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Quantitative atom-resolved force gradient imaging using noncontact atomic force microscopy

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2001-09-17
Oral, Ahmet
GRIMBLE, RA
ÖZER, HAKAN ÖZGÜR
HOFFMANN, PM
PETHICA, JB
Quantitative force gradient images are obtained using a sub-angstrom amplitude, off-resonance lever oscillation method during scanning tunneling microscopy imaging. We report the direct observation of short-range bonds, and the measured short-range force interaction agrees well in magnitude and length scale with theoretical predictions for single bonds. Atomic resolution is shown to be associated with the presence of a prominent short-range contribution to the total force interaction. It is shown that the background longer-range interaction, whose relative magnitude depends on the tip structure, has a significant effect on the contrast observed at the atomic scale. (C) 2001 American Institute of Physics.