An individual carbon nanocoil was clamped between two AFM cantilevers and loaded in tension to a maximum relative elongation of ∼42%. The deformation of the nanocoil agrees well with an analytical model of the spring constant that accounts for the geometric nonlinearity. The nanocoil behaves like an elastic spring with a spring constant K of 0.12 N/m in the low strain region. No plastic deformation was detected. High-resolution microscopy images and the electron energy loss spectrum (EELS) indicate that the nanocoils are amorphous with a sp 2 /sp 3 bonded-carbon ratio of ∼4:1.

We report a controlled process to make carbon-nanotube tips for scanning probe microscopes. The process consists of three steps: (1) purification and alignment of carbon nanotubes using electrophoresis, (2) transfer of a single aligned nanotube onto a conventional Si tip under the view of a scanning electron microscope, and (3) attachment of the nanotube on the Si tip by carbon deposition. Nanotube tips fabricated using this procedure exhibit strong adhesion and are mechanically robust. Finally, the performance of these tips is demonstrated by imaging the fine structure of twinned deoxyribonucleic acid with tapping-mode atomic force microscopy in air.

Orientation and purification of carbon nanotubes have been demonstrated using ac electrophoresis in isopropyl alcohol. Nanotubes move towards the electrodes for all frequencies of applied electric field from 10 Hz to 10 MHz. However, carbon particles contained as impurites become harder to move with increasing frequency. The degree of orientation of nanotubes is higher when the frequency is higher and nanotubes are longer.

We have developed nanotweezers consisting of carbon nanotubes that will operate in an atomic force microscope. The two nanotubes were attached on the metal electrodes patterned on a conventional Si tip and their fixations were made by carbon deposition. These processes were made under the view of a scanning electron microscope. The application of a dc voltage to the two nanotube arms induces their movement to approach each other. The numerical simulation by taking into account the balance between the electrostatic attraction and the bending moment of the nanotubes well explains the motