ABSTRACT
‘Mapping’ in the scanning transmission electron microscopy (STEM) means displaying in two dimensions the distribution of (usually) an element or elements in a region of a sample. Although mapping is frequently not quantitative, it is a very commonly used data acquisition technique. Digital mapping, as implemented on the majority of STEMs today, relies on control of the probe position on the specimen by the computer which is also processing the X-rays. A number of windows corresponding to the X-rays of interest are defined and each window’s map is stored separately. The digital method provides faster response but there is a limit to the number of possible windows. Clearly, the maps for all the elements are acquired simultaneously, unlike dot-mapping where the specimen must be scanned for each element. Since all the maps (and images) are acquired during a single scan, they are of course in perfect register, even if the image is not absolutely stable.
