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Topics Covered
Background
Performing AFM in
Liquids
Materials and Equipment Used
Sample
AFM Equipment and Probe
Background
NT-MDT
Co. was established in 1991 with the purpose to apply all accumulated
experience and knowledge in the field of nanotechnology to supply researchers
with the instruments suitable to solve any possible task laying in nanometer
scale dimensions. The company NT-MDT was
founded in Zelenograd - the center of Russian Microelectronics. The products
development are based on the combination of the MEMS technology, power of modern
software, use of high-end microelectronic components and precision mechanical
parts. As a commercial enterprise NT-MDT Co.
exists from 1993.
Performing AFM in Liquids
It's a widely spread idea that performing AFM in liquids is a rather
complicated research approach. Actually, many tasks related to the investigation
of molecular structures and complexes in a liquid environment claim high demands
on the SPM equipment. The picture below shows an AFM scan of surfactant
molecules dynamically self-assembled into parallel, hemicylindrical micelles on
a hydrophobic graphite surface.
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Observation of the dynamically self-assembled molecular structure in this
case was a challenge. The imaging mode used is the "soft contact mode" -
scanning with constant force using a very low set point. The vertical force of
the probe needs to be kept as close as possible to the set point, in this case ~
100 pN. If the force exceeds this value, the native molecular assembly will be
disturbed (the periodicity of the micelles is ~5 nm.). For lower forces, the
contrast vanishes. Note that the vertical topography modulation is only 0.1-0.2
nm, but still significantly above the noise level. This example shows also that
NTEGRA
nanolaboratory provides enough sensitivity and stability to study dynamic
molecular structures in an aqueous environment.
Materials and Equipment Used
Sample
10 mM aqueous solution of cetyltrimethylammonium bromide surfactant in
contact with HOPG.
AFM Equipment and Probe
AFM Equipment - NTEGRA Prima, Constant force imaging mode in liquid cell using
a very low set point ("so contact mode"- force ~100pN).
AFM Probe - CSG01, 0.03 N/m
Source: "Surfactant micelles in aqueous solution: critical resolution in AFM" by Hannes Schniepp, The College of William and Mary, Williamsburg, VA, USA
For more information on this source please visit NT-MDT
Co.