Download or read book Theoretical Studies of Molecule substrate Interaction at Complex Gold and Silicon Oxide Surfaces Using Surface and Cluster Models written by Chao-Ming Ting and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The formation and patterns of a monolayer are determined by the interplay of two fundamental interactions, adsorbate-substrate and intermolecular interactions. The binding strength between adsorbate and substrate affects the mobility of the adsorbate at the surface and the stability of the complex. The intermolecular interaction plays a significant role in the monolayer patterns on the epitaxial layer of the substrate. A monolayer can be formed either by a spontaneous self-assembly, or by fabrication via atomic-layer deposition (ALD). The physical and chemical properties of the resulting monolayer have a broad array of applications in fabricating functional materials for hydrophobic or hydrophilic surfaces, biological sensors, alternating the properties of the substrate, catalysis and forming ordered layered structures. In this dissertation, the investigation focuses primarily on the influence of the surface topology on the binding behaviour of adsorbate-surface complexes. The state of the art DFT-TS method is used to simulate the sulfur-containing amino acids at complex gold surfaces and examine the relationship between the binding strengths and the binding sites with various nearest neighbouring environments. The same method is also used to determine if a chemical reaction will take place for various catalytic silicon precursors at a silicon oxide surface. Simulating surface chemistry using the DFT-TS method requires intensive com- puting resources, including CPU use and computing time. Another focus of this dissertation is to increase the data generating speed by reducing the size of the sim- ulated systems without altering the outcome. A relatively small gold cluster is used to study the binding behaviours of small organic molecules on the cluster. The same strategy is also used to simulate the chemical reactions between various self-catalying silicon precursors and a water molecule.
Download or read book Ab initio Studies of Molecule surface Interactions written by Eric J. Walter and published by . This book was released on 2001 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Chemical Abstracts written by and published by . This book was released on 2002 with total page 2668 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Theory of Chemisorption written by J. R. Smith and published by Springer Science & Business Media. This book was released on 2013-03-08 with total page 247 pages. Available in PDF, EPUB and Kindle. Book excerpt: The theory of the chemical interaction of molecules with surfaces has advanced handsomely in the last few years. This is due in part to the application of the entire arsenal of bulk solid-state theory and molecular quantum chemistry methods. This considerable activity was stimulated by an outpouring of experimental data, particularly of photoemission spectra. In many cases the theoretical techniques are now such that accurate, atomistic pictures of chemisorption phenomena are computed from first principles. This level of capability has been reached only recently, and has not been described anywhere in a comprehensive manner. The purpose of this monograph is to review these recent advances and, at the same time, to indicate a number of important questions which have not been answered. We discuss chemisorption on oxides, semiconductors, and both simple and transition metals. Solid surfaces as well as clusters are considered. While the review should be valuable to workers in the field, care has been taken to make the chapters understandable to the nonspecialist.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1992 with total page 1556 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Hybrid Quantum and Molecular Mechanics Embedded Cluster Models for Chemistry on Silicon and Silicon Carbide Surfaces written by James Richard Shoemaker and published by . This book was released on 1997-01-01 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fabrication of silicon carbide (SiC) semiconductor devices are of interest for aerospace applications because of their high-temperature tolerance. Growth of an insulating SiO2 layer on SiC is a poorly understood process, and sometimes produces interface defects that degrade device performance. Accurate theoretical models of surface chemistry, using quantum mechanics (QM), do not exist because of the huge computational cost of solving Schroedinger's equation for a molecular cluster large enough to represent a surface. Molecular mechanics (MM), which describes a molecule as a collection of atoms interacting through classical potentials, is a fast computational method, good at predicting molecular structure, but cannot accurately model chemical reactions. A new hybrid QM/MM computational method for surface chemistry was developed and applied to silicon and SiC surfaces. The addition of MM steric constraints was shown to have a large effect on the energetics of O atom adsorption on SiC. Adsorption of O atoms on Si-terminated SiC(111) favors above surface sites, in contrast to Si(111), but favors subsurface adsorption on C-terminated SiC(111). This difference, and the energetics of C atom etching via CO2 desorption, can explain the observed poor performance of SiC devices in which insulating layers were grown on C-terminated surfaces.
