Transmission electron applied

Several structural characterisations of carbon nanotubes (CNTs) with the cylindrical graphite are reviewed from the viewpoint of transmission electron microscopy (TEM). Especially, electron energy loss spectroscopy (EELS) by using an energy-fdtered TEM is applied to reveal the dependence of fine structure of EELS on the diameter and the anisotropic features of CNTs. 

High Resolution Transmission Electron Microscopy (HRTEM, Philips CM20, 200 kV) was applied to get structural and nanotextural information on the fibers, by imaging the profile of the aromatic carbon layers in the 002-lattice fringe mode. A carbon fiber coated with pyrolytic carbon was incorporated in epoxy resin and a transverse section obtained by ultramicrotomy was deposited on a holey carbon film. An in-house made image analysis procedure was used to get quantitative data on the composite. 

The contribution by Rouzaud et al. teaches to apply a modified version of high resolution Transmission Electron Microscopy (TEM) as an efficient technique of quantitative investigation of the mechanism of irreversible capacity loss in various carbon candidates for application in lithium-ion batteries. The authors introduce the Corridor model , which is interesting and is likely to stimulate active discussion within the lithium-ion battery community. Besides carbon fibers coated with polycarbon (a candidate anode material for lithium-ion technology), authors study carbon aerogels, a known material for supercapacitor application. Besides the capability to form an efficient double electric layer in these aerogels, authors... 

Tomography was applied during Transmission Electron Microscopy (TEM) analysis of various reduced Au/zeolite samples. The size and location of the gold nanoparticles as a function of the support characteristics and preparation method are discussed. 

Ffirai and Toshima have published several reports on the synthesis of transition-metal nanoparticles by alcoholic reduction of metal salts in the presence of a polymer such as polyvinylalcohol (PVA) or polyvinylpyrrolidone (PVP). This simple and reproducible process can be applied for the preparation of monometallic [32, 33] or bimetallic [34—39] nanoparticles. In this series of articles, the nanoparticles are characterized by different techniques such as transmission electronic microscopy (TEM), UV-visible spectroscopy, electron diffraction (EDX), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) or extended X-ray absorption fine structure (EXAFS, bimetallic systems). The great majority of the particles have a uniform size between 1 and 3 nm. These nanomaterials are efficient catalysts for olefin or diene hydrogenation under mild conditions (30°C, Ph2 = 1 bar)- In the case of bimetallic catalysts, the catalytic activity was seen to depend on their metal composition, and this may also have an influence on the selectivity of the partial hydrogenation of dienes. 

The forty-eighth volume of Advances in Catalysis includes a description of a new and increasingly well understood class of catalysts (titanosilicates), a review of transmission electron microscopy and related methods applied to catalyst characterization, and summaries of the chemistry and processes of isobutane-alkene alkylation and partial oxidation and C02 reforming of methane to synthesis gas. 

Some typical transmission electron micrographs of these polystyrene lattices are shown (Sample 2 and Sample 3) in Figure 10.6. The effects ofthe amount of stabilizer S is the relative amount of stabilizer) on the particle size is strong the more stabilizer applied, the smaller the particles are. It must be emphasized that this effective stabilization of nanopowders by our fluorinated block copolymers is not restricted to polymerization processes, but can be generalized to the fabrication of all organic nanopowders in media with low cohesion energy density, e.g., to the dispersion of dyes, explosives, or drugs. 

Equations (8.43) suggest that the image width is zero when g.b = 0. This is of course the classic criterion, originally applied to transmission electron... 

To characterize dendrimers, analytical methods used in synthetic organic chemistry as well as in macromolecular chemistry can be applied. Mass spectrometry and NMR spectroscopy are especially useful tools to estimate purity and structural perfection. To get an idea of the size of dendrimers, direct visualization methods such as atomic force microscopy (AFM) and transmission electron microscopy (TEM), or indirect methods such as size exclusion chromatography (SEC) or viscosimetry, are valuable. Computer aided simulation also became a very useful tool not only for the simulation of the geometry of a distinct molecule, but also for the estimation of the dynamics in a dendritic system, especially concerning mobility, shape-persistence, and end-group disposition. 

In contrast transmission electron microscopy (TEM) can in skilled hands yield detailed quantitative data on pore structure, and can even provide valuable information on the wet state of resins by plunge freezing such samples and microtom-ing on a cold stage [105]. To obtain quantitative information it is necessary to use advanced image analysis methodology which is extremely powerful [106]. Unfortunately the approach is time consuming and costly and can rarely be applied routinely in morphology studies. 

This approximation, known as the "ratio method" (16), is particularly attractive for applications in solid-state chemistry because it should apply under the normal working conditions of a transmission electron microscope. If the approximation holds, then a determination of k using any well-characterised compound containing x and y will then afford a simple method for measuring the x y ratio in any other compound. This approach will be illustrated below with the results obtained for some standards... 

An example of a study in which this approach was applied involved the use of a transmission electron microscopy (TEM) grid as the collector plate in the electrostatic precipitator (Witkowski et a ., 1988). After sample collection, analysis by TEM (vide infra) could then be carried out. 

Another, more often applied, method is the irradiation of matrices with neutrons or charged particles (electrons, a-particles, heavy ions). Advantages of this method include short time of irradiation (min or h) direct visibility of structural damage (observed in situ during irradiation using a transmission electron microscope) and... 

Numerous techniques have been applied for the characterization of StOber silica particles. The primary characterization is with respect to particle size, and mostly transmission electron microscopy has been used to determine the size distribution as well as shape and any kind of aggregation behavior. Figure 2.1.7 shows a typical example. As is obvious from the micrograph, the StOber silica particles attract a great deal of attention due to their extreme uniformity. The spread (standard distribution) of the particle size distribution (number) can be as small as 1%. For particle sizes below SO nm the particle size distribution becomes wider and the particle shape is not as perfectly spherical as for all larger particles. Recently, high-resolution transmission electron microscopy (TEM) has also revealed the microporous substructure within the particles (see Fig. 2.1.8) (51), which is further discussed in the section about particle formation mechanisms. 

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