Influence of stiffness of carbon-nanotube probes in atomic force microscopy

Abstract

We report the influence of stiffness of carbon nanotubes for probes of a scanning probe microscope on images. Multiwalled carbon-nanotube probes are fabricated by manipulation under the direct view of a scanning electron microscope. Using this manipulation, it is also revealed that a Hamaker constant of 60×10-20 J for the van der Waals attraction is for a sidewall of the nanotube and the metallic surface at a vacuum of ~10-3 Pa. The force curve measurements at a steep slope in air reveal the influence of the force acting not only on the tip of the probes but also on the wall of the tip. The origin of this effect is discussed in terms of the van der Waals attraction and the adhesive energy estimated from the force curve. This phenomenon is suppressed using a nanotube probe consisting of bundled nanotubes at the base to improve the stiffness for samples of high roughness.

Mechanical and Electrical Properties of Multiwall Nanotube under Interlayer Sliding

“…It is found that the sliding force is independent of x, because the contact area of the interlayer is linearly proportional to x. Using the parameters of A = 6 × 10 −19 J [20], d = 0.34 nm, r = 2.5 nm, the van der Waals force is estimated to be ∼ 2 nN, which is comparable to the experimental value.…”

Imaging artefacts in atomic force microscopy with carbon nanotube tips

“…While much has been reported on the improved imaging capabilities of CNT AFM probes, this paper explores undesirable image artefacts that actually degrade image resolution when using CNT AFM probes in the attractive regime. This paper builds on prior work using CNT AFM probes by Akita et al [15,16], Kuwahara et al [17], and Park et al [18]. Through carefully designed experiments, each artefact is qualitatively linked to CNT AFM probe characteristics, such as CNT orientation, bending, stiction, and to DFM operating parameters, such as amplitude set-point ratio and driving amplitude.…”

Carbon Nanotube AFM Probe Technology

“…These results from the trapping of the nanotube probe by attraction between the sidewalls of the nanotube and the pit. The adhesion force of the nanotube suffered near the pit edge is tested about 10nN (Akita et al, 2000a). At this point, it is impossible to control the position of the probe height for the AFM observation because that there is no distance dependence of the amplitude on the force curve.…”

“…10. The CNT probe image of a DVD surface (a), and the force curve measurement performed near the pit edge and on a plane surface (b) (Akita et al, 2000a).…”

“…Larger scan amplitude ratio was employed to depress the ringing artefact, by increased from 66% to 96% of the 34 nm unconstrained vibration amplitude (Strus et al, 2005). Akita found that the CNT probe's image instability near the wall of the DVD surface pits can be avoided by slightly increasing the probe's free tapping amplitude to avoid the pit's attractions (Akita et al, 2000a). Solares has theoretically explored that spectral inversion method and dualfrequency-modulation method can mitigate the imaging artifacts when using short nanotube probes (<100 nm in length) in air.…”