随机噪声激励下轻敲式原子力显微镜动力学特性研究

Dynamic analysis of tapping mode atomic force microscopy under random noise excitation

针对有界随机噪声激励下轻敲式原子力显微镜(AFM:Atomic force microscope)系统的非线性动力学问题,建立Lennard-Jones力场作用下针尖-样品的集总参数模型,应用现代微分方程和分岔理论,分析了随机扰动强度和弯月面接触角对AFM针尖-样品耦合系统动力学特性的影响。结果表明,轻敲式AFM耦合动力学系统中存在丰富的周期运动和混沌运动,表现出复杂的非线性行为,混沌特性随着随机扰动强度增大而增强,弯月面接触角越大混沌特性越明显,因此在轻敲式AFM优化设计中,随机噪声对AFM系统的影响不可忽视。

The nonlinear dynamic behavior of tapping mode atomic force microscope（AFM） under bounded random noise excitation was investigated.The microcantilever was modeled as a lumped-parameter model and the interaction between the microcantilever and sample was described by the Lennard-Jones（LJ） potential.Effects of the density of random disturbance and the contact angle of meniscus force on the dynamic system were analyzed and discussed.The results indicate that various periodic and chaotic motions occur in the coupled dynamic AFM system,and the dynamic system goes through a complex nonlinear behavior.As the density of the random disturbance and the contact angle of meniscus force increase,more and more chaotic components occur in the dynamic AFM system.It demonstrates that the effect of random noise cannot be ignored in the optimization design of tapping mode AFM.