Synchrotron Radiation Research

This book has grown out of our shared experience in the development of the Stanford Synchrotron Radiation Laboratory (SSRL), based on the electron-positron storage ring SPEAR at the Stanford Linear Accelerator Center (SLAC) starting in Summer, 1973. The immense potential of the photon beam from SPEAR became obvious as soon as experiments using the beam started to run in May, 1974. The rapid growth of interest in using the beam since that time and the growth of other facilities using high-energy storage rings (see Chapters 1 and 3) demonstrates how the users of this source of radiation are finding applications in an increasingly wide variety of fields of science and technology. In assembling the list of authors for this book, we have tried to cover as many of the applications of synchrotron radiation, both realized already or in the process of realization, as we can. Inevitably, there are omissions both through lack of space and because many projects are at an early stage. We thank the authors for their efforts and cooperation in producing what we believe is the most comprehensive treatment of synchrotron radiation research to date.

1. An Overview of Synchrotron Radiation Research.- 1. Introduction.- 2. An Interdisciplinary Tool.- 3. Some Recent History.- 4. Earlier History.- 5. Photon Physics.- 6. The Future.- References.- 2. Properties of Synchrotron Radiation.- 1. Introduction.- 2. Radiated Power.- 3. Spectral and Angular Distribution.- 4. Polarization.- 5. Pulsed Time Structure.- 6. Brightness and Emittance.- References.- 3. Synchrotron Radiation Sources, Research Facilities, and Instrumentation.- 1. Introduction.- 2. Sources of Synchrotron Radiation.- 2.1. General.- 2.2. Storage Rings.- 2.3. Synchrotrons.- 3. Synchrotron Radiation Research Facilities.- 3.1. General.- 3.2. Beam Channels.- 3.2.1. Vacuum Considerations.- 3.2.2. Thermal Problems.- 3.2.3. Beryllium Windows.- 3.3. Radiation Shielding and Personnel Protection Interlock Systems.- 3.3.1. General.- 3.3.2. Low-Energy Storage Rings.- 3.3.3. High-Energy Storage Rings.- 3.4. Synchrotron Radiation Beam Position Monitoring and Control.- 3.5. Experimental Support Facilities.- 4. Instrumentation for Synchrotron Radiation Research.- 4.1. General.- 4.2. Mirrors.- 4.3. Monochromators.- 4.4. Detectors.- References.- 4. Inner-Shell Threshold Spectra.- 1. Introduction.- 1.1. Kossel-Kronig Structure.- 1.2. Lifetime Effects.- 1.3. Early Work on Excitons.- 1.4. Atomic Effects.- 2. Experimental Techniques.- 2.1. Use of Synchrotron Radiation.- 2.2. Synchrotron Radiation Monochromators.- 2.3. Various Spectroscopic Techniques.- 2.4. Absorption Measurements on Solids and Gases.- 3. Hydrogenlike Photoabsorption Spectra.- 3.1. The Hydrogen Model for X-Ray Absorption; K Edge of Argon.- 3.2. K Edge of Chlorine in Cl2 Gas.- 4. Oscillator Strength for Rydberg and Continuum Transitions.- 4.1. Atomic Absorption in the Dipole Approximation.- 4.2. Oscillator Strength and Spectral Density.- 4.3. Comparison of Hydrogen and Lithium Valence Transitions.- 4.4. K Edge of Neon Gas.- 5. Core Excitons in Insulators.- 5.1. Valence Excitons in Solid Neon.- 5.2. L Edge of Solid Argon; Altarelli-Bassani Theory.- 5.3. N2, 3 Edge of Rubidium in RbCl; Satoko-Sugano Theory.- 5.4. Deeper Core Structure in RbCl.- 5.5. Recent Reflectivity Data on the Potassium Halides.- 5.6. K Edge of Lithium in the Lithium Halides; Zunger-Freeman Theory.