Electronic Structure And Reactivity Of Metal Surfaces

eBook Download

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.

Product Details :

Genre : Science
Author : E. Derouane
Publisher : Springer Science & Business Media
Release : 2013-03-09
File : 636 Pages
ISBN-13 : 9781468427967


Principles Of Adsorption And Reaction On Solid Surfaces

eBook Download

BOOK EXCERPT:

Principles of Adsorption and Reaction on Solid Surfaces As with other books in the field, Principles of Adsorption and Reaction on Solid Surfaces describes what occurs when gases come in contact with various solid surfaces. But, unlike all the others, it also explains why. While the theory of surface reactions is still under active development, the approach Dr. Richard Masel takes in this book is to outline general principles derived from thermodynamics and reaction rate theory that can be applied to reactions on surfaces, and to indicate ways in which these principles may be applied. The book also provides a comprehensive treatment of the latest quantitative surface modeling techniques with numerous examples of their use in the fields of chemical engineering, physical chemistry, and materials science. A valuable working resource and an excellent graduate-level text, Principles of Adsorption and Reaction on Solid Surfaces provides readers with: * A detailed look at the latest advances in understanding and quantifying reactions on surfaces * In-depth reviews of all crucial background material * 40 solved examples illustrating how the methods apply to catalysis, physical vapor deposition, chemical vapor deposition, electrochemistry, and more * 340 problems and practice exercises * Sample computer programs * Universal plots of many key quantities * Detailed, class-tested derivations to help clarify key results The recent development of quantitative techniques for modeling surface reactions has led to a number of exciting breakthroughs in our understanding of what happens when gases come in contact with solid surfaces. While many books have appeared describing various experimental modeling techniques and the results obtained through their application, until now, there has been no single-volume reference devoted to the fundamental principles governing the processes observed. The first book to focus on governing principles rather than experimental techniques or specific results, Principles of Adsorption and Reaction on Solid Surfaces provides students and professionals with a quantitative treatment of the application of principles derived from the fields of thermodynamics and reaction rate theory to the investigation of gas adsorption and reaction on solid surfaces. Writing for a broad-based audience including, among others, chemical engineers, chemists, and materials scientists, Dr. Richard I. Masel deftly balances basic background in areas such as statistical mechanics and kinetics with more advanced applications in specialized areas. Principles of Adsorption and Reaction on Solid Surfaces was also designed to provide readers an opportunity to quickly familiarize themselves with all of the important quantitative surface modeling techniques now in use. To that end, the author has included all of the key equations involved as well as numerous real-world illustrations and solved examples that help to illustrate how the equations can be applied. He has also provided computer programs along with universal plots that make it easy for readers to apply results to their own problems with little computational effort. Principles of Adsorption and Reaction on Solid Surfaces is a valuable working resource for chemical engineers, physical chemists, and materials scientists, and an excellent text for graduate students in those disciplines.

Product Details :

Genre : Technology & Engineering
Author : Richard I. Masel
Publisher : John Wiley & Sons
Release : 1996-03-22
File : 826 Pages
ISBN-13 : 0471303925


Electronic Structure And Surfaces Of Sulfide Minerals

eBook Download

BOOK EXCERPT:

Electronic Structure and Surfaces of Sulfide Minerals: Density Functional Theory and Applications examines the mineral structure and electronic properties of minerals and their relationship to mineral floatability by density functional theory (DFT). This pragmatic guide explores the role of minerals in flotation by focusing on the mineral surface structure, electronic properties, and the adsorption of flotation agents through the study of the microscopic mechanism of reagents from the structure and properties of minerals. The flotation mechanism is explained from the point-of-view of solid physics, which is of great significance for both theoretical research and practical applications. The study of the structure and properties of the minerals can reveal the essential nature of mineral flotation, hence why minerals have floatability, the mechanism of response of different minerals to different chemicals, and the origin of the selectivity of flotation agents. - Discusses the relationship between mineral properties and floatability in terms of crystal structure, atomic coordination structure and electronic properties - Covers the influence of the surface structure of the mineral on surface charge distribution, reactivity and electron density, including a quantitative calculation method for the atomic reactivity of the mineral surface - Includes research on the microstructure and mechanism of reagent molecules adsorption on the surface of minerals, focusing on the interactions between water molecules, oxygen molecules and reagents

