Measurement of shear strength for HOPG with scanning tunneling microscopy by thermal excitation method
2012
Abstract 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.
Keywords:
- Non-contact atomic force microscopy
- Scanning tunneling spectroscopy
- Scanning probe microscopy
- Analytical chemistry
- Highly oriented pyrolytic graphite
- Conductive atomic force microscopy
- Spin polarized scanning tunneling microscopy
- Chemistry
- Scanning tunneling microscope
- Photoconductive atomic force microscopy
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