Feedback-induced instability in tapping mode atomic force microscopy: theory and experiment
Feedback-induced instability in tapping mode atomic force microscopy: theory and experiment
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DOI：
10.1098/rspa.2010.0451
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发表时间：
2011-06-08
影响因子：
3.5
通讯作者：
Miles, M. J.
中科院分区：
文献类型：
--
作者：
Payton, O.;Champneys, A. R.;Miles, M. J.
我们研究了敲击模式原子力显微镜 (AFM) 的数学模型，其中包括通过范德华力和弯月面力进行的表面相互作用。我们还特别注意真实地表达真实显微镜固有的积分控制。独立地改变驱动幅度、幅度设定点和驱动频率表明该模型可以捕获在平坦样品和校准网格上的 AFM 实验中观察到的定性特征。特别是，该模型可以预测不稳定的发生，即使是在平坦的样本上，也可以观察到大振幅的跳动型运动。实验结果证实了这一点，也证实了模拟所暗示的动力学的定性特征。模拟还揭示了打浆效应背后的机制。控制环路过度补偿足够高的增益。该数学模型还用于提供有效使用 AFM 的建议，以避免出现不必要的伪影。
We investigate a mathematical model of tapping mode atomic force microscopy (AFM), which includes surface interaction via both van der Waals and meniscus forces. We also take particular care to include a realistic representation of the integral control inherent to the real microscope. Varying driving amplitude, amplitude setpoint and driving frequency independently shows that the model can capture the qualitative features observed in AFM experiments on a flat sample and a calibration grid. In particular, the model predicts the onset of an instability, even on a flat sample, in which a large-amplitude beating-type motion is observed. Experimental results confirm this onset and also confirm the qualitative features of the dynamics suggested by the simulations. The simulations also suggest the mechanism behind the beating effect; that the control loop over-compensates for sufficiently high gains. The mathematical model is also used to offer recommendations on the effective use of AFMs in order to avoid unwanted artefacts.