Bøger i Nato Science Series E: serien

Heterogeneous catalysis provides the backbone of the world's chemical and oil industries. The innate complexity of practical catalytic systems suggests that useful progress should be achievable by investigating key aspects of catalysis by experimental studies on idealised model systems. Thin films and supported clusters are two promising types of model system that can be used for this purpose, since they mimic important aspects of the properties of practical dispersed catalysts. Similarly, appropriate theoretical studies of chemisorption and surface reaction clusters or extended slab systems can provide valuable information on the factors that underlie bonding and catalytic activity. This volume describes such experimental and theoretical approaches to the surface chemistry and catalytic behaviour of metals, metal oxides and metal/metal oxide systems. An introduction to the principles and main themes of heterogeneous catalysis is followed by detailed accounts of the application of modern experimental and theoretical techniques to fundamental problems. The application of advanced experimental methods is complemented by a full description of theoretical procedures, including Hartree-Fock, density functional and similar techniques. The relative merits of the various approaches are considered and directions for future progress are indicated.

Among the many intense light sources, excimer lasers have a unique set of properties that place them at the forefront of tooling for material processing. Their extreme versatility means that they can be used in many areas of materials science and medicine. But three conditions need to be fulfilled in order that their versatility be truly appreciated and exploited: the characteristics and limitations of the sources must be known; the basic excimer laser processes should become reasonably widely known; and problems in search of a solution should be clearly identified. Excimer Lasers covers all three of these points in an instructive and logical way. Probably for the first time, both instrumental and fundamental aspects of excimer laser interaction with matter are presented side-by-side, with examples drawn from the widest range of materials. The articles gathered here are tutorial in their nature, thus making them suitable for a wide readership, from recent graduates and postgraduate students to those established scientists entering the field, all of whom could not find a better, nor more authoritative work with which to start their reading.

Sensors and Sensory Systems for an Electronic Nose reviews the current state of progress in the development of an electronic instrument capable of olfaction. The instrument -- the so-called electronic nose -- has enormous potential for application in such areas as product flavor control and environmental monitoring. The book discusses the essential elements of an electronic nose, such as chemical sensors, signal processing, and pattern recoginiton techniques. It is also one of the first contributions to the new and exciting field of machine olfaction.

In the ten years since the scientific rationale for the design, synthesis and application of inorganic and organometallic polymers (IOPs) was first conceptualised, we have witnessed the first tentative exploration of IOPs as precursors to new materials, with efforts focusing on the design and synthesis of novel ceramic precursors. Developing expertise led to precursor studies combined with the characterisation of the transformation processes that occur when IOPs are converted to ceramic materials. Now at maturity, the science presented in this volume reveals the polymer precursor approach to materials synthesis together with examples of processing ceramic shapes for a range of mechanical properties, the development of sophisticated, noninvasive analytical techniques, and IOP design rationales relying on well-defined processing-property relationships. The production of multifunctional IOPs is described, providing ion conductivity, gas sensing, bioactivity, magnetic properties, etc., combined with processability. The existence of well-defined IOPs and the exquisite control that can be exerted on sol-gel systems now provide access to such a variety of mixed organic-organometallic and/or inorganic hybrid systems that their exploitation is likely to develop into an entirely new field of materials chemistry. Future exciting avenues of research are also being opened up with the advent of buckyballs, Met-Cars, dopable preceramics, rigid-rod organometallics, and molecular tinkertoys.

Corrosion behaviour is one of the most poorly understood characteristics of ceramics. A balanced mixture of scientists from material science, metallurgy, physics, chemistry and mineralogy sum up the state of the art of measurement and modelling and reveal future research directions. The book reviews the theory of corrosion of ceramics, including the diffusion of gases and the predictions of thermodynamics; it discusses critically the kinetic models and representation tools for layer growths and material destruction. Corrosion of nitrides, carbides and oxides by simple and complex gases (O2, H2O, SO2, halides) and melts (ionic and metallic) reveal current measurement and modelling methods, advanced experimental techniques, such as laser diagnostics, TV holography, Raman spectroscopy and NDE surface methods. Frontier areas (e.g. the modelling of porous materials corrosion and protection) are revealed. For scientists and engineers in materials science, dealing with ceramics and their application. A valuable source for research students, solid state physicists and physical chemists.