- 6. Threshold Resonances in Solids.- 6.1. White Lines, the K Edge of Germanium, and the L Edge of Tantalum.- 6.2. K Edge of Arsenic; Recent Theory.- 6.3. L Edge of Silicon and the Elliot Exciton.- 6.4. K Edge of Titanium in Some Transition-Metal Compounds, TiSe2 and MnO2.- 7. Simple Polyatomic Gases.- 7.1. Inner-Outer Well Potential.- 7.2. K Edge of Nitrogen in N2 Gas.- 7.3. K Edge of Carbon in Methane and the Fluoromethanes.- 7.4. Second-Row Hydrides and Fluorides; Effect of Condensation on the SiH4 and SiF4 Spectra.- 7.5. K Edge of Germanium in GeCl4, GeBr4, and GeH4.- 7.6. Summary Remarks.- References.- 5. Electron Spectrometry of Atoms and Molecules.- 1. Introduction.- 2. The Domain of Synchrotron Radiation.- 3. Basic Relations and Background.- 3.1. Energies.- 3.2. Photoionization Cross Sections.- 3.3. Angular Distribution of Photoelectrons.- 3.4. Two-Electron Processes.- 3.5. Level Widths.- 4. Experimental Apparatus and Procedures.- 4.1. The Monochromator.- 4.2. The Electron Spectrometer.- 4.2.1. Energy Calibration.- 4.2.2. Spectrometer Function.- 4.2.3. Transmission Function and Intensity Measurements.- 4.3. Source for Circularly Polarized Light.- 4.4. Comparison with Discrete Sources.- 5. Restricted Photoelectron Spectrometry—Energies.- 6. Level Widths and Line Widths.- 7. Partial Photoionization Cross Sections.- 7.1. Atoms.- 7.1.1. Spin-Orbit Photoelectron Intensity Ratios.- 7.1.2. Two-Electron Transitions.- 7.2. Threshold Laws.- 7.3. Quasi-Atomic Systems.- 7.4. Molecules.- 8. Angular Distributions of Photoelectrons.- 8.1. Closed-Shell Atoms.- 8.2. Open-Shell Atoms.- 8.3. Molecules.- 9. Resonances and Autoionization.- 9.1. Atoms.- 9.2. Molecules.- 10. Post-Collision Interactions.- 11. Photoexcited Auger Spectra.- 12. Coincidence Experiments.- 13. Outlook.- References.- 6. Photoemission as a Tool to Study Solids and Surfaces.- 1. General Considerations.- 1.1. The Physics of the Photoemission Process.- 1.2. The Characteristics of Synchrotron Radiation Important for Photoemission Studies.- 1.3. The Probing Depth in Photoemission.- 1.4. The Energy Dependence of Partial Photoionization Cross Sections.- 1.5. Different Photoemission Techniques.- 2. Experimental Details.- 2.1. Synchrotron Radiation Beam Lines.- 2.2. Monochromators.- 2.3. Sample Chambers, Energy Analyzers, and Detector Systems.- 2.4. Concluding Remarks.- 3. Research Applications.- 3.1. Introduction.- 3.2. Bulk Electronic Structure.- 3.2.1. The Bulk Electronic Structure of the Ge Valence Band.- 3.2.2. The Density of States of Some IV, III–V, II–VI, and I–VII Compounds: A Comparison between Theory and Experiment.- 3.2.3. The Electronic Structure of the Gold Valence Band.- 3.3. Surface Electronic Structure.- 3.3.1. Surface States and Resonances on Single Crystals of Metals.- 3.3.2. The Surface Electron Structure of GaAs (110).- 3.4. Chemisorption and Oxidation Studies.- 3.4.1. Oxygen Chemisorption and the Initial Oxidation Stages on the GaAs (110) Surface.- 3.4.2. Chemisorption of CO on Transition Metal Surfaces—Molecular Levels.- 3.4.3. The Effect of Chemisorption on the Substrate Core Levels.- 3.4.4. The Chemisorption and Oxidation Properties of Al Surfaces.- 3.5. The Electronic Structure of Interfaces.- 3.5.1. Oxygen Chemisorption onto Si (111) and the Si-SiO2 Interface.- 3.5.2. Metal Overlayers on III–V Semiconductor Surfaces.- 3.5.3. Cesium-Oxygen Overlayers on GaAs (110).