Product Details :

Genre : Science
Author : Jianhua Chen
Publisher : Elsevier
Release : 2020-04-23
File : 398 Pages
ISBN-13 : 9780128179758


Electronic Structure Of Conjugated Materials And Their Effect On Organic Photovoltaics

eBook Download

BOOK EXCERPT:

The great tunability of structure and electronic properties of ?-conjugated organic molecules/polymers combined with other advantages such as light weight and flexibility etc., have made organic-based electronics the focus of an exciting still-growing field of physics and chemistry for more than half a century. The application of organic electronics has led to the appearance of wide range of organic electronic devices mainly including organic light emitting diodes (OLED), organic field effect transistors (OFET) and organic solar cells (OSC). The application of the organic electronic devices mainly is limited by two dominant parameters, i.e., their performance and stability. Up to date, OLED has been successfully commercialized in the market while the OSC are still on the way to commercialization hindered by low efficiency and inferior stability. Understanding the energy levels of organic materials and energy level alignment of the devices is crucial to control the efficiency and stability of the OSC. In this thesis, energy levels measured by different methods are studied to explore their relationship with device properties, and the strategies on how to design efficient and stable OSC based on energy level diagrams are provided. Cyclic Voltammetry (CV) is a traditional and widely used method to probe the energy levels of organic materials, although there is little consensus on how to relate the oxidation/reduction potential ((Eox/Ered) to the vacuum level. Ultraviolet Photoelectron Spectroscopy (UPS) can be used to directly detect vertical ionization potential (IP) of organic materials. In this thesis, a linear relationship of IP and Eox was found, with a slope equal to unity. The relationship provides for easy conversion of values obtained by the two techniques, enabling complementarily use in designing and fabricating efficient and stable OSC. A popular rule of thumb is that the offset between the LUMO levels of donor and acceptor should be 0.3 eV, according to which a binary solar cell with the minimum voltage losses around 0.49 V was designed here. Introduction of the ternary blend as active layer is an efficient way to improve both efficiency and stability of the OSC. Based on our studied energy-level diagram within the integer charge transfer (ICT) model, we designed ternary solar cells with enhanced open circuit voltage for the first time and improved thermal stability compared to reference binary ones. The ternary solar cell with minimum voltage losses was developed by combining two donor materials with same ionization potential and positive ICT energy while featuring complementary optical absorption. Furthermore, the fullerene acceptor was chosen so that the energy of the positive ICT state of the two donor polymers is equal to the energy of negative ICT state of the fullerene, which can enhance dissociation of all polymer donor and fullerene acceptor excitons and suppress bimolecular and trap-assistant recombination. Rapid development of non-fullerene acceptors in the last two years affords more recipes of designing both efficient and stabile OSC. We show in this thesis how non-fullerene acceptors successfully can be used to design ternary solar cells with both enhanced efficiency and thermal stability. Besides improving the efficiency of the devices, understanding of the stability and degradation mechanism is another key issue. The degradation of conjugated molecules/polymers often follow many complicated pathways and at the same time many factors for degradation are coupled with each other. Therefore, the degradation of non-fullerene acceptors was investigated in darkness by photoelectron spectroscopy in this thesis with the in-situ method of controlling exposure of O2 and water vapor separately.

