SEM/EDS Analytical Services Using Axia ChemiSEM

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EDS is a chemical analysis technique that can be used to measure the local composition of a material. This technique collects the characteristic x-rays generated when the electron beam strikes the sample. The x-rays can be collected and measured to quantify the chemicals present. In addition, EDS chemical maps such as those shown on the left can be acquired by collecting an EDS spectrum at each point and displaying each pixel intensity as a function of the composition.

Our software can also analyze the EDS spectrum acquired at each point in a map and can find statistically significant phases present. This method uses Principal Component Analysis (PCA) to compare the shape of the EDS spectrum at each point. The software can then calculate the area fraction of each calculated phase along with the average composition of the phase and a phase map showing the distribution of the phase.

EDS can also be used to create a chemical line profile in order to measure how the elemental distribution in a sample changes across an interface.  In the example on the left, a line scan containing 50 points was collected across an interface of interest. The linescan clearly shows increasing levels of lead (Pb) and aresenic (As) in the brighter contrast region of the glass sample being analyzed.

An EDS x-ray spectrum can be collected and using advanced algorithms such as ZAF and PhiRhoZ, a semi-quantitative result can be calculated for each element present. Note that this technique works best for heavier elements such as transition metals. While EDS can detect light elements such as Carbon, Oxygen and Nitrogen, the errors in measurement of these light elements can be significant.