Elemental mapping is carried out by using EDS. EDS (or EDX ) can analyse a single spot to give a spectrum that provides information about what elements are present and the quantities of each. However, if you analyse an area rather than a spot by raster scanning that area, and taking a spectrum at each point, you can build up an areal distribution of the elements present in the sample. An energy window needs to be defined for each element of interest (this can be manual or automatic depending on software). Then if counts are detected in that energy window for a given point in the scan then a corresponding pixel in the X-ray map for that element is given brightness. These eventually build up to create a map. It takes time.
Elemental mapping is carried out by using EDS. EDS (or EDX ) can analyse a single spot to give a spectrum that provides information about what elements are present and the quantities of each. However, if you analyse an area rather than a spot by raster scanning that area, and taking a spectrum at each point, you can build up an areal distribution of the elements present in the sample. An energy window needs to be defined for each element of interest (this can be manual or automatic depending on software). Then if counts are detected in that energy window for a given point in the scan then a corresponding pixel in the X-ray map for that element is given brightness. These eventually build up to create a map. It takes time.
Ian gives a very good explanation. An elemental map on an SEM is really nothing more than a series of EDS analyses spread across a pre-defined area of your sample. It uses the intensities of the peaks from each element at each point to color in a map showing where that element is most abundant. You can analyze for several elements at once, and produce maps of the distribution of each element across the same area.
Map may be interpreted as an image formed using signal provided by characteristic radiation of a given element. Brighter pixel = greater concentration of the element. Something like image in SE or BSE, except that for maps brightness is usually coded by pseudo colors.
Another point to bear in mind when mapping is peak overlaps. It is very easy to misinterpret a simple X-ray element map. For example we have studied heavy mineral suites which contain zircon (ZrSiO4) and fluorapatite (Ca5(PO4)3F). But the La line for Zr is 2.042 keV and the Ka line for P is 2.012 keV. Any energy window created for P will overlap that of Zr.
So the simple X-ray maps for P and Zr will appear identical and you will not be able to distinguish the zircon from the apatite from this alone. In these cases is in essential to perform spectral deconvolution at each pixel to remove peak overlaps in order to see the true elemental distribution.
Other well known overlaps are Na Ka and Zn La, Al Ka and Br La, Si Ka and W Ma, S Ka and Mo La and Pb Ma, Ti Ka and Ba La. If your systems contain any of these combinations beware of simple X-ray maps.
Sorry, I realize that the question is long overdue. Just indicate the difference.
In SEM X-rays are induced by the bombardment with electron. The EDS, EDAX or EDX is just the quantification. So whether you irradiate a small size, normally called point analyses and of the area 20 nm by4 micrometer or any area of 5 by 5 micrometers square, it is still EDS. the difference is not in the analysis but in the amount of information one obtains. thus with mapping one can discern, at times, the compositions of elements.Eg in the analysis of bone, one can obtain the correlation on concentration between Ca and P over a wide area and not just a single point.
Hope this helps. Please let me know.
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