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O: Fachverband Oberflächenphysik

O 3: Scanning Probe Techniques: Method Development I

O 3.6: Vortrag

Montag, 20. März 2017, 11:45–12:00, TRE Phy

Sensing complex tip-surface interactions with multifrequency AFM — •Daniel Platz^{1, 2}, Daniel Forchheimer², and David B. Haviland² — ¹Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Straße 38, 01187 Dresden, Germany — ²KTH Royal Institute of Technology, Albanova University Center, 10691 Stockholm, Sweden

In recent years multifrequency atomic force microscopy (AFM) revealed its potential to overcome limitations in the spatial and compositional resolution of conventional force microscopy methods. Conventionally tip-surface interactions are considered as functions of the tip position only, so-called force curves. However, especially for soft materials tip-surface interactions often depend on the tip velocity and the past tip trajectory. Here, we introduce a compact and general description of these interactions appropriate to dynamic AFM where the measurement of force is restricted to a narrow frequency band. We represent the tip-surface interaction in terms of a force disk in the phase space of position and velocity. Determination of the amplitude dependence of tip-surface forces at a fixed static probe height allows for a comprehensive treatment of conservative and dissipative interactions. We illuminate the fundamental limitations of force reconstruction with narrow band dynamic AFM and we show how the amplitude dependence of the Fourier component of the force at the tip oscillation frequency, gives insight into the detailed nature of the tip-surface interaction and allows for a quantitative force reconstruction.