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Non-contact atomic force microscopy (nc-AFM), also known as dynamic force microscopy (DFM), is a mode of atomic force microscopy, which itself is a type of scanning probe microscopy. In nc-AFM a sharp probe is moved close (order of Angstroms ) to the surface under study, the probe is then raster scanned across the surface, the image is then ...
Non-contact mode AFM does not suffer from tip or sample degradation effects that are sometimes observed after taking numerous scans with contact AFM. This makes non-contact AFM preferable to contact AFM for measuring soft samples, e.g. biological samples and organic thin film. In the case of rigid samples, contact and non-contact images may ...
The non-contact feedback loop is used to control that changes in the oscillations of the cantilever. [37] The application of AFM on non-conducting samples (c-AFM) has in recent years evolved into the modification used for analysis of morphologies on the local scale, particularly morphologies at heterojunctions of multilayered samples.
The first mode relies on the AFM contact mode, and the second mode of operation employs a scanning thermal microscopy probe (invented in 1986 [20]) to measure the polymer's temperature increase. In 2007, AFM was combined with infrared attenuated total reflection (IR-ATR) spectroscopy to study the dissolution process of urea in a cyclohexane ...
Traditional contact resonance AFM requires an external actuator to excite the cantilever contact resonances. In AFM-IR these contact resonances are automatically excited every time an infrared pulse is absorbed by the sample. So the AFM-IR technique can measure the infrared absorption by the amplitude of the cantilever oscillation response and ...
Simulating an AFM scansion in contact mode, It has been found that a vacancy or an adatom can be detected only by an atomically sharp tip. Whether in non-contact mode vacancies and adatoms can be distinguished with the so-called frequency modulation technique with a non-atomically sharp tip.
In this mode the cantilever is oscillated at a resonant frequency of the cantilever and the AFM tip is held such that it only senses with long range electrostatic forces without entering the repulsive contact regime. In this non-contact regime, the electric force gradient causes a shift in the resonance frequency of the cantilever.
In AFM, feedback loops control the operation of the microscope by keeping a fixed value a parameter of the tip's oscillation. [11] If the main feedback loop operates with the amplitude, the AFM mode is called amplitude modulation (AM). If it operates with the frequency shift, the AFM mode is called frequency modulation (FM).