Intermodulation Frictional Force Microscopy (ImFFM)

(ImFFM) uses torsional resonance to achieve very high tip velocity ~ 5 cm/sec while measuring frictional forces with very high spatial resolution ~ 10 nm. At each image pixel you can observe how conservative and dissipative lateral force depends on the amplitude of tip oscillation. As the sliding velocity increases there is a transition from stick-slip to free-sliding friction.

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ImFFM on HOPG. Dynamic force quadrature curves F<sub>I<sub>(A) and F<sub>Q<sub>(A) are shown at three pixels marked in the image. The bands in the image are due to changing the load force by changing the feedback setpoint, where darker corresponds to higher load force. The scan size is 1um.

ImFFM in publications

Imaging high-speed friction at the nanometer scale
Per-Anders Thorén, Astrid S. de Wijn, Riccardo Borgani, Daniel Forchheimer and David B. Haviland
Nature Commmunications 7, 13836 (2016)
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Calibrating torsional eigenmodes of micro-cantilevers for dynamic measurement of frictional forces
Per-Anders Thorén, Riccardo Borgani, Daniel Forchheimer, and David B. Haviland
Review of Scientific Instruments, 89, 075044 (2018)
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