Tunneling Spectroscopy

1. Introduction.- 1. Why? Why? Why?.- 1.1. Why Do Vibrational Spectroscopy?.- 1.2. Why Do Tunneling Spectroscopy?.- 1.3. Why Not Do Infrared, Raman, or Electron Loss Spectroscopy Instead?.- 2. A Water Analogy for Tunneling Spectroscopy.- 2.1. Water Flow.- 2.2. Tunneling.- 3. Strengths of Tunneling Spectroscopy.- 3.1. Spectral Range.- 3.2. Sensitivity.- 3.3. Resolution.- 3.4. Selection Rules.- 4. Weaknesses of Tunneling Spectroscopy.- 4.1. Junction Geometry.- 4.2. Top Metal Electrode.- 4.3. Cryogenic Temperatures.- 5. General Experimental Techniques.- 5.1. Introduction.- 5.2. Sample Preparation.- 5.2.1. The Substrates.- 5.2.2. The Vacuum Evaporator.- 5.2.3. Junction Fabrication.- 5.2.4. Care and Handling of Completed Junctions.- 5.2.5. Cryogenics.- 5.2.6. Characterizing Junctions and Obtaining Spectra.- 5.2.7. Calibration and Measuring Peak Positions.- 6. Conclusions.- References.- 2. The Interaction of Tunneling Electrons with Molecular Vibrations.- 1. Introduction.- 2. Elastic Tunneling.- 3. Inelastic Tunneling.- 3.1. Simple Long-Range Models.- 3.2. Complex Long-Range Models.- 3.3. Short-Range Models.- 4. Conclusions.- References.- 3. Tunneling Spectroscopies of Metal and Semiconductor Phonons.- 1. Introduction.- 2. Threshold Spectroscopy of Normal State Phonons.- 2.1. Semiconductors.- 2.2. Metals.- 3. Superconductive Tunneling: The Effective Phonon Spectrum ?2F(?).- 3.1. Superconductivity.- 3.2. The Tunneling Density of States in C—I—S Junctions.- 3.3. McMillan—Rowell Inversion for ?2F(?).- 4. Proximity Tunneling Methods.- 4.1. C — I — NS Junctions in the Thin-N Limit.- 4.2. Phonons in the Superconductor S.- 4.3. Phonons in the Proximity Layer N.- 5. Conclusions.- References.- 4. Electronic Transitions Studied by Tunneling Spectroscopy.- 1. Introduction.- 2. Experimental.- 3. Results.- 3.1. Rare Earth Oxides.- 3.2. Large Molecules.- 4. What Are Not Electronic Transitions?.- 5. Conclusions.- References.- 5. Light Emission from Tunnel Junctions.- 1. Introduction.- 2. Planar Tunnel Junctions and Surface Polaritons.- 3. Light Emission from Tunnel Junctions: The Theoretical Picture and Examples.- 3.1. General Remarks.- 3.2. Light Emission from Slightly Roughened Junctions.- 3.3. Light Emission from Junctions Grown on Holographic Gratings.- 3.4. Light Emission from Small-Particle Junctions.- 3.5. Summary.- 4. Conclusions.- References.- 6. Comparisons of Tunneling Spectroscopy with Other Surface Analytical Techniques.- 1. Introduction.- 2. Major Surface Analytical Techniques: A Brief Survey.- 2.1. Techniques for Studying Surface Chemical Composition.- 2.1.1. X-Ray Photoelectron Spectroscopy.- 2.1.2. Auger Electron Spectroscopy.- 2.1.3. Secondary Ion Mass Spectrometry.- 2.2. Determination of Surface Electronic Structure.- 2.2.1. Ultraviolet Photoelectron Spectroscopy.- 2.2.2. Electron Energy Loss Spectroscopy.- 2.3. Techniques for Surface Structural Analysis.- 2.3.1. Surface Extended X-Ray Absorption Fine Structure.- 2.3.2. Low-Energy Electron Diffraction.- 2.3.3. Transmission Electron Microscopy.- 2.3.4. Gas Adsorption.- 2.3.5. Scanning Electron Microscopy.- 2.4. Observation of Surface Vibrational Modes.- 2.4.1. Infrared Spectroscopy.- 2.4.2. Surface Raman Spectroscopy.- 2.4.3. High-Resolution Electron Energy Loss Spectroscopy.- 2.4.4. Inelastic Neutron Scattering Spectroscopy.