- 3.6. The Electronic Structure of Cu-Ni Alloy Surfaces.- 3.7. Concluding Remarks.- 4. Future Prospects and Developments.- References.- 7. Microlithography with Soft X Rays.- 1. Introduction.- 2. X-Ray Replication and Results.- 3. Fundamentals.- 3.1. X-Ray Sources.- 3.1.1. Synchrotron Radiation.- 3.1.2. Electron Bombardment X-Ray Sources.- 3.2. Optics.- 3.3. Absorption.- 3.4. Photoelectrons.- 3.5. Energy Deposition.- 3.6. Energy Deposition Effects.- 4. X-Ray Lithography Technology.- 4.1. X-Ray Sources.- 4.1.1. Novel X-Ray Sources.- 4.1.2. Electron Bombardment Sources.- 4.1.3. Synchrotron Radiation Sources.- 4.2. Windows and Masks.- 4.3. Resists.- 4.4. Alignment and Distortion.- 4.5. Radiation Damage to Devices.- 5. System Approaches.- References.- 8. Soft X-Ray Microscopy of Biological Specimens.- 1. Introduction.- 2. Contrast Mechanisms.- 2.1. Removal of Photons; Transmission X-Ray Microscopy.- 2.2. Reaction Products; Fluorescence X-Ray Microscopy and Electron-Emission X-Ray Microscopy.- 2.3. Damage to the Absorbing Material.- 2.4. Quantitative Relationships.- 2.5. Summary.- 3. Image Formation.- 3.1. Magnification by Electron Optics.- 3.1.1. Contact Microradiography: General.- 3.1.2. Contact Microradiography: Resolution and Sensitivity of Resists.- 3.1.3. Contact Microradiography: Resolution of the Technique.- 3.1.4. Contact Microradiography: Details of the Technique.- 3.1.5. Contact Microradiography with Direct Photon-Electron Conversion.- 3.1.6. Image Formation Using Electrons Emitted from the Specimen.- 3.2. Magnification by X-Ray Optics.- 3.2.1. Grazing-Incidence Mirrors.- 3.2.2. Point Projection Microscopy.- 3.2.3. Microscopy with Zone Plate Objectives.- 3.2.4. Holographic Microscopy.- 3.3. Scanning Microscopy.- 3.3.1. The Microscope of Horowitz and Howell.- 3.3.2. Future Prospects for Scanning Microscopy.- 3.4. Summary.- 4. Sources of Soft X Rays for Microscopy.- 4.1. Requirements.- 4.2. Soft X-Ray Sources.- 4.2.1. Synchrotron Radiation.- 4.2.2. Conventional X-Ray Generators.- 4.2.3. Plasma Sources.- 5. Mapping the Concentration of a Particular Atomic Species.- 5.1. Absorption Microanalysis.- 5.2. Fluorescence Microanalysis.- 5.3. Summary.- 6. Additional Technical Aspects.- 6.1. Wet Specimens.- 6.2. Readout of Resist Images by Transmission Electron Microscopy.- 6.3. 3-D Imaging.- 7. Summary and Conclusions.- References.- 9. Synchrotron Radiation as a Modulated Source for Fluorescence Lifetime Measurements and for Time-Resolved Spectroscopy.- 1. Introduction: Source Properties.- 2. Time Modulation of Synchrotron Radiation Sources.- 2.1. Storage Rings.- 2.2. Synchrotrons.- 2.3. Electron Bunches and Their Behavior in a Storage Ring.- 2.4. Optical Properties of the Pulsed Source.- 2.5. Source Parameters.- 2.6. Comparison with Other Sources.- 3. Experimental Techniques for Time-Resolved Measurements.- 3.1. Direct Time Measurements.- 3.2. Single-Photon Counting Method.- 3.3. Phase-Shift Measurements.- 3.4. Time-Resolved Spectroscopy.- 4. Research Applications.- 4.1. Fluorescence Lifetime Measurements of Organic Molecules.- 4.2. Time-Resolved Spectroscopy of Rare Gases.- 4.2.1. Pure Rare-Gas Solids.- 4.2.2. Solid Rare-Gas Mixtures.- 4.2.3. Rare-Gas Measurements.- 4.3. Time-Resolved Fluorescence Spectroscopy of Large Molecules.- References.- 10. The Principles of X-Ray Absorption Spectroscopy.- 1. Introduction—Overview of X-Ray Absorption Spectroscopy and exafs Applications.- 2. Physics of Photoabsorption in Atoms.