Product Details :

Genre :
Author : Chuanfei Wang
Publisher : Linköping University Electronic Press
Release : 2017-11-15
File : 102 Pages
ISBN-13 : 9789176853931


Modern Heterogeneous Catalysis

eBook Download

BOOK EXCERPT:

Written by one of the world's leading experts on the topic, this advanced textbook is the perfect introduction for newcomers to this exciting field. Concise and clear, the text focuses on such key aspects as kinetics, reaction mechanism and surface reactivity, concentrating on the essentials. The author also covers various catalytic systems, catalysis by design, and activation-deactivation. A website with supplementary material offers additional figures, original material and references.

Product Details :

Genre : Technology & Engineering
Author : Rutger A. van Santen
Publisher : John Wiley & Sons
Release : 2017-02-15
File : 592 Pages
ISBN-13 : 9783527694525


Chemisorption And Reactivity On Supported Clusters And Thin Films

eBook Download

BOOK EXCERPT:

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.

Product Details :

Genre : Science
Author : R.M. Lambert
Publisher : Springer Science & Business Media
Release : 2013-04-17
File : 534 Pages
ISBN-13 : 9789401589116


Theoretical Heterogeneous Catalysis

eBook Download

BOOK EXCERPT:

The molecular basis of surface chemical reactivity forms the central theme of this book. It is an attempt to survey current understanding about the working of heterogeneous catalysts, emphasizing surface chemical bonding in relation to reaction mechanisms.

Product Details :

Genre : Science
Author : Rutger A Van Santen
Publisher : World Scientific
Release : 1991-07-22
File : 409 Pages
ISBN-13 : 9789814506625


The Structure Of Rare Earth Metal Surfaces

eBook Download

BOOK EXCERPT:

The Structure of Rare-Earth Metal Surfaces introduces the concepts of surface crystallography and surface-structure determination, outlines the principles of the most widely used experimental techniques and theoretical simulations, and reviews their application to the surfaces of rare-earth metals. In particular, the results of quantitative low-energy electron-diffraction experiments and multiple-scattering calculations are covered in some depth. The book is aimed at science graduates with an interest in surface crystallography.

Product Details :

Genre : Technology & Engineering
Author : S D Barrett
Publisher : World Scientific
Release : 2001-08-30
File : 260 Pages
ISBN-13 : 9781783262021


Catalysis With Supported Size Selected Pt Clusters

eBook Download

BOOK EXCERPT:

In his thesis, Florian Schweinberger investigates the influence of the precise size of catalytically active species on reactivity. In order to do this he carries out studies both in UHV and under ambient conditions for supported, size-selected Platium clusters (8-68 atoms). Schweinberger probed the electronic structure, adsorption properties and reactivity of two olefins on surfaces and Pt clusters in the submonolayer range. With adsorbed trichloroethene (TCE) a possible cluster-adsorbate induced change in the electronic structure, and for ethene a low-temperature, size-dependent self-/hydrogenation was observed.In a collaborative approach, Schweinberger and colleagues investigated Pt clusters under ambient pressure conditions. They characterised the clusters at at the local and integral level and tested for temperature stability. Experiments in gas phase ?-reactors and in liquid, as part of a hybrid photocatalytic system, revealed size-dependent reactivity.Overall this thesis is not only of interest for those who want to perform similar experiments but also provides superb scientific insights for researchers in the field.

Product Details :

Genre : Science
Author : Florian Frank Schweinberger
Publisher : Springer Science & Business Media
Release : 2013-11-01
File : 231 Pages
ISBN-13 : 9783319014999


Electronic Structure Of Alloys Surfaces And Clusters

eBook Download

BOOK EXCERPT:

Understanding the electronic structure of solids is a basic part of theoretical investigation in physics. Application of investigative techniques requires the solid under investigation to be "periodic." However, this is not always the case. This volume addresses three classes of "non-periodic" solids currently undergoing the most study: alloys, sur

Product Details :

Genre : Technology & Engineering
Author : Abhijit Mookerjee
Publisher : CRC Press
Release : 2002-11-28
File : 385 Pages
ISBN-13 : 9781482288124