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This volume contains all of the papers presented at the American Chemical Society Symposium on Reflectance Spectroscopy. The Symposium was presented under the sponsorship of the Division of Analytical Chemistry, and was held on September 11 and 12,1967, at the 154th National Meeting of the American Chemical Society, Chicago, Illinois. The papers presented herein represent a renaissance of interest in reflectance spectroscopy. The techni~ue of reflec tance spectroscopy is not, of course, a new techni~ue, however, it has only been applied to problems of a chemical interest in the last decade or so. The instrumentation for this techni~ue in the ultraviolet, visible, and near infrared regions of the spectrum has been available for many years. New and exciting research is being carried out at the present time to extend these techni~ues to the infrared and far infrared regions as well. It is a pleasure for the Editor to express his gratitude to Drs. John K. Taylor and E. C. Dunlop of the Division of Analytical Chemistry, ACS, for their cooperation in making the Symposium a reality. The assistance of Miss Julie Norris of the University of Houston for her typing and manuscript organi zation skill is greatly appreciated. And lastly, but certainly not the least, the Editor would like to acknowledge the coopera tion of all of the contributors to this volume. Certainly without their cooperation, this Symposium would not have been a success.
Reflectance spectroscopy is the investigation of the spectral composi tion of surface-reflected radiation with respect to its angularly dependent intensity and the composition of the incident primary radiation. Two limiting cases are important: The first concerns regular (specular) reflection from a smooth surface, and the second diffuse reflection from an ideal matte surface. All possible variations are found in practice between these two extremes. For the two extreme cases, two fundamentally different methods of reflectance spectroscopy are employed: The first of these consists in evaluating the optical constants n (refractive index) and x (absorption index) from the measured regular reflection by means of the Fresnel equations as a function of the wave A. This rather old and very troublesome procedure, which is length incapable of very accurate results, has recently been modified by Fahren fort by replacing the air-sample phase boundary by the phase boundary between a dielectric of higher refractive index (n ) and the sample (n ). 1 2 If the sample absorbs no radiation and the angle of incidence exceeds a certain definite value, total reflection occurs. On close optical contact between the two phases, a small amount of energy is transferred into the less dense phase because of diffraction phenomena at the edges of the incident beam. The energy flux in the two directions through the phase boundary caused by this is equal, however, so that 'total reflection takes place.
Until comparatively recently, trace analysis techniques were in general directed toward the determination of impurities in bulk materials. Methods were developed for very high relative sensitivity, and the values determined were average values. Sampling procedures were devised which eliminated the so-called sampling error. However, in the last decade or so, a number of developments have shown that, for many purposes, the distribution of defects within a material can confer important new properties on the material. Perhaps the most striking example of this is given by semiconductors; a whole new industry has emerged in barely twenty years based entirely on the controlled distribu tion of defects within what a few years before would have been regarded as a pure, homogeneous crystal. Other examples exist in biochemistry, metallurgy, polyiners and, of course, catalysis. In addition to this of the importance of distribution, there has also been a recognition growing awareness that physical defects are as important as chemical defects. (We are, of course, using the word defect to imply some dis continuity in the material, and not in any derogatory sense. ) This broadening of the field of interest led the Materials Advisory Board( I} to recommend a new definition for the discipline, "Materials Character ization," to encompass this wider concept of the determination of the structure and composition of materials. In characterizing a material, perhaps the most important special area of interest is the surface.
An essential reference for researchers and students of planetary remote sensing on the interaction of electromagnetic radiation with planetary surfaces.
Spectroscopy in Heterogeneous Catalysis deals with the applications of spectroscopy in heterogeneous catalysis. The concepts and capabilities of a particular technique, experimental procedures, and examples of all proven or potentially important applications are discussed. The use of spectroscopic measurements in guiding empirical approaches to applied problems and to fundamental studies of the chemical identity of catalytic surfaces is also described. This book is comprised of eight chapters and begins with a discussion on the scope of spectroscopy in catalysis and applications of spectroscopy to zeolite catalysts. The following chapters focus on infrared spectroscopy, with emphasis on the theory and interpretation of infrared spectra; Raman spectroscopy and the theory of the Raman effect; diffuse reflectance and photoacoustic spectroscopies; and Mössbauer spectroscopy. Electron spin resonance spectroscopy and nuclear magnetic resonance spectroscopy are also considered. The final chapter is devoted to X-ray photoelectron spectroscopy (XPS) and its application to core electrons, along with the experimental equipment and procedures used. The applications of XPS to studies of surface behavior and catalyst composition and chemistry are outlined. This monograph will be a useful resource for physicists, researchers, and potential researchers in heterogeneous catalysis.
Here in one source is a wide variety of practical, everydayinformation often required by chemists but seldom found together,if at all, in the standard handbooks, data collections, manuals,and other usual sources. Discussing physical, chemical, andmechanical properties of substances and systems, the authors answersuch questions as: * How do I test for and destroy peroxides in different solventsand what is the best way to purify such solvents? * What are the structure, physical properties, and recentreferences to the use of common-name solvents and solvent aids suchas the "Skellysolves," "Cellosolves," "Crownanes," and"Glymes"? * What is the utility of a particular molecular sieve, orpermeation gel, or epoxy cement, or liquid crystal, and where do Ibuy them and find references to their application? The book is divided into nine chapters and covers properties ofatoms and molecules, spectroscopy, photochemistry, chromatography,kinetics and thermodynamics, various experimental techniques, andmathematical and numerical information, including the definitions,values, and usage rules of the newly adopted International Systemof Units (SI Units). A section on statistical treatment of datawhich provides an actual least-squares computer program is alsoincluded. In the spectroscopy chapter, very extensive andup-to-date collections of spectral correlation data are presentedfor ir, uv-vis, optical rotation, nmr, and mass spectra, along withdata on esr and nqr spectroscopy. Also included is a variety ofhard-to-classify but frequently sought information, such as namesand addresses of microanalysis companies and chemistry publishers,descriptions and commercial sources of atomic and molecular models,and safety data for hazardous chemicals. More than 500 keyreferences are also included, most of which are recent. There areimportant hints and definitions associated with the art as well asthe state of the art for the appropriate subjects. Also foundthroughout the book are about 250 suppliers and directions forobtaining special booklets or other material. Containing a wealth of useful information, The Chemist'sCompanion will be an indispensable guide for students andprofessional chemists in nearly all the chemical disciplines. Inaddition, it will provide for the teacher and student an unusualadjunct for use in a broad cross-section of chemistry courses.
In recent years mineralogy has developed even stronger links with solid-state chemistry and physics and these developments have been accompanied by a trend towards further quantification in the theoretical as well as the experimental aspects of the subject. The importance of solid-state chemistry to mineralogy was reflected in a symposium held at the 1982 Annual Congress of The Royal Society of Chemistry at which the original versions of most of the contributions to this book were presented. The meeting brought together chemists, geologists and mineralogists all of whom were interested in the application of modern spectroscopic techniques to the study of bonding in minerals. The interdisci plinary nature of the symposium enabled a beneficial exchange of information from the various fields and it was felt that a book presenting reviews of the key areas of the subject would be a useful addition to both the chemical and mineralogical literature. The field of study which is commonly termed the 'physics and chemistry of minerals' has itself developed very rapidly over recent years. Such rapid development has resulted in many chemists, geologists, geochemists and mineralogists being less familiar than they might wish with the techniques currently available. Central to this field is an understanding of chemical bonding or 'electronic structure' in minerals which has been developed both theoretically and by the use of spectroscopic techniques.