Surface morphology characterization methods

Microscopic methods. While microscopic methods provide direct visual information on membrane morphology as discussed earlier, determination of pore size, especially meaningful pore size distribution, by this type of methods is tedious and difficult. Advances have been made on the electron microscopy techniques to visualize membrane surface pores. For example, Merin and Cheryan [1980] have developed a replica-TEM technique to observe membrane surface pores. Nevertheless, microscopic methods have remained primarily as a surface morphology characterization tool and not as a pore size determination scheme. 

One difficulty with many synthetic preparations of semiconductor NCs that complicates any interpretation of NMR results is the inevitable distribution of sizes (and exact shapes or surface morphologies). Therefore attempts to make semiconductors as a sort of molecular cluster having a well-defined stoichiometry are of interest to learn potentially about size-dependent NMR parameters and other properties. One approach is to confine the semiconductor inside a template, for instance the cuboctahedral cages of the sodalite framework or other zeolite structures, which have been characterized by multinuclear NMR methods [345-347], including the mesoporous channel material MCM-41 [341, 348]. 

In Chapters 4 and 6, several methods of characterization of solids that are normally used for catalyst testing were described. In particular, the parameters which characterize the surface morphology of a porous catalyst are the same that characterize a porous adsorbent, that is, the specific surface area, S [m2/g], the micropore volume, W1 [cm3/g], the sum of the micropore andmesopore volumes, that is, the pore volume, W [cm3/g], and the pore size distribution (PSD), AVp/ADp (see Chapter 6). 

Although both the laboratory and industrial scale materials science of catalysts requires an integrated approach as already mentioned above, it is customary to classify the characterization methods by their objects and experimental tools used. I will use the object classification and direct the introductory comments to analysis, primarily elemental and molecular surface analysis, determination of geometric structure, approaches toward the determination of electronic structure, characterization by chemisorption and reaction studies, determination of pore structure, morphology, and texture, and, finally, the role of theory in interpreting the often complex characterization data as well as predicting reaction paths. 

The dependence of E of RF aerogels on water content has to be investigated further. The described investigations are not only a method to characterize the material and the parameters of the inner surface (chemistry, surface morphology, pores etc.) but might also be the first step towards RF aerogels as sensor for humidity or environmental pollution. 

Recently, STS and STM have been applied to study the onset of the catalytic activity of Au particles grown on titania [238], which appeared to be correlated with the layer thickness of the particles on the surface and, as shown above, the bonding of CO with small gold clusters could be characterized in STM/STS experiments (Fig. 1.39 see Morphological Properties of Supported Clusters ) [190]. The above presentation of the spectroscopic results on deposited, size-selected clusters clearly shows that valuable information on these nanosystems can only be obtained by the application of an arsenal of local and nonlocal surface science analysis methods. Therefore, in the near future a much more intense employment of scanning probe techniques such as STM, STS, AFM, and others will beyond any doubt improve considerably assembly, characterization, and functionalization of size-selected clusters on solid surfaces. 

Characterizes materials in terms of thermochemical data, chemical composition, (level of impurities), crystallographic structure, specific surface area (various methods), the particular size, and morphology... 

Scanning electron microscopy (SEM) combined with energy dispersive X-ray (EDX) analysis could be used to physico-chemical characterization of SILMs [26]. This technique allows the characterization of the membrane surface morphology and the examination of the global chemical composition of the membranes and the distribution of the ILs within pores. Figure 11.2 shows examples of SEM micrographs of a plain nylon membrane and supported liquid membranes based on [bmim ][PF ] prepared by using the pressure method [26]. 

For the structural characterization of model electrodes it was shown that on the base of well-defined substrates, composite electrodes tvith defined mesoscopic structure can be prepared. Rather different methods such as low-efficiency electrochemical deposition or adsorption of colloidal particles can be employed for this purpose, and the effect on the surface morphology can be adequately characterized with STM. Knowledge of the mesoscopic siarface properties facilitates the interpretation of results obtained from other techniques, e. g., conventional electrochemical methods or infrared spectroscopy [6], since these are affected by the surface structure but do not contain detailed information about the morphology. 

Another aspect of morphology characterization is spectroscopic analyses of the molecular orientation. The simplest and most often used method is infrared (IR) spectroscopy. Although IR techniques cannot investigate the multilayered texture, they can readily provide vivid one- or two-dimensional profiles of molecular orientation vs. position. Bensaad et al. [17] used normal incidence specular reflection to characterize the orientation profile on the surface of an injection molded plaque (6 cm X 6 cm x 0.4 cm) made of a wholly aromatic thermotropic... 

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