Atomically Resolved Graphitic Surfaces in Air by Atomic Force Microscopy
Atomically Resolved Graphitic Surfaces in Air by Atomic Force Microscopy
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DOI：
10.1021/nn501696q
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发表时间：
2014-05-01
期刊：
影响因子：
17.1
通讯作者：
Giessibl, Franz J.
中科院分区：
文献类型：
--
作者：
Wastl, Daniel S.;Weymouth, Alfred J.;Giessibl, Franz J.
在生物相容性环境中使用原子力显微镜进行原子尺度成像是一个持续的挑战。我们展示了碳化硅上石墨和插氢石墨烯在空气中的原子分辨率。主要挑战来自整体表面清洁度和几乎所有表面上形成的水层。为了进一步研究水层的影响，我们将亲水性块状硅尖端与疏水性块状蓝宝石尖端获取的数据进行了比较。虽然两种尖端材料在中等相互作用力下都可以实现原子分辨率，但与尖端和样品上的水层相关的力与距离光谱存在很大差异。在非常低的尖端样品相互作用力下成像可以观察到氢插层石墨烯上自然存在的条纹结构的大平台。这种结构之前已在环境条件下未被无序吸附物覆盖的石墨表面上报道过（即在石墨和 SiC 上的双层石墨烯上，但不在 SiC 上的单层石墨烯上）。这两个观察结果都表明氢。插层石墨烯接近于周围环境中的理想石墨烯样品。
Imaging at the atomic scale using atomic force microscopy in biocompatible environments is an ongoing challenge. We demonstrate atomic resolution of graphite and hydrogen-intercalated graphene on SiC in air. The main challenges arise from the overall surface cleanliness and the water layers which form on almost all surfaces. To further investigate the influence of the water layers, we compare data taken with a hydrophilic bulk-silicon tip to a hydrophobic bulk-sapphire tip. While atomic resolution can be achieved with both tip materials at moderate interaction forces, there are strong differences in force versus distance spectra which relate to the water layers on the tips and samples. Imaging at very low tip sample interaction forces results in the observation of large terraces of a naturally occurring stripe structure on the hydrogen-intercalated graphene. This structure has been previously reported on graphitic surfaces that are not covered with disordered adsorbates in ambient conditions (i.e., on graphite and bilayer graphene on SiC, but not on monolayer graphene on SiC). Both these observations indicate that hydrogen. intercalated graphene is close to an ideal graphene sample in ambient environments.