Structure solids, characterization techniques

In order to discuss the various techniques we must distinguish between diffusive and non-diffusive systems (J8). Diffusive systems, such as liquids, are characterized by the eventual diffusion of particles over all of the available space non-diffusive systems such as solids, glasses and macromolecules with a definite average structure are characterized by time independent average positions around which the atoms fluctuate. 

XPS has typically been regarded primarily as a surface characterization technique. Indeed, angle-resolved XPS studies can be very informative in revealing the surface structure of solids, as demonstrated for the oxidation of Hf(Sio.sAso.5)As. However, with proper sample preparation, the electronic structure of the bulk solid can be obtained. A useful adjunct to XPS is X-ray absorption spectroscopy, which probes the bulk of the solid. If trends in the XPS BEs parallel those in absorption energies, then we can be reasonably confident that they represent the intrinsic properties of the solid. Features in XANES spectra such as pre-edge and absorption edge intensities can also provide qualitative information about the occupation of electronic states. 

Some of the major questions that semiconductor characterization techniques aim to address are the concentration and mobility of carriers and their level of compensation, the chemical nature and local structure of electrically-active dopants and their energy separations from the VB or CB, the existence of polytypes, the overall crystalline quality or perfection, the existence of stacking faults or dislocations, and the effects of annealing upon activation of electrically-active dopants. For semiconductor alloys, that are extensively used to tailor optoelectronic properties such as the wavelength of light emission, the question of whether the solid-solutions are ideal or exhibit preferential clustering of component atoms is important. The next... 

The structural state of dendritic macromolecules at air-water (Langmuir mono-layers) and air-solid (adsorbed monolayers, self-assembled films and cast films) interfaces have been reviewed by Tsukruk [17]. Although this work summarizes various characterization techniques for dendritic films by AFM techniques, in this chapter, we will present recent progress on the characterization of the dendritic film surface morphologies. 

The surface structure and reactivity of vanadium oxide monolayer catalysts supported on tin oxide were investigated by various physico-chemical characterization techniques. In this study a series of tin oxide supported vanadium oxide catalysts with various vanadia loadings ranging from 0.5 to 6. wt.% have been prepared and were characterized by means of X-ray diffraction, oxygen chemisorption at -78°C, solid state and nuclear magnetic resonance... 

Inspired by these Surface Science studies at the gas-solid interface, the field of electrochemical Surface Science ( Surface Electrochemistry ) has developed similar conceptual and experimental approaches to characterize electrochemical surface processes on the molecular level. Single-crystal electrode surfaces inside liquid electrolytes provide electrochemical interfaces of well-controlled structure and composition [2-9]. In addition, novel in situ surface characterization techniques, such as optical spectroscopies, X-ray scattering, and local probe imaging techniques, have become available and helped to understand electrochemical interfaces at the atomic or molecular level [10-18]. Today, Surface electrochemistry represents an important field of research that has recognized the study of chemical bonding at electrochemical interfaces as the basis for an understanding of structure-reactivity relationships and mechanistic reaction pathways. 

Decatungstate, in the form of a lipophilic tetrabutilamonium salt ((n-C4H9N)4 W10O32), has been homogeneously dispersed in porous membranes made of PVDF (PVDF-W10). Solid-state characterization techniques confirmed that catalyst structure and spectroscopic properties of decatungstate have been preserved once immobilized within the membranes [42-44]. 

Raman spectroscopy, which is also used to measure the crystal size of nano-structured solids through the phonon confinement model (PCM), provides only semi-quantitative results for size measurements in ND powders due to insufficient understanding of the Raman spectra of ND and a lack of agreement between theoretical predictions of the model and experimental Raman data. However, taking into account the broad size distribution of ND powders and the contributions of lattice defects, a significant improvement in the predictions of the model was achieved. However, a correct interpretation of Raman data and quantitative size measurements still requires additional information on sample structure and composition. Therefore, a combined use of various characterization techniques such as XRD, HRTEM, and Raman spectroscopy can be recommended for a reliable determination of the average size of ND crystals and their distribution. 

TTus paper is concerned with the particular class of molecular sieves having periodic mesoporous structure with pore sizes in the range of 2 to 10 nm. They are comprised of the M41S mesoporous molecular sieves and solids with related structures. In the first part, the preparation methods and characterization techniques will be reviewed and discussed. Silicate-based materials and non-silicate materials will be dealt with separately. In the second part of this review particular emphasis will be put on potential applications reported in both the patent and the open literature. Early progress in tWs field has been presented in the previous Summer School by Casci [37]. Potential catalytic applications of M41S were also reviewed rprPTitlv 1381... 

In principle all of the techniques used for the investigation of crystalline solids are equally useful in the investigation of glasses. Several such characterization techniques are described briefly in other chapters where they are of immediate relevance. The effort in this chapter has been to put together the most important structural techniques used in glass science. 

---