Noncontact Atomic Force Microscopy - Yale School of Engineering ...

Kelvin probe force microscopy in application to organic thin films:
P.I-11
frequency modulation, amplitude modulation, and hover mode KPFM
Brad Moores 1 , Francis Hane 2 , Lukas Eng 3 , and Zoya Leonenko 1,2
1 Department of Physics and Astronomy, University of Waterloo, Waterloo, Canada
2 Department of Biology, University of Waterloo, Waterloo, Canada
3 Institute of Applied Photophysics, Technical University of Dresden, Dresden, Germany
We applied Kelvin probe force microscopy (KPFM) to visualize the lateral surface
potential distribution in thiol self-assembled monolayers and lipid-protein films. We have
shown earlier (Leonenko, et al. Biophys. J. 2007) that function of Bovine Lipid Extract
Surfactant (BLES) is related to the specific molecular architecture of surfactant films.
Defined molecular arrangement of the lipids and proteins of the surfactant film give rise
to a local highly variable electrical surface potential of the interface. In this work the
resolution of frequency modulation (FM-KPFM), amplitude modulation (AM-KPFM)
and hover (HM-KPFM) modes were compared. At larger scale and larger surface
potential deviations all modes give high resolution images. At smaller scans and smaller
differences in surface potential FM-KPFM mode gives superior resolution, and therefore
is preferable for imaging lipid- and lipid-protein films. The response and sensitivity of
KPFM modes was addressed with the help of force measurements.
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