- 3. The Application of Modern Surface Analytical Techniques to the Characterization of Carbon Monoxide Adsorbed on Alumina Supported Rhodium.- 3.1. Sample Preparation and Morphology.- 3.1.1. High-Surface-Area Samples.- 3.1.2. Low-Surface-Area Samples.- 3.2. Vibrational Spectroscopic Analysis.- 3.3. 13C Nuclear Magnetic Resonance Studies.- 3.4. Adsorbate Structure and Bonding from Studies of Model Systems.- 4. Conclusions.- References.- 7. The Detection and Identification of Biochemicals.- 1. Introduction.- 2. IET Spectra of Biological Compounds.- 2.1. Amino Acids.- 2.2. Pyrimidine and Purine Bases.- 2.3. Nucleotides and Nucleosides.- 3. Surface Adsorption and Orientation Effects on the IETS of Nucleotides.- 4. uv Radiation Damage Studies with IETS.- 5. Conclusions.- References.- 8. The Study of Inorganic Ions.- 1. Introduction.- 2. Why Study Inorganic Ions by Tunneling Spectroscopy?.- 2.1. Direct Observation of Transitions Forbidden in Photon Spectroscopy.- 2.1.1. Vibrational Transitions.- 2.1.2. Electronic Transitions.- 2.2. Impregnation Catalysts.- 2.3. Speciation of Metal Ions in Natural Waters.- 3. Doping Techniques and Insulator Surfaces.- 3.1. Solution Phase Doping of Alumina Barriers.- 3.2. AlOx and MgO Supported OySiHx Barriers.- 4. Solution Phase versus Gas Phase Adsorption.- 5. Representative Spectra.- 5.1. Metal Cyanide Complexes.- 5.2. Metal Glycinates.- 5.3. Other Inorganic Systems.- 6. The Role of Counterions.- 7. Oxidation and Reduction Processes.- 8. What’s Next?.- 9. Conclusions.- References.- 9. Studies of Electron-Irradiation-Induced Changes to Monomolecular Structure.- 1. Introduction.- 1.1. Why Study Irradiation-Induced Molecular Structure Changes?.- 1.2. Why Use Tunneling Spectroscopy?.- 1.3. Scope of this Chapter.- 2. Present State-of-the-Art Experiments.- 2.1. Electron Irradiation Experiments.- 2.2. Underlying Assumptions.- 2.3. Determination of “Damage” Cross-Sections.- 2.4. General Trends.- 3. Suggestions for Future Experiments.- 3.1. Review of Zeroth-Order Experiments.- 3.2. First-Order Experiments.- 3.3. Second-Order Experiments.- 4. Conclusions.- References.- 10. Study of Corrosion and Corrosion Inhibitor Species on Aluminum Surfaces.- 1. Introduction.- 1.1. General Remarks.- 1.2. Corrosion of Aluminum in Organic Media.- 1.3. Corrosion by Chlorinated Hydrocarbons.- 1.4. Corrosion Inhibitors for Aluminum in Chlorinated Solvents.- 1.5. Corrosion and Inhibitor Surface Species.- 2. Corrosion of Aluminum by Carbon Tetrachloride.- 2.1. Proposed Reactions.- 2.2. Tunneling Spectroscopy Studies.- 2.2.1. Experimental Procedure.- 2.2.2. Surface Species.- 3. Inhibition of Corrosion by Formamide.- 3.1. Surface Species.- 3.2. Inhibition Mechanism.- 4. Corrosion of Aluminum by Trichloroethylene.- 4.1. Reaction with Aluminum.- 4.2. Surface Species and Reactions.- 4.3. Corrosion Mechanism.- 5. Corrosion Inhibitors for Aluminum in Hydrochloric Acid.- 5.1. Acridine Surface Species.- 5.2. Orientation of Thiourea on Aluminum Oxide.- 6. Conclusions.- References.- 11. Adsorption and Reaction on Aluminum and Magnesium Oxides.- 1. Introduction.- 2. Clean Aluminum Oxide.- 3. Dirty Aluminum Oxide.- 4. Doped Aluminum Oxide.- 4.1. Formic Acid.- 4.2. Acetic Acid and Closely Related Molecules.- 4.3. Higher Acids.- 4.4. Unsaturated Acids.- 4.5. Unsaturated Hydrocarbons.- 4.6. Phenols.- 4.7. Aromatic Alcohols and Amines.- 4.8. Bifunctional Molecular Species.