For reliable EDS quantification, the accurate knowledge of the sample and the detector geometry is imperative. However, for materials with rough topography, it is difficult to know the local sample geometry at the point where spectrum is acquired. One approach to improve the quantification is to acquire several spectra with sample rotation. This will blur the effect of sample topography on quantification, giving results closer to the stoichiometric concentration.
Fig. 1 presents the SE image of a ternary alloy with rough sample topography and certified concentration values (Element A = 33.4 %, B = 41.3 % and C = 25.3 % in mass percent). To evaluate the material composition, five point-spectra were acquired on the sample surface (Fig. 1a). The sample was rotated by 180˚, and five point-spectra are acquired additionally, nearly at the same location as before (Fig. 1b). The averaged spectra gave the composition of the material: Element A = 33.5 %, B = 40.8 % and C = 25.7 % which are very close to the certified concentration. A convenient way to measure rough surface is to use Bruker's unique EDS XFlash® FlatQUAD detector.