Electron microscopy chemical analysis

Analyses of insertion electrodes include structural analysis by XRD, neutron diffraction, HRTEM with electron diffraction, chemical analysis by EDAX, XPS and dissolution followed by ICP, morphological analysis by electron microscopy, surface area measurements by gas adsorption, and electrochemical analysis by voltammetry chronopotentiometry (primary techniques) and fine electrochemical tools such as EIS, PITT, GITT, and... 

Coupling FFF with other techniques can enhance measurement capabilities. Here, the possibility of taking fractions after the FFF separation is of great advantage. The use of photon correlation spectroscopy, for example, to determine the size of spheres eluted from sedimentation FFF yields both size and density [75]. Further comparison can be achieved with electron microscopy. In principle, every analytical technique (spectroscopy, microscopy, chemical analysis, etc.) can be performed off-line on fractions from FFF. 

M.S. Anderson and W.T. Pike, Chemical Imaging with a Raman Atomic-Force Microscope, Electron Microscopy and Analysis 2001 (Institute of Physics Conference Series, 2001) Chap. 168. 

The presence of two independent waves and rather low velocities of burning have allowed to stop the thermochemical reaction by fast dumping of pressure from reactor (chill). With the help of electronic microscopy, chemical and X-ray phase methods of the analysis, the products of reaction of chill samples were established. Chemical stages of process were studied, the mechanism of interaction of components in researched systems was found out. 

The problem of chemical analysis is most topical for the mixtures of inorganic solids. Physical diffraction and spectroscopic methods prevail here XRD, IR, Raman spectroscopy, NGR, NMR, and electron microscopy. Chemical methods of phase analysis play only a minor part now. 

In fact, other synthetic methods for colloidal metal particles have been developed in the early 20th century, both physical or chemical, until the fundamental work of Turkevitch in 1951 [16]. Interestingly, he started a systematic study of gold nanoparticle (NP) synthesis with various methods by using transmission electron microscopy (TEM) analysis to optimise the preparative conditions until obtaining what is commonly known as the Turkevitch method. 

The analysis of siUcon carbide involves identification, chemical analysis, and physical testing. For identification, x-ray diffraction, optical microscopy, and electron microscopy are used (136). Refinement of x-ray data by Rietveld analysis allows more precise deterrnination of polytype levels (137). 

The combined use of energy-dispersive X-ray spectroscopy and TEM/STEM is a routine method of analytical electron microscopy enabling both qualitative and quantitative chemical analysis of interfaces and interlayers with high lateral resolution. Reso-... 

Analytical electron microscopy permits structural and chemical analyses of catalyst areas nearly 1000 times smaller than those studied by conventional bulk analysis techniques. Quantitative x-ray analyses of bismuth molybdates are shown from lOnm diameter regions to better than 5% relative accuracy for the elements 61 and Mo. Digital x-ray images show qualitative 2-dimensional distributions of elements with a lateral spatial resolution of lOnm in supported Pd catalysts and ZSM-5 zeolites. Fine structure in CuLj 2 edges from electron energy loss spectroscopy indicate d>ether the copper is in the form of Cu metal or Cu oxide. These techniques should prove to be of great utility for the analysis of active phases, promoters, and poisons. 

Analytical electron microscopy (AEM) permits elemental and structural data to be obtained from volumes of catalyst material vastly smaller in size than the pellet or fluidized particle typically used in industrial processes. Figure 1 shows three levels of analysis for catalyst materials. Composite catalyst vehicles in the 0.1 to lOim size range can be chemically analyzed in bulk by techniques such as electron microprobe, XRD, AA, NMR,... 

Analytical electron microscopy (AEM) can use several signals from the specimen to analyze volumes of catalyst material about a thousand times smaller than conventional techniques. X-ray emission spectroscopy (XES) is the most quantitative mode of chemical analyse in the AEM and is now also useful as a high resolution elemental mapping technique. Electron energy loss spectroscopy (EELS) vftiile not as well developed for quantitative analysis gives additional chemical information in the fine structure of the elemental absorption edges. EELS avoids the problem of spurious x-rays generated from areas of the spectrum remote from the analysis area. 

Thus we shall be concerned with properties that furnish information about the nature of the ligands, the oxidation state of the metal, and the geometry of the field of ligands. Techniques such as radio-isotope tracer studies, neutron-activation analysis, and electron microscopy are powerful methods for locating a metal within constituents of the cell and are particularly suited to heavy-metal rather than organic drugs but since they do not provide information about the chemical environment of the metal they will not concern us here. After each section below we shall give an example, not necessarily from platinum chemistry, where the method has been used with success in biochemistry. 

Jose-Yacaman, M. and J. A. Ascencio (2000), Electron microscopy and its application to the study of archaeological materials and art preservation, in Ciliberto, E. and G. Spoto (eds.), Modern Analytical Methods in Art and Archaeology, Chemical Analysis Series, Vol. 155, Wiley, New York, pp. 405-443. 

---