COMP Centre of Excellence, Department of Applied Physics, Aalto University, Helsinki FI-00076, Finland.
Nanotechnology. 2016 Oct 14;27(41):415709. doi: 10.1088/0957-4484/27/41/415709. Epub 2016 Sep 9.
Frequency modulation atomic force microscopy (FM-AFM) experiments were performed on the calcite (10[Formula: see text]4) surface in pure water, and a detailed analysis was made of the 2D images at a variety of frequency setpoints. We observed eight different contrast patterns that reproducibly appeared in different experiments and with different measurement parameters. We then performed systematic free energy calculations of the same system using atomistic molecular dynamics to obtain an effective force field for the tip-surface interaction. By using this force field in a virtual AFM simulation we found that each experimental contrast could be reproduced in our simulations by changing the setpoint, regardless of the experimental parameters. This approach offers a generic method for understanding the wide variety of contrast patterns seen on the calcite surface in water, and is generally applicable to AFM imaging in liquids.
调频原子力显微镜（FM-AFM）实验在纯净水中对方解石（10[Formula: see text]4）表面进行，对各种频率设定点的二维图像进行了详细分析。我们观察到了在不同实验和不同测量参数下重复出现的八种不同的对比模式。然后，我们使用原子分子动力学对相同的系统进行了系统的自由能计算，以获得针尖-表面相互作用的有效力场。通过在虚拟 AFM 模拟中使用这个力场，我们发现，通过改变设定点，可以在我们的模拟中再现每个实验对比，而不管实验参数如何。这种方法为理解在水中的方解石表面上看到的各种对比模式提供了一种通用的方法，并且通常适用于液体中的 AFM 成像。
