Transmission electron staining, examples

One major problem of all these techniques is the sensitivity in the parameter selected to detect the presence of inhomogeneities. With visible light for example, inhomogeneous samples can appear transparent if the difference in the refractive index between the phases is less than 0.01. Staining (in the case of transmission electron microscopy, TEM), or chemical etching (in the case of scanning electron microscopy, SEM), can be helpful in revealing the structure. 

Figure 2. Molecular organization of coronin 1. A) Transmission electron micrographs of affinity-purified and negatively stained coronin 1 (coronin lA) complexes isolated from macrophages. The gallery shows multiple examples of the trimeric structure. Scale bar, 10 nm. From. B) Cartoon presenting the organization of the coronin 1 trimer deduced from the image analysis.

Fig. 12.12 Some examples of diblock copolymer morphologies. Transmission electron micrographs of stained samples of (a) the lamellar phase of a polystyrene-polyisoprene (PS-PI) diblock with PS fraction 0.64 (b) the hexagonal phase of a PS-poly(2-vinylpyridene) diblock with fps = 0.35 and (c) and (d) the gyroid phase of a PS-PI diblock with fps = 0.39, showing projections with approximate threefoid and fourfoid symmetries, respectiveiy. Aii sampies were rapidiy cooied from the meit and thus exhibit the meit-state morphoiogy. (Reprinted with permission from the American Chemicai Society.)...

Electron stains, used in the preparation of material for electron microscopy, are described as electron-dense as they interfere with the transmission of electrons. Examples are lead citrate, phosphotungstic acid (PTA), and uranyl acetate (UA). 

High-powered microscopes can be used to reveal the internal structure, e.g. an interpenetrating phase, which is impossible to see with the naked eye. The normal technique used to observe phase boundaries under normal light is optical microscopy. However, as some blends have very tiny components, other more powerful techniques are required, i.e. transmission electron microscopy, scanning electron microscopy and atomic force microscopy. It should be noted that in order to see the structures clearly, preliminary treatments are sometimes necessary, for example etching or staining." ... 

Another use of microscopy is the study of competitive materials, which is similar to doing failure analysis as the full nature of the material is not known. In this example, the question was to learn the nature of the process used to make a dual ovenable food tray. Transmission electron microscopy cross sections, stained with... 

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