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Uncertainties in forces extracted from non-contact atomic force microscopy measurements by fitting of long-range background forces

Sweetman, Adam; Stannard, Andrew

Authors

Adam Sweetman

Andrew Stannard



Abstract

In principle, non-contact atomic force microscopy (NC-AFM) now readily allows for the measurement of forces with sub-nanonewton precision on the atomic scale. In practice, however, the extraction of the often desired ‘short-range’ force from the experimental observable (frequency shift) is often far from trivial. In most cases there is a significant contribution to the total tip–sample force due to non-site-specific van der Waals and electrostatic forces. Typically, the contribution from these forces must be removed before the results of the experiment can be successfully interpreted, often by comparison to density functional theory calculations. In this paper we compare the ‘on-minus-off’ method for extracting site-specific forces to a commonly used extrapolation method modelling the long-range forces using a simple power law. By examining the behaviour of the fitting method in the case of two radically different interaction potentials we show that significant uncertainties in the final extracted forces may result from use of the extrapolation method.

Journal Article Type Article
Publication Date Apr 1, 2014
Journal Beilstein Journal of Nanotechnology
Print ISSN 2190-4286
Electronic ISSN 2190-4286
Publisher Beilstein-Institut
Peer Reviewed Peer Reviewed
Volume 5
APA6 Citation Sweetman, A., & Stannard, A. (2014). Uncertainties in forces extracted from non-contact atomic force microscopy measurements by fitting of long-range background forces. Beilstein Journal of Nanotechnology, 5, doi:10.3762/bjnano.5.45
DOI https://doi.org/10.3762/bjnano.5.45
Keywords Background subtraction, DFM, F(z), Force, Atomic resolution, NC-AFM, Si(111), STM, van der Waals
Publisher URL http://www.beilstein-journals.org/bjnano/single/articleFullText.htm?publicId=2190-4286-5-45
Copyright Statement Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by/4.0

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Copyright Statement
Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by/4.0





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