Various methods of force measurement with the Atomic Force Microscope (AFM) are compared for their ability to accurately determine the tip-surface force from analysis of the nonlinear cantilever motion. It is explained how intermodulation, or the frequency mixing of multiple drive tones by the nonlinear tip-surface force, can be used to concentrate the nonlinear motion in a narrow band of frequency near the cantilevers fundamental resonance, where accuracy and sensitivity of force measurement are greatest. Two different methods for reconstructing tip-surface forces from intermodulation spectra are explained. The reconstruction of both conservative and dissipative tip-surface interactions from intermodulation spectra are demonstrated on simulated data.
@article{arxiv.1202.5217,
title = {The Role of Nonlinear Dynamics in Quantitative Atomic Force Microscopy},
author = {Daniel Platz and Daniel Forchheimer and Erik A. Tholén and David B. Haviland},
journal= {arXiv preprint arXiv:1202.5217},
year = {2013}
}