Spectroscopy of the anharmonic cantilever oscillations in tapping-mode atomic-force microscopy

By spectroscopic analysis of the cantilever oscillation in tapping-mode atomic-force microscopy (TM-AFM), we demonstrate that the transition from an oscillatory state dominated by a net attractive force to the state dominated by repulsive interaction is accompanied by the enhanced generation of higher harmonics. The higher harmonics are a consequence of the nonlinear interaction and are amplified to significant amplitudes by the eigenmodes of the cantilever. The results show that in a quantitative description of TM-AFM higher eigenmode excitation must be considered to account for internal energy dissipation. (C) 2000 American Institute of Physics. [S0003-6951(00)01946-X].