Department of Physics, Tampere University of Technology, PO Box 692, FI-33010 Tampere, Finland.
Nanotechnology. 2011 Jan 28;22(4):045702. doi: 10.1088/0957-4484/22/4/045702. Epub 2010 Dec 15.
In this paper we use simulations to investigate the role of the tip in nc-AFM measurements of dissipated energy. Using a virtual AFM we simulate the experiment focusing on the atomic scale energy dissipation on an NaCl(100) flat surface. The non-conservative interaction was treated with the theory of dynamic response and all the calculations were carried out using an atomistic model; several sets of tips were tested using ionic crystals (NaCl, KBr, MgO), each in different configurations (ideal, vacant, divacant, doped). Using an MgO-doped tip we were able to calculate a dissipation signal comparable to what is typically measured in experiments. It was not possible to see any dissipation with ideal tips, although they still have a significant interaction with the surface and give atomic contrast in the frequency shift signal. The effect of the scanning speed on measured frequency shift and dissipation is also calculated and discussed.
在本文中，我们使用模拟来研究尖端在 nc-AFM 测量耗散能中的作用。我们使用虚拟 AFM 模拟了实验，重点关注 NaCl(100) 平坦表面上的原子级能量耗散。非保守相互作用采用动态响应理论进行处理，所有计算均使用原子模型进行；使用离子晶体（NaCl、KBr、MgO）测试了几组尖端，每种晶体都采用不同的构型（理想、空位、双空位、掺杂）。使用掺杂 MgO 的尖端，我们能够计算出与实验中通常测量到的耗散信号相当的信号。虽然理想尖端与表面仍有显著的相互作用，并在频率位移信号中给出原子对比度，但无法观察到任何耗散现象。还计算并讨论了扫描速度对测量的频率位移和耗散的影响。
