Chemistry and Physics of Solid Surfaces VI

This volume contains review articles which were written by the invited speak­ ers of the seventh International Summer Institute in Surface Science (ISISS), held at the University of Wisconsin - Milwaukee in July 1985. The form of ISISS is a set of tutorial review lectures presented over a one-week period by internationally recognized experts on various aspects of surface science. Each speaker is asked, in addition, to write a review article on his lecture topic. No single volume in the series Chemistry and Physics of Solid Surfaces can possibly cover the entire field of modern surface science. However, the series as a whole is intended to provide experts and students alike with a comprehensive set of reviews and literature references, particularly empha­ sizing the gas-solid interface. The collected articles from previous Summer Institutes have been published under the following titles: Surface Science: Recent Progress and Perspectives, Crit. Rev. Solid State Sci. 4, 125-559 (1974) Chemistry and Physics of Solid Surfaces, Vols. I, II, and III (CRC Press, Boca Raton, FL 1976, 1979 and 1982), Vols. IV and V, Springer Ser. Chern. Phys., Vols. 20 and 35, (Springer, Berlin, Heidelberg 1982 and 1984). The field of catalysis, which has provided the major impetus for the de­ velopment of modern surface science, lost two of its pioneers during 1984 and 1985: Professors G.-M. Schwab (1899-1984) and p.k. Emmett (1900-1985).

1. Georg-Maria Schwab: Early Endeavours in the Science of Catalysis.- References.- 2. The Life and Times of Paul H. Emmett.- 3. Three Decades of Catalysis by Metals.- 3.1 Bifunctional Catalysis.- 3.2 Characterization of Dispersed Metals.- 3.2.1 Chemisorption Isotherms.- 3.2.2 Application of Extended X-Ray Absorption Fine Structure.- 3.2.3 Application of Nuclear Magnetic Resonance.- 3.3 Hydrocarbon Reactions on Metals.- 3.3.1 Hydrogenolysis.- 3.3.2 Hydrogenation and Dehydrogenation.- 3.3.3 Isomerization.- 3.4 Bimetallic Catalysts.- 3.4.1 Metal Alloys as Catalysts.- 3.4.2 Bimetallic Aggregates of Immiscible Components.- 3.4.3 Bimetallic Clusters.- 3.5 Summary.- References.- 4. Molecular Organometallic Chemistry and Catalysis on Metal-Oxide Surfaces.- 4.1 Synthesis.- 4.2 Structure Determination by Physical Methods.- 4.2.1 Infrared Spectroscopy.- 4.2.2 Laser Raman Spectroscopy.- 4.2.3 Inelastic Electron Tunneling Spectroscopy.- 4.2.4 Extended X-Ray Absorption Fine Structure Spectroscopy.- 4.2.5 Ultraviolet-Visible Reflectance Spectroscopy.- 4.2.6 Nuclear Magnetic Resonance (NMR).- 4.2.7 Temperature-Programmed Decomposition.- 4.2.8 High-Resolution Transmission Electron Microscopy.- 4.2.9 Other Methods and General Points.- 4.3 Reactivity.- 4.4 Catalytic Activity.- 4.5 Supported Metals with Simple Structures Derived from Supported Organometallics.- 4.6 Summary.- References.- 5. Catalysis by Molybdena-Alumina and Related Oxide Systems.- 5.1 Nature of the Catalyst.- 5.2 Nature of the Catalytic Centers.- 5.3 The Chemisorption of Hydrogen on the Catalytic Centers.- 5.4 Relationships with Catalysis.- References.- 6. Structure and Catalytic Performance of Zeolites.- 6.1 Introduction to Zeolites.- 6.2 Some Structural Considerations.- 6.3 Fundamentals of Catalysis by Zeolites: A Resumè.- 6.4 Converting a Zeolite to Its Catalytically Active Form.- 6.5 Influence of Intergrowths on Catalytic Performance.