Structure And Reactivity Of Surfaces

Between the area known as surface science (which mainly deals with single crystal surfaces) and the vast area of the surface properties of dispersed solids (knowledge of which is widely applied in catalysis and materials science) there is still a remarkably wide, although gradually decreasing, gap. Because fundamental physico-chemical problems are involved, this borderline area needs to be explored. With this objective, the Trieste meeting brought together specialists with a variety of origins and backgrounds, with the aim of stimulating the growth of our knowledge in this area. This proceedings volume contains ninety-three papers, comprising plenary lectures, short communications, and poster contributions on the applications of physical and theoretical methods to perfect and dispersed (microcrystalline and amorphous) metals, oxides, and mixed systems. Special emphasis is given to metal-support interfaces. The book thus provides a wealth of up-to-date information on a topic of current interest which will be of value to researchers who use chemical and/or physical methods for the study of surfaces.

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.

Molecular surface science has made enormous progress in the past 30 years. The development can be characterized by a revolution in fundamental knowledge obtained from simple model systems and by an explosion in the number of experimental techniques. The last 10 years has seen an equally rapid development of quantum mechanical modeling of surface processes using Density Functional Theory (DFT). Chemical Bonding at Surfaces and Interfaces focuses on phenomena and concepts rather than on experimental or theoretical techniques. The aim is to provide the common basis for describing the interaction of atoms and molecules with surfaces and this to be used very broadly in science and technology. The book begins with an overview of structural information on surface adsorbates and discusses the structure of a number of important chemisorption systems. Chapter 2 describes in detail the chemical bond between atoms or molecules and a metal surface in the observed surface structures. A detailed description of experimental information on the dynamics of bond-formation and bond-breaking at surfaces make up Chapter 3. Followed by an in-depth analysis of aspects of heterogeneous catalysis based on the d-band model. In Chapter 5 adsorption and chemistry on the enormously important Si and Ge semiconductor surfaces are covered. In the remaining two Chapters the book moves on from solid-gas interfaces and looks at solid-liquid interface processes. In the final chapter an overview is given of the environmentally important chemical processes occurring on mineral and oxide surfaces in contact with water and electrolytes. Gives examples of how modern theoretical DFT techniques can be used to design heterogeneous catalysts This book suits the rapid introduction of methods and concepts from surface science into a broad range of scientific disciplines where the interaction between a solid and the surrounding gas or liquid phase is an essential component Shows how insight into chemical bonding at surfaces can be applied to a range of scientific problems in heterogeneous catalysis, electrochemistry, environmental science and semiconductor processing Provides both the fundamental perspective and an overview of chemical bonding in terms of structure, electronic structure and dynamics of bond rearrangements at surfaces

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

Starting with an overview of the theory behind - and demonstrations of the effect of - electric fields on structure and reactivity, this accessible reference work aims to encourage those new to the field to consider harnessing these effects in their own work.

During the past fifteen years there has been a dramatic increase in the number of different surfaces whose structures have been determined experimentally. For example, whereas in 1979 there were only 25 recorded adsorption structures, to date there are more than 250. This volume is therefore a timely review of the state-of-the-art in this dynamic field. Chapter one contains a compilation of the structural data base on surfaces within a series of tables that allows direct comparison of structural parameters for related systems. Experimental structural trends amongst both clean surfaces and adsorbate systems are highlighted and discussed. The next chapter outlines the successes of local density functional theory in predicting the relaxations and reconstructions of clean metal and semiconductor surfaces, and the behaviour of adsorbates such as hydrogen, oxygen and alkali elements on metal surfaces, thereby explaining some of the experimental trends observed within the database. These ab initio density functional calculations are of ground state properties at the absolute zero of temperature. Chapter three provides an introduction to finite temperature effects in a pedagogical review of current statistical mechanical treatments of phase transitions at surfaces, many of which display the prominent role of fluctuations or non-mean field behaviour. The final chapter discusses the relationship of the reactivity of a surface to its morphology and composition, which is particularly relevant to a fundamental understanding of catalysis.