A NATO Advanced Study Institute (ASI) on the Behavior of Systems in the Space Environment was held at the Atholl Palace Hotel, Pitlochry, Perthshire, Scotland, from July 7 through July 19, 1991. This publication is the Proceedings of the Institute. The NATO Advanced Study Institute Program of the NATO Science Committee is a unique and valuable forum, under whose auspices almost one thousand international tutorial meetings have been held since the inception of the program in 1959. The ASI is intended to be primarily a high-level teaching activity at which a carefully defined subject is presented in a systematic and coherently structured program. The subject is treated in considerable depth by lecturers eminent; in their :(ield and of international standing. The subject is presented to other scientists who either will already have specialized in the field or possess an advanced general background. The ASI is aimed at approximately the post-doctoral level. This ASI emphasized the basic physics of the space environment and the engineering aspects of the environment's interactions with spacecraft.

Within the last 10 years the world has come to a point where the easily explorable oil deposits have now been found, and it is anticipated that such deposits will be depleted by the beginning of the Twenty-first Century. However, the increasing demand of man- kind for energy has caused technologists to look into ways of find- ing new sources or to reevaluat:e unconventional sources which, in the past, have not been economical. In this respect, heavy crude and tar sand oils are becoming important in fulfilling the world's energy requirements. What are heavy crude and tar sand oils? There is still some confusion as to their definitions, inasmuch as they vary among organizations and countries. In an effort to set agreed meanings, UNITAR, in a meeting in February 1982 in Venezuela, proposed the following definitions (see also Table 1): 1. Heavy crude oil and tar sand oil are petroleum or petroleum- like liquids or semi-solids naturally occurring in porous media. The porous media are sands, sandstone, and carbonate rocks. 2. These oils will be characterized by viscosity and density. Viscosity will be used to define heavy crude oil and tar sand oil, and density (oAPI) will be used when viscosity measurements are not available. 3. Heavy crude oil has a gas-free viscosity of 100-10000 mPa.s (cp) 3 o at reservoir temperatures, or a density of 943 kg/m (20 API) 3 o o to 1000 kg/m (10 API) at 15.6 C and at atmospheric oressure.

After an introduction by J.G. Bednorz, describing the discovery of high Tc superconductivity and its consequences, the book goes on to describe modern research, dealing with general problems, new materials and structures, phase separation, electronic homogeneities and related problems, and applications. Specific systems dealt with include the La-cuprates. the Bi-cuprates and the Y-cuprates and related compounds.

The workshop on "e;Optical Properties of Low Dimensional Silicon sL Structures"e; was held in Meylan, France on March, I yd, 1993. The workshop took place inside the facilities of France Telecom- CNET. Around 45 leading scientists working on this rapidly moving field were in attendance. Principal support was provided by the Advanced Research Workshop Program of the North Atlantic Treaty Organisation (NATO). French Delegation a l'Armement and CNET gave also a small financial grant, the organisational part being undertaken by the SEE and CNET. There is currently intense research activity worldwide devoted to the optical properties of low dimensional silicon structures. This follow the recent discovery of efficient visible photoluminescence (PL) from highly porous silicon. This workshop was intended to bring together all the leading European scientists and laboratories in order to reveal the state of the art and to open new research fields on this subject. A large number of invited talks took place (12) together with regular contribution (20). The speakers were asked to leave nearly 1/3 of the time to the discussion with the audience, and that promoted both formal and informal discussions between the participants.

