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Individual heteroatom identification with X-ray spectroscopy

Individual heteroatoms in nanoscale materials often play a pivotal role in materials properties. To obtain maximum control over materials properties, researchers must be able to detect and identify diverse heteroatoms in samples with varying thickness and composition. Here, we demonstrate the identification of individual Si, S, P, and Ca heteroatoms in two-phase carbonaceous nanoscale mixtures with energy dispersive X-ray spectroscopy in a scanning transmission electron microscope. In order to fully demonstrate the robustness of the technique and the potential advantages over electron energy loss spectroscopy for single-atom speciation, no a priori constraint was placed on the sample thickness or types of heteroatom species. The various heteroatoms were identified with X-ray spectrum collection times ranging from 8 to 57 s, and normalized count rates of 0.096–0.007 counts s-1 pA-1. The lowest times/highest effective count rates were achieved by maximizing the effective dwell time on the atom, through minimizing the oversampling area of the electron beam raster.

Authors:

R. M. Stroud,1,a) T. C. Lovejoy,2 M. Falke,3 N. D. Bassim,1 G. J. Corbin,2 N. Dellby,2 P. Hrncirik,2 A. Kaeppel,3 M. Noack,3 W. Hahn,3 M. Rohde,3,b) and O. L. Krivanek2

1 Materials Science and Technology Division, Naval Research Laboratory, 4555 Overlook Ave. South West, Wash. D.C. 20375, USA

2 Nion Co., 11511 NE 118th St., Kirkland, Wash. 98034, USA

3 Bruker Nano GmbH, Am Studio 2D, 12489 Berlin, Germany


© Author(s) 2016. (CC BY) Applied Physics Letters 108, 163101 (2016).

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