Discriminating short-range from van der Waals forces using total force data in noncontact atomic force microscopy
Discriminating short-range from van der Waals forces using total force data in noncontact atomic force microscopy
复制标题
使用非接触原子力显微镜中的总力数据区分短程力和范德华力
DOI：
10.1103/physrevb.89.235417
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发表时间：
2014
影响因子：
3.7
通讯作者：
Philipp Rahe
中科院分区：
文献类型：
--
作者：
Stefan Kuhn;Philipp Rahe
非接触式原子力显微镜 (NC-AFM) 能够以最高的空间分辨率和灵敏度测量力，以亚分子分辨率分辨皮牛顿量级的力。然而，测量到的总力是由各种相互作用组成的混合物。虽然通过仔细的实验设计可以排除一些相互作用，例如静电力或磁力，但范德华力的减去仍然是一个挑战，范德华力主要源于宏观尖端柄和大块样品之间的伦敦色散相互作用。我们通过拟合合适的模型来确定总相互作用力数据中固有存在的范德华力，从而提取短程力分量。我们根据方解石表面的实验相互作用数据比较了几种范德华模型的适用性。批判性地讨论了将这些模型与实验数据拟合的可行性。我们还引入了基于横向和垂直力数据的方差来评估从纯远程相互作用到混合短程和远程力的过渡点的标准。这一确定使我们能够提取短程相互作用力，这在 NC-AFM 实验中迄今为止仍然是一个挑战。
Noncontact atomic force microscopy (NC-AFM) features the measurement of forces with highest spatial resolution and sensitivity, resolving forces of the order of pico-Newtons with submolecular resolution. However, the measured total force is a mixture composed of various interactions. While some interactions such as electrostatic or magnetic forces can be excluded by a careful design of the experiment, the subtraction of van der Waals forces, which mainly originate from London dispersion interactions between the macroscopic tip shank and the bulk sample, remains a challenge. We present the determination of the inherently present van der Waals forces in total interaction force data from fitting a suitable model, allowing for extraction of the short-range force component. We compare the applicability of several van der Waals models based on experimental interaction data from the calcitesurface. The feasibility to fit these models to experimental data is critically discussed. We furthermore introduce criteria to assess the transition point from pure long-range interaction to mixed short- and long-range forces based on the variance of lateral and vertical force data. This determination allows us to extract the short-range interaction forces, which remained a challenge so far in NC-AFM experiments.