Principles and Practice of X-Ray Spectrometric Analysis

Since the first edition of this book was published early in 1970, three major developments have occurred in the field of x-ray spectrochemical analysis. First, wavelength-dispersive spectrometry, in 1970 already securely established among instrumental analytical methods, has matured. Highly sophisticated, miniaturized, modular, solid-state circuitry has replaced elec­ tron-tube circuitry in the readout system. Computers are now widely used to program and control fully automated spectrometers and to store, process, and compute analytical concentrations directly and immediately from ac­ cumulated count data. Matrix effects have largely yielded to mathematical treatment. The problems associated with the ultralong-wavelength region have been largely surmounted. Indirect (association) methods have extended the applicability of x-ray spectrometry to the entire periodic table and even to certain classes of compounds. Modern commercial, computerized, auto­ matic, simultaneous x-ray spectrometers can index up to 60 specimens in turn into the measurement position and for each collect count data for up to 30 elements and read out the analytical results in 1--4 min-all corrected for absorption-enhancement and particle-size or surface-texture effects­ and wholly unattended. Sample preparation has long been the time-limiting step in x-ray spectrochemical analysis. Second, energy-dispersive spectrometry, in 1970 only beginning to assume its place among instrumental analytical methods, has undergone phenomenal development and application and, some believe, may supplant wavelength spectrometry for most applications in the foreseeable future.

I. X-Ray Physics.- 1. Excitation and Nature of X-Rays; X-Ray Spectra.- 1.1. Historical.- 1.2. Definition of X-Rays.- 1.3. Properties of X-Rays.- 1.4. Units of X-Ray Measurement.- 1.4.1. Frequenc.- 1.4.2. Wavelengt.- 1.4.3. Energy.- 1.4.4. Intensity.- 1.5. The Continuous Spectrum.- 1.5.1. Nature.- 1.5.2. Generation.- 1.5.3. Short-Wavelength Limit.- 1.5.4. Origin of the Continuum.- 1.5.5. Effect of X-Ray Tube Current, Potential, and Target.- 1.5.6. Significance.- 1.6. The Characteristic Line Spectrum.- 1.6.1. Atomic Structure.- 1.6.2. Nature and Origin.- 1.6.2.1. General.- 1.6.2.2. Band Spectra.- 1.6.2.3. Selection Rules.- 1.6.2.4. Notation.- 1.6.2.5. Wavelength.- 1.6.2.6. Intensity.- 1.6.3. Excitation—General.- 1.6.4. Primary Excitation.- 1.6.5. Secondary Excitation.- 1.6.5.1. X-Ray Absorption Edges.- 1.6.5.2. Principles.- 1.6.5.3. Relationship of Absorption Edges and Spectral-Line Series.- 1.6.5.4. Excitation with Polychromatic X-Rays.- 1.6.5.5. Other Contributions to the Specimen Emission.- 1.7. Comparison of Primary and Secondary Excitation.- 1.7.1. X-Ray Tube Potential.- 1.7.2. Features.- 1.8. Excitation by Ion Bombardment.- 2. Properties of X-Rays.- 2.1. Absorption.- 2.1.1. X-Ray Absorption Coefficients.