Download or read book Theoretical Studies of the Electronic Structure of Metal Semiconductor Hydrogen Systems written by and published by . This book was released on 1991 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cesium, hydrogen and oxygen adsorption on beryllium clusters are studied using restricted Hartree-Fock (RHF) calculations and ab initio relativistic effective core potentials. The clusters are taken as cylindrical plugs from beryllium wafers. Cs( - ), H( - ) and 0-to-substrate internuclear distances are optimized. For each system numerous low-lying electronic states are investigated and Mulliken electron populations analyzed. RHF calculations show that Be19, with three layers of atoms, is too small to adequately model the Be surface, while Be33, a five-layered system, and Be45, a seven-layered system, are more accurate representations of the bulk metal. The emitted electron is clearly seen as vacating a molecular orbital which is localized in the surface layer of the cluster, thereby giving further credence to the model. RHF calculations are completed for Pbl and Bil semiconductor clusters. Blue shifts in optical spectra and geometry changes are shown to be due to quantum size effects. Scanning tunneling microscopy is used to investigate the nature of colloidal particles in the 15 nm diameter size range. Images show a near monodispersion of small gold clusters. A model of the STM tip as a polyatomic crystalline surface is shown to correctly explain observations of anomalous long range order.
Download or read book Theoretical and STM Studies of the Electronic Structure of Metal Semiconductor Hydrogen Systems written by and published by . This book was released on 1992 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: The structure of atomic clusters is investigated using methods of ab initio quantum chemistry in conjunction with scanning tunneling microscopy (STM) . Gold sols are imaged via STM and their sizes characterized. Atomic resolution reveals facets, steps, and reconstructed surfaces of the sols. STM images of graphite surfaces are characterized by two mechanisms: a twisted top layer configuration and a graphite-flake contaminated tip. A crystalline tip model reproduces anomalous long range periodicity, attributed to defect-mediated tip- substate convolution. Ab initio calculations of electronic states of a 135 atom Be cluster show bulk behavior for many properties centered at the middle of the cluster. The density of states agrees well with band theory models. Full spin- orbit CI calculations of the electronic spectrum and potential energy curves of LiBe, including Rydberg states, are definitive and accurate. A procedure for the incorporation of core/valence polarization effects in all-valence electron calculations is presented for use with relativistic effective core potentials. The method allows the treatment of large clusters at the ab initio level including procedures for the inclusion of electron correlation ...
Download or read book Electronic Structure and Properties of Hydrogen in Metals written by C.B. Satterthwaite and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 682 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrogen is the smallest impurity atom that can be implanted in a metallic host. Its small mass and strong interaction with the host electrons and nuclei are responsible for many anomalous and interesting solid state effects. In addition, hydrogen in metals gives rise to a number of technological problems such as hydrogen embrittlement, hydrogen storage, radiation hardening, first wall problems associated with nuclear fusion reactors, and degradation of the fuel cladding in fission reactors. Both the fundamental effects and applied problems have stimulated a great deal of inter est in the study of metal hydrogen systems in recent years. This is evident from a growing list of publications as well as several international conferences held in this field during the past decade. It is clear that a fundamental understanding of these problems re quires a firm knowledge of the basic interactions between hydrogen, host metal atoms, intrinsic lattice defects and electrons. This understanding is made particularly difficult by hyrogen's small mass and by the large lattice distortions that accompany the hydrogenation process. The purpose of the "International Symposium on the Electronic Structure and Properties of Hydrogen in Metals" held in Richmond, Virginia, March 4-6, 1982 was to increase our fundamental under standing of hydrogen in metals. Such knowledge is essential in solving technologically important questions. The symposium con sisted of twenty-two invited papers and seventy-two contributed poster presentations and attracted nearly 150 participants from thirteen countries. The proceedings of this symposium constitute this book.
Download or read book Transition Metal Impurities in Semiconductors written by K. A. Kikoin and published by World Scientific. This book was released on 1994 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses the theory of the electron states of transition metal impurities in semiconductors in connection with the general theory of isoelectronic impurities. It contains brief descriptions of the experimental data available for transition metal impurities belonging to iron, palladium and platinum groups and for rare-earth impurities in elemental semiconductors (III-IV, II-VI and IV-VI compounds) and in several oxide compounds (Ti2, BaTiO3, SrTiO3). Also included are applications of the theory to the optical, electrical and resonance properties of semiconductors doped by the transition metal impurities.The book presents a theory unifying previously proposed ligand-field and band descriptions of transition metal impurities. It describes the theory in the context of the general theory of neutral impurities in semiconductors and demonstrates the capabilities of this description to explain the basic experimental properties of semiconductors doped by transition metal impurities. A detailed discussion of various experimental results and their theoretical interpretation is carried out.This book comprises three parts. The first two parts consider several exactly solvable models and describe numerical techniques. All the models and simulations constitute a general pattern describing transition metal and rare-earth impurities in semiconductors. The final part uses this theory in order to address various experimentally observed properties of these systems.
