The Chemical Physics of Surfaces

ISBN-13: 9781461580096 / Angielski / Miękka / 2012 / 418 str.

S. Morrison

Opis

* At the present stage of development of surface science, there has seemed to be a need for a book-length review spanning the disciplines of surface physics and surface chemistry-a review to summarize and show the con nection between the observations from each discipline. The various results and theories, derived on the one hand from studies of the physical, electronic, and optical properties of surfaces and on the other hand from studies of the chemical activity of surfaces, supplement each other in the search for a realistic model of the surface. The improved understanding possible with such an interdisciplinary approach has been confirmed by recent develop ments which cannot be classified as either surface chemistry or surface physics. Specifically, recent new experimental techniques and quantum mechanical models have provided a much more accurate picture of the nature of the electronic energy levels (bonding orbitals) present at a solid surface. With this more accurate picture we are now able to reconcile the various chemical and physical models that appeared in the early literature on surfaces. The objective of this work has therefore been to describe the results and current models of surface science spanning a broad gray area between surface physics and surface chemistry with some overlap into each of these disciplines. Relevant aspects of surface chemistry are discussed; we cover chemical interactions where bonding and electronic properties dominate, but stop short of specialized topics such as surfactants or liquid/liquid interfaces."

Spis treści

1. Introduction.- 1.1. Surface States and Surface Sites.- 1.1.1. The Chemical Versus Electronic Representation of the Surface.- 1.1.2. The Surface State on the Band Diagram.- 1.1.3. The Fermi Energy in the Surface State Model.- 1.1.4. Need for Both Surface Site and Surface State Models.- 1.2. Bonding of Foreign Species to the Solid Surface.- 1.2.1. Types of Interaction.- 1.2.2. The Chemical Bond.- 1.2.3. Acid and Basic Surface Sites on Solids.- 1.2.4. Adsorbate Bonding on Various Solid Types.- 1.2.5. Movement of Surface Atoms: Relaxation, Reconstruction, and Relocation.- 1.2.6. The Electronic Energy Level (Surface State) of a Sorbate/Solid Complex.- 1.3. Surface Hydration on Ionic Solids.- 1.4. Surface Heterogeneity.- 2. Space Charge Effects.- 2.1. General.- 2.1.1. The Double Layer Involving Two Planar Sheets of Charge.- 2.1.2. The Space Charge due to Immobile Ions: The Depletion Layer.- 2.1.3. The Double Layer in the Band Diagram, Fermi Energy Pinning.- 2.2. Space Charge Effects with Reactive Surface Species.- 2.2.1. The Accumulation Layer.- 2.2.2. The Inversion Layer.- 2.3. Electron and Hole Transfer between the Solid and Its Surface.- 2.3.1. Basic Physical Model of Electron and Hole Capture or Injection.- 2.3.2. Electron and Hole Transfer with Large Changes in the Surface Barrier.- 2.3.3. Charge Transfer to a Surface Species in a Polar Medium: The Fluctuating Energy Level Mechanism.- 3. Experimental Methods.- 3.1. Surface Measurements Based on Electrical and Optical Techniques.- 3.1.1. Work Function.- 3.1.2. Surface Conductivity.- 3.1.3. Electroreflectance.- 3.1.4. Field Effect.- 3.1.5. Surface Photovoltage.- 3.1.6. Capacity of the Double Layer.- 3.1.7. Channel Measurements.- 3.1.8. Powder Conductance.- 3.1.9. Ellipsometry.- 3.1.10. Other Electrical and Optical Measurements.- 3.2. The Surface Spectroscopies.- 3.2.1. Ultraviolet Photoelectron Spectroscopy (UPS).- 3.2.2. Energy Loss Spectroscopy (ELS).- 3.2.3. Soft X-Ray Appearance Potential Spectroscopy (SXAPS).- 3.2.4. Field Emission (FEM).- 3.2.5. Field Ion Microscopy (FIM).- 3.2.6. Ion Neutralization Spectroscopy (INS).- 3.2.7. Low-Energy Electron Diffraction (LEED).- 3.2.8. Methods of Chemical Composition Determination for the Surface.- 3.2.9. Studies of Chemical Reactions due to the Impinging Beam.- 3.3. Chemical Measurements.- 3.3.1. Infrared Absorption.- 3.3.2. Temperature-Programmed Desorption.- 3.3.3. Adsorption of Gaseous Acids and Bases or of Indicators.- 4. The Adsorbate-Free Surface.- 4.1. Introduction.- 4.1.1. The Classification of Solids.- 4.1.2. Preparation of a Clean Surface.- 4.2. Theoretical Models.- 4.2.1. Quantum Models.- 4.2.2. Semiclassical Models: The Madelung Model for Ionic Solids.- 4.2.3. Models for Electron Pair Sharing: Lewis and Bronsted Sites.