The NATO Advanced Research Workshop on "e;Nanomagnetic Devices"e; was held in Miraflores de la Sierra, Madrid, Spain, from 14 to 19 September 1992. This book contains 21 invited articles related to suggestive and relevant aspects of Magnetism. The NATO Advanced Research Workshop was Co-directed by R.C. O'Handley, B. Heinrich and A. Hernando. The organisers as well as the participants are gratefully acknowledged to the NATO Science Committee. I also wish to thank the publishers for their advice and help in organizing the book. xi DESIDERATA OF STORAGE DEVICES C.E. YEACK-SCRANTON IBM Corporation, E02/005 5600 Cottle Road San Jose, CA 95139 USA ABSTRACT. Typical requirements on cost, capacity, and performance of today's magnetic storage devices and industry trends in these attributes are given. Scaling components, devices, and materials is shown to be a key factor in further improvement, Challenges to continued scaling are reviewed, particularly as they relate to magnetic nano-structures, materials, and characterization techniques.

Proceedings of the NATO Advanced Study Institute, Cesme, Izmir, Turkey, 27 June-8 July, 1988

Prior to the so-called "energy crisis" of 1973, energy played a relatively minor role in our daily lives.and received limited attention from economists, planners and politicians. As a means of production its share in the total cost of the average product was considerably less than 10%. After the decisive events of 1973/74 however, all of this is changed. Energy now affects our daily lives more than anything else; it is the most current issue in business circles, the academia, the civil services and politics; and it is likely to become the most important factor in a potential international instability. The jump in oil prices in 1973 did not just lead to global inflation. but it also made the world a much more complicated environment to live in. Most decisions now require the analysis of yet another dimension; the alternatives have increased in number; the penalty for errors has gone up, and the like. In contrast to the interwoven, complicated, and mostly incompre­ hensible reality, progress is being made in the realm of mathe­ matical modelling that is comprehensible and has the advantage that it can be designed~o the degree of complication desired. Viewed in this way, it can be said that the aim of the Advanced Study Institute held in Istanbul in June 1979 was to try to bridge the gap between the real system and its model.

Thirty years ago, the sharp development of the nuclear phy-­ SlCS has given scope to some connected areas such as radiochemis­ try, radiobiology, radioprotection, radiation damages. In this last subject - damages induced by radiations in mate­ rials, the earlier studies are essentially connected to the me­ chanism of defect creation. Several workers, for instance, SEITZ (1949), DIENES and VINEYARD (1957), BILLINGTON and CRAWFORD (1961) have developed the first approach in the damage processes theories. In the 65th years a "saturation effect" occurs in the studies of the mechanisms and correlatively a strong development appears in the physics of the defect itself. If it is possible in many cases to study defects without a good ~nowledge of their origin many researchs, in particular in the field of defects induced by energetic heavy ions, needs a better understanding of the damage processes. The track phenomena for instance is of special interest in heavy ions problems, cosmic ray tracks in lunar and meteorite crystals or glasses are a good indicator of the solar activity. On the other hand, color centers, induced by energetic heavy ions in alkali-halides crystals, shown a quite different behaviour than those created by light particles, it is necessary to assume that the ionic bombardement creates centers in a well located re­ gion : a core around the path of the incident particle.

John Keats, writing to Fanny Brawne [1], said "I long to believe in immortality ..... I wish to believe in immortality - I wish to live with you forever". So much of this talk will be concerned with the ductile behaviour of crystals, plasticity in its narrower sense. We shall consider a crystal which is deforming by slip, and shall expose a surface in this crystal. We first think of the sur­ face as a simple mathematical cut along a low-index plane. Then we allow for the relaxation of the newly-exposed atoms, and for surface irregularities, and we consider the effect of lattice va­ cancies which can enter at the surface. We consider the effect of dissolving off the surface layers, either intermittently or contin­ uously. Then the effects of adsorption or oxidation by normal con­ stituents of the atmosphere must be considered, the effects of sur­ face alloying, and finally those of special surface-active agents. But "All/Life death does end and each day dies with sleep" [2], and plasticity in its broader sense includes the fracture ~'1hich term­ inates flow. Here there is a bewildering array of effects. The medium in which the crystal flows may enhance its ductility enor­ mously, or it may cause it to break almost without plastic deform­ ation, or under a load which it has already supported.