Download or read book Theoretical Investigations of Selected Heavy Elements and Metal hydrogen Systems by Means of Electronic Structure Calculations written by Per Andersson and published by . This book was released on 2001 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electronic Structure and Reactivity of Metal Surfaces written by E. Derouane and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 636 pages. Available in PDF, EPUB and Kindle. Book excerpt: Imagine that a young physicist would approach a granting agen cy and propose to contribute to heterogeneous catalysis by studying the heat conductivity of gases in contact with a hot filament. How would he be received now? How would he have been treated sixty years ago ? Yet, more than sixty years ago, Irving Langmuir, through his study of heat transfer from a tungsten filament, uncovered most of the fundamental ideas which are used to-day by the scientific com munity in pure and applied heterogeneous catalysis. Through his work with what were for the first time "clean" metal surfaces, Langmuir formulated during a period of a little over ten years un til the early thirties, the concepts of chemisorption, monolayer, adsorption sites, adsorption isotherm, sticking probability, cata lytic mechanisms by way of the interaction between chemisorbed spe cies, behavior of non-uniform surfaces and repulsion between adsor bed dipoles. It is fair to say that many of these ideas constituting the first revolution in surface chemistry have since been refined through thousands of investigations. Countless papers have been pu blished on the subject of the Langmuir adsorption isotherm, the Langmuir catalytic kinetics and the Langmuir site-exclusion adsorp tion kinetics. The refinements have been significant. ThE original concepts in their primitive or amended form are used everyday by catalytic chemists and chemical engineers allover the world in their treatment of experimental data, design of reactors or inven tion of new processes.
Download or read book Electronic Structure of Metal Semiconductor Contacts written by Winfried Mönch and published by Springer. This book was released on 1990-11-30 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: Interface and surface science have been important in the development of semicon ductor physics right from the beginning on. Modern device concepts are not only based on p-n junctions, which are interfaces between regions containing different types of dopants, but take advantage of the electronic properties of semiconductor insulator interfaces, heterojunctions between distinct semiconductors, and metal semiconductor contacts. The latter ones stood almost at the very beginning of semi conductor physics at the end of the last century. The rectifying properties of metal-semiconductor contacts were first described by Braun in 1874. A physically correct explanation of unilateral conduction, as this deviation from Ohm's law was called, could not be given at that time. A prerequisite was Wilson's quantum theory of electronic semi-conductors which he published in 1931. A few years later, in 1938, Schottky finally explained the rectification at metal-semiconductor contacts by a space-
Download or read book Theoretical Studies of Hydrogen in Metals written by and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Electronic band structure studies of metal-hydrogen systems have demonstrated the existence of large metal-hydrogen and hydrogen-hydrogen interactions. These interactions lead to the formation of stable hydride phases. Factors governing this interaction are investigated for various different structures. Possible new directions for theoretical research are indicated.
Download or read book The Electronic Structure of Complex Systems written by P. Phariseau and published by Springer. This book was released on 1984 with total page 824 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present here the transcripts of lectures and talks which were delivered at the NATO ADVANCED STUDY INSTITUTE "Electronic Structure of Complex Systems" held at the State University of Ghent, Belgium during the period July 12-23, 1982. The aim of these lectures was to highlight some of the current progress in our understanding of the electronic structure of com plex systems. A massive leap forward is obtained in bandstructure calculations with the advent of linear methods. The bandtheory also profitted tremendously from the recent developments in the density functional theories for the properties of the interacting electron gas in the presence of an external field of ions. The means of per forming fast bandstructure calculations and the confidence in the underlying potential functions have led in the past five years or so to a wealth of investigations into the electronic properties of elemental solids and compounds. The study of the trends of the electronic structure through families of materials provided invalu able insights for the prediction of new materials. The detailed study of the electronic structure of specific solids was not neglected and our present knowledge of d- and f-metals and metal hydrides was reviewed. For those systems we also investi gated the accuracy of the one electron potentials in fine detail and we complemented this with the study of small clusters of atoms where our calculations are amenable to comparison with the frontiers of quantum chemistry calculations.
