Capabilities of modern energy dispersive X-ray spectrometry (EDS) in TEM and SEM are explored. Various materials problems were studied, including life science samples, polymers, semiconductor and magnetic nanostructures, core-shell nanoparticles, coated multiwall carbon nanotubes and impurities in graphene and meteorite material.
We discuss the optimization of the conditions important for EDS, such as the detection geometry including solid angle, take-off angle, shielding from stray radiation and suitable sample holders. Geometric optimization in combination with high beam current and aberration correction allows the fast identification of single light atoms [1].
For quantitative EDS of electron transparent samples, reaching ppm level now, the relative Cliff-Lorimer-method and the absolute Zeta-factor-method are available. To correctly interpret EDS element maps of atomic columns however, simulations of relevant scattering effects are necessary [2].
Multi-detector arrangements allow the realization of particularly large solid angles. An annular detector arrangement in SEM achieves a solid angle of more than 1sr at superb take-off angles of 50° to 70° [3]. This enables element analysis of electron transparent samples in SEM on the nm scale, including nanoparticle analysis and statistics [4] as well as fast EDS of samples with high topography, high radiation sensitivity and large areas of interest.
EDS of electron transparent samples in SEM can be combined with other complementary techniques: micro-XRF allows trace analysis and Transmission Kikuchi Diffraction offers crystallographic analysis on the nm-scale.
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[2] Forbes B D et al., Phys. Rev. B 86 (2013) 024108.
[3] R. Terborg et al., Microsc. Microanal.16 (Suppl. 2) (2010) 1302-1303.
[4] D.-V. Hodoroaba et al., IOP Conf. Ser. MSE, EMAS (2015).