Abstract :
Non-contact atomic force microscopy NCAFM.minimizes the physical interaction between the AFM tip and the surface
of interest. Several recent studies have reported observation of single atom defects using this technique. The repulsive force
is presumably the primary interatomic force cf. our paper on pseudo-non-contact mode in this issue.responsible for the
reported atomic resolution in these studies. The combination of these factors, minimal tip–sample deformation and repulsive
force interaction, are responsible for the observation of the single atom defects. In the present study, we show that similar
resolution can be achieved utilizing the same two factors but which employs scanning in a surfactant. The method decreases
the tip–sample interaction by eliminating the attractive forces between the tip and sample. The surfactant solution induces an
electrical double-layer EDL.on the surface of the tip and sample. This EDL creates additional repulsion that is distributed
over a large area, and hence does not contribute noticeably to the image contrast during scanning. However, it does
compensate for the high pressures normally experienced by the tip in the absence of surfactant. In addition, the presence of
the EDL enhances tip stability during the image scan. This method has been tested on surfaces of such minerals as mica,
chlorite, and anhydrite. q1999 Elsevier Science B.V. All rights reserved.