- 4.9. Chemical Mixtures.- 5. Clean Magnesium Oxide.- 6. Doped Magnesium Oxide.- 6.1. Benzaldehyde.- 6.2. Formic, Acetic, and Propionic Acids.- 6.3. Phenol.- 6.4. Carboxylate Mode Shift.- 6.5. Benzyl Alcohol.- 6.6. Unsaturated Hydrocarbons.- 6.7. Diketone.- 7. Technical Postscript.- 8. Conclusions.- References.- 12. The Structure and Catalytic Reactivity of Supported Homogeneous Cluster Compounds.- 1. Introduction.- 2. Experimental Procedures.- 3. Results and Discussion.- 3.1. Zr(BH4)4 on Al2O3 at 300 K.- 3.2. Zr(BH4)4 on Al2O3 at 475 K.- 3.3. The Interaction of Zr(BH4)4 on Al2O3 with D2, D2O, and H2O.- 3.4. The Interaction of Zr(BH4)4 on Al2O3with C2H4, C3H6, and C2H2.- 3.5. The Interaction of Zr(BH4)4 on Al2O3 with Cyclohexene, 1,3-Cyclohexadiene and Benzene.- 3.6. Ru3(CO)12 on Al2O3.- 3.7. [RhCl(CO)2]2 on Al2O3.- 3.8. Fe3(CO)12 on Al2O3.- 4. Conclusions.- References.- 13. Model Supported Metal Catalysts.- 1. Introduction.- 2. Special Techniques.- 3. Experimental Results.- 3.1. Carbon Monoxide on Rhodium.- 3.1.1. Chemisorption of CO on Rhodium.- 3.1.2. Hydrogenation of CO on Rhodium.- 3.2. Carbon Monoxide on Iron.- 3.3. Carbon Monoxide and Hydrogen on Nickel.- 3.4. Carbon Monoxide on Cobalt.- 3.5. Ethanol on Silver.- 4. Future Areas of Study.- 4.1. Acetylene on Palladium.- 4.2. Carbon Monoxide on Ruthenium.- 4.3. Carbon Monoxide on Platinum.- 4.4. Other Molecules; Other Reactions.- 4.5. Low-Temperature Adsorption.- 5. Conclusions.- References.- 14. Computer-Assisted Determination of Peak Profiles, Intensities, and Positions.- 1. Introduction.- 2. Measurement of Tunneling Conductance and Its Derivatives.- 2.1. Modulation Spectroscopy.- 2.2. A Survey of Measuring Circuits.- 2.3. Calibration of Tunnel Conductance and Its Derivatives.- 3. Interfacing with a Computer.- 3.1. General Considerations.- 3.2. Analog-to-Digital Conversion.- 3.3. Digital Data Transmission from Analog Instrumentation.- 3.3.1. IEEE 488 Standard Interface.- 3.3.2. The BCD Interface.- 3.3.3. The Serial Interface (RS-232C).- 3.3.4. The Parallel Interface.- 4. Peak Profile Determination.- 4.1. General Remarks.- 4.2. Factors Affecting Peak Profile.- 4.3. Peak Profiles of Junctions with Composite Barriers.- 4.4. Peak Intensities.- 4.5. Peak Positions.- 5. Data Handling.- 5.1. General Comments.- 5.2. Data Calibration.- 5.3. Data Storage.- 5.4. Data Analysis.- References.- 15. Infusion Doping of Tunnel Junctions.- 1. Introduction.- 1.1. Doping Requirements.- 1.2. Review of Other Doping Methods.- 1.2.1. Vapor Phase Doping.- 1.2.2. Liquid Phase Doping.- 1.2.3. Infusion Doping.- 2. Experimental Description of Infusion.- 2.1. Junction and Film Preparation.- 2.2. Infusion Techniques.- 2.3. Infusion Monitoring—Resistance and Capacitance.- 3. Experiments Relating to Physical Mechanisms of Infusion.- 3.1. Resistance and Capacitance Behavior.- 3.2. Film Porosity.- 3.3. Water Infusion and Organic Molecules.- 3.4. Masking Experiments.- 3.5. Sn and Au Overlay Films.- 4. Examples of Molecules Infused.- 4.1. Acids and Bases.- 4.2. Solvents and Alcohols.- 4.3. Solid Phase Molecules.- 5. Applications of Infusion.- 5.1. Hydrogenation and Deuteration of Propiolic Acid.- 5.2. Solid-State Anodization of Aluminum.- 5.3. Other Applications.- 6. Conclusions.- References.- 16. Vibrational Spectroscopy of Subnanogram Samples with Tunneling Spectroscopy.- References.