- 6.6 Siting and Energetics of Guest Species Inside Zeolite Catalysts.- 6.7 Evaluating Currently Unsolved Zeolitic Structures.- 6.8 Analogy Between Zeolitic and Selective Oxidation Catalysts.- References.- 7. Structural Characterization of Molecules and Reaction Intermediates on Surfaces Using Synchrotron Radiation.- 7.1 Principles of X-Ray Absorption.- 7.1.1 General Features.- 7.1.2 Surface Extended X-Ray Absorption Fine Structure.- 7.1.3 Near Edge X-Ray Absorption Fine Structure.- 7.1.4 Apparatus.- 7.2 SEXAFS Studies of Polyatomic Adsorbates.- 7.2.1 Structure of Formate on the Cu{100} Surface.- 7.2.2 Structure of Formate on the Cu{110} Surface.- 7.2.3 Structure of Methoxy on the Cu{100} Surface.- 7.3 NEXAFS Studies of Polyatomic Adsorbates.- 7.3.1 Oxidation Intermediates on Cu{100} and Cu{110}.- 7.3.2 Hydrocarbons on Pt{111}.- 7.3.3 Sulfur-Containing Hydrocarbons on Pt{111}.- 7.4 Conclusions and Outlook.- References.- 8. Effects of Surface Impurities in Chemisorption and Catalysis.- 8.1 Experimental Details.- 8.2 Discussion.- 8.2.1 Electronegative Impurities.- a) Chemisorption.- b) Catalytic Activity.- c) Catalytic Selectivity.- 8.2.2 Electroneutral Impurities.- a) Copper Overlayer Structure.- b) Chemisorption.- c) Catalytic Activity.- 8.2.3 Electropositive Impurities.- a) Chemisorption.- b) Carbon Monoxide Dissociation Kinetics.- c) Methanation Kinetics.- d) Promotion of Higher Hydrocarbon Formation.- e) Electronic Compensation Effects.- 8.2.4 Related Theory.- 8.3 Conclusions.- References.- 9. Thermodynamics and Kinetics in Weakly Chemisorbed Phases.- 9.1 Evaluation of the Isosteric Heat and Entropy of Adsorption.- 9.2 Correlation Between Thermodynamic and Kinetic Experiments.- 9.3 Structural and Thermodynamic Data on Weakly Chemisorbed Phases.- 9.3.1 Phase Diagram for N2 Adsorbed on Ni{110} and Data for N2 on Ni {100}.- 9.3.2 The Isosteric Heat of Adsorption and the Entropy in the Adsorbed Phase for N2/Ni{110} and N2/NHIOO}.- 9.3.3 Carbon Monoxide on Low-Index Copper Single Surfaces.- 9.3.4 Thermodynamic Measurements at Very Small Coverages.- 9.4 Kinetics in Weakly Adsorbed Phases.- 9.4.1 Adsorption and Desorption Kinetics.- 9.4.2 Chemical Reactions in Weakly Chemisorbed Phases.- 9.5 Summary.- References.- 10. Kinetic and Spectroscopic Investigations of Surface Chemical Processes.- 10.1 Experimental Methods.- 10.2 Kinetic Studies of Methanol Decomposition on Ni{111}.- 10.2.1 Isothermal Decomposition of Methanol on Clean Ni{111}.- 10.2.2 Steady-State Kinetics of Methanol Decomposition on Ni {111}.- 10.3 Scanning Kinetic Spectroscopy (SKS) Methods for the Study of the Decomposition of Alcohols on Ni{111}.- 10.3.1 Rationale for the SKS Method.- 10.3.2 Methanol Decomposition on Ni{111} ―SKS Measurements.- 10.3.3 Ethanol Decomposition on Ni{111} Using SKS.- 10.4 Summary of Results.- References.- 11. Raman Spectroscopy of Adsorbed Molecules.- 11.1 Unenhanced Raman Spectroscopy of Adsorbed Molecules.- 11.1.1 Surface Electromagnetic Fields.- 11.1.2 Angle-Resolved Surface Raman Scattering.- 11.1.3 Selection Rules.- 11.1.4 Examples.- 11.2 Surface-Enhanced Raman Spectroscopy.- 11.2.1 Electromagnetic Enhancement.- 11.2.2 Chemical Enhancement.- 11.3 Future Work.- References.- 12. The Time-of-Flight Atom-Probe and Its Application to Surface Analysis and Gas-Surface Interactions.- 12.1 The Time-of-Flight Atom-Probe.