Nonlinear Tapping-Tip Dynamics in Atomic Force Microscopy

Tapping or intermittent contact atomic force microscopy (AFM) is widely used scanning probe techniques for high resolution imaging, manipulation and nanolithography. The presence of van der Waals forces and nanoscale impacts render highly nonlinear the dynamics of the AFM microcantilever while it operates in the tapping mode. A comprehensive nonlinear analysis of the nonlinear dynamics of AFM microcantilevers tapping on a nanostructure using the theoretical and computational tools of modern nonlinear dynamics has not yet been presented. Also, a rational connection between certain features of the tip-sample interaction potential and the nonlinear response has not been established satisfactorily. To address this problem, we have combined both experimental and nonlinear computational analysis of the tapping response of a microcantilever as a function of the excitation frequency. We show that this approach enables a comprehensive understanding of the nonlinear dynamic behavior observed in AFM experiments.