Coherence and Energy Transfer in Glasses


Book Description

In recent years the physics of disordered systems has been one of the most active and fruitful areas of research in condensed matter science. In contrast to the considerable attention paid by conferences, schools and workshops to the static and structural aspects of glasses, there has been no forum devoted primarily to the dynamic and energetic aspects of amorphous solids. The NATO Workshop on Coherence and Energy Transfer in Glasses was organized to address this deficiency. The intent was to bring together in an intense and interactive environment, experts in several rather disparate subfields relating to the dynamics and energetics of disordered systems. This volume represents the Proceedings of that Workshop, which took place in September 1982 at Clare College of Cambridge University. Forty-three scientists from eight NATO countries participated. These included representatives from universities and industrial laboratories, as well as government research institutions. The meeting was organized into eight formal sessions and one informal session devoted entirely to unstructured discussion. Each formal session featured two comprehensive lectures. An additional 60 to 90 minutes was devoted in each session to discussions and contributions related to the lectures. Since only about 60% of the session time was devoted to formal presentations, the discussions formed an equally important part of the workshop. The chairmen and discussion leaders - as well as the workshop participants themselves - brought forth lively and illuminating discussions for each session.







Coherence and Energy Transfer in Glasses


Book Description

In recent years the physics of disordered systems has been one of the most active and fruitful areas of research in condensed matter science. In contrast to the considerable attention paid by conferences, schools and workshops to the static and structural aspects of glasses, there has been no forum devoted primarily to the dynamic and energetic aspects of amorphous solids. The NATO Workshop on Coherence and Energy Transfer in Glasses was organized to address this deficiency. The intent was to bring together in an intense and interactive environment, experts in several rather disparate subfields relating to the dynamics and energetics of disordered systems. This volume represents the Proceedings of that Workshop, which took place in September 1982 at Clare College of Cambridge University. Forty-three scientists from eight NATO countries participated. These included representatives from universities and industrial laboratories, as well as government research institutions. The meeting was organized into eight formal sessions and one informal session devoted entirely to unstructured discussion. Each formal session featured two comprehensive lectures. An additional 60 to 90 minutes was devoted in each session to discussions and contributions related to the lectures. Since only about 60% of the session time was devoted to formal presentations, the discussions formed an equally important part of the workshop. The chairmen and discussion leaders - as well as the workshop participants themselves - brought forth lively and illuminating discussions for each session.




Optical Spectroscopy of Glasses


Book Description

During the last fifteen years the field of the investigation of glasses has experienced a period of extremely rapid growth, both in the development of new theoretical ap proaches and in the application of new experimental techniques. After these years of intensive experimental and theoretical work our understanding of the structure of glasses and their intrinsic properties has greatly improved. In glasses we are con fronted with the full complexity of a disordered medium. The glassy state is characterised not only by the absence of any long-range order; in addition, a glass is in a non-equilibrium state and relaxation processes occur on widely different time scales even at low temperatures. Therefore it is not surprising that these complex and novel physical properties have provided a strong stimulus for work on glasses and amorphous systems. The strikingly different properties of glasses and of crystalline solids, e. g. the low temperature behaviour of the heat capacity and the thermal conductivity, are based on characteristic degrees of freedom described by the so-called two-level systems. The random potential of an amorphous solid can be represented by an ensemble of asymmetric double minimum potentials. This ensemble gives rise to a new class of low-lying excitations unique to glasses. These low-energy modes arise from tunneling through a potential barrier of an atom or molecule between the two minima of a double-well.




Disordered Solids


Book Description

This book presents an account of the course "Disordered Solids: Structures and Processes" held in Erice, Italy, from June 15 to 29, 1987. This meeting was organized by the International School of Atomic and Molecular Spectroscopy of the "Ettore Majorana" Centre for Scientific Culture. The objective of this course was to present the advances in physical modelling, mathematical formalism and experimental techniques relevant to the interpretation of the structures of disordered solids and of the physical processes occurring therein. Traditional solid-state physics treats solids as perfect crystals and takes great advantage of their symmetry, by means of such mathematical formalisms as the reciprocal lattice, the Brillouin zone, and the powerful tools of group theory. Even if in reality no solid is a perfect crystal, this theoretical approach has been of great usefulness in describing solids: deviations from perfect order have been treated as perturbations of the ideal model. A new situation arises with truly disordered solids where any vestige of long range order has disappeared. The basic problem is that of describing these systems and gaining a scientific understanding of their physical properties without the mathematical formalism of traditional solid state physics. While some of the old approaches may occasionally remain valid (e. g. chemical bonding approach for amorphous solids), the old ways will not do. Disorder is not a perturbation: with disorder, something basically new may be expected to appear.




Semiconducting Chalcogenide Glass II


Book Description

Chalcogenide glass is made up of many elements from the Chalcogenide group. The glass is transparent to infrared light and is useful as a semiconductor in many electronic devices. For example, chalcogenide glass fibers are a component of devices used to perform laser surgery. The properties of chalcogenide glass result not only from their chemical composition and atomic structure, but also from the impact of numerous external factors. A comprehensive survey is presented of the properties of chalcogenide glass under various external impacts. Practical recommendations are presented for a wide range of applications. Part II is the second part of a three-volume work within the Semiconductors and Semimetals series.* The first collective monograph written by Eastern European scientists on the electrical and optical properties of chalcogenide vitreous semiconductors (CVS).* Contributions by B.G. Kolomiets, who discovered the properties of chalcogenide glass in 1955!* Provides objective evidence and discussion by authors from opposing positions.




Energy Transfer Processes in Condensed Matter


Book Description

This book presents an account of the NATO Advanced Study Institute on "Energy Transfer Processes in Condensed Matter", held in Erice, Italy, from June 16 to June 30, 1983. This meeting was organized by the International School of Atomic and Molecular Spectroscopy of the "Ettore Majorana" Centre for Scientific Culture. The objective of the Institute was to present a comprehensive treatment of the basic mechanisms by which electronic excitation energy, initially localized in a particular constituent or region of a condensed material, transfers itself to the other parts of the system. Energy transfer processes are important to such varied .fields as spectroscopy, lasers, phosphor technology, artificial solar energy conversion, and photobiology. This meeting was the first encounter of this sort entirely dedicated to this important topic. A total of 65 participants came from 47 laboratories and 16 nations (Belgium, Czechoslovakia, F.R. of Germany, France, Greece, India, Ireland, Israel, Italy, The Netherlands, Poland, Portugal, Switzerland, Turkey, United Kingdom, and the United States of A America). The secretaries of the course were: Ms. Aliki Karipidou for the scientific aspects and Mr. Massimo Minella for the admini strative aspects of the meeting.




Optical Coherence Tomography in Dentistry


Book Description

Optical Coherence Tomography (OCT), a method to "see inside of things" without destroying them, has been applied to subjects ranging from materials science to medicine. This book focuses on the biomedical application of OCT in dentistry, covering topics from dental materials to clinical practice. Since the introduction of the OCT method in ophthalmology in 1991, and then dentistry in 1998, developments in OCT methods, particularly in biomedical areas, have led to its dissemination worldwide. The chapters of this book cover the basics and recent global advances of OCT in dentistry, including an overview of the method and its use in cariology, restorative dentistry, dental materials, endodontics, pediatric dentistry, orthodontics, prosthodontics, soft oral tissues and nanodentistry. This book will be of interest to both newcomers in the field as well as those already working in OCT, either in research and/or the clinic. It will be of great use in courses on optical imaging applied to biomedical areas, particularly where it can provide real-life examples of the application of OCT.







Lasers and Masers


Book Description