EXPERIMENTAL-STUDY OF PROBE-SURFACE INTERACTION IN NEAR-FIELD OPTICALMICROSCOPY

The physical mechanism of shear-force interaction between a fiber tip and a sample in near-field optical microscopy has been studied using t unneling current measurements between the tip and a sample. Optical an d non-optical (tuning fork) shear-force distance controls have been us ed. In both cases a tunneling current between the tip and the sample h as been detected at the very beginning of shear-force approach curve w hen the amplitude of tip vibration was just slightly smaller than its initial value. These results indicate that fiber-tips generally mechan ically touch samples under shear-force distance feed-back control. (C) 1998 Elsevier Science B.V. All rights reserved.