- 2.1.2. X-Ray Absorption Phenomena.- 2.1.3. Relationship of ?\?, ?, and Z.- 2.1.4. Absorption Edges.- 2.1.5. Comparison of X-Ray and Optical Absorption.- 2.1.6. Significance.- 2.1.7. Half-Thickness and Absorption Cross Section.- 2.1.8. Inverse-Square Law.- 2.2. Scatter.- 2.2.1. General.- 2.2.2. Modified (Compton) Scatter.- 2.2.3. Relationship of Unmodified and Modified Scatter.- 2.2.4. Significance.- 2.3. Diffraction by Crystals.- 2.4. Specular Reflection; Diffraction by Gratings.- 2.4.1. Specular Reflection.- 2.4.2. Diffraction by Gratings.- 2.5. Auger Effect; Fluorescent Yield.- 2.5.1. Auger Effect.- 2.5.2. Fluorescent Yield.- 2.5.3. Satellite Lines.- II. The X-Ray Spectrometer, its Components, and their Operation.- 3. X-Ray Secondary-Emission (Fluorescence) Spectrometry; General Introduction.- 3.1. Nomenclature.- 3.2. Principle and Instrument.- 3.2.1. Principle.- 3.2.2. The X-Ray Spectrogoniometer.- 3.2.3. Electronic Readout Components.- 3.2.4. Qualitative, Semiquantitative, and Quantitative Analysis.- 3.2.5. Phases of a Quantitative X-Ray Spectrometric Analysis.- 3.3. Appraisal.- 3.3.1. Advantages.- 3.3.1.1. X-Ray Spectra.- 3.3.1.2. Excitation and Absorption.- 3.3.1.3. Absorption-Enhancement Effects.- 3.3.1.4. Spectral-Line Interference.- 3.3.1.5. Nondestruction of Specimen.- 3.3.1.6. Specimen Versatility.- 3.3.1.7. Operational Versatility.- 3.3.1.8. Versatility of Analytical Strategy.- 3.3.1.9. Selected-Area Analysis.- 3.3.1.10. Semiquantitative Estimations.- 3.3.1.11. Concentration Range.- 3.3.1.12. Sensitivity.- 3.3.1.13. Precision and Accuracy.- 3.3.1.14. Excitation.- 3.3.1.15. Speed and Convenience.- 3.3.1.16. Operating Cost.- 3.3.1.17. Automation.- 3.3.1.18. Process Control.- 3.3.1.19. Use with Other Methods.- 3.3.2. Disadvantages.- 3.3.2.1. Light Elements.- 3.3.2.2. Penetration.- 3.3.2.3. Absorption-Enhancement Effects.- 3.3.2.4. Sensitivity.- 3.3.2.5. Qualitative Analysis.- 3.3.2.6. Standards.- 3.3.2.7. Instrument Preparation.- 3.3.2.8. Components.- 3.3.2.9. Instrument Settings.- 3.3.2.10. Error.- 3.3.2.11. Tedium.- 3.3.2.12. Cost.- 3.4. Trends in X-Ray Spectrochemical Analysis.- 4. Excitation.- 4.1. Principles.- 4.1.1. General.- 4.1.2. Excitation by Monochromatic X-Rays.- 4.1.3. Excitation by Continuous Spectra.- 4.2. The X-Ray Tube.- 4.2.1. Function and Requirements.- 4.2.2. Construction.- 4.2.3. Design Considerations.- 4.2.4. Practical Considerations.- 4.2.4.1. Excitation Efficiency.- 4.2.4.2. Spectral-Line Interference.- 4.2.4.3. Temperature.- 4.2.4.4. Evaluation of the Condition of the X-Ray Tube.- 4.2.5. Special X-Ray Tubes.- 4.2.5.1. Dual-Target Tube.- 4.2.5.2. End-Window Tube.- 4.2.5.3. Demountable Tubes.- 4.2.5.4. Tubes for Ultralong Wavelength.- 4.2.5.5. Low-Power Tubes.- 4.2.5.6. Field-Emission Tubes.- 4.3. X-Ray Power Supply.- 4.3.1. Function and Requirements.- 4.3.2. Components and Operation.- 4.3.2.1. High-Potential Supply.- 4.3.2.2. X-Ray Tube Filament Supply.- 4.3.2.3. Operation.