Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 48: Scanning Probe Methods I
O 48.6: Vortrag
Mittwoch, 2. April 2014, 11:45–12:00, GER 38
SubSurface-AFM: unravelling the contrast formation mechanism — Gerard J. Verbiest1 and •Marcel J. Rost2 — 1JARA-FIT and II. Institute of Physics, RWTH Aachen University, 52074 Aachen, Germany — 2Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
Subsurface-AFM is realized by Heterodyne Force Microscopy (HFM), in which two ultrasonic signals of slightly different frequencies are sent through the sample and the cantilever, respectively. The sound wave through the sample contains subsurface information. The nonlinear interaction between the cantilever’s tip and the sample generates a low-frequency heterodyne force that is detected in the cantilever’s motion, if one tunes this force below its fundamental resonance frequency.
Despite some reported subsurface observations that clearly demonstrate the power of this technique, a decent quantitative understanding of the physical contrast mechanism was (until now) still missing.
Our recent insight in the working principles of HFM [1-3] enabled us to perform a quantitative analysis of our measurements on a well-characterized sample and to determine the physical contrast mechanism. Totally unexpected, the contrast is neither related to ultrasonic Rayleigh scattering nor elasticity variations in the sample, but to the rattling motion (and the involved friction) of shaking nanoparticles [4].
[1] G.J. Verbiest et al., Ultramicroscopy 135, 113 (2013)
[2] G.J. Verbiest et al., Nanotechnology 24, 365701 (2013)
[3] G.J. Verbiest, and M.J. Rost, Nature Physics submitted
[4] G.J. Verbiest and M.J. Rost, http://arXiv/abs/1307.1292