This book contains the papers presented at the NATO Advanced Study Institute on "Scientific Aspects of Sorption and Filtration Methods for Gas and Water Purification". The Study Institute was held at Fauske Hotel, Fauske, a small town in the northern part of Norway, 2)rd-29th June, 1974. The members of the Scien­ tific Advisory Committee were: The Engineering Research Foundation at T. Halm¢ the Norwegian Institute of Technology, Trondheim, Norway W.H. Hardwick AERE, Harwell, Didcot, Berks., U.K. B. Ottar Norwegian Institute of Air Research, Kjeller, Norway J .A. Wilhelm Karlsruhe Nuclear Research Center, Karlsruhe, Germany R. Berg Institutt for Atomenergi, Kjeller, Norway The members of the Organizing Committee were: E. Andersen M. Bonnevie-Svendsen G. Jarrett all from Institutt for Atomenergi, Kjeller, Norway. The Advanced Study Institute was financially sponsored by the NATO Scientific Affairs Division. The aim of the Study Institute was to bring together scien­ tists concerned with fundamental aspects of sorption, solid state physics and reaction kinetics and workers who are occupied with the development of filter systems for controlled and efficient removal of impurities and poisons from air, off-gases, potable water and industrial effluents. The papers presented covered both theoretical and practical aspects of sorption and membrane filtration. The emphasis was on factors which may effect the filter efficiency, on evaluation, optimalization, controlled development of "tailor made" systems, mathematical models and VI economical consideration. The publication of these lectures was made possible through the kind cooperation of the lecturers.

An Advanced Study Institute on solid-state imaging was held in Louvain-la-Neuve, Belgium on September 3-12, 1975 under the auspices of the Scientific Affairs Division of NATO. The Institute was organized by a scientific organizing committee consisting of Professor Paul Jespers and Professor Fernand Van de Wiele of the Universite' Catholique de Louvain and Dr. Marvin H. White of the Westinghouse Electric Corporation. This book represents the con­ tributions of the lecturers at the Institute and the chapters pre­ sert, for the first time, a concise treatment of a very timely subject, namely, solid-state imaging. The organization of the book parallels the program at the Institute with an introduction r. omprised of historical development and applications. This is f0~lowed by the physics of photosensors which leads quite naturally into the various solid-state photosensor arrays. The subject of signal extraction, which is often an overlooked area, follows and the last part of the book is devoted to the various system's con­ siderations. The subject matter of this book is suitable for a Wide range of interests from the advanced·student, through the practicing physcist and engineer, to the research worker. Although a novice may find some difficulty with the mathematical development, he can acquire a perspective into the field of solid-state imaging with this book. Likewise, portions of this book may be used as a text­ book since ~he chapters are instructional and self-contained.

The photosynthetic process of higher plants converts carbon dioxide, water, and, light quanta into reduced sugars. The enzymes which catalyze this conversion are contained within the chloroplasts and can be thought of as split into two distinct groups. In one group are the enzymes of the IIlightll reactions, which harvest the light, oxidize water and generate two energy-rich intermediates, ATP and NADPH. These two intermediates plus carbon dioxide are the substrates for the second group, the IIdarkll reactions or Cal vi n cycle, which produce the reduced sugars. The chloroplast is completely bounded by an outer membrane. There is a separate, highly convoluted membrane system, the thyla­ koid system, enclosed within the chloroplast. The enzymes of the light reactions are physically associated with the thylakoid mem­ branes, while the Calvin cycle enzymes are free-floating within the stroma, or soluble part of the chloroplast (Fig. 1). GRANA MEMBRANES ARE REG I ONS WHERE THE MEMBRANES ARE APPRESSED ON EACH OTHER MEMBRANES WH ICH ARE UNAPPRESSED THT1.AKO ID t1EHBRANE ARE STROMA MEMBRANES ( ) (VES I OJLAR) (c _______ Figure 1. Schematic representation of the photosynthetic process in plant chloroplasts. PC and PCred are the oxidized and reduced ox forms of plastocyanin. PQ and PQH2 are plastoquinone and plasto­ quinol. For explanation, see text.