- 4.3.2.4. Stabilization.- 4.3.2.5. Safety and Protective Devices.- 4.3.3. Practical Considerations.- 4.3.3.1. Constant Potential.- 4.3.3.2. Maximum Target Potential.- 4.3.3.3. Operating Conditions.- 4.4. Filters in Secondary Excitation.- 4.4.1. Attenuation Filters.- 4.4.2. Enhancement Filters.- 4.4.3. Enhancement Radiators.- 4.5. Specimen Presentation.- 5. Dispersion.- 5.1. Introduction.- 5.2. Collimators.- 5.2.1. Function.- 5.2.2. Features and Considerations.- 5.3. Radiation Path.- 5.4. Analyzer Crystals.- 5.4.1. Introduction.- 5.4.2. Features.- 5.4.2.1. Wavelength Range.- 5.4.2.2. Diffracted Intensity.- 5.4.2.3. Resolution.- 5.4.2.4. Peak-to-Background Ratio; Crystal Emission.- 5.4.2.5. Thermal Expansion.- 5.4.2.6. Miscellaneous Features.- 5.4.2.7. Aligning and Peaking the Goniometer.- 5.4.3. Other Dispersion Devices.- 5.4.3.1. Gratings and Specular Reflectors.- 5.4.3.2. Multilayer Metal Films.- 5.4.3.3. Metal Disulfide-Organic Intercalation Complexes.- 5.4.3.4. Multilayer Soap Films.- 5.4.3.5. Pyrolytic Graphite.- 5.5. Basic Crystal-Dispersion Arrangements.- 5.5.1. Multichannel Spectrometers.- 5.5.2. Flat-Crystal Dispersion Arrangements.- 5.5.2.1. Bragg and Soller.- 5.5.2.2. Edge-Crystal.- 5.5.2.3. Laue.- 5.5.2.4. Other Flat-Crystal Arrangements.- 5.5.3. Curved-Crystal Dispersion Arrangements.- 5.5.3.1. General.- 5.5.3.2. Transmission.- 5.5.3.3. Reflection.- 5.5.3.4. Von Hamos Image Spectrograph.- 5.6. Curved-Crystal Spectrometers.- 5.6.1. Semifocusing Spectrometer.- 5.6.2. Continuously Variable Crystal Radius.- 5.6.3. Naval Research Laboratory Design.- 5.6.4. Applied Research Laboratories Design.- 5.6.5. Cauchois Spectrometer.- 5.6.6. Spherically Curved-Crystal Spectrometers.- 5.7. Photographic X-Ray Spectrographs.- 6. Detection.- 6.1. Introduction.- 6.2. Gas-Filled Detectors.- 6.2.1. Structure.- 6.2.1.1. Components, Classifications.- 6.2.1.2. Windows.- 6.2.1.3. Gas Fillings.- 6.2.2. Operation.- 6.2.2.1. Phenomena in the Detector Gas Volume.- 6.2.2.2. Proportionality in Gas Detectors.- 6.2.2.3. Gas Amplification; Types of Gas Detectors.- 6.2.2.4. Quenching.- 6.2.3. Proportional Counters.- 6.2.3.1. Phenomena in the Detector Gas Volume.- 6.2.3.2. Detector Output; Escape Peaks.- 6.3. Scintillation Counters.- 6.3.1. Structure.- 6.3.1.1. Scintillation Crystal.- 6.3.1.2. Multiplier Phototube.- 6.3.2. Operation.- 6.3.2.1. Proportionality in Scintillation Counters.- 6.3.2.2. Phenomena in the Scintillation Counter.- 6.4. Lithium-Drifted Silicon and Germanium Detectors.- 6.4.1. Structure.- 6.4.2. Operation.- 6.4.3. Advantages.- 6.4.4. Limitations.- 6.4.5. Avalanche Detectors.- 6.5. Evaluation of X-Ray Detectors.- 6.5.1. Detector Characteristics.- 6.5.1.1. Rise Time.- 6.5.1.2. Dead Time.- 6.5.1.3. Resolving Time.- 6.5.1.4. Recovery Time.- 6.5.1.5. Linear Counting Range.- 6.5.1.6. Coincidence Loss.- 6.5.1.7. Choking.- 6.5.1.8. Plateau.- 6.5.1.9. Slope.- 6.5.1.10. Inherent Noise and Background.