Graphene investigated by dynamic non-contact atomic force microscopy

该项目的目的是利用动态非接触原子力显微镜（NC-AFM）的方法研究单层和双层石墨烯薄片的原子分辨率。三个中心目标是：1。通过动态NC-AFM成像和从介观到原子尺度的3D力场光谱测量，以最高精度确定石墨烯的详细表面和界面结构。特别是，我们的目标是详细比较单层和双层石墨烯的结构和机械性能。此外，我们希望研究源自几何缺陷（如五边形环）、原子空位或单一吸附物的原子局部应变对石墨烯纳米力学性能的影响。纳米力学性能（例如有效弹性模量）的评估将通过精确测量原子尖锐AFM尖端的机械响应来进行，这些机械响应是从原子分辨率的3D力场光谱中提取的。利用同步动态NC-AFM成像和三维力场光谱测量，利用三维空间分辨率的能量损失声发射测量来评估原子缺陷及其与软振动模式的相关性。特别是，我们将研究原子缺陷的类型和位置与软振动模式的局部激发之间的关系。考虑到碳层的数量、二维晶体域的大小、由于存在缺陷而存在的原子局域应变以及石墨烯与衬底的电子耦合程度，局部电子和静电特性与电子传输的相关性。

The aim of the project is the investigation of mono- and bi-layer graphene flakes with atomic resolution using the method of dynamic non-contact atomic force microscopy (NC-AFM). The three central goals are:1. The determination of the detailed surface and interface structure of graphene with the highest accuracy by means of dynamic NC-AFM imaging and 3D force-field spectroscopy measurements on mesoscopic down to atomic scales. In particular, we aim at a detailed comparison of structural and mechanical properties between mono- and bi-layers of graphene. Furthermore, we would like to study the influence of atomically-localized strain, originating from geometrical defects (e.g. pentagonal rings), atomic vacancies, or single adsorbates, on the nanomechanical properties of graphene. The evaluation of the nanomechanical properties (e.g. effective elastic modulus) will be performed by precise measurements of the mechanical responses to the atomically sharp AFM tip as extracted from 3D force-field spectroscopy with atomic resolution.2. The evaluation of atomic defects and their correlation with soft vibrational modes by means of energy-loss AE measurements with threedimensional spatial resolution, using simultaneous dynamic NC-AFM imaging and 3D force-field spectroscopy measurements. In particular, we will investigate the relationship between types and locations of atomic defects and local excitations of soft vibrational modes.3. The correlation of local electronic and electrostatic properties with electron transport, taking into account the number of carbon layers, the size of two-dimensional crystal domains, the presence of atomically-localized strain due to the presence of defects, and the degree of the electronic coupling of graphene to the substrate.