ABSTRACT
However, the details of the damping mechanism in the tapping mode are still controversial, and so is the interpretation of the phase, or even the topography data obtained in this mode [14, 16, 18, 19]. There have been several attempts by different groups to develop models describing the damping process in the tapping mode [13, 19-28]. In the so-called dynamic force spectroscopy (DFS) measurements, where the amplitude and phase shift are monitored while the tip is approaching the sample surface, a transition from a regime of pure attractive forces (for large sample-tip separations) to a regime of both attractive and repulsive forces could be shown [20, 21]. Moreover, it was shown that the phase shift is connected to dissipative forces [26, 28] and that the amount of energy dissipated in the sample can be calculated from the phase shift [26]. Presently, the relative importance of the different surface forces for the damping process is one of the most important topics of research in this context.
