Transient Force Atomic Force Microscopy: A New Nano-Interrogation Method

Atomic force microscopes (AFMs) are the primary investigation systems at the nanoscale. In existing dynamic mode AFM methods steady-state response of microcantilever is monitored for imaging tip-surface interaction forces at the nano-scale. In these methods microcantilevers with high quality factor are employed for high force sensitivity but at the cost of speed due to dependence on steady-state signals. In this paper, a novel methodology for fast interrogation of material that exploits the transient part of the cantilever response is presented. This method effectively addresses the perceived fundamental limitation on bandwidth due to high quality factors. Analysis and experiments show that the method results in significant increase in bandwidth and resolution as compared to the steady-state-based methods. This paper demonstrates the effectiveness of a systems perspective to the field of imaging at the nano-scale and for the first time reports real-time imaging at the nanoscale using the transient method with scan speed 40 times faster than conventional methods.