TRIMODAL TAPPING-MODE ATOMIC FORCE MICROSCOPY: A POSSIBLE METHOD FOR SIMULTANEOUS MEASUREMENT OF CONSERVATIVE AND DISSIPATIVE INTERACTIONS

摘要

Multifrequency Atomic Force Microscopy (AFM) techniques, where the cantilever oscillation is measured and sometimes driven at multiple frequencies, have become an active research topic in recent years. This is in part because these methods can provide increased compositional contrast during surface characterization. Since 2004 bimodal AFM imaging has been used extensively to complement the information that can be obtained using the standard single-frequency tapping-mode operation. More recently we have implemented a trimodal tapping-mode scheme, in which we have incorporated a frequency-modulated third eigenmode into bimodal tapping-mode operation in order to acquire topography, phase and frequency shift information simultaneously. We have also studied numerically the effect of different levels of sample stiffness, tip-sample dissipative forces, oscillation amplitudes for each of the eigenmodes and cantilever rest positions above the sample on the frequency response of the higher eigenmodes in bimodal and trimodal operations. Here we explore the ability to separate conservative and dissipative effects using the different channels available in trimodal overation.