Harnessing the transient signals in atomic force microscopy

In the existing dynamic-mode operation of atomic force microscopes (AFMs) steady-state signals like amplitude and phase are used for detection and imaging of material. Due to the high quality factor of the cantilever probe the corresponding methods are inherently slow. In this paper, a novel methodology for fast interrogation of material that exploits the transient part of the cantilever motion is developed. This method effectively addresses the perceived fundamental limitation on bandwidth due to high quality factors. It is particularly suited for the detection of small time scale tip-sample interactions. Analysis and experiments show that the method results in significant increase in bandwidth and resolution as compared to the steady-state-based methods. This article demonstrates the effectiveness of a systems perspective to the field of imaging at the nano-scale and for the first time reports realtime experimental results and scanning applications of the transient method.