Transmission electron microscopy fringe images

The length and the diameter of MWCNT can be measured directly by TEM. From high-resolution transmission electron microscopy (HRTEM) images exhibiting oo.l fringes follows the number of coaxial tubes and possibly the microstructure of the caps in MWCNT, as viewed along the incident electron beam [24], Also anomalous intercylinder spacings and defects are revealed in this way [1,11]. 

Figure 7.26 A transmission electron microscopy lattice image of a growth microtwin in an InSb epitaxial layer. The mirror (twin) planes are marked and one set of lattice fringes are highlighted to emphasize the mirror reflection.

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. 

FIGURE 15.1 High-resolution transmission electron microscopy images of CNTs. (a) SWNT (b) MWNT (c) closed MWNT tips (MWNT tips) and (d) closed SWNT tip. The separation between the closely spaced fringes in the MWNT (b, c) is 0.34 nm, close to the spacing between graphite planes. The diameter of the SWNT (a, d) is 1.2nm. (Reprinted with permission from [8]. Copyright (1999) American Chemical... 

Chemical Modifications to Pitch. The earlier attempts to improve the commercial value of pitch residues must have been essentially exploratory research. Sanada et al, (71) in 1973 methylated the hydroxyl groups of 3,5-dimethyl phenol formaldehyde resin and noted, on carbonization, the formation of spheres of mesophase, the original resin giving an optical texture of mosaics in resultant carbons. Mochida et al. (72) carbonized naphthalene, anthracene and pyrene with aluminium chloride, sodium and potassium and examined the structure of the resultant carbons by optical microscopy and high resolution, fringe-imaging transmission electron microscopy (TEM),... 

Using transmission electron microscopy the lattice fringe image can be seen. Also the scanning electron microscopy image showed that the montmoriilonite layer structures still remained after Si-heterostructure and no occluded clay by SiOj is observed. The results further indicate the expansion of the basal spacing. 

Images Using High-Resolution, Fringe-imaging Transmission Electron Microscopy, Marsh et al. (1982), Figure 3.21 (a c)... 

In all microscopy a primary concern is the spatial resolution that can be obtained. If the details are points, the resolution may be specified as point to point resolution. An object with regularly repeating details such as a set of lines will give a different value for resolution. Convenient test objects are ruled lines in optics and lattice fringes (sheets of atoms) in transmission electron microscopy. Near the resolution limit an image will be formed with reduced contrast. A precise measure of resolution requires a quantitative test to determine if the detail can be distinguished. 

High resolution transmission electron microscopy (TEM) was further used to confirm the results described above. Figure 12.14 shows the TEM images of the catalyst after stable operation and after the aging stress test. While the catalyst after stable operation only shows the lattice fringes of anatase covered by a layer of amorphous vanadium oxide surface species, the stressed catalyst shows a more complex structure. The core of the support oxide particle still shows the lattice fringes of anatase, but lattice distances of rutile can be seen in a surface-near layer around... 

Figure 3 shows a high-resolution transmission electron microscopy (HR f EM) image of a typical boron nanowire. No ciystalline fringes can be identified in the HR f EM image at the lattice-resolved scale. This indicates that the boron nanowires are amorphous. No diffraction spots, but some diffuse rings, shown in the selected area electron diffraction (SAED) pattern [Fig. 3, inset] from the boron nanowire, further confirm the amorphous nature of the boron wires. The boron nanowire is sheathed by an amorphous oxide coating that is formed when the boron nanowires are exposed to air after deposition. The chemiced characterization of the boron nanowires using EELS shows that the boron nanowire is composed of boron with neglectable traces of oxygen [Fig. 4]. Quantitative EELS studies reveal that the total content of oxygen in the boron wire is less than 5%.

Fig. 13. a Off-axis electron holographic transmission microscopy by means of an electron biprism, the image and the reference waves are superimposed (taken from [32]), b electron hologram example with 0.075 nm fringes modulated according to amplitude and phase of the wave for Nb205... 

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