TEM image analysis method

Besides the molecular probe method using gas adsorption,107 162 recently, the TEM image analysis method163"167 has been applied to evaluate the surface fractal dimension of porous materials. The most attractive fact in this method is that the pores in different size ranges can be extracted from the TEM images which include contributions from many different pore sizes by the inverse fast Fourier transform (FFT) operation by selecting the specific frequency range.165 167... 

Several simple relations have been proposed for the determination of the fractal dimensions from the results of such experiments as gas molecular probe method, transmission electron microscopy (TEM), small-angle X-ray scattering, neutron scattering, and laser light scattering.63,66,113 116 Among those techniques, gas molecular probe method and image analysis method have been widely used for the calculation of the surface... 

Even if they are usually called primary particles, spheres that constitute aggregate are partially fused together and never exist by themselves. Anyway, their size is of great importance because it defines the actual surface of interaction between carbon black and elastomeric phase the lower the size of primary particles, the higher the interface extension. Primary particle size distribution has been estimated by TEM image analysis, but carbon black surface area is usually more efficiently obtained by adsorption methods (see later section on surface area). 

Walter and Bryant [414] described a method for freeze drying latex specimens in a home made vacuum system rather than a commercially available device (as was typical of the state of the art at that time). Later, a freeze drying/image analysis method using commercially available equipment was described [413]. Important details of that method included specimen preparation, placement onto a TEM (or SEM) grid, the hardware for the experiment and the metal coating. 

Figure 9.4. Characterization of mesoporous Si02 films with cylindrical mesopores (ca. 3nm in diameter) templated using Brij 58 surfactant TEM image a), 2D GISAXS pattern with crystallographic indexation b), and SRSAXS/XRR analysis c).The experimental data in c) thus correspond to a detailed scan along the sz axis in b), using a suitable diffractometer. The films were prepared according to Ref. 39 and analyzed by the methods described therein.

X-ray powder diffraction (XRD) patterns of the sample were recorded on a Rigaku D/Max 2400 X-ray diffractometer with Cu-Ka radiation (X=0.15418nm). The surface areas and pore diameters were measured by BET and BJH methods on a Micromeritics ASAP 2010 Sorptometer. Before analysis, the sample was degassed at 423K and 1.07xl0 3 KPa for 12h. The TEM image was obtained on a JEM-100C transmission microscope. The TG analysis was carried out on a DuPont 1090 Thermal Analyzer. 

TEM images of Ir/TiOz prepared by DP at 3 and 5 pH are also shown in Fig.5 (c) and (d). In the case of these catalysts, aggregates of clusters and small clusters were respectively deposited as the major species on the TiOz surfaces. This result and that of ICP analysis produce good evidence that the amount of loading and the structure of the Ir can be controlled by changing the pH of the precursor solution while using the DP method. 

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