Dispersion beam damage

Many of the preparations noted for SEM and TEM also can cause artifacts for microanalysis in these same instruments. Note the various factors in Table 7.8 that describe the details and limits of energy and wavelength dispersive microanalysis. Contamination can cause problems, especially in the case of light element analysis. The source of foreign material is usually organic material on the specimen surface or in the vacuum system. The polymer microscopist has the added difficulty of working with polymers that are often the source of the contamination as the electron beam damages... 

Thus far, IL has mainly been applied to detect rare-earth dements, and it is reasonable to assume that it could equally be applied to these dements dispersed in polymer matrices. It is feasible also that analysis of the light given off by polymers when irradiated by ion beams could be of value in understanding the mechanisms of beam damage processes. 

With direct observation, the sample must be kept cold in the electron microscope, and care is required to prevent sample damage in the beam and to prevent microscope contamination. In addition, these frozen samples are often difficult to image because of charging effects that distort the image. The benefit of this extra care in sample handling, however, is that electron beam interactions with the sample produce characteristic X-ray signals that allow identification of components of the emulsion being observed. This technique has been refined to the point where, in special cases, chemical compositional differences at the emulsion interface can be identified, as well as the composition of the dispersed and continuous phases 109, 110),... 

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