Scanning electron microscopy mapping

Because of the instrumental requirements, these are usually not routine monitoring techniques. However, unlike other methods, they give detailed information on particle shapes. In addition, chemical composition information can be obtained using transmission electron microscopy (TEM) or scanning electron microscopy (SEM) combined with energy-dispersive spectrometry (EDS). The electron beam causes the sample to emit fluorescent X-rays that have energies characteristic of the elements in the sample. Thus a map showing the distribution of elements in the sample can be produced as the electron beam scans the sample. 

Lawrence, J. R., Swerhone, G. D. W., Leppard, G. G., Araki,T., Zhang, X., West, M. M., and Hitchcock, A. P. (2003). Scanning transmission X-ray, laser scanning, and transmission electron microscopy mapping of the exopolymeric matrix of microbial biofilms. Appl. Environ. Microbiol. 69,5543-5554. 

Figure 9-6 The scanning electron microscopy (SEM) in the backscattered mode, the energy dispersive X-ray (EDX) spectrum and X-ray distribution maps of a spherical particle from Sudbury soil showing Ni and Fe microstructures in a silicate matrix (from Adamo et al., 1996).

Figure 22 Si02 supported, MAO-activated zirconocene catalyst grains, Scanning Electron Microscopy (SEM) micrograph and element mapping by Energy-Dispersive X-ray Microanalysis.

Fig. 15.7 (a) Scanning electron microscopy (SEM) image of two intersected ZnO nanobelts. Raman intensity map of two nanobelts shown in (a), (b) E2 mode, (c) Ai(TO) mode, (d) Boolean map of the full width at the half maximum of the E2 mode, (e) intensity map of the silicon signal at 520 cm showing the modulation in different belts, (f) Schematic shows the waveguiding of the Raman scattered light from the substrate along the c-axis (Reprinted from [44])... 

A. Bansal, R.R. Biederman, Y.H. Ma and W.M. Clark, Protein adsorption and fouling of ceramic membranes as measured by scanning electron microscopy with digital X-ray mapping. Chem. Eng. Comm., 108 (1991) 365. 

As new membranes are developed, methods for characterization of these new materials are needed. Sarada et al. (34) describe techniques for measuring the thickness of and characterizing the structure of thin microporous polypropylene films commonly used as liquid membrane supports. Methods for measuring pore size distribution, porosity, and pore shape were reviewed. The authors employed transmission and scanning electron microscopy to map the three-dimensional pore structure of polypropylene films produced by stretching extended polypropylene. Although Sarada et al. discuss only the application of these characterization techniques to polypropylene membranes, the methods could be extended to other microporous polymer films. Chaiko and Osseo-Asare (25) describe the measurement of pore size distributions for microporous polypropylene liquid membrane supports using mercury intrusion porosimetry. 

For surface structure studies, perhaps the most popular technique has been LEED (373). Elastically diffracted electrons from a monoenergetic beam directed to a single-crystal surface reveal structural properties of the surface that may differ from those of the bulk. Some applications of LEED to electrocatalyst characterization were cited in Section IV (106,148,386). Other, less specific, but valuable surface examination techniques, such as scanning electron microscopy (SEM) and X-ray microprobe analysis, have not been used in electrocatalytic studies. They could provide information on surface changes caused by reaction, some of which may lead to catalyst deactivation (256,257). Since these techniques use an electron beam, they can be coupled with previously discussed methods (e.g. AES or XPS) to obtain a qualitative mapping of the structure and composition of a catalytic surface. 

After being removed from the centrifuge, samples were examined and analyzed by optical microscopy, scanning electron microscopy (SEM), x-ray mapping, computerized image analysis, and x-ray diffraction analysis (XRD). 

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