| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1677690 | Ultramicroscopy | 2012 | 6 Pages |
An experimental observation of force interactions in scanning tunneling microscopy (STM) is presented. A technique for measuring force interactions between a conventional STM probe and a sample by spectra analysis of its thermal fluctuations from tunneling current in STM is developed theoretically and experimentally. Thermally excited fluctuation of the STM probe is exactly discerned in air and then force gradient is determined from its corresponding eigen-frequency with a formula similar to that for a small-amplitude atomic force microscopy (AFM). The observed force interactions are consistent with forces in dynamic AFM. Shear strength of 7 GPa for highly oriented pyrolytic graphite (HOPG) under compressive stress is obtained from the experiment and using the elastic theory. We believe that this technique is of scientific significance as it enables accurate measurement of short-range force interactions at atomic scale under true STM conditions.
Research highlights► An experimental observation of force interactions in conventional STM. ► Thermally excited vibration mode in an STM tip used as a shear force sensor. ► Spectra analysis of the thermal fluctuations of the probe from tunneling current. ► Shear strength of 7 Gpa for HOPG is obtained under compressive stress. ► Stimulating ideas for the measurement of short-range forces at atomic scale.
