Atomic force-displacement measurements

Atomic Force Microscopy (ATM). A Nanoscope IIIA Multimode (Digital Instruments, Santa Barbara, CA) was used for atomic force microscopy measurements. The AFM was operated in force mode, with a scan rate of 1 Hz, and a 2 -piezo total displacement of 500 nm, without calibrating the scanner before each measurement (routine calibration only). Both ap-proach/extension and retraction force curves of the cantilever were recorded. 

A most recent commercial Nano Indenter (Nano Indenter XP (MTS, 2001)) consists of three major components [66] the indenter head, an optical/atomic force microscope, and x-y-z motorized precision table for positioning and transporting the sample between the optical microscopy and indenter (Fig. 28). The load on the indenter is generated using a voice coil in permanent magnet assembly, attached to the top of the indenter column. The displacement of the indenter is measured using a three plate capacitive displacement sensor. At the bottom of the indenter rod, a three-sided... 

The shear work done for one atomic (molecular) displacement, b is the applied force times the displacement, or xb3. This work must equal the promotion energy 2Eg. Therefore, letting b3 equal the molecular volume, Vm, the required shear stress is approximately 2Eg/Vm. The parameter [Eg/Vm] is called the bond modulus. It has the dimensions of stress (energy per unit volume). The numerator is a measure of the resistance of a crystal to kink movement, while the denominator is proportional to the work done by the applied stress when a kink moves one unit distance. Overall, the bond modulus is a measure of the shear strengths of covalent bonds. 

Abstract. Quantitative measurements of lateral force required for displacement of SWNTs bundle on the surface of highly oriented pyrolytic graphite with the help of atomic force microscope (AFM) were performed in real time . New method of quantitative calibration of lateral forces was used for interpretation results of lateral force microscopy (LFM). It allows us to receive numerical values of adhesion force of bundle to substrate easy and without specific equipment. 

Figures Atomic force microscope image of a carbon nanotube deposited on a filtration membrane for measuring the displacement-force curves for the evaluation of the...

Atomic force microscopy (AFM) allows the topography of a sample to be scanned by using a very small tip made from silicon nitride. The tip is attached to a cantilever that is characterised by its spring constant, resonance frequency, and a quality factor. The sample rests on a piezoceramic tube which can be moved horizontally x,y motion) and vertically (z motion). Displacement of the cantilever is measured by the position of a laser beam reflected from the mirrored surface on the top side of the cantilever, whereby the reflected laser beam is detected by a photodetector. AFM can be operated in either contact or a noncontact mode. In contact mode the tip travels in close contact with the surface, whereas in noncontact mode the tip hovers 5-10 nm above the surface. 

Modification of the atomic force microscope with feedback loops enabled force-extension curves for individual polysaccharide molecules to be measured under constantly increasing force (rather than constant displacement), in a nanoscale version of the INSTRON tester for measuring paper strength. ... 

The actual trend in hardness testing is to use the nanoindentation instruments in conjimction with atomic force microscopes (45). Load-displacement measurements are used to derive hardness and elastic modulus data while the atomic force microscope yields additional topographic information of the indentation area. Measurements at depths of 1 nm can be performed. 

Friedt JM, Choi KH, Francis L, Campitelli A (2002) Simultaneous atomic force microscope and quartz crystal microbalance measurements interactions and displacement field of a quartz crystal microbalance. Jpn J Appl Phys 1 41(6A) 3974-3977... 

An atomic force microscope is used to stuviscoelastic state at the temperature of experiment. It is shown that, during the preliminary phase of friction and before the transition to the sliding regime, the contact area remains nearly constant. This allows for a determination of the relaxation and of the complex modulus of the material. A good agreement is found between moduli measured by this method and macroscopically determined ones. The position of the transition is seen to scale with the characteristic size of the contact area but it does not depend on the displacement velocity. Finally, a transient stick-slip regime is observed before the sliding steady state is reached. 

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