- 2.1. Fully Relaxed Transitions.- 2.2. Shake Up and Shake Off.- 2.3. Form of the One-Electron Cross Section.- 2.4. Effect of Core-Hole Lifetime.- 3. Photoabsorption in Molecular and Condensed Systems.- 3.1. General Features of the Spectrum.- 3.2. Photoabsorption in the exafs Region.- 3.3. The Thermal Average of the exafs Cross Section.- 3.4. Determination of Electron-Atom Scattering Phase Shifts and Amplitudes in the exafs Region.- 3.5. Many-Electron Effects in the exafs Spectrum.- 3.5.1. Inelastic Events.- 3.5.2. Effect of Screening in Metals.- 3.5.3. Exchange and Correlation Effects on the One-Electron Potential.- 3.6. The Near-Edge Region of the X-Ray Absorption Spectrum—Multiple Scattering Effects.- 4. Instrumentation for X-Ray Absorption Spectroscopy.- 4.1. Introduction.- 4.2. X-Ray Monochromators.- 4.3. X-Ray Detectors.- 4.3.1. Ionization Chambers.- 4.3.2. Proportional Counters.- 4.3.3. Scintillation Counters.- 4.3.4. Semiconductor Devices.- 4.3.5. Analyzing Detectors.- 5. Numerical Analysis of X-Ray Absorption Data—Extraction of Physical Parameters.- 5.1. General Considerations in the Analysis of exafs Data.- 5.2. Subtracting the Background—Setting the k Scale.- 5.3. Fourier Filtering.- 5.4. Nonlinear Curve Fitting of exafs Data—Application to Model Compounds and Multishell Parameter Determination.- 5.5. Numerical Analysis of X-Ray Absorption Edge Data.- References.- 11. Extended X-Ray Absorption Fine Structure in Condensed Materials.- 1. Introduction.- 2. Periodic and Quasi-Periodic Solids.- 3. Surface exafs.- 4. Disordered Solids.- 5. Liquids.- 6. X-Ray Sources.- 7. Future Directions.- References.- 12. X-Ray Absorption Spectroscopy: Catalyst Applications.- 1. Introduction.- 2. Nature of Catalysts.- 3. Analysis of exafs Data.- 4. Experimental Procedures.- 5. Structure of Catalysts.- 5.1. Dispersed Metal Catalysts.- 5.2. Metal Oxide Catalysts.- 5.3. Homogeneous Catalysts.- 6. Near-Edge Structure.- 7. Status and Outlook.- References.- 13. X-Ray Absorption Spectroscopy of Biological Molecules.- 1. Introduction.- 2. Discussion of Experimental Techniques Appropriate to Biological Molecules.- 2.1. Transmission versus Fluorescence.- 2.2. Fluorescence Detectors with Energy Discrimination.- 3. exafs Data Analysis for Biological Molecules.- 3.1. Scatterer Identification.- 3.2. Amplitudes and Numbers of Scatterers.- 3.3. An Example of Structure Determination.- 4. Selected exafs Applications to Problems of Biological Significance.- 4.1. Rubredoxin.- 4.2. Hemoglobin.- 4.3. Nitrogenase.- 4.4. Cytochrome P-450 and Chloroperoxidase.- 4.5. The “Blue” Copper Proteins.- 4.6. Xanthine Oxidase and Sulfite Oxidase.- 4.7. Hemocyanin.- 4.8. Ferritin.- 4.9. Cytochrome Oxidase.- 4.10. Calcium Binding Proteins.- 5. X-Ray Absorption Edge Structure for Biological Molecules.- 5.1. The Effect of Oxidation State on Edge Position.- 5.2. Continuum Spectral Features.- 5.3. Applications to Specific Biological Molecules.- 6. Prospects.- References.- 14. X-Ray Fluorescence Microprobe for Chemical Analysis.- 1. Introduction.- 2. Quantitative Analysis and Fluorescence Cross Sections.- 2.1. Equations for Quantitative X-Ray Fluorescence Analysis.- 2.2. Minimum Detectable Limit.- 2.3. Comparison of X-Ray and Charged-Particle Fluorescence Cross Sections.- 2.4. Backgrounds Beneath the Fluorescence Signals.- 2.5. Energy Deposited Versus Fluorescence Production.