CEMES-CNRS, Centre d'élaboration des matériaux et d'études structurales, 29 rue Jeanne-Marvig, BP 94347, F-31055 Toulouse Cedex 4, France.
Beilstein J Nanotechnol. 2012;3:301-11. doi: 10.3762/bjnano.3.34. Epub 2012 Apr 2.
Characterization at the atomic scale is becoming an achievable task for FM-AFM users equipped, for example, with a qPlus sensor. Nevertheless, calculations are necessary to fully interpret experimental images in some specific cases. In this context, we developed a numerical AFM (n-AFM) able to be used in different modes and under different usage conditions.
Here, we tackled FM-AFM image calculations of three types of graphitic structures, namely a graphite surface, a graphene sheet on a silicon carbide substrate with a Si-terminated surface, and finally, a graphene nanoribbon. We compared static structures, meaning that all the tip and sample atoms are kept frozen in their equilibrium position, with dynamic systems, obtained with a molecular dynamics module allowing all the atoms to move freely during the probe oscillations.
We found a very good agreement with experimental graphite and graphene images. The imaging process for the deposited nanoribbon demonstrates the stability of our n-AFM to image a non-perfectly planar substrate exhibiting a geometrical step as well as a material step.
配备 qPlus 传感器等设备的调频原子力显微镜用户现在能够实现原子级的特征描述。然而，在某些特定情况下，仍需要计算来全面解释实验图像。在这种情况下，我们开发了一种可用于不同模式和不同使用条件的数值原子力显微镜（n-AFM）。
在这里，我们对三种石墨结构的调频原子力显微镜图像进行了计算，分别是石墨表面、碳化硅衬底上的石墨烯片和硅终止表面，以及石墨烯纳米带。我们比较了静态结构，即所有针尖和样品原子都保持在其平衡位置，以及通过允许所有原子在探针振动过程中自由移动的分子动力学模块获得的动态系统。
我们发现与实验石墨和石墨烯图像非常吻合。对于沉积的纳米带的成像过程证明了我们的 n-AFM 能够稳定地对具有几何台阶和材料台阶的非完美平面衬底进行成像。