- 4.2.4. Comparison of the Various Surface States and Sites.- 4.3. Measurements on Adsorbate-Free Ionic Solids.- 4.3.1. Reconstruction on Ionic Solids.- 4.3.2. Physical Measurements on Ionic Solids.- 4.3.3. Chemical Measurements on Ionic Solids.- 4.4. Measurements on Adsorbate-Free Covalent or Metallic Solids.- 4.4.1. Reconstruction on Covalent and Metallic Solids.- 4.4.2. Electrical Measurements of Intrinsic Surface States on Covalent Solids.- 4.4.3. Measurement by the Surface Spectroscopies.- 5. Bonding of Foreign Species at the Solid Surface.- 5.1. Reconstruction and Relocation in Bonding.- 5.2. The Semiclassical Model of Bonding: The Surface Molecule.- 5.2.1. Surface Molecule Versus Rigid Band Model.- 5.2.2. Adsorbate Bonding to Covalent or Metallic Solids.- 5.2.3. Adsorbate Bonding to Ionic Solids.- 5.2.4. Multilayer Adsorption: The Development of a New Phase.- 5.3. Quantum Models of the Adsorbate/Solid Bond.- 5.3.1. Solid State Theories: The Semi-infinite Crystal.- 5.3.2. Cluster Models.- 5.3.3. The Interacting Surface Molecule (the Model Hamiltonian Analysis).- 5.3.4. Other Quantum Models.- 5.3.5. Remarks.- 5.4. Measurement of Adsorbate Surface States on Covalent or Metallic Solids.- 5.4.1. Screening Shifts and Other Inaccuracies in Measurement.- 5.4.2. Bond Angles.- 5.4.3. Surface State Energy Levels of Sorbate/Sorbent Bonds.- 5.5. The Chemistry of Surface States.- 5.5.1. Change of Surface State Energy Associated with Bonding.- 5.5.2. The Influence of a Polar Medium or Coadsorbate on the Surface State Energy.- 5.5.3. Surface States due to Multiequivalent Foreign Adsorbates.- 5.6. The Formation of Surface State Bands.- 6. Nonvolatile Foreign Additives on the Solid Surface.- 6.1. General.- 6.2. Dispersion of Additives.- 6.2.1. Techniques for Dispersing Additives.- 6.2.2. Measurement of Dispersion.- 6.2.3. Sintering of Dispersed Particles: Surface Diffusion of Adsorbates.- 6.3. The Cluster, the Transition between a Molecule and a Solid.- 6.4. The Control of Surface Properties with Additives.- 6.4.1. Theoretical Discussion.- 6.4.2. Observations of Additive Effects.- 6.5. The Real Surface.- 7. Adsorption.- 7.1. Adsorption Isotherms and Isobars.- 7.1.1. Physical Adsorption.- 7.1.2. Heat and Activation Energy of Adsorption, Irreversible Chemisorption.- 7.1.3. The Adsorbate Superstructure.- 7.2. Ionosorption on Semiconductors.- 7.2.1. The Surface State Representation of Adsorbed Species.- 7.2.2. Observations of Ionosorption.- 7.3. Adsorption with Local Bonding.- 7.3.1. Adsorption on Ionic Solids.- 7.3.2. Adsorption on Platinum.- 8. The Solid/Liquid Interface.- 8.1. Introduction.- 8.2. Theory.- 8.2.1. Double Layers and Potentials in Electrochemical Measurements.- 8.2.2. Charge Transfer between the Solid and Ions in Solution.- 8.2.3. Energy Levels of Surface Species Relative to Band Edges.- 8.3. Observations with Semiconductor Electrodes.- 8.3.1. Measurement Methods.- 8.3.2. Radical Generation (Current Doubling).- 8.3.3. Measurements of Energy Levels and Band Edges.- 8.3.4. Other Charge Transfer Measurements, Capture Cross Section.- 8.4. Comparison of the Solid/Liquid with the Solid/Gas Interface.- 9. Photoeffects at Semiconductor Surfaces.- 9.1. General.- 9.2. Simple Hole/Electron Recombination.- 9.2.1. Theory.- 9.2.2. Experimental Results.- 9.3. Photoadsorption and Photodesorption.- 9.3.1. Theory.- 9.3.2. Experimental Observations of Photoadsorption and Photodesorption.- 9.4. Photocatalysis.- 9.4.1. Photodecomposition of Adsorbed Species.- 9.4.2. Photostimulated Catalytic Reactions.- 9.5. Direct Excitation of Surface States by Photons.- 10. Surface Sites in Heterogeneous Catalysis.- 10.1. General Concepts.- 10.1.1. The Role of the Catalyst.- 10.1.2. Some Correlations in Heterogeneous Catalysis.- 10.2. Surface Sites Associated with Steps and Other Geometrical Factors.- 10.3. The Role of Acid and Basic Sites in Catalytic Reactions.- 10.4. Covalent Bonding to Coordinatively Unsaturated Metal and Cationic Sites.- 10.5. Sites in Oxidation Catalysis.- 10.5.1. Introduction.- 10.5.2. Oxygen Exchange Sites in Oxidation Catalysis.- 10.5.3. Dangling Bonds as Active Sites for Adsorption and Electron Exchange.- 10.5.4. Wide Bands as Electron Sources and Sinks: n-Type and p-Type Semiconductors.- 10.6. Examples of Oxidation Catalysis.- 10.6.1. Platinum.- 10.6.2. Partial Oxidation Catalysts: Bismuth and Iron Molybdate.- References.- Author Index.