Download or read book The Synergy Between Dynamics and Reactivity at Clusters and Surfaces written by L.J. Farrugia and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 365 pages. Available in PDF, EPUB and Kindle. Book excerpt: The analogy between the chemistry of molecular transition metal clusters and the processes of chemisorption and catalysis at metal surfaces (the Cluster Surface analogy) has for a number of years provided an interplay between experimental and theoretical inorganic and physical chemists. This collaborative approach has born fruit in the use of well defined modes of metal-ligand bonding in discrete molecular clusters, models for metal-ligand binding on surfaces. Some of the key topics discussed in The Synergy between Dynamics and Reactivity at Clusters and Surfaces are: (1) Mechanisms of the fluxional behaviour in clusters in the liquid phase and the connections with diffusion processes on extended surfaces. The role of metal-metal bond breaking in diffusion. (2) Analogies in the structure of chemisorbed species and related ligands on metallic clusters. (3) Analogies between benzene surface chemistry on extended metal surfaces and on metal surfaces in molecular cluster compounds with particular reference to structural distortions. (4) The role of mobile precursors for dissociation of chemisorption on extended metals and on clusters. Are there analogies in the ligand attachment during cluster compound synthesis? (5) The role of defect sites on metal surfaces in catalyzing chemical reactions and the connection to the special bonding properties of sites on metal clusters having lowest metal-metal coordination. (6) The size of metal clusters needed to mimic surface phenomena on bulk metal surfaces. Different sites needed for different phenomena.
Download or read book Self Assembly of Flat Organic Molecules on Metal Surfaces written by Manuela Mura and published by Springer. This book was released on 2012-07-01 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Manuela Mura's thesis is devoted to ab initio studies of self-assembled organic molecules on a gold surface. This area of research is particularly vibrant because of the various applications such studies have in nanoscience and surface chemistry and physics. In this thesis Manuela Mura uses theory to suggest atomistic models for the observed assembled and she proposes an assembly mechanism. The methods and results developed as part of this work will be of wide interest to physicists and chemists working on the assemblies of organic molecules on crystal surfaces.
Download or read book American Doctoral Dissertations written by and published by . This book was released on 2000 with total page 816 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics Briefs written by and published by . This book was released on 1994 with total page 1118 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Computational and Experimental Studies of Adsorption and Reactions on Molybdenum Nitride and Silica Covered Ruthenium Surfaces written by Muhammad Sajid and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamental studies of material surfaces are of continued interest to the development and improvement of many modern technologies, e.g. catalysis, energy efficient electronics, and high-capacity batteries etc. This dissertation targets two distinct sets of molecule-surface interactions relevant to the continued development of structure-property correlations using tools from Density Functional Theory with added verification from ultrahigh vacuum surface-science experiments. These include Haber-Bosch interactions at molybdenum-nitride surfaces and separation-dependent interactions between simple aromatics and Ru(0001) used to model a metal contact of Organic Electronic Devices (OEDs). In the first study, we focus on computational modelling of nitrogen fixation reactions on Mo- and N-terminated [delta]-MoN(0001). A comparative analysis to analogous predictions reported for Mo-terminated [gamma]-Mo2N(111) sites demonstrates a near-total dependence on the atomic surface-structure with little to no impact from changes in sub-surface stoichiometry. Changing from Mo- to N-terminated surface drastically changes the reaction barriers such that the rate-limiting-step in the overall ammonia evolution reaction changes from NH[subscript x] hydrogenation to N2 dissociative adsorption. In the second one, we explored the effect of changing metal-organic molecule separation on charge-transfer across the interface and the electronic properties of organic matter pertinent to OEDs. We studied various computational models of benzene and pyridine molecules held at fixed distances from Ru(0001) by introducing two-dimensional hexagonal SiO2 thin-films between molecules and the metal. Substantial metal-to-molecule charge-transfer is noted when molecules bind directly to the Ru interface, but virtually no interaction is noted when increasing metal-molecule separations up to ~12 Å. An analogous series of experiments investigating pyridine-Ru interactions introduced after exposing SiO2/Ru(0001) thin-films to varied doses of pyridine exhibits behavior similar to that predicted by theory.
