Transmission electron microscopy examples

In one other example, Raman spectroscopy was employed along with FTIR spectroscopy, XPS, elemental analysis, TGA, SEM and transmission electron microscopy (TEM) to follow the compositional and structure variations of polymethylsilsesquioxane samples pyrolysed at different temperatures in an atmosphere of nitrogen [56]. At 900°C the main product was silica, with formation too of some silica oxycarbide and amorphous carbon, with Raman spectroscopy showing complementary evidence for presence of both the minor species. 

Many hydrogenation and polymerization reactions in the chemical industry are carried out with liquid-phase reactants. An example is the hydrogenation of aliphatic dinitriles to produce diamines (108,109), which are subsequently converted with adipic acid in solution and polymerized to produce linear polyamides, including nylon 6,6. Recently, the development of wet-environmental transmission electron microscopy (wet-ETEM) for direct nanoscale probing of... 

Figure 3. Example of intracellular membrane organisation a transmission electron microscopy (TEM) image of a section through the thylakoid stack from a chloroplast. (Source http //www.ru.ac.za/administrative/emu/grl0p6.htm, Reproduced with permission from Dr. R. Cross)...

If the sample is thin enough, for example a specially prepared thin section, electrons may go straight through and be detected, as well as elastically and inelastically scattered electrons which are scattered in a forward direction. These form the basis of transmission electron microscopy (TEM). 

Covering monometallic (Pd, Sn) and multimetallic (Pd-Sn, Pd-Ag) systems, several examples are presented in this chapter to illustrate the possibility offered by this chemistry to control the particle size distribution and the bimetallic interaction at a molecular level. This work is supported by a multitechnique characterization approachusing SnM6ssbauerspectroscopy,X-rayphotoelectron spectroscopy (XPS), low-energy ion spectroscopy (LEIS), and transmission electron microscopy (TEM). Catalytic performances in hydrogenation of different unsaturated hydrocarbons (phenylacetylene, butadiene) are finally discussed in order to establish structure-reactivity relationships. 

The most significant advantage of these more quantitative methods is that, in a binary system, only one sample is needed to determine the position of both phase boimdaries in a two-phase field. Further, if the alloy lies in the two-phase field over a wide range of temperatures, it is feasible that only one alloy need be used to fix the phase boundaries over this range of temperature. In a ternary system the analogous position is found with three-phase fields and, as these also define the limiting tie-lines of the three sets of two-phase fields, substantial information can be gained from the accurate determination of only one alloy. More recently transmission electron microscopy (TEM) has been used which is particularly valuable when microstructures are very fine as, for example, found in yTiAl alloys (Chen et al. 1994). 

Under the conditions of Example 5-23 the rubber phase of the end product shows an interesting micro-morphology. It consists of particles of 1-3 microns diameter into which polystyrene spheres with much lower diameters are dispersed. These included polystyrene spheres act as hard fillers and raise the elastic modulus of polybutadiene. As a consequence, HIPS with this micro-morphology has a higher impact resistance without loosing too much in stiffness and hardness. This special morphology can be visualized with transmission electron microscopy. A relevant TEM-picture obtained from a thin cut after straining with osmium tetroxide is shown in Sect. 2.3.4.14. 

Some examples of ternary alloy precursors are also shown. Their general properties were examined and their microstructures were directly observed by transmission electron microscopy. Thus, catalysts synthesized from multi-system alloys had high solubility of additional elements into a major element, and might be expected to work as new catalysts. 

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