EDS/WDS Measurements of Sulfur (S)
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Table 1384 lists the main lines of sulfur (S) used in EDS analysis. However, it is very often that the S K line overlaps with X-ray lines from other elements, e.g. molybdenum (Mo).
Table 1384. Main lines of sulfur (S) used in EDS analysis.
It is very general to use SEM-EDS and TEM-EDS techniques to qualitatively map the distribution of sulfur in structures and nanoparticles. However, quantification of sulfur content using EDS technique is very challenging because:
For MoS2, the overlap between the L series peaks of Mo and the S Kα peak is very pronounced: only a broadened peak with a tail towards the high energy end can be seen with EDS. Figure 1384 shows the sulfur and molybdenum peaks overlap in the EDS spectrum, but are separated and sharp in the WDS spectrum.
INCA EDS software is used to extract the maps in Figure 1384b.
As discussed on page4650, X-ray absorption is a function of the energy of X-rays. Low energy peaks will be more strongly absorbed than high energies ones. For thick TEM samples, k-factor correction due to X-ray absorption is needed in order to accurately quantify EDS measurements. Table 1384 lists S-examples of thicknesses at which the thin-film approximation is no longer valid due to X-ray absorption effects in specific materials.