include a study of some simple one dimensional basis sets and the presentation of two methods for band structure calculation using localized basis sets, both of which have important implications for the use of localized basis sets within LS-DFT.

The recent discovery of high-temperature superconductivity has resulted in a remarkable growth in the amount of research and the number of researchers working in this exciting field. Superconductivity is not a new phenomenon: in 1991 it will be 80 years old. Even though it was the newer discoveries which motivated us to write this book, the book itself is mainly a description of the fundamentals of the phenomenon. The book is written for a very broad audience, including students, engin eers, teachers, scientists, and others who are interested in learning about this exciting frontier of science. We have focused on the qualitative aspects, so that the reader can develop a basic understanding of the fundamental physics without getting bogged down in the details. Because of this approach, our list of refer ences is not comprehensive, and it is supplemented with a summary of additional reading consisting of monographs and selected review articles. (The articles we have referenced were either not reflected in the review articles on monographs or were milestones in the development of the field. ) In addition, some of the sections which can be skipped during the first reading have been marked with asterisks (*). Until recently, superconductivity was considered to belong to the field of low-temperature physics. This field was born, simultaneously with quantum physics, at the beginning of this century. Initially these two contemporaneous fields developed independently, but they soon became strongly coupled."