Visualizing and identifying single atoms using electron energy-loss spectroscopy with low accelerating voltage


Visualizing atoms and discriminating between those of different elements is a goal in many analytical techniques. The use of electron energy-loss spectroscopy (EELS) in such single-atom analyses is hampered by an inherent difficulty related to the damage caused to specimens by incident electrons. Here, we demonstrate the successful EELS single-atom spectroscopy of various metallofullerene-doped single-wall nanotubes (known as peapods) without massive structural destruction. This is achieved by using an incident electron probe with a low accelerating voltage (60 kV). Single calcium atoms inside the peapods were unambiguously identified for the first time using EELS. Elemental analyses of lanthanum, cerium and erbium atoms were also demonstrated, which shows that single atoms with adjacent atomic numbers can be successfully discriminated with this technique.

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Figure 1: Endohedral metallofullerenes and their peapods.
Figure 2: STEM–EELS analysis of a Ca metallofullerene peapod.
Figure 3: Element-selective imaging of single La and Er atoms.
Figure 4: Single-atom spectroscopy for La and Ce.


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This work was supported by the Japan Science and Technology Agency—Core Research for Evolutional Science and Technology.

Author information




K.S. and K.K. designed and conceived the experiments. H.K. and T.O. contributed the specimens. H.S., T.S., K.O., T.T., T.K. and Y.K. designed and developed the microscope. K.S., Y.S. and Z.L. analysed data and co-wrote the paper.

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Correspondence to Kazu Suenaga.

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Suenaga, K., Sato, Y., Liu, Z. et al. Visualizing and identifying single atoms using electron energy-loss spectroscopy with low accelerating voltage. Nature Chem 1, 415–418 (2009).

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