Dynamics of atomic force microscopes: experiments and simulations

This paper focuses on how AFM in-contact dynamics change with amplitude of disturbance, i.e. sample surface topography, and force set-point. The models presented by El Rifai et al. (2000, 2001) were used to compare simulations to experimental results. The models were able to reproduce experimental behavior observed in frequency response data and AFM images. Three main effects were observed, namely, changes in the DC gain, in modal damping, and in the pole-zero pattern. The results were analyzed and explanations were provided. These large changes in the dynamics of the AFM impose a challenge on its feedback system. It requires a controller that provides robust performance to ensure high fidelity of data and reduce image artifacts. Consequently, the selection of scan parameters should be tied-in to controller parameters to achieve potentially higher levels of performance.