A Considered Approach to Force Extraction from Dynamic Force Microscopy Measurements

High-accuracy measurements of short-range chemical interactions between well-defined atomic and molecular species are possible using dynamic force microscopy (DFM). For these measurements to be quantitatively reliable, proper attention must be paid to the analysis techniques used to process experimental data; a considered approach is detailed here. We describe a rigorous implementation of the ‘on–off’ method to remove long-range interactions and quantify the uncertainty arising from implementation of this technique. We also explore the validity of approximation formulae used to convert from frequency shift to force, finding that these approximations are only valid when the oscillation amplitude is at least an order of magnitude different than any characteristic interaction length scale.