Electronic Dissipation Processes During Chemical Reactions on Surfaces

Electronic Dissipation Processes During Chemical Reactions on Surfaces
Title Electronic Dissipation Processes During Chemical Reactions on Surfaces PDF eBook
Author Kevin Stella
Publisher disserta Verlag
Pages 257
Release 2011
Genre Science
ISBN 3942109883

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Every day in our life is larded with a huge number of chemical reactions on surfaces. Some reactions occur immediately, for others an activation energy has to be supplied. Thus it happens that though a reaction should thermodynamically run off, it is kinetically hindered. Meaning the partners react only to the thermodynamically more stable product state within a mentionable time if the activation energy of the reaction is supplied. With the help of catalysts the activation energy of a reaction can be lowered. Such catalytic processes on surfaces are widely used in industry. Around 90% of chemicals are produced via a heterogeneously catalyzed process where a reaction occurs on the surface of a catalyst. However, why is it generally possible that such reactions run off with the help of heterogeneous catalysis, meaning with lower activation energy than without presence of a catalyst? What happens with the energy which is released during a reaction of gas particles on surfaces? How is this energy released, when some part of the energy is transferred to the reactant and some to the chemically active surface? Which physical mechanisms play a key role in the energy transfer? These questions are summarized in the concept of the energy dissipation. To observe this energy dissipation phenomenon, we use a new method, the chemoelectronics. With this method we try to detect the released energy, induced by reactions on surfaces, via thin-layered electronic device elements. An aim of this work is to build up very sensitive chemoelectronic sensors to measure electronic excitations released during such simple reactions of molecules as adsorption and desorption and more complicated reactions as the water formation reaction. Therefore a new line of chemoelectronic sensors is developed and characterized in terms of internal photoemission and stability. Meaning the previously used aluminum (Al-AlOx-Ag) and tantalum based (Ta-TaOx-Au) metal-insulator-metal sensors (MIM) are tested and new titanium based (Ti-TiOx-Au) MIMs are developed. Additionally silicon based stepped-metal-insulator-semiconductor sensors (stepped-MIS, Si-SiOx-Au, Si-SiOx-Pt) are set up and characterized. For the characterization of the chemoelectronic sensors the process of internal photoemission is used. Both, chemical- and photoexcitation release hot charge carriers (electrons and holes). Due to the existence of excited carriers in the sensor, a current can be measured without applying a bias voltage. It will be shown that the chemo- and the photosensitivity are strongly related to each other. As a first experiment for the chemical selectivity of the detectors, a stream of excited hydrogen molecules and hydrogen atoms is used. The excitation and radical formation is produced by the interaction of ground state molecules with a hot tungsten surface according to the pioneering experiments of Irving Langmuir. Additionally, excited oxygen beams are studied in this work.

Reactions at Solid Surfaces

Reactions at Solid Surfaces
Title Reactions at Solid Surfaces PDF eBook
Author Gerhard Ertl
Publisher John Wiley & Sons
Pages 150
Release 2010-06-17
Genre Science
ISBN 9780470535288

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Expanding on the ideas first presented in Gerhard Ertl's acclaimed Baker Lectures at Cornell University, Reactions at Solid Surfaces comprises an authoritative, self-contained, book-length introduction to surface reactions for both professional chemists and students alike. Outlining our present understanding of the fundamental processes underlying reactions at solid surfaces, the book provides the reader with a complete view of how chemistry works at surfaces, and how to understand and probe the dynamics of surface reactions. Comparing traditional surface probes with more modern ones, and bringing together various disciplines in a cohesive manner, Gerhard Ertl's Reactions at Solid Surfaces serves well as a primary text for graduate students in introductory surface science or chemistry, as well as a self-teaching resource for professionals in surface science, chemical engineering, or nanoscience.

