Surface techniques, applications chemical bonding studies

Applications of Surface Techniques to Chemical Bonding Studies of Minerals... 

Perry, D. L. "Application of Surface Techniques to Chemical Bonding Studies of Geologic Materials," Davis, J. A. and Hayes, K. F., eds., ACS Symposium Series, 1986. 

The study of the functionalization of nanoparticles by molecules requires a good knowledge of both the structure and the chemical nature of the surface state but the chemical procedure may influence on the density of grafting, the chemical and structural evolution of the surface and the chemical bonding at the interface defined by the molecule and the nanoparticulate substrate. It is important to emphasize that the characterization of the chemical bonding is crucial in order to make the functionalized nanoparticles useful and suitable for some biomedical applications as drug delivery. Some relevant information can be obtained by comparing Mossbauer spectra recorded in the same conditions on nanoparticles before and after functionalization, combined to further spectroscopic techniques. 

The information contained in ESCA (Electron Spectroscopy for Chemical Analysis) spectra [331] makes the method particularly suitable for determinations of surface compositions, chemical bonding of surface atoms and changes which occur at solid surfaces during reaction [312], Applications of this technique to the study of reactions of and between solids are awaited with interest. 

The book has been written as an introductory text, not as an exhaustive review. It is meant for students at the start of their Ph.D. projects and for anyone else who needs a concise introduction to catalyst characterization. Each chapter describes the physical background and principles of a technique, a few recent applications to illustrate the type of information that can be obtained, and an evaluation of possibilities and limitations. A chapter on case studies highlights a few important catalyst systems and illustrates how powerful combinations of techniques are. The appendix on the surface theory of metals and on chemical bonding at surfaces is included to provide better insight in the results of photoemission, vibrational spectroscopy and thermal desorption. 

In spite of the development of physicochemical techniques for surface analysis, spectroscopic methods applicable to the study of bonding between adsorbed metal ion species and substrate are limited, especially those applicable to in situ measurement at interfaces between solid and aqueous phases (1,2). In previous papers, we showed that emission Mossbauer measurement is useful in clarifying the chemical bonding environment of dilute metal ions adsorbed on magnetic metal oxide surfaces (3,1 ) ... 

Porous anodic alumina is a very promising material for nanoelectronics. The injection of different types of impurities inside an alumina matrix can substantially improve its electrophysical properties. It is very important to study the local environment (chemical bonds, electronic structure, etc.) of injected atoms for understanding physical principles of the electronic elements formation. A number of techniques can be used to determine a chemical state of atoms in near surface layers. The most informative and precise technique is X-ray photoelectron spectroscopy. At the same time, Auger electron spectroscopy (AES) is also used for a chemical analysis [1] and can be even applicable for an analysis of dielectrics. The chemical state analysis of Ti and Cu atoms implanted into anodic aliunina films was carried out in this work by means of AES. 

The application of laser light scattering techniques to molecular characterization of dielectric films offers the ability to directly probe chemical bonding within the film and at the film-substrate interface. Real-time measurements can be carried out under ambient conditions or in hostile environments allowing transient film stability studies to be conducted. Such laser-based techniques require only an optically clear line of sight between sample and analyzer and offer several advantages over the high vacuum surface analytical techniques commonly applied to film characterization. These include nondestructive measurement capability, rapid data acquisition time, and ability to use the optical properties of the sample to enhance the sensitivity of the measurement. 

New instrumental surface techniques (24) have been introduced to study adhesion during the last ten years. Among them, ESCA (or electron spectroscopy for chemical analysis) techniques (25) have given us insights about the structure of the polymeric interface within the first 50A. New applications of ESCA are discussed by Briggs (26). A combination of ESCA and AES (27) has been used to investigate the interfacial bonding between aluminum and chromium(III) fumarato-coordination compounds. 

The covalent chemistry of fullerenes has developed very rapidly in the past decade in an effort to modify fuUerene properties for a number of applications such as photovoltaic cells, infrared detectors, optical limiting devices, chemical gas sensors, three-dimensional electroactive polymers, and molecular wires [8, 25, 26, 80-82]. Systematic studies of the redox properties of Cgo derivatives have played a crucial role in the characterization of their unique electronic properties, which lie at the center of these potential applications. Furthermore, electrochemical techniques have been used to synthesize and separate new fullerene derivatives and their isomers as well as to prepare fullerene containing thin films and polymers. In this section, to facilitate discussion of their redox properties, Cgo derivatives have been classified in three groups on the basis of the type of attachment of the addend to the fullerene. In group one, the addends are attached via single bonds to the Cgo surface as shown in Fig. 6(a) and are referred to as singly bonded functionalized derivatives. The group includes... 

Spectroscopic techniques are extremely useful for the characterization of filler surfaces treated with surfactants or coupling agents in order to modify interactions in composites. Such an analysis makes possible the study of the chemical composition of the interlayer, the determination of surface coverage and possible coupling of the filler and the polymer. This is especially important in the case of reactive coupling, since, for example, the application of organofunctional silanes may lead to a complicated polysiloxane interlayer of chemically and physically bonded molecules [65]. The description of the principles of the techniques can be found elsewhere [15,66-68], only their application possibilities are discussed here. 

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