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Direct Determination of the Chemical Bonding of Individual Impurities in Graphene

 

Wu Zhou, Myron D. Kapetanakis, Micah P. Prange, Sokrates T. Pantelides, Stephen J. Pennycook, and Juan-Carlos Idrobo, Physical Review Letters 109, 206803 (2012).


The atomic and electronic structure of individual Si impurities bonded to three or four carbon atoms in graphene are revealed by Z-contrast imaging, electron energy-loss spectroscopy using an aberration-corrected scanning transmission electron microscope in combination with density functional theory calculations.

Using a combination of Z-contrast imaging and atomically resolved electron energy-loss spectroscopy on a scanning transmission electron microscope in combination with density functional theory calculations, we show that the chemical bonding of individual impurity atoms can be deduced experimentally. We find that when a Si atom is bonded with four atoms at a double-vacancy site in graphene, Si 3d orbitals contribute significantly to the bonding, resulting in a planar sp2d-like hybridization, whereas threefold coordinated Si in graphene adopts the preferred sp3 hybridization. The present study1 suggests that it would be possible in the near future to reveal the bonding characteristic of individual atoms in molecules and other low-dimensional materials using low-voltage aberration-corrected scanning transmission electron microscopy.


 Oak Ridge National Laboratory