The Chemical Structure of a Molecule Resolved by Atomic Force Microscopy
The Chemical Structure of a Molecule Resolved by Atomic Force Microscopy
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DOI：
10.1126/science.1176210
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发表时间：
2009-08-28
期刊：
影响因子：
56.9
通讯作者：
Meyer, Gerhard
中科院分区：
文献类型：
--
作者：
Gross, Leo;Mohn, Fabian;Meyer, Gerhard
分辨单个原子一直是表面显微镜的最终目标。扫描隧道显微镜成像表面上的原子尺度特征，但解析吸附分子内的单个原子仍然是一个巨大的挑战，因为隧道电流主要对接近费米能级的局部电子态密度敏感。我们展示了前所未有的原子分辨率的分子成像探测短程化学力与使用非接触式原子力显微镜。关键的一步是功能化显微镜的尖端顶点与合适的，原子定义良好的终端，如CO分子。我们的实验结果证实了从头计算密度泛函理论计算。与理论比较表明，泡利排斥是原子分辨率的来源，而货车德瓦耳斯力和静电力只增加了一个扩散的吸引背景。
Resolving individual atoms has always been the ultimate goal of surface microscopy. The scanning tunneling microscope images atomic-scale features on surfaces, but resolving single atoms within an adsorbed molecule remains a great challenge because the tunneling current is primarily sensitive to the local electron density of states close to the Fermi level. We demonstrate imaging of molecules with unprecedented atomic resolution by probing the short-range chemical forces with use of noncontact atomic force microscopy. The key step is functionalizing the microscope's tip apex with suitable, atomically well-defined terminations, such as CO molecules. Our experimental findings are corroborated by ab initio density functional theory calculations. Comparison with theory shows that Pauli repulsion is the source of the atomic resolution, whereas van der Waals and electrostatic forces only add a diffuse attractive background.