Backscattered electron imaging BEI

Figure 2.1. A backscattered electron image (BEI) of synthesized eucrites cut perpendicular to axis of the rod. It shows a basaltic texture, composed of fine-grained pyroxene (px) and plagioclase (pi). Note that there is a strong preferred orientation in the direction of rod axis, v vesicle.

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 12. Backscattered electron image (BEI) of a polished cross-section of a commercial bicomponent glass fiber (4000x). Courtesy of Micron Inc., Analytical ivices, Wilmington, DE.

Scanning Electron Microscopy (SEM) Secondary Electron Imaging (SEI) Backscattered Electron Imaging (BEI) Transmission Electron Microscopy (TEM) Scanning Transmission Electron Microscopy (STEM) Scanning Tunneling Microscopy (STM) Atomic Force Microscopy (AFM) Frictional Force Microscope (FFM). 

The backscattered electron image is produced from signals coming from almost the same excitation volume as the x-ray signal (Fig. 2.3). This is helpful, as BEI can be used to scan the specimen quickly for atomic number differences to guide the slower x-ray mapping. 

Polymer matrices are also commonly reinforced with mineral fillers or fibers, such as calcium carbonate, talc, wollastonite, clay and mica [306]. SE images of fracture surfaces show the wetting behavior or adhesion of the filler by the polymer matrix. Figure 4.34 shows secondary electron image (A) and backscattered electron image (B) micrographs of a mineral filler in a matrix of a commercial polymer. SEI does not reveal the nature of the filler in the matrix whereas BEI does reveal the mineral filler due to atomic number contrast. BE imaging is important in the... 

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