INVESTIGATION OF THE PHYSICAL-MECHANISMS OF SHEAR-FORCE IMAGING

It is shown that shear-force imaging, as is commonly used for distance regulation in scanning near-field optical microscopy, is not a reliab le technique for accurate topographic measurements. This is because di fferent materials experience different shear-force damping. Results of the shear-force damping characteristics are presented for a number of different materials, and some consequences of the different dampings for different materials are demonstrated. It is also shown that there are at least two distinct shear force damping mechanisms. Results of i maging small conducting islands on a glass substrate show that the dam ping characteristics depend on the islands' size. (C) 1996 American In stitute of Physics.