The intensities of low energy X-rays in EDS measurements can be reduced by the X-ray absorption in carbon contaminants on the EM specimens (see Figure 1730). All their intensities decrease with the thickness of the carbon contaminants due to X-ray absorption except for carbon itself. The intensity of carbon X-ray increases due to the increase of its thickness. Table 1730 lists their k-ratios affected by 10 nm layer of carbon contaminants as a function of the accelerating voltage of the electron beam.

Table 1730. k-ratios affected by 10 nm layer of carbon contaminants. [1]

Figure 1730. Normalized intensities of C K_α, Si K_α, N K_α, and O K_α lines of X-rays.

[1] D. G. Rickerby, Barriers to energy dispersive spectrometry with low energy X-rays, Microbeam and Nanobeam Analysis, edited by Daniele Benoi, 1996.