Borca B, Calleja F, Hinarejos J J, Vázquez de Parga A L, Miranda R
Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain.
J Phys Condens Matter. 2009 Apr 1;21(13):134002. doi: 10.1088/0953-8984/21/13/134002. Epub 2009 Mar 12.
We report here the reactivity of epitaxial graphene islands and complete monolayers on Ru(0001) towards molecular oxygen and air. The graphene is prepared by thermal decomposition of ethylene molecules pre-adsorbed on an Ru(0001) surface in an ultra-high vacuum chamber. The graphene layer presents a periodically rippled structure that is dictated by the misfit between graphene and Ru(0001) lattice parameters. The periodic ripples produce spatial charge redistribution in the graphene and modifies its electronic structure around the Fermi level. In order to investigate the reactivity of graphene we expose graphene islands to a partial pressure of oxygen and following the evolution of the surface by STM during the exposure. For the exposure to air we removed the sample from the UHV chamber and we re-introduce it after several hours, taking STM images before and after. The surface areas not covered by the graphene islands present a dramatic change but the graphene structure, even the borders of the islands, remain intact. In the case of a complete graphene monolayer the exposure to oxygen or to air does not affect or destroy the rippled structure of the graphene monolayer.
我们在此报告外延石墨烯岛以及Ru(0001)上的完整单层石墨烯对分子氧和空气的反应活性。石墨烯是通过在超高真空腔室中热分解预先吸附在Ru(0001)表面的乙烯分子制备而成。石墨烯层呈现出周期性的波纹结构，这是由石墨烯与Ru(0001)晶格参数之间的失配所决定的。周期性波纹在石墨烯中产生空间电荷重新分布，并改变其费米能级附近的电子结构。为了研究石墨烯的反应活性，我们将石墨烯岛暴露于氧气分压下，并在暴露过程中通过扫描隧道显微镜（STM）跟踪表面的变化。对于暴露于空气中的情况，我们将样品从超高真空腔室中取出，数小时后重新放入，并在前后拍摄STM图像。未被石墨烯岛覆盖的表面区域发生了显著变化，但石墨烯结构，甚至岛的边界，仍保持完整。在完整石墨烯单层的情况下，暴露于氧气或空气中不会影响或破坏石墨烯单层的波纹结构。
