Interpreting motion and force for narrow-band intermodulation atomic force microscopy
2013 (English)In: Beilstein Journal of Nanotechnology, ISSN 2190-4286, Vol. 4, 45-56 p.Article in journal (Refereed) Published
Intermodulation atomic force microscopy (ImAFM) is a mode of dynamic atomic force microscopy that probes the nonlinear tip-surface force by measurement of the mixing of multiple modes in a frequency comb. A high-quality factor cantilever resonance and a suitable drive comb will result in tip motion described by a narrow-band frequency comb. We show, by a separation of time scales, that such motion is equivalent to rapid oscillations at the cantilever resonance with a slow amplitude and phase or frequency modulation. With this time-domain perspective, we analyze single oscillation cycles in ImAFM to extract the Fourier components of the tip-surface force that are in-phase with the tip motion (F-I) and quadrature to the motion (F-Q). Traditionally, these force components have been considered as a function of the static-probe height only. Here we show that F-I and F-Q actually depend on both static-probe height and oscillation amplitude. We demonstrate on simulated data how to reconstruct the amplitude dependence of F-I and F-Q from a single ImAFM measurement. Furthermore, we introduce ImAFM approach measurements with which we reconstruct the full amplitude and probe-height dependence of the force components F-I and F-Q, providing deeper insight into the tip-surface interaction. We demonstrate the capabilities of ImAFM approach measurements on a polystyrene polymer surface.
Place, publisher, year, edition, pages
2013. Vol. 4, 45-56 p.
atomic force microscopy, AFM, frequency combs, force spectroscopy, high-quality-factor resonators, intermodulation, multifrequency
IdentifiersURN: urn:nbn:se:kth:diva-118243DOI: 10.3762/bjnano.4.5ISI: 000313722200001ScopusID: 2-s2.0-84876109153OAI: oai:DiVA.org:kth-118243DiVA: diva2:605406
QC 201302142013-02-142013-02-142015-02-09Bibliographically approved