Electron microscopy analytical, characterization

The origins of analytical electron microscopy go back only about 15 years when the first x-ray spectra were obtained from submicron diameter areas of thin specimens in an electron microscope [1]. Characterization of catalyst materials using AEM is even more recent[2,3] but is currently a very active research area in several industrial and academic laboratories. The primary advantage of this technique for catalyst research is that it is the only technique that can yield chemical and structural information from individual submicron catalyst particles. 

Chemical Characterization of Oxide Superconductors by Analytical Electron Microscopy... 

Characterization thus involves analytical electron microscopy, ordinary microprobe analysis or other techniques for localizing elements or chemical compounds (Scanning Auger Spectroscopy, Raman Microprobe, Laser Microprobe Mass Spectrometry). It also requires, in most cases, some physical separation of the catalyst for separate analysis (e.g., near surface parts and center of pellets, by peeling or progressive abrasion pellets present at various heights in the catalyst bed, etc.). 

Most primary condensates are extremely small, ranging from 5 nm to 50 nm in diameter. Adequate characterization of such grains must rely on very high spatial resolution techniques such as transmission electron microscopy (TEM) or analytical electron microscopy (AEM). In the former technique, the emphasis is on obtaining very clear pictures of the morphology, homogeneity, elemental and mineralogical... 

Webb, S.M., Leppard, G.G., and Gaillard, J.-F., Zinc speciation in a contaminated aquatic environment Characterization of environmental particles by analytical electron microscopy, Environ. Sci. Technol., 34, 1926, 2000. 

A multifaceted characterization effort to stndy these materials as a function of thermal treatment has been undertaken. The techniques include BET surface area measurements. X-ray diffraction, chemisorption, scanning and high-resolution transmission electron microscopy, analytical electron microscopy, neutron activation analysis, atomic absorption spectroscopy, FTIR and isotopic tracer studies. The details of catalyst preparation have been previously... 

Furthermore, we investigated the effect of water on the activity of the above-mentioned sulfated zirconia catalysts and the observed activities were compared. We have extensively characterized the different catalysts by XPS, physical adsorption, analytical electron microscopy, and thermogravimetry. 

Analytical electron microscopy (AEM) was used to determine if there were any microstructural differences between the samples crept In nitrogen and air, A low magnification micrograph of the general microstructure of the sample crept In air is shown in Fig. 12. Overall, the bulk structure appeared the same In both samples, There was no cavitation observed, The grain boundary phase was crystalline and the composition was found to be very close to that determined for the sample crept in nitrogen. No aluminum was observed in the crystallized pockets. Characterization (X-ray and AEM) of the sample crept in air Is ongoing,... 

Ceramic characterization 30-32 range from a process as simple as determining the bulk density of a green powder compact from its mass and dimensions, to a process as complicated as identifying the composition and structure of a submicron size crystal in a dense ceramic matrix using analytical electron microscopy (AEM). Some of the important characteristics evaluated during ceramic consolidation are outlined in Figure 5.2. 

Gallezot P, Leclercq C. Characterization of catalysts by conventional and analytical electronic microscopy. In Imelik B, Vedrine JC, editors. Catalyst characterization, physical techniques for solid materials, fundamental and applied catalysis. Heidelberg Springer 1994. p. 509-58. 

Analytical electron microscopy (AEM) (characterization) A combination of transmission electron microscopy (TEM) and electron diffraction. 

Analytical investigations may be undertaken to identify the presence of an ABS polymer, characterize the polymer, or identify nonpolymeric ingredients. Fourier transform infrared (ftir) spectroscopy is the method of choice to identify the presence of an ABS polymer and determine the acrylonitrile—butadiene—styrene ratio of the composite polymer (89,90). Confirmation of the presence of mbber domains is achieved by electron microscopy. Comparison with available physical property data serves to increase confidence in the identification or indicate the presence of unexpected stmctural features. Identification of ABS via pyrolysis gas chromatography (91) and dsc ((92) has also been reported. 

The structure of the catalysts was characterized by X-ray diffraction, IR-spectroscopy and transmission electron microscopy, their thermal stability was followed by thermal analytical method. The specific surface area and pore size distribution of the samples were determined by nitrogen adsorption isotherms. 

---