Current Trends of Surface Science and Catalysis

Current Trends of Surface Science and Catalysis
Title Current Trends of Surface Science and Catalysis PDF eBook
Author Jeong Young Park
Publisher Springer Science & Business Media
Pages 265
Release 2013-10-23
Genre Science
ISBN 1461487420

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This unique book covers the latest surface science studies on model catalysts, including single crystals, non-colloidal nanocatalysts, and nanoparticles in various forms with the control of size, shape and composition. This book addresses the issue of bridging “materials and pressure gaps” and also discusses the important issue of metal-oxide interface and hot electron flows in heterogeneous catalysis. The current development of in-situ surface techniques that is relevant to bridging “pressure gaps” is also highlighted.

Laser Spectroscopy and Photochemistry on Metal Surfaces

Laser Spectroscopy and Photochemistry on Metal Surfaces
Title Laser Spectroscopy and Photochemistry on Metal Surfaces PDF eBook
Author Hai-Lung Dai
Publisher World Scientific
Pages 819
Release 1995
Genre Science
ISBN 981431725X

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Using lasers to induce and probe surface processes has the advantages of quantum state specificity, species selectivity, surface sensitivity, fast time-resolution, high frequency resolution, and accessibility to full pressure ranges. These advantages make it highly desirable to use light to induce, control, or monitor surface chemical and physical processes. Recent applications of laser based techniques in studying surface processes have stimulated new developments and enabled the understanding of fundamental problems in energy transfer and reactions. This volume will include discussions on spectroscopic techniques, energy transfer, desorption dynamics, and photochemistry.

Laser Spectroscopy And Photochemistry On Metal Surfaces (In 2 Parts) - Part 2

Laser Spectroscopy And Photochemistry On Metal Surfaces (In 2 Parts) - Part 2
Title Laser Spectroscopy And Photochemistry On Metal Surfaces (In 2 Parts) - Part 2 PDF eBook
Author Hai-lung Dai
Publisher World Scientific
Pages 819
Release 1995-12-16
Genre Science
ISBN 981450209X

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Using lasers to induce and probe surface processes has the advantages of quantum state specificity, species selectivity, surface sensitivity, fast time-resolution, high frequency resolution, and accessibility to full pressure ranges. These advantages make it highly desirable to use light to induce, control, or monitor surface chemical and physical processes. Recent applications of laser based techniques in studying surface processes have stimulated new developments and enabled the understanding of fundamental problems in energy transfer and reactions. This volume will include discussions on spectroscopic techniques, energy transfer, desorption dynamics, and photochemistry.

Exoemission from Processed Solid Surfaces and Gas Adsorption

Exoemission from Processed Solid Surfaces and Gas Adsorption
Title Exoemission from Processed Solid Surfaces and Gas Adsorption PDF eBook
Author Yoshihiro Momose
Publisher Springer Nature
Pages 238
Release 2022-11-24
Genre Technology & Engineering
ISBN 9811969485

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This book focuses on surface activity of electron emission (EE). Prior to protective painting, a steel surface is usually grit blasted or sandblasted to remove scale and contaminants and to roughen the surface. This book emphasizes that such surface treatment causes EE, increasing the strength of paint adhesion. Introduced here are the experimental results of thermally assisted photoelectron emission (TAPE) and tribo-stimulated (rubbing) electron emission (TriboEE) from practical metals after different kinds of surface-treatment processes. A detailed description is given of how Arrhenius activation energies relating to electron transfer through the surface overlayer and also the energy levels of electrons trapped in the overlayer can be obtained, and how TAPE and TriboEE data can be influenced by the chemical properties of that overlayer. This book is composed of four parts: I. Surface treatment processes; II. The principle of EE analysis used for practical surfaces; III. Materials and methods of EE and X-ray photoelectron spectroscopy (XPS); IV. EE and XPS characteristics of practical surfaces. In the last part, the EE and XPS results for metals, semiconductors, and carbon materials are drawn from the author’s own publications. The book will be useful for researchers engaging in surface-treatment processes of various materials.

Encyclopedia of Interfacial Chemistry

Encyclopedia of Interfacial Chemistry
Title Encyclopedia of Interfacial Chemistry PDF eBook
Author
Publisher Elsevier
Pages 5276
Release 2018-03-29
Genre Science
ISBN 0128098945

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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