Modeling of Tip-Cantilever Dynamics in Atomic Force Microscopy

Abstract

AbstractAtomic force microscopy (AFM) is commonly used for atomic and nanoscale surface measurements. Two operational modes of AFM exist: static mode and dynamic mode. In dynamic AFM mode, a cantilever is driven to vibrate by its holder or the sample. The changes of cantilever vibration parameters (amplitude, resonance frequency, and phase angle) due to tip-sample interaction are used to reveal surface properties. Analytical and numerical models that can accurately simulate surface-coupled cantilever dynamics are essential for explaining AFM scanning images and evaluating the sample’s material properties. In this chapter, the existing dynamic modes of AFM are categorized in terms of cantilever deflection and excitation mechanism. Cantilever models for cantilever response simulation are summarized. Using these models, the important relations of cantilever frequency shift, vibration amplitude and phase angle with tip-sample interaction in various dynamic modes are derived, with an emphasis on newly-developed torsional resonance (TR) mode and lateral excitation (LE) mode. Some specific issues, such as the excitation of higher-order vibration modes in TappingMode (TM), the effects of tip eccentricity on cantilever responses in TR and LE modes, and how the cantilever dynamics affects the atomic-scale topographic and friction maps obtained in friction force microscopy (FFM) measurements, are investigated. Based on the derived relations between cantilever responses and tip-sample interaction, methods for quantitative evaluation of the sample’s mechanical parameters are described.KeywordsAtomic Force MicroscopyGraphite SurfaceSample InteractionTorsional ResonanceFriction Force MicroscopyThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.