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...
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...
Microscopic measurement of penetration depth in YBa2Cu3O7-delta thin films by scanning Hall probe microscopy
Oral, Ahmet; HUMPHREYS, RG; HENİNİ, M (1997-01-01)
We have used a low noise scanning Hall probe microscope to measure the penetration depth microscopically in a YBa2Cu3O7-delta thin film as a function of temperature. The instrument has high magnetic field (approximate to 2.9 x 10(-8) T HZ(-1/2) at 77 K) and spatial resolution ( approximate to 0.85 mu m). Magnetic field profiles of single vortices in the superconducting film have been successfully measured and the microscopic penetration depth of the superconductor has been extracted. We find surprisingly la...
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...
Contrast Enhancement of Microscopy Images Using Image Phase Information
Çakır, Serhat; Atalay, Rengül; ÇETİN, AHMET ENİS (2018-01-01)
Contrast enhancement is an important preprocessing step for the analysis of microscopy images. The main aim of contrast enhancement techniques is to increase the visibility of the cell structures and organelles by modifying the spatial characteristics of the image. In this paper, phase information-based contrast enhancement framework is proposed to overcome the limitations of existing image enhancement techniques. Inspired by the groundbreaking design of the phase contrast microscopy (PCM), the proposed ima...
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.