CVD graphene grown on metallic substrates presents, in several cases, a long-range periodic structure due to a lattice mismatch between the graphene and the substrate. For instance, graphene grown on Ir(111), displays a corrugated supercell with distinct adsorption sites due to a variation of its local electronic structure. This type of surface reconstruction represents a challenging problem for a detailed atomic surface structure determination for experimental and theoretical techniques. In this work, we revisited the surface structure determination of graphene on Ir(111) by using the unique advantage of surface and chemical selectivity of synchrotron-based photoelectron diffraction. We take advantage of the Ir 4f photoemission surface state and use its diffraction signal as a probe to investigate the atomic arrangement of the graphene topping layer. We determine the average height and the overall corrugation of the graphene layer, which are respectively equal to 3.40 ± 0.11 Å and 0.45 ± 0.03 Å. Furthermore, we explore the graphene topography in the vicinity of its high-symmetry adsorption sites and show that the experimental data can be described by three reduced systems simplifying the Moiré supercell multiple scattering analysis.

中文翻译：

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选择“方便的观察者”通过光电子衍射探测 Ir(111) 上 CVD 石墨烯的原子结构

由于石墨烯和基板之间的晶格失配，在一些情况下，在金属基板上生长的 CVD 石墨烯呈现出长程周期性结构。例如，在 Ir(111) 上生长的石墨烯由于其局部电子结构的变化而显示出具有不同吸附位点的波纹状超级电池。这种类型的表面重建对于实验和理论技术的详细原子表面结构确定来说是一个具有挑战性的问题。在这项工作中，我们利用基于同步加速器的光电子衍射的表面和化学选择性的独特优势，重新审视了石墨烯在 Ir(111) 上的表面结构测定。我们利用 Ir 4f 光发射表面态并使用其衍射信号作为探针来研究石墨烯顶层的原子排列。我们确定石墨烯层的平均高度和整体波纹，分别等于 3.40 ± 0.11 Å 和 0.45 ± 0.03 Å。此外，我们探索了其高对称吸附位点附近的石墨烯形貌，并表明实验数据可以通过三个简化的系统来描述，从而简化了莫尔超晶胞多重散射分析。