Download or read book Hydrogen in Semiconductors II written by and published by Academic Press. This book was released on 1999-05-05 with total page 541 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since its inception in 1966, the series of numbered volumes known as Semiconductors and Semimetals has distinguished itself through the careful selection of well-known authors, editors, and contributors. The "Willardson and Beer" Series, as it is widely known, has succeeded in publishing numerous landmark volumes and chapters. Not only did many of these volumes make an impact at the time of their publication, but they continue to be well-cited years after their original release. Recently, Professor Eicke R. Weber of the University of California at Berkeley joined as a co-editor of the series. Professor Weber, a well-known expert in the field of semiconductor materials, will further contribute to continuing the series' tradition of publishing timely, highly relevant, and long-impacting volumes. Some of the recent volumes, such as Hydrogen in Semiconductors, Imperfections in III/V Materials, Epitaxial Microstructures, High-Speed Heterostructure Devices, Oxygen in Silicon, and others promise that this tradition will be maintained and even expanded. Reflecting the truly interdisciplinary nature of the field that the series covers, the volumes in Semiconductors and Semimetals have been and will continue to be of great interest to physicists, chemists, materials scientists, and device engineers in modern industry. Provides the most in-depth coverage of hydrogen in silicon available in a single source Includes an extensive chapter on the neutralization of defects in III*b1V semiconductors Combines both experimental and theoretical studies to form a comprehensive reference
Download or read book Electronic Structure of Metals and Semiconductors written by and published by . This book was released on 1976 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A theoretical study of the electronic structure of various metals and semiconductors is presented with the emphasis on understanding the properties of these materials when they are subjected to extreme conditions and in various different configurations. Among the bulk systems studied, the properties of cesium under high pressure are discussed in terms of the electronic structure calculated at various cell volumes using the pseudopotential method. Local fields or umklapp processes in semiconductors are studied within the random phase approximation (RPA). Specifically the dielectric response matrix epsilon/sub GG'/ (q = 0,omega) is evaluated numerically to determine the effects of local-field corrections in the optical spectrum of Si. Also, some comments on the excitonic mechanism of superconductivity are presented and the role of local fields is discussed. The pseudo-potential method is next extended to calculate the electronic structure of a transition metal Nb. The calculation is performed self-consistently with the use of a non-local ionic potential determined from atomic spectra. Finally the theory of the superconducting transition temperature T/sub c/ is discussed in the strong-coupling formulation of the BCS theory. The Eliashberg equations in the Matsubara representation are solved analytically and a general T/sub c/ equation is obtained. A new method is developed using pseudopotentials in a self-consistent manner to describe non-periodic systems. The method is applicable to localized configurations such as molecules, surfaces, impurities, vacancies, finite chains of atoms, adsorbates, and solid interfaces. Specific applications to surfaces, metal-semiconductor interfaces and vacancies are presented.
Download or read book Advances in Metal and Semiconductor Clusters written by M.A. Duncan and published by Elsevier. This book was released on 2001-07-10 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt: In previous volumes in this series, Advances in Metal and Semiconductor Clusters, the focus has been on atomic clusters of metals, semiconductors and carbon. Fundamental gas phase studies have been surveyed, and most recently scientists have explored new materials which can be produced from clusters or cluster precursors. In this latest volume, the focus shifts to clusters composed primarily of non-metal molecules or atoms which have one or more metal atoms seeded into the cluster as an impurity. These clusters provide model systems for metal ion solvation processes and metal-ligand interactions. Metal-ligand bonding underlies the vast fields of organometallic chemistry, transition metal chemistry and homogeneous catalysis. Catalytic activity, ligand displacement reactions and photochemical activity depend on the specific details of metal-ligand bonding. Likewise, metal ions are ubiquitous in chemistry and biology and weaker electrostatic interactions play a leading role in their function. In solution, metals exist in different charge states depending on the conditions, and the solvation environment strongly influences their chemistry. Many enzymes have metal ions at their active sites, and electrostatic interactions influence the selectivity for metal ion transport through cell membranes. Metal ions (e.g., Mg+, Ca+) are deposited into the earth's atmosphere by meteor ablation, resulting in a rich variety of atmospheric chemistry. Similarly, metal ions ( Mg+) have been observed in planetary atmospheres and in the impact of the comet Shoemaker-Levy 9 on Jupiter. In various circumstances, the electrostatic interactions of metal ions determine the outcome of significant chemistry. Cluster chemistry has made significant contributions to the understanding of these stronger metal ligand interactions and weaker metal ion solvation interactions. In this volume, the authors explore a variety of work in these general areas, where new cluster science techniques in the gas phase have made it possible to synthesize new kinds of complexes with metals and to measure their properties in detail.
Download or read book Electronic Structure written by Kurt Allen Johnson and published by . This book was released on 1998 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bell Laboratories Talks and Papers written by Bell Telephone Laboratories. Libraries and Information Systems Center and published by . This book was released on 1979 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electronic Structure of Metal hydrogen Systems Studied by Positron Annihilation written by Ewa Dębowska and published by . This book was released on 1992 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Theory of Atomic and Molecular Clusters written by Julius Jellinek and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt: The emergence and spectacularly rapid evolution of the field of atomic and molecular clusters are among the most exciting developments in the recent history of natural sciences. The field of clusters expands into the traditional disciplines of physics, chemistry, materials science, and biology, yet in many respects it forms a cognition area of its own. This book presents a cross section of theoretical approaches and their applications in studies of different cluster systems. The contributions are written by experts in the respective areas. The systems discussed range from weakly (van der Waals) bonded, through hydrogen- and covalently bonded, to semiconductor and metallic clusters. The theoretical approaches involve high-level electronic structure computations, more approximate electronic structure treatments, use of semiempirical potentials, dynamical and statistical analyses, and illustrate the utility of both classical and quantum mechanical concepts.
