Transmission electron images

Figure 3.7 (a) Voltammetric response of (A) bamboo MWNTs and (B) high-puritycatalystfree MWNTs in a solution containing 1 mM hydrazine in PBS. (b) Typical transmission electron image of MWNTs in which an iron metal particle sheathed by graphene layers is observed. Such impurities can lead to misinterpretations in... 

Figure 3.9 Schematic representation of the typical noncovalent CNT functionalizations and the hybrid approach by using pyrene linkers. The figure also shows transmission electron images of SWNT modified with streptavidin labeled with 10 nm gold nanoparticles that were covalently coupled to pyrene linkers that were stacked on...

Figure 2. Transmission electron images of ultramicrotomed section of the alloy coated with sol-gel with incorporated nanoparticles (a) at the coating/substrate interface (b) high-resolution image of the coating showing individual nanoparticles.

Quantum dots are detectable by SEM by topographical contrast with secondary electron imaging (SEI), compositional contrast with backscattered electron imaging (BEI), and scanning transmission electron imaging. By SEI, the quantum dots appear as particles on exposed surfaces that can resemble normal biological structures. However, the CdSe core and ZnS coating impart... 

Figure 18 shows a transmission electron image of a fraction of the cornea aoss-section. The dark spots and lines correspond... 

Transmission electron image obtained from an unirradiated A508 Gr4N steel. Note the mixed tempered martensite-tempered bainite microstructure. Several M3C and M7C3 carbides are labelled from reference 12. 

FIGURE 3.17 Schematic of scanning transmission electron imaging of metallic nanoparticles in a liquid. SOURCE Reproduced from N. de Jonge, D.B. Peckys, G.J. Kremers, and D.W. Piston, Electron microscopy of whole cells in liquid with nanometer resolution, Proceedings of the National Academy of Sc/ences 106 2159-2164, 2009. 

FIGURE 19.9 Transmission electron image of silica microspheres containing weU-ordered mesostruc-tures templated by P104 surfactant. Scale bar is 100 nm. (Reprinted from Carroll, N. S. et al. 2008. Langmuir 24 658-661. With permission.)... 

Fig. Vni-3. (a) Atomic force microscope (AFM) and (b) transmission electron microscope (TEM) images of lead selenide particles grown under arachidic acid monolayers. (Pi Ref. 57.)...

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. 

Blodgett films direct imaging by scanning tunneling microscopy and high-resolution transmission electron... 

Figure C2.17.1. Transmission electron micrograph of a Ti02 (anatase) nanocrystal. The mottled and unstmctured background is an amorjihous carbon support film. The nanocrystal is centred in die middle of die image. This microscopy allows for die direct imaging of die crystal stmcture, as well as the overall nanocrystal shape. This titania nanocrystal was syndiesized using die nonhydrolytic niediod outlined in [79].

In many ways the nanocrystal characterization problem is an ideal one for transmission electron microscopy (TEM). Here, an electron beam is used to image a thin sample in transmission mode [119]. The resolution is a sensitive fimction of the beam voltage and electron optics a low-resolution microscope operating at 100 kV might... 

Figure C2.17.4. Transmission electron micrograph of a field of Zr02 (tetragonal) nanocrystals. Lower-resolution electron microscopy is useful for characterizing tire size distribution of a collection of nanocrystals. This image is an example of a typical particle field used for sizing puriDoses. Here, tire nanocrystalline zirconia has an average diameter of 3.6 nm witli a polydispersity of only 5% 1801.

Figure C2.17.5. Transmission electron micrograph of a field of anisotropic gold nanocrystals. In tliis example, a lower magnification image of gold nanocrystals reveals tlieir anisotropic shapes and faceted surfaces [36],...

Figure C2.17.6. Transmission electron micrograph and its Fourier transfonn for a TiC nanocrystal. High-resolution images of nanocrystals can be used to identify crystal stmctures. In tliis case, tire image of a nanocrystal of titanium carbide (right) was Fourier transfonned to produce tire pattern on tire left. From an analysis of tire spot geometry and spacing, one can detennine that tire nanocrystal is oriented witli its 11001 zone axis parallel to tire viewing direction [217].

Figures 4.1 la and b, respectively, are examples of dark-field and direct transmission electron micrographs of polyethylene crystals. The ability of dark-field imaging to distinguish between features of the object which differ in orientation is apparent in Fig. 4.11a. The effect of shadowing is evident in Fig. 4.11b, where those edges of the crystal which cast the shadows display sharper contrast.

Transmission electron microscopy (tern) is used to analyze the stmcture of crystals, such as distinguishing between amorphous siUcon dioxide and crystalline quartz. The technique is based on the phenomenon that crystalline materials are ordered arrays that scatter waves coherently. A crystalline material diffracts a beam in such a way that discrete spots can be detected on a photographic plate, whereas an amorphous substrate produces diffuse rings. Tern is also used in an imaging mode to produce images of substrate grain stmctures. Tern requires samples that are very thin (10—50 nm) sections, and is a destmctive as well as time-consuming method of analysis. 

A progressive etching technique (39,40), combined with x-ray diffraction analysis, revealed the presence of a number of a polytypes within a single crystal of sihcon carbide. Work using lattice imaging techniques via transmission electron microscopy has shown that a-siUcon carbide formed by transformation from the P-phase (cubic) can consist of a number of the a polytypes in a syntactic array (41). 

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