Typical transmission electron microscope

The history of EM (for an overview see table Bl.17,1) can be interpreted as the development of two concepts the electron beam either illuminates a large area of tire sample ( flood-beam illumination , as in the typical transmission electron microscope (TEM) imaging using a spread-out beam) or just one point, i.e. focused to the smallest spot possible, which is then scaimed across the sample (scaiming transmission electron microscopy (STEM) or scaiming electron microscopy (SEM)). In both situations the electron beam is considered as a matter wave interacting with the sample and microscopy simply studies the interaction of the scattered electrons. 

As mentioned above, employment of MWCNT for field emitter will be one of the most important applications of MWCNT. For this purpose, MWCNT is prepared by the chemical purification process [30,38], in which graphite debris and nanoparticles are removed by oxidation with the aid of CuCl2 intercalation [38]. Purified MWCNT is obtained in the form of black and thin "mat" (a flake with thickness of ca. a few hundreds of [im). Figure 7 shows a typical transmission electron microscope (TEM) picture of MWCNT with an open end, which reveals that a cap is etched off and the central cavity is exposed. 

The structure and the surface morphology of the nanocomposite samples were studied using the atomic force microscopy (Solver P-47) and transmission electron microscopy (PEM-100) techniques. Analysis showed that the samples contained the uniformly distributed nanopartides of used materials with sizes of 10-25 nm. Figure 7.2 presents the typical transmission electron microscope image of a nanocomposite sample containing 5% nanopartides MnO. As can be seen, MnO particles are situated on the sample surface. These particles are distributed quite uniformly and have dimensions of about 10 nm, but not exceeding 20 nm. 

Transmission electron microscopic observaiion reveals various morphologies of precipitates depending upon the constituents and composition of an alloy system, history of heat treatments etc. Typical examples are spherical precipitates found in Nl-Cr-Al system and cuboidal precipitates in Fe-Mo system [1]. The first question raised is what determines the shape of a precipitate. 

The hybridization of carbon atoms is the major structural parameter controlling DLC film properties. Electron energy loss spectroscopy (EELS) has been extensively used to probe this structural feature [5. 6]. In a transmission electron microscope, a monoenergetic electron beam is impinged in a very thin sample, being the transmitted electrons analyzed in energy. Figure 27 shows a typical... 

Normally, substrates are impermeable and deposits are held out on the surface. However, some years ago, workers Q) at Xerox observed, while depositing selenium onto flexible plastic substrates, that "good", continuous films were grown except under certain circumstances when the deposit took the form of particles. Examination of these deposits revealed that the particles were spherical, fairly uniform in size and, most remarkable, were organized into a monolayer array just beneath the surface of the substrate. Figure 2 shows a top view of a typical deposit as observed using the transmission electron microscope. There are usually the order of 109 particles per cm of deposit. 

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