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1998 with total page 980 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Engineering Index Annual written by and published by . This book was released on 1992 with total page 2264 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since its creation in 1884, Engineering Index has covered virtually every major engineering innovation from around the world. It serves as the historical record of virtually every major engineering innovation of the 20th century. Recent content is a vital resource for current awareness, new production information, technological forecasting and competitive intelligence. The world?s most comprehensive interdisciplinary engineering database, Engineering Index contains over 10.7 million records. Each year, over 500,000 new abstracts are added from over 5,000 scholarly journals, trade magazines, and conference proceedings. Coverage spans over 175 engineering disciplines from over 80 countries. Updated weekly.
Download or read book Comprehensive Dissertation Index written by and published by . This book was released on 1989 with total page 712 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Theoretical Studies of Silicon Surfaces Using Finite Clusters written by Antonio Redondo-Muiño and published by . This book was released on 1977 with total page 474 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Encyclopedia of Interfacial Chemistry written by and published by Elsevier. This book was released on 2018-03-29 with total page 5276 pages. Available in PDF, EPUB and Kindle. Book excerpt: Encyclopedia of Interfacial Chemistry: Surface Science and Electrochemistry, Seven Volume Set summarizes current, fundamental knowledge of interfacial chemistry, bringing readers the latest developments in the field. As the chemical and physical properties and processes at solid and liquid interfaces are the scientific basis of so many technologies which enhance our lives and create new opportunities, its important to highlight how these technologies enable the design and optimization of functional materials for heterogeneous and electro-catalysts in food production, pollution control, energy conversion and storage, medical applications requiring biocompatibility, drug delivery, and more. This book provides an interdisciplinary view that lies at the intersection of these fields. Presents fundamental knowledge of interfacial chemistry, surface science and electrochemistry and provides cutting-edge research from academics and practitioners across various fields and global regions
Download or read book Dynamics and Interactions of Organic Molecules Bound to the Cu 111 Surface written by Jonathan Eugene Wyrick and published by . This book was released on 2013 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: The progress of modern technology is dominated by shrinking component size (with a goal of reaching angstrom scale resolution), particularly with respect to electronics and optimization of common industrial processes such as heterogeneous catalysis. Understanding of such systems lies at the upper end of applicability for first-principles calculations and existing theoretical models, and a scientific framework is needed to understand, predict, and control these systems at the molecular level. My research has focused on organic molecules adsorbed on a Cu(111) surface as model systems, studied experimentally by means of scanning tunneling microscopy (STM) as well as theoretically by density functional theory (DFT) and development of simplified explanatory models. Results of this investigation show that: 1) on Cu(111) full mono-layer coverages of acetylene undergo long-range ordering which at short-range is driven by a need to minimize localized stress induced in the upper substrate layers by adsorption while at longer ranges DFT finds an oscillatory interaction that correlates well with the surface state, 2) long-range ordered networks of anthraquinone (AQ) are found to mold the surface state into optimized quantum dots--this need for optimization under the constraint that neighbors must form H-bonds drives formation of the network at the precise size and shape observed in STM, 3) CO molecules co-adsorbed into the AQ network's pores titrate the surface state quantum dots and experience increased mobility, 4) the adsorption of anthracene modified with chalcogen linkers onto Cu(111) when viewed within a molecular orbital theory framework yields a chemical explanation for the diffusion behavior observed in STM. In combination, these observations and derived explanatory models help to characterize and quantify the fundamental physics underlying the interactions of adsorbates with one another and with the Cu(111) substrate, in a broader context acting as a model for other confined surface systems where the same kinds of interactions play a dominant role.
