Backscattered electrons, information obtained

Figure 4.16 Comparison between (a) a secondary electron image and (b) a backscattered electron image for the same area of nickel alloy. Additional compositional information is obtained from the backscattered image. (Reproduced with kind permission of Springer Science and Business Media from J.I. Goldstein et al, Scanning Electron Microscopy and X-ray Microanalysis, 2nd ed., Plenum Press, New York. 1992 Springer Science.)...

Scanning transmission electron microscopy (STEM) uses X-ray backscattering analysis to obtain information on the size, morphology, and chemical composition of the active components on support materials (Fig. 5-47). 

Energy-dispersive X-ray (EDX) spectroscopy utilizes the characteristic spectrum of X-rays that is emitted by a sample, following initial excitation by the high-energy electron beam. Information about the elemental composition of the sample can be obtained, where the spatial resolution is determined by the probe size, any beam broadening occurring within the specimen, and the effects of any backscattered electrons on the specimen around the point of analysis. EDX is relatively simple and can be used to provide rapid qualitative microanalysis. Quantitative elemental analysis can also be achieved, with an... 

In transmission electron microscopy (TEM), a beam of highly focused and highly energetic electrons is directed toward a thin sample (< 200 nm) which might be prepared from solution as thin film (often cast on water) or by cryocutting of a solid sample. The incident electrons interact with the atoms in the sample, producing characteristic radiation. Information is obtained from both deflected and nondeflected transmitted electrons, backscattered and secondary electrons, and emitted photons. 

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