title: Direct determination of the chemical bonding of individual impurities in graphene.
abstract: Using a combination of Z-contrast imaging and atomically resolved electron energy-loss spectroscopy on a scanning transmission electron microscope, 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 sp(2) d-like hybridization, whereas threefold coordinated Si in graphene adopts the preferred sp(3) hybridization. The conclusions are confirmed by first-principles calculations and demonstrate that chemical bonding of two-dimensional materials can now be explored at the single impurity level.
authors.affiliation: Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA. wu.zhou@vanderbilt.edu
authors.forename: Wu
authors.initials: W
authors.lastname: Zhou
authors.forename: Myron D
authors.initials: MD
authors.lastname: Kapetanakis
authors.forename: Micah P
authors.initials: MP
authors.lastname: Prange
authors.forename: Sokrates T
authors.initials: ST
authors.lastname: Pantelides
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Pennycook
authors.forename: Juan-Carlos
authors.initials: JC
authors.lastname: Idrobo