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Measurement of friction
behaviour
The
lateral force mode in AFM/SPM uses the tip as a probe for friction
measurements. Lateral force means that the sytems detects lateral
deflections of the cantilever
during the contact mode measurements. However, differently from other
commercially available AFMs using
the torsion effect S.I.S. implemented an improved lateral force mode:
During the contact mode measurement an additional oscillation along the
direction of the cantilever is applied. The oscillation amplitude can
be set from 1 to several 10 nm.
Depending on the strength of the friction the cantilever's deflection
is being modulated by the oscillation. In
case of zero friction the modulation is zero likewise.
This improved lateral force mode provides enhanced material sensitive
contrast simultaneously to the topographic
measurement. Due to its adjustable amplitude the S.I.S. lateral force
mode even allows to study transitions between
sticking and sliding friction. |
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Providing
material contrast by studying friction
 image
courtesy Dr. Pilar Cea, University of Zaragoza |
The images demonstrate the capability of the method on a
Langmuir-Blodgett monolayer film. The film
does not completely cover the substrate. Therefore, holes in the film
should be detectable by the instrument.
Left: Topographic image; right: Improved Lateral Force image
Both images were acquired during the same measurement, scan range 5
µm by 5 µm.
Domains in the film are only visible in the Improved Lateral Force
scan.
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