- 12.1.1 Basic Principles.- 12.1.2 Mass Resolution.- 12.1.3 Pulsed High-Voltage Atom-Probes.- 12.1.4 The Pulsed-Laser Time-of-Flight Atom-Probe.- 12.1.5 A Statistical Method of Counting Single Ions.- 12.1.6 Imaging Atom-Probes.- 12.1.7 A Method for Ion-Reaction-Time Amplification.- 12.2 Structural and Compositional Analysis of Solid Surfaces.- 12.2.1 Atomic Structures of Emitter Surfaces.- 12.2.2 Compositional Analysis of Surface Atomic Layers: Alloy Segregations and Impurity Segregation.- 12.3 Gas-Surface Interactions.- 12.3.1 Field Adsorption.- 12.3.2 Surface Reactivity in the Formation of H3.- 12.3.3 Atomic Steps and Reaction Intermediates in Ammonia Synthesis.- 12.4 Ion-Reaction-Time Measurement ― Field Dissociation by Atomic Tunneling.- 12.5 Summary.- References.- 13. Field Emission Microscopy―Trends and Perspectives.- 13.1 Historical Background.- 13.2 Some Comments Related to Curved and Planar Surfaces.- 13.3 Field-Electron Emission Microscopy.- 13.3.1 Conceptual.- 13.3.2 The Microscopy.- a) The Microscope.- b) Magnification.- c) Contrast.- d) Resolution.- e) The Specimen.- f) Criteria for a Clean Surface.- g) Specimen Materials.- 13.3.3 Selected Field-Electron Emission Microscopy Research.- a) Visibility of Atomic and Molecular Objects.- b) Surface Diffusion.- c) Nucleation and Crystal Growth.- d) Cleaning Platinum Field Emitters.- e) Electron Energy Distributions.- 13.4 Field-Ion Microscopy.- 13.4.1 The Microscopy.- a) The Microscope.- b) The Image.- c) More About Field Evaporation.- d) The Specimen.- 13.4.2 Selected Field-Ion Microscopy Research.- a) Surface Diffusion.- b) Clean-Surface bcc{001} Atomic Structure.- 13.5 Summary and Future Outlook.- References.- 14. Scanning Tunneling Microscopy.- 14.1 Introduction.- 14.2 Experimental Considerations.- 14.3 Tunnel Current and Tunnel Barrier.- 14.3.1 Basic Model Calculations and Approximations.- 14.3.2 Calculations for Nonplanar Tip-Surface Geometries.- 14.3.3 The Effect of the Image Potential.- 14.3.4 Resolution of the STM.- 14.3.5 Sample Conductivity.- 14.3.6 Effect of Adsorbates.- 14.4 Surface Microscopy.- 14.4.1 Topography of Flat Surfaces.- 14.4.2 Periodic Structures of Single-Crystalline Surfaces.- 14.4.3 Surface Defects.- 14.4.4 Reactivity and Stability of Surfaces.- 14.4.5 Non-Surface-Science Applications of the STM.- 14.4.6 Surface Diffusion and Surface Mobility.- 14.5 Tunneling Spectroscopy.- 14.5.1 Valence Band Spectroscopy.- 14.5.2 Resonant Tunneling.- 14.5.3 Scanning Tunneling Spectroscopy.- 14.5.4 The Work Function and Work Function Images.- 14.6 Conclusions.- References.- 15. High-Resolution Electron Microscopy in Surface Science.- 15.1 Imaging Methods.- 15.1.1 Transmission Electron Microscopy.- 15.1.2 Reflection Electron Microscopy.- 15.2 Instrumentation and Accessories.- 15.3 Survey of Results.- 15.3.1 Bright-Field Transmission Electron Microscopy.- 15.3.2 Dark-Field Transmission Electron Microscopy.- 15.3.3 Reflection Electron Microscopy.- 15.3.4 Profile Imaging.- 15.3.5 Dynamic Processes.- 15.3.6 Image Contrast Calculations.- 15.4 Perspective and Outlook.- 15.5 Further Reading.- References.- 16. Surface Electronic States.- 16.1 Experimental Techniques.- 16.2 Valence Electronic States: Ideal Surfaces.- 16.3 Valence States: New Developments.- 16.4 Core Levels: Surfaces and Interfaces in Technology.- References.