Intermittent contact resonance atomic force microscopy
Gheorghe Stan, Richard S. Gates
The intermittent contact resonance atomic force microscopy (ICR-AFM) mode proposed here is a new frequency modulation technique performed in scanning force controlled AFM modes like force volume or peak force tapping. It consists of tracking the change in the resonance frequency of an eigenmode of an AFM vibrated cantilever during scanning as the AFM probe intermittently contacts a surface at a controlled applied maximum force (setpoint). A high speed data capture was used during individual oscillations to obtain detailed contact stiffness-force curve measurements on a two-phase polystyrene/poly(methyl methacrylate) film with sub-micrometer size domains. Through a suitable normalization, the measurements were analyzed by linear fits to provide an improved quantitative characterization of these materials in terms of their elastic moduli and adhesive properties.