Glass ... Current Issues is the proceedings of a NATO Advanced Study Institute held in Puerto de la Cruz, Tenerife between the 2nd and 13th April 1984. The objectives of the School were twofold. Firstly to inform participants of actual and developing technolog­ ical applications of glassy materials in which fundamental science makes a strong contribution, and secondly to bring together scientists from the widely different backgrounds of glass science and technology to promote mutual understanding and collaboration. The amorphous state has for more than a decade now been a renaissance of scientific and technological activity extending beyond traditional glass technology research. Striking developments of amorphous materials have been made in fields such as metallurgy, electronics and telecommunications and even in disciplines until recently less concerned by materials science, such as colloid chemistry, medicine and agriculture. The physical and chemical properties brought into application here result from the interaction between the glass composition and its non-crystalline structure. One role of the basic research is to understand this interaction, which in time through development, helps to extend the range of properties and applications. In this meeting we hoped to sensitize participants to the vast range of applications of amorphous materials which exploit their unique properties, and thus broaden future investigation. The program was organised around seven topics, signposts of scientific and technological activity in the 1980'S: optical materials, amorphous metals, crystallisation phenomena, electronic and electrical devices, sol-gel preparative methods, composite materials and long-term applications.

The impact of Materials Science in our environment has probably never been as massive and decisive as it is today. In every aspect of our lives, progress has never been so dependent on the techniques involved in producing ever more sophisticated materials in ever larger quantities, nor so demanding for technologists to imagine novel processes and circumvent difficulties, or take up new challenges. Every technique is based on a physical process which is put into practice and optimized. The better we know that process, the better the optimization, and more powerful the technique. Laser processing of materials is inscribed in that context. As soon as powerful coherent light sources were made available, it was realized that such intense sources of energy could be used to "heat, melt and crystallize" materials, i.e., to promote phase transitions in atomic systems. As early as 1964, attempts in that direction were made but received very little (if any) attention. Reasons for this lack of interest were several. For one thing, laser technology was not fully developed, so that the process offered poor reliability and no versatility. Also, improving the existing techniques was believed to be sufficient to meet the needs of the time, and there was no real motivation to explore new ways. Finally, and more important, the fundamentals of the physics behind the scenes were, and continue to be, way out of the runni~g stream.

A NATO Advanced Study Institute on "Large Scale Integrated Circuits Technology: State of the Art and Prospects" was held at Ettore Majorana Centre for Scientific Culture, Erice (Italy) on July 15-27, 1981, the first course of the International School of Solid-State Device Research. This volume contains the School Proceedings: fundamentals as well as up-to-date information on each subject presented by qualified authors. The material covered in this volume has been arranged in self-consistent chapters. Therefore, the Proceedings may be used as a suitable textbook or authoritative review for research workers and advanced students in the relevant field. The nascent information society is based on advanced technologies which will revolutionize human abilities to manipulate and communicate information. One of the most important underpinnings for developing such an information society lies in innovations in semiconductor microelectronics. Such innova­ tions, indeed, are dramatically reducing the cost of transmitting, storing, and processing information with improved performance, ushering in an era charac­ terized by large scale integration -the subject of this book.

Most industrial and natural materials exhibit a macroscopic behaviour which results from the existence of microscale inhomogeneities. The influence of such inhomogeneities is commonly modelled using probabilistic methods. Most of the approaches to the evaluation of the safety of structures according to probabilistic criteria are somewhat scattered, however, and it is time to present such material in a coherent and up-to-date form. Probabilities and Materials undertakes this task, and also defines the great tasks that must be tackled in coming years. For engineers and researchers dealing with materials, geotechnics, solid mechanics, soil mechanics, statistics and stochastic processes. The expository nature of the book means that no prior knowledge of statistics or probability is required of the reader. The book can thus serve as an excellent introduction to the nature of applied statistics and stochastic modelling.