- 17. The Use of Spin-Polarized Electrons in Surface Analysis.- 17.1 Introduction to Spin-Polarized Electrons.- 17.2 Nonmagnetic Materials.- 17.2.1 Electron Diffraction.- 17.2.2 Application of Spin-Polarized LEED: Spin-Polarization Detectors.- 17.2.3 Photoemission.- 17.2.4 Application of Spin-Polarized Photoemission: Polarized Electron Sources.- 17.3 Magnetic Materials.- 17.3.1 Elastic Electron Scattering.- 17.3.2 Secondary Electron Emission and Magnetic Structure Analysis.- 17.3.3 Electronic Structure and Stoner Excitations.- 17.4 Conclusion.- References.- 18. Inverse Photoemission Spectroscopy.- 18.1 Historical Overview.- 18.2 Instrumentation.- 18.3 Density of States.- 18.4 Band Structures and Surface States.- 18.5 Adsorbate States.- 18.6 Summary and Outlook.- References.- 19. The Structure of Surfaces.- 19.1 Structure of the GaAs{lll}-(2 x2) Surface.- 19.1.1 Reconstruction Mechanisms on the GaAsdll} Surface.- 19.1.2 Vacancy-Buckling Model of GaAs{lll}-(2×2).- 19.2 Structure of the GaAs{110}-(l ×1) Surface.- 19.2.1 Surface Relaxation on the {110} Surface.- 19.2.2 Value of the ? Tilt Angle on the {110} Surface.- 19.3 Structure of the GaP{lll}-(2 x2) Surface.- 19.4 General Trend on Reconstructed {110} and {111} Faces of 111-V Compounds.- 19.5 Forward-Focusing Effects in X-Ray Photoemission Spectroscopy.- 19.5.1 Physical Origin of Peaks in Egelhoff’s- Experiment.- 19.5.2 The Small-Atom (Plane-wave) Approximation.- 19.5.3 Temperature Effect.- 19.5.4 Effect of Multiple Scattering.- 19.6 Structure Analysis by High-Resolution Electron Energy-Loss Spectroscopy.- 19.7 Conclusion.- References.- 20. Surface Structure Analysis by Low-Energy Alkali Ion Scattering.- 20.1 Theoretical Background.- 20.1.1 Single Scattering and Differential Scattering Cross Section.- 20.1.2 Double Scattering.- 20.1.3 Shadowing, Blocking, and Focusing; Thermal Vibrations; Inelastic Scattering.- 20.1.4 Neutralization.- 20.2 Experimental Techniques.- 20.3 Basic Studies of the Scattering Mechanisms.- 20.4 Structure Analysis.- 20.5 Conclusions and Summary.- References.- 21. Multilayer Adsorption and Wetting Phenomena.- 21.1 Introduction to Wetting and Layering Behaviors.- 21.2 Theoretical Approaches.- 21.3 Applications.- 21.3.1 Importance of Relative Potential Strengths and Ranges.- 21.3.2 Solid Films: Wetting and Melting.- 21.3.3 Triple-Point Wetting.- 21.3.4 Epitaxy.- 21.4 Summary and Future Directions.- References.- 22. Diffraction Studies of Layering and Wetting Transitions.- 22.1 Introduction.- 22.2 Electron Diffraction Studies of Wetting Behavior.- 22.2.1 Experimental Methods.- 22.2.2 RHEED Studies of Wetting.- a) Two- and Three-Dimensional Diffraction Patterns ― Streaks vs. Spots.- b) Experimental Results.- 22.2.3 Combined RHEED and LEED Studies of the CF4-on- Graphite Wetting Transition.- a) RHEED Measurements.- b) LEED Measurements.- 22.2.4 Summary of RHEED and LEED Investigations.- 22.3 X-Ray and Neutron Studies of Layering Transitions.- 22.3.1 Experimental Methods.- a) X-Ray Spectrometers.- b) Neutron Spectrometers.- c) Samples.- d) Diffraction from 2D Powders.- e) Samples and Thermometry.- 22.3.2 X-Ray and Neutron Studies of Layering Transitions in Ethylene Adsorbed on Graphite Basal Plane Surfaces.- 22.3.3 X-Ray and Neutron Studies of Layering Transitions in Co-Adsorbed Xenon and Ethylene Films on Graphite.- 22.3.4 Summary of X-Ray and Neutron Investigations.- References.