- 6.5.1.11. Quantum Efficiency.- 6.5.1.12. Resolution.- 6.5.2. Comparison of Conventional Detectors.- 6.5.3. Modified Gas-Filled and Scintillation Detectors.- 6.6. Other X-Ray Detectors.- 6.6.1. Photographic Film.- 6.6.2. Photoelectric Detectors.- 6.6.2.1. The Phosphor-Phototube Detector.- 6.6.2.2. Photoelectric Detectors for the Ultralong-Wave-length Region.- 6.6.3. Crystal Counters.- 7. Measurement.- 7.1. Instrumentation.- 7.1.1. Introduction.- 7.1.2. Preamplifier.- 7.1.3. Amplifier.- 7.1.4. Pulse-Height Selectors.- 7.1.4.1. Pulse-Height Selector; Discriminator.- 7.1.4.2. Pulse Reverter.- 7.1.4.3. Pulse-Shape Selector.- 7.1.5. Ratemeter and Recorder.- 7.1.6. Scaler and Timer.- 7.1.7. Computers.- 7.2. Measurement of Intensity.- 7.2.1. Ratemeter Methods.- 7.2.2. Scaler-Timer Methods.- 7.2.2.1. Preset-Time Method.- 7.2.2.2. Preset-Count Method.- 7.2.2.3. Integrated-Count Method.- 7.2.2.4. Monitor and Ratio Methods.- 7.2.3. X-Ray Dose and Dose Rate.- 7.3. Background.- 7.3.1. Definition and Significance.- 7.3.2. Origin and Nature.- 7.3.3. Measurement.- 7.3.4. Reduction.- 7.3.5. Considerations.- 8. Pulse-Height Selection; Energy-Dispersive Analysis; Nondispersive Analysis.- 8.1. Pulse-Height Selection.- 8.1.1. Principle of Pulse-Height Selection.- 8.1.2. Pulse-Height Distribution Curves.- 8.1.2.1. Introduction.- 8.1.2.2. Single-Channel Pulse-Height Selector.- 8.1.2.3. Multichannel Pulse-Height Analyzer.- 8.1.3. Pulse-Height Selector Displays.- 8.1.4. Pulse-Height Selector Operating Controls.- 8.1.5. Use of the Pulse-Height Selector.- 8.1.5.1. Evaluation of Detector and Amplifier Characteristics.- 8.1.5.2. Establishment of Pulse-Height Selector Settings.- 8.1.6. Applications and Limitations.- 8.1.7. Automatic Pulse-Height Selection.- 8.1.8. Problems with Pulse-Height Selection.- 8.1.8.1. General.- 8.1.8.2. Shift of Pulse-Height Distribution.- 8.1.8.3. Distortion of Pulse-Height Distribution.- 8.1.8.4. Additional Pulse-Height Distributions Arising from the Measured Wavelength.- 8.1.9. Unfolding of Overlapping Pulse-Height Distributions.- 8.1.9.1. Principle.- 8.1.9.2. Application.- 8.1.9.3. Simplified Variations.- 8.2. Energy-Dispersive Analysis.- 8.2.1. Introduction.- 8.2.1.1. Principles.- 8.2.1.2. Advantages.- 8.2.1.3. Limitations.- 8.2.2. Instrumentation.- 8.2.2.1. General.- 8.2.2.2. Excitation by X-Rays.- 8.2.2.3. Excitation by Radioisotopes.- 8.2.2.4. Energy-Dispersive Multichannel X-Ray Spectrometer Systems.- 8.2.3. Energy-Dispersive Diffractometry-Spectrometry.- 8.3. Nondispersive Analysis.- 8.3.1. Selective Excitation.- 8.3.2. Selective Filtration.- 8.3.2.1. Methods.- 8.3.2.2. X-Ray Transmission Filters.- 8.3.3. Selective Detection.- 8.3.4. Modulated Excitation.- 9. Laboratory, Automated, and Special X-Ray Spectrometers.- 9.1. Introduction.- 9.2. Laboratory X-Ray Spectrometers.- 9.2.1. General.- 9.2.2. Instrument Arrangements.- 9.2.3. Accessories.- 9.3. Automated X-Ray Spectrometers.- 9.3.1. General.