Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA.
Phys Rev Lett. 2012 Nov 16;109(20):206803. doi: 10.1103/PhysRevLett.109.206803. Epub 2012 Nov 15.
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.
利用扫描透射电子显微镜中的 Z 衬度成像和原子分辨电子能量损失谱，我们证明了单个杂质原子的化学键合可以通过实验推断出来。我们发现，当硅原子与石墨烯中的双空位位点上的四个原子键合时，Si 3d 轨道对成键有显著贡献，导致平面 sp(2) d 型杂化，而石墨烯中配位为三配位的硅则采用优选的 sp(3)杂化。这些结论得到了第一性原理计算的证实，并表明现在可以在单个杂质水平上探索二维材料的化学键合。
