Issue 5, 2015

Bimodal frequency-modulated atomic force microscopy with small cantilevers


Small cantilevers with ultra-high resonant frequencies (1–3 MHz) have paved the way for high-speed atomic force microscopy. However, their potential for multi-frequency atomic force microscopy is unexplored. Because small cantilevers have small spring constants but large resonant frequencies, they are well-suited for the characterisation of delicate specimens with high imaging rates. We demonstrate their imaging capabilities in a bimodal frequency modulation mode in constant excitation on semi-crystalline polypropylene. The first two flexural modes of the cantilever were simultaneously excited. The detected frequency shift of the first eigenmode was held constant for topographical feedback, whereas the second eigenmode frequency shift was used to map the local properties of the specimen. High-resolution images were acquired depicting crystalline lamellae of approximately 12 nm in width. Additionally, dynamic force curves revealed that the contrast originated from different interaction forces between the tip and the distinct polymer regions. The technique uses gentle forces during scanning and quantified the elastic moduli Eam = 300 MPa and Ecr = 600 MPa on amorphous and crystalline regions, respectively. Thus, multimode measurements with small cantilevers allow one to map material properties on the nanoscale at high resolutions and increase the force sensitivity compared with standard cantilevers.

Graphical abstract: Bimodal frequency-modulated atomic force microscopy with small cantilevers

Supplementary files

Article information

Article type
08 Oct 2014
10 Dec 2014
First published
18 Dec 2014
This article is Open Access
Creative Commons BY license

Nanoscale, 2015,7, 1849-1856

Bimodal frequency-modulated atomic force microscopy with small cantilevers

C. Dietz, M. Schulze, A. Voss, C. Riesch and R. W. Stark, Nanoscale, 2015, 7, 1849 DOI: 10.1039/C4NR05907G

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