Quantitative analysis of scanning force microscopy data using harmonic models

The separate identification of dissipative and elastic force contributions in Atomic Force Microscopy (AFM) is discussed. We show that within a harmonic approximation the interaction of the AFM tip with the sample surface can be described by average interaction parameters, namely an effective elastic tip-sample interaction $k_{ts}$ and an effective dissipation $\alpha_{ts}$, which can be extracted in a simple way from measured data. The method is applied to force spectroscopy curves on hard and soft polymeric model surfaces. The approach enables a thorough discussion of the influence of experimental parameters on the measured data. In imaging a clear identification of phases in systems with hard-soft contrast as for instance in semicrystalline polymers is made possible.