- 2.6. Summary of the Properties of X Rays and Charged Particles for Fluorescence Excitation.- 2.7. Microprobe Spatial Resolutions; Charged-Particle Intensities.- 3. Results of X-Ray Fluorescence Measurements with Synchrotron Radiation.- 3.1. Fluorescence Excitation with the Continuum Radiation.- 3.2. Fluorescence Excitation with Monochromatic Radiation.- 3.2.1. Experimental Arrangement.- 3.2.2. Fluorescence Spectra and Detectable Limits.- 3.2.3. Minimum Detection Limits for 37-keV Radiation.- 3.2.4. Intrinsic Background for X-Ray-Excited Fluorescence: Summary of Signal-to-Background Ratios.- 4. Optics for an X-Ray Microprobe.- 4.1. Mirrors for Focusing the Continuum Spectrum.- 4.2. Mirrors and Crystals for Focusing Monoenergetic X Rays.- 5. Final Comparative Analysis and Conclusions.- References.- 15. Small-Angle X-Ray Scattering of Macromolecules in Solution.- 1. Introduction.- 2. The Small-Angle Scattering Intensity.- 2.1. The Probability of Small-Angle Scattering from a Dilute Solution.- 2.2. The Energy Spectrum of the Source.- 2.3. The Efficiency of Gas-Filled Chambers.- 3. Small Angle Scattering Instruments.- 3.1. Instruments with One Monochromator Crystal.- 3.2. The Mirror-Monochromator System.- 3.3. The Double-Monochromator System.- 3.4. The Energy Dispersive Method.- 4. Experimental Results.- 5. Conclusions.- References.- 16. Small-Angle Diffraction of X Rays and the Study of Biological Structures.- 1. Design Criteria for Small-Angle Diffraction.- 1.1. Conditions Imposed by the Specimen and Experiment.- 1.1.1. Specimens.- 1.1.2. Experimental Requirements.- 1.2. X-Ray Optics and Optimalization.- 1.2.1. Definitions.- 1.2.2. Optical Principles of Curved Mirrors and Curved Crystal Monochromators.- 1.2.3. Optical Phase Space.- 1.2.4. The Optimum Condition.- 1.2.5. Choice of Wavelength.- 1.3. Small-Angle Diffraction Cameras for Synchrotron Radiation.- 1.3.1. Remote Control.- 1.3.2. Vacuum Window.- 1.3.3. Curved Mirrors.- 1.3.4. Curved Crystal Monochromators.- 1.3.5. Mirror-Monochromator Camera at desy.- 1.3.6. Mirror-Monochromator Camera at nina.- 1.3.7. Mirror-Monochromator Camera at spear.- 1.3.8. Monochromator-Mirror Camera at vepp-3.- 1.3.9. Mirror-Monochromator Cameras at doris.- 1.3.10. The Separated Function Focusing Monochromator at spear.- 1.4. Conditions Imposed by Detector Technology.- 1.5. A Comparison of the Theoretical and Actual Performance of Mirror-Monochromator Systems.- 2. Applications.- 2.1. Muscle Fibers; Real Time Experiments on Muscle.- 2.1.1. Frog Muscle.- 2.1.2. Insect Flight Muscle.- 2.2. Collagen.- 2.3. DNA Fibers.- 3. Extensions of the Methodology.- 3.1. Wide-Band Monochromators—A Technological Challenge.- 3.2. Towards an Optimum Design.- References.- 17. Single-Crystal X-Ray Diffraction and Anomalous Scattering Using Synchrotron Radiation.- 1. Introduction.- 1.1. Uses of Synchrotron Radiation in Macromolecular Crystallography.- 1.1.1. High Intensity.- 1.1.2. The Phase Problem.- 1.1.3. Large Unit Cells.- 1.2. Early Protein Crystallography Results at spear.- 1.3. Crystallography at Other Synchrotron Radiation Laboratories.- 1.4. Scope of the Remainder of the Chapter.- 2. A Four-Circle Diffractometer Used with Synchrotron Radiation.- 2.1. Introduction.- 2.2. Description of the System.- 2.2.1. Focusing Mirror-Monochromator System.- 2.2.2. Diffractometer Modifications.- 2.2.3. Alignment Carriage.- 2.2.4. Transportable Radiation Hutch.- 2.2.5. Computer Control and Software.- 2.3. Pe...