Lateral Force Imaging

Lateral Force mode allows to distinguish areas with different friction and also to obtain edge-enhanced images of any surface. This capability may be used in conjunction with topographical images during one scan to characterize your samples more completely.

The physical basics of the Lateral Force mode are as follows. When scanning in the Constant Force mode perpendicularly to longitudinal axis of the cantilever, besides the cantilever's deflection in the normal direction, an additional torsion bending of the cantilever occurs. It is caused by the moment of forces acting on the tip. With minor deflections, the angle of torsion is proportional to the side (lateral) force. The cantilever's torsion bending is measured by the microscope optical recording system.

When moving over a flat surface with zones of different friction factors, the angle of torsion will be changing in every new zone. This allows measuring of the local friction force. If the surface is not absolutely flat, such an interpretation is complicated. To distinguish zones of different friction and relief influence one can utilize second pass on the same line in opposite direction. Nevertheless, this type of measuring allows obtaining images with clearly seen minor relief details and facilitates their search. In addition, the lateral force measuring mode easily provides the atomic resolution on mica and some other laminar materials.

Lateral Force mode has important usage for semiconductors, polymers, deposited films, data storage devices, investigative studies of surface contamination, chemical speciation and frictional characteristics, and a growing list of new applications.

References

1. Phys. Rev. Lett. 59, 1942 (1987). 2. Magonov, Sergei N. Surface Analysis with STM and AFM. Experimental and Theotetical Aspects of Image Analysis. VCH 1996.