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

Oral, Ahmet
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.


Real-time scanning hall probe microscopy
Oral, Ahmet; HENİNİ, M (1996-08-26)
We describe a low-noise scanning Hall probe microscope having unprecedented magnetic field sensitivity (similar to 2.9x10(-8) T/root Hz at 77 K), high spatial resolution, (similar to 0.85 mu m),nd operating in real-time (similar to 1 frame/s) for studying flux profiles at surfaces. A submicron Hall probe manufactured in a GaAs/A1GaAs two-dimensional electron gas (2DEG) is scanned over the sample to measure the surface magnetic fields using conventional scanning tunneling microscopy positioning techniques. F...
Non-contact atomic force microscope in ultra high vacuum using radiation pressure excitation of cantilever with Fabry-Perot interferometer
Karagöz, Ercan; Oral, Ahmet; Department of Physics (2017)
In this study Non-Contact Atomic Force Microscope (NC-AFM) imaging was performed by excitation of the cantilever via radiation pressure in a custom Ultra-High Vacuum (UHV) system. Both the excitation of the cantilever and the measurement of the deflection of the cantilever were done by employing a fiber Fabry-Pérot interferometer obtained by a TiO2 coating of the fiber end. This coating allows for a several times higher interference slope. The second normal mode of the cantilever oscillation, along with the...
Simultaneous non-contact atomic force microscopy (nc-AFM)/STM imaging and force spectroscopy of Si(1 0 0)(2 × 1) with small oscillation amplitudes
Özer, H.Özgür; Atabak, Mehrdad; Ellialtǧlu, Recai M.; Oral, Ahmet (2002-03-28)
Si(1 0 0)(2 x 1) surface is imaged using a new non-contact atomic force microscopy (nc-AFM)/STM with sub-Angstrom oscillation amplitudes using stiff tungsten levers. Simultaneous force gradient and STM images of individual dimers and atomic scale defects are obtained. We measured force-distance (f-d) curves with different tips. Some of the tips show long force interactions, whereas some others resolve short-range interatomic force interactions. We observed that the tips showing short-range force interaction...
3D scanning Hall probe microscopy with 700 nm resolution
DEDE, MUNIR; AKRAM, RİZWAN; Oral, Ahmet (2016-10-31)
In this report, we present a three dimensional (3D) imaging of magnetic field vector (B) over right arrow (x,y,z) emanating from the magnetic material surfaces using a scanning Hall probe microscopy (3D-SHPM) down to a 700 nm spatial resolution. The Hall probe is used to measure B-z(x,y) on the specimen surface at different heights with the step size of Delta z = 250 nm, as we move away from the surface in z direction, until the field decays to zero. These set of images are then used to get partial derivati...
Quantitative electrostatic force measurement in AFM
JEFFERY, Steve; Oral, Ahmet; Pethica, John B. (2000-04-02)
We describe a method for measuring forces in the atomic force microscope (AFM), in which a small amplitude oscillation(similar to 1 Angstrom(p-p)) is applied to a stiff(similar to 40 N/m) cantilever below its first resonant frequency, and the force gradient is measured directly as a function of separation. We have used this instrument to measure electrostatic forces by applying an ac voltage between the tip and the sample, and observed a variation in contact potential difference with separation. We also sho...
Citation Formats
A. Oral, H. Ö. ÖZER, P. HOFFMANN, and J. PETHICA, “Quantitative atom-resolved force gradient imaging using noncontact atomic force microscopy,” APPLIED PHYSICS LETTERS, pp. 1915–1917, 2001, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/39340.