Department of Physics, University of Alberta, Edmonton, Alberta, Canada T6G 2J1.
National Institute for Nanotechnology, National Research Council of Canada, Edmonton, Alberta, Canada T6G 2M9.
Nat Commun. 2017 Feb 13;8:14222. doi: 10.1038/ncomms14222.
The origin of bond-resolved atomic force microscope images remains controversial. Moreover, most work to date has involved planar, conjugated hydrocarbon molecules on a metal substrate thereby limiting knowledge of the generality of findings made about the imaging mechanism. Here we report the study of a very different sample; a hydrogen-terminated silicon surface. A procedure to obtain a passivated hydrogen-functionalized tip is defined and evolution of atomic force microscopy images at different tip elevations are shown. At relatively large tip-sample distances, the topmost atoms appear as distinct protrusions. However, on decreasing the tip-sample distance, features consistent with the silicon covalent bonds of the surface emerge. Using a density functional tight-binding-based method to simulate atomic force microscopy images, we reproduce the experimental results. The role of the tip flexibility and the nature of bonds and false bond-like features are discussed.
键分辨原子力显微镜图像的起源仍然存在争议。此外，迄今为止的大多数工作都涉及到金属基底上的平面共轭碳氢化合物分子，从而限制了对成像机制得出的发现的普遍性的了解。在这里，我们报告了一个非常不同的样品的研究；一个氢终止的硅表面。定义了获得钝化氢官能化尖端的程序，并显示了在不同尖端高度下原子力显微镜图像的演变。在相对较大的尖端-样品距离下，最上面的原子表现为明显的突出物。然而，随着尖端-样品距离的减小，与表面硅共价键一致的特征出现了。使用基于密度泛函紧束缚的方法来模拟原子力显微镜图像，我们再现了实验结果。讨论了尖端的灵活性以及键和假键样特征的性质的作用。
