During the past few years there has been a marked increase in the use of advanced chemical methods in studies of soil and clay mineral systems, but only a relatively small number of soil and clay scientists have become intimately associ ated and acquainted with these new techniques. Perhaps the most important obstacles to technology transfer in this area are: 1) many soil and clay chemists have had insufficient opportunities to explore in depth the working principles of more recent spectroscopic developments, and therefore are unable to exploit the vast wealth of information that is available through the application of such ad vanced technology to soil chemical research; and 2) the necessary equipment gen erally is unavailable unless collaborative projects are undertaken with chemists and physicists who already have the instruments. The objective of the NATO Advanced Study Institute held at the University of Illinois from July 23 to August 4, 1979, was to partially alleviate these obstacles. This volume, which is an extensively edited and reviewed version of the proceedings of that Advanced Study Institute, is an essential aspect of that purpose. Herein are summarized the theory and most current applications of six different spectroscopic methods to soil and/or clay mineral systems. The instrumental methods examined are Mossbauer, neutron scattering, x-ray photoelectron (XPS, ESCA), nuclear magnetic resonance (NMR), electron spin resonance (ESR, EPR), and photoacoustic spectroscopy. Contributing authors were also lecturers at the Advanced Study Institute, and are each well known and respected authorities in their respective disciplines.
Table of Contents1. Mössbauer Spectroscopy.- 1-1. Introduction to the Mössbauer Effect.- 1-2. Basic Principles of Mössbauer Spectroscopy.- 1-3. Instrumentation and Experimental Procedures.- 1-4. Application of Mössbauer Spectroscopy to the Study of Silicate Minerals.- 1-5. The Study of Mineral Alteration Reactions.- 1-6. Iron Oxides and their Characterization in Soils.- 1-7. Critical Assessment of the Potential of Mössbauer Spectroscopy, and its Application to Nuclei Other than Iron.- References.- 2. Neutron Scattering Methods of Investigating Clay Systems.- 2-1. Introduction.- 2-2. Elementary Neutron Scattering Theory.- 2-3. Neutron Scattering Instrumentation and Methods.- 2-4. Applications of Neutron Spectroscopy to Studies of Clay Minerals.- Appendix 2-1. Macroscopic Cross Section for a Montmorillonite-Water System.- Appendix 2-2. Calculation of Incoherent Scattering Intensity Ratios for a Clay-Water System.- References.- 3. Introduction to X-ray Photoelectron Spectroscopy.- 3-1. Introduction.- 3-2. Trend of XPS Spectra.- 3-3. Instrumentation.- 3-4. Peak Position.- 3-5. Explored Depth.- 3-6. Peak Intensity.- 3-7. Overview of Methods of Characterization of Solids Based on X-ray, Electron and Ion Beams.- References.- 4. Application of X-ray Photoelectron Spectroscopy to the Study of Mineral Surface Chemistry.- 4-1. Uniqueness of XPS for the Investigation of Mineral Surface Phenomena Probing Depth.- 4-2. Sample Handling Techniques.- 4-3. Analytical Applications.- 4-4. Electron Take-Off (Grazing) Angle Analysis Applications.- 4-5. Qualitative Bonding Investigations.- 4-6. Summary.- References.- 5. The Application of NMR to the Study of Clay Minerals.- 5-1. Introduction: Fundamentals of NMR.- 5-2. The Bloch Equations.- 5-3. Line Shape.- 5-4. Relaxation Mechanisms.- 5-5. Review of Some Problems: Order and Disorder in Adsorbed Water Molecules.- References.- 6. Distribution of Ions in the Octahedral Sheet of Micas.- 6-1. Introduction.- 6-2. Influence of the Fe2+ Ions.- 6-3. H+ Spectra of Phlogopites.- 6-4. H+ Spectra of Biotites.- 6-5. F? Spectra.- 6-6. Correlation with I.R. Results.- References.- 7. General Theory and Experimental Aspects of Electron Spin Resonance.- 7-1. Introduction.- 7-2. G-Factor Tensor.- 7-3. Hyperfine Interaction.- 7-4. Analysis of ESR Spectra.- 7-5. Fine Structure.- 7-6. Summary.- Appendix 7-1.- Appendix 7-2.- Appendix 7-3.- References.- 8. Applications of ESR Spectroscopy to Inorganic-Clay Systems.- 8-1. Introduction.- 8-2. Surface-Bound Metal Ions.- 8- 3. Framework Paramagnetic Centers.- References.- 9. Application of Spin Probes to ESR Studies of Organic-Clay Systems.- 9- 1. Nitroxide Spin Probes Origin of the ESR Spectrum.- 9-2. Nitroxides in Low-Viscosity Media Rapid Isotropic Motion.- 9-3. Nitroxides in High-Viscosity Media.- 9-4. Nitroxides Adsorbed on Clay Surfaces.- 9-5. Experimental Considerations in Using Nitroxide Spin Probes.- References.- 10. Applications of Photoacoustic Spectroscopy to the Study of Soils and Clay Minerals.- 10-1. Introduction.- 10-2. Instrumentation.- 10-3. Results.- 10-4. Conclusions.- References.