High-sensitivity noncontact atomic force microscope/scanning tunneling microscope (nc AFM/STM) operating at subangstrom oscillation amplitudes for atomic resolution imaging and force spectroscopy

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2003-08-01
Oral, Ahmet
ÖZER, HAKAN ÖZGÜR
PETHICA, JB
We describe a new, highly sensitive noncontact atomic force microscope/scanning tunneling microscope (STM) operating in ultrahigh vacuum (UHV) with subangstrom oscillation amplitudes for atomic resolution imaging and force-distance spectroscopy. A novel fiber interferometer with similar to4x10(-4) A/rootHz noise level is employed to detect cantilever displacements. Subangstrom oscillation amplitude is applied to the lever at a frequency well below the resonance and changes in the oscillation amplitude due to tip-sample force interactions are measured with a lock-in amplifier. Quantitative force gradient images can be obtained simultaneously with the STM topography. Employment of subangstrom oscillation amplitudes lets us perform force-distance measurements, which reveal very short-range force interactions, consistent with the theory. Performance of the microscope is demonstrated with quantitative atomic resolution images of Si(111)(7x7) and force-distance curves showing short interaction range, all obtained with <0.25 Angstrom lever oscillation amplitude. Our technique is not limited to UHV only and operation under liquids and air is feasible. (C) 2003 American Institute of Physics.
REVIEW OF SCIENTIFIC INSTRUMENTS

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Citation Formats
A. Oral, H. Ö. ÖZER, and J. PETHICA, “High-sensitivity noncontact atomic force microscope/scanning tunneling microscope (nc AFM/STM) operating at subangstrom oscillation amplitudes for atomic resolution imaging and force spectroscopy,” REVIEW OF SCIENTIFIC INSTRUMENTS, pp. 3656–3663, 2003, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/44753.