Single-atom electron energy loss spectroscopy of light elements.

Ryosuke Senga,Kazu Suenaga

doi:10.1038/ncomms8943

Ryosuke Senga, Kazu Suenaga

Open Access

https://doi.org/10.1038/ncomms8943

Copy DOI

Abstract

Light elements such as alkali metal (lithium, sodium) or halogen (fluorine, chlorine) are present in various substances and indeed play significant roles in our life. Although atomic behaviours of these elements are often a key to resolve chemical or biological activities, they are hardly visible in transmission electron microscope because of their smaller scattering power and higher knock-on probability. Here we propose a concept for detecting light atoms encaged in a nanospace by means of electron energy loss spectroscopy using inelastically scattered electrons. In this method, we demonstrate the single-atom detection of lithium, fluorine, sodium and chlorine with near-atomic precision, which is limited by the incident probe size, signal delocalization and atomic movement in nanospace. Moreover, chemical shifts of lithium K-edge have been successfully identified with various atomic configurations in one-dimensional lithium compounds.

Highlights

Light elements such as alkali metal or halogen are present in various substances and play significant roles in our life
Imaging single atoms of light element by means of transmission electron microscopy (TEM) has two major difficulties compared with heavier elements: the smaller scattering power, e
The detection of light elements as single atoms demonstrated here was made possible by taking advantage of a ‘cage effect’ to overcome the two major difficulties described in the introduction; the smaller scattering power and the higher knock-on probability

Summary

Na I Na I Na I Na I

Cs map Single halogen atoms such as F and Cl (Z 1⁄4 9 and 17, respectively) are detectable in a similar way. Similar to the previous case, the CsCl atomic chain is supposed to align in alternation in the DWNT (Fig. 3a). In this case, the heavier Cs atoms (Z 1⁄4 55) are clearly visible, while the Cl atoms are apparently missing in the ADF image (Fig. 3b). The intensity maxima of the Cl L-edge appear between the Cs atoms with hardly visible ADF contrast (Fig. 3d).

Results

Discussion

Methods