- 9.3.2. Sequential Automatic Spectrometers.- 9.3.3. Simultaneous Automatic Spectrometers.- 9.3.4. “Slewing” Goniometers.- 9.4. Special X-Ray Spectrometers.- 9.4.1. Portable Spectrometer.- 9.4.2. Primary Excitation.- 9.4.3. Ultralong-Wavelength Spectrometry.- 9.5. X-Ray Safety and Protection.- III. Qualitative and Semiquantitative Analysis.- 10. Qualitative and Semiquantitative Analysis.- 10.1. General.- 10.2. Recording the Spectrum.- 10.3. Instrument Conditions.- 10.4. Identification of the Peaks.- 10.4.1. Spectral-Line Tables.- 10.4.2. Identification of Peaks.- 10.5. General Procedures for Qualitative and Semiquantitative Analysis.- 10.5.1. Normalization Factor Method.- 10.5.2. Method of Salmon.- IV. Performance Criteria and other Features.- 11. Precision and Error; Counting Statistics.- 11.1. Error in X-Ray Spectrometric Analysis.- 11.1.1. Nature of Error.- 11.1.2. Elementary Statistics.- 11.1.3. Sources of Error.- 11.1.3.1. General.- 11.1.3.2. Instrumental and Operational Error.- 11.1.3.3. Specimen Error.- 11.1.3.4. Chemical Effects.- 11.2. Counting Statistics.- 11.2.1. Nature of the Counting Error.- 11.2.2. Calculation of Counting Error.- 11.2.2.1. Counting Error for Accumulated Counts.- 11.2.2.2. Counting Error for Intensities.- 11.2.3. Counting Strategy.- 11.2.3.1. Measurement of Net Intensity.- 11.2.3.2. The Ratio Method.- 11.2.4. Figure of Merit.- 11.3. Analytical Precision.- 11.3.1. Nature of Analytical Precision.- 11.3.2. Evaluation of Precision.- 11.3.2.1. General Considerations.- 11.3.2.2. Instrumental Instability.- 11.3.2.3. Operational Error.- 11.3.2.4. Specimen Error.- 11.3.2.5. Evaluation of Internal Consistency of Data.- 12. Matrix Effects.- 12.1. Introduction.- 12.2. Absorption-Enhancement Effects.- 12.2.1. General; Definitions.- 12.2.2. Effects on Calibration Curves.- 12.2.3. Prediction of Absorption-Enhancement Effects.- 12.2.3.1. K Lines.- 12.2.3.2. L Lines.- 12.2.4. Nonspecific Absorption Effects.- 12.2.5. Specific Absorption-Enhancement Effects.- 12.2.6. Secondary Absorption-Enhancement Effects.- 12.2.6.1. General.- 12.2.6.2. Secondary Absorption Effects.- 12.2.6.3. Secondary Enhancement Effects.- 12.2.7. Unusual Absorption-Enhancement Effects.- 12.3. Particle-Size, Heterogeneity, and Surface-Texture Effects.- 13. Sensitivity and Resolution; Spectral-Line Interference.- 13.1. Sensitivity.- 13.1.1. Definitions.- 13.1.2. Factors Affecting Sensitivity.- 13.1.2.1. Excitation Conditions.- 13.1.2.2. Specimen Conditions.- 13.1.2.3. Optical System.- 13.1.2.4. Detector and Readout Conditions.- 13.1.3. Photon Losses in the X-Ray Spectrometer.- 13.1.4. Sensitivity Performance.- 13.2. Resolution.- 13.2.1. Definitions.- 13.2.1.1. Resolution.- 13.2.1.2. Dispersion.- 13.2.1.3. Divergence.- 13.2.2. Factors Affecting Resolution.- 13.3. Spectral-Line Interference.- 13.3.1. Definition.- 13.3.2. Origin of Interfering Spectral Lines.- 13.3.2.1. Wavelength Interference.- 13.3.2.2. Energy Interference.- 13.3.2.3. Common Sources of Spectral Interference.- 13.3.3. Reduction of Spectral Interference.- 13.3.3.1. General Methods.- 13.3.3.2. Excitation of Analyte and Interferant Lines.- 13.3.3.3. Transmission and Detection of Analyte and Interferant Lines.- 13.3.3.4. Experimental and Mathematical Correction of Spectral Interference.- V. Quantitative Analysis.- 14. Methods of Quantitative Analysis.- 14.1. Introduction.- 14.2. Standard Addition and Dilution Methods.- 14.2.1. Principles and Considerations.- 14.2.2. Methods.- 14.2.2.1. Standard Addition.- 14.2.2.2. Standard Dilution.- 14.2.2.3. Multiple Standard Addition.- 14.2.2.4. Slope-Ratio Addition.- 14.2.2.5. Double Dilution.- 14.3. Calibration Standardization.- 14.3.1. Principles.- 14.3.2. Special Calibration Methods.- 14.3.2.1. Single-Standard Method.- 14.3.2.2. Two-Standard Method.- 14.3.2.3. Binary-Ratio Method.- 14.3.2.4. Mutual Standards Method.- 14.3.2.5. Sets of Calibration Curves.- 14.4. Internal Standardization.- 14.4.1. Principles.- 14.4.2. Selection of Internal-Standard Element.- 14.4.3. Advantages and Limitations.- 14.4.4. Considerations.- 14.4.5. Special Internal-Standardization Methods.- 14.4.5.1. Single-Standard Internal-Standard Method.- 14.4.5.2. Variable Internal-Standard Method.- 14.4.6. Other Standardization Methods.- 14.4.6.1. Internal Control-Standard Method.- 14.4.6.2. Internal Intensity-Reference Standard Method.- 14.4.6.3. External-Standard Method.- 14.5. Standardization with Scattered X-Rays.- 14.5.1. Background-Ratio Method.- 14.5.2. Graphic Method.- 14.5.3. Scattered Target-Line Ratio Method.- 14.5.4. Scattered Internal-Standard Line Method.- 14.5.5. Ratio of Coherent to Incoherent Scattered Intensities.- 14.5.6. Slurry-Density Method.- 14.6. Matrix-Dilution Methods.- 14.6.1. Principles.- 14.6.2. Discussion.- 14.7. Thin-Film Methods.- 14.7.1. Principles.- 14.7.2. Infinite (Critical) Thickness.- 14.7.3. Discussion.- 14.8. Special Experimental Methods.- 14.8.1. Emission-Absorption Methods.- 14.8.2. Method of Variable Takeoff Angle.- 14.8.2.1. Basic Excitation Equations.- 14.8.2.2. Evaluation of Mean Wavelength and Excitation Integral.- 14.8.2.3. Mass per Unit Area of an Element Film from Its Own Line.- 14.8.2.4. Mass per Unit Area of an Element Film from a Substrate Line.- 14.8.2.5. Mass per Unit Area and Composition of Multielement Films.- 14.8.2.6. Composition of Bulk Multielement Specimens.- 14.8.3. Indirect (Association) Methods.- 14.8.4. Combinations of X-Ray Spectrometry and Other Methods.- 15. Mathematical Correction of Absorption-Enhancement Effects.- 15.1. Introduction.- 15.2. Geometric Methods.- 15.3. Absorption Correction.- 15.4. Empirical Correction Factors.- 15.5. Influence Coefficients.- 15.5.1. Introduction.- 15.5.2. Derivation of the Basic Equations.- 15.5.2.1. Birks’ Derivation.- 15.5.2.2. Müller’s Derivation; Regression Coefficients.- 15.5.2.3. Influence Coefficient Symbols.- 15.5.3. Solution of the Basic Equ...