Basic properties of dynamic force spectroscopy with the scanning force microscope in experiment and simulation

Cantilever dynamics characterizing the operation of a scanning force microscope (SFM) in the dynamic mode at high oscillation amplitudes were investigated in experiment and computer simulation. Measuring the oscillation amplitude of the probing tip and the phase-shift between the during force and the cantilever response a a function of the tip-sample distance allows us to analyse the dynamic interaction of the SFM tip with the sample surface. We call this process dynamic force spectroscopy (DFS). Computer simulations were applied to analyse discontinuities observed in experimental DFS curves. The investigations show that a sudden change in the amplitude signal and even more pronounced in the phase signal on approaching the tip is related to the transition from a non-contact oscillation (pure attractive interaction) to the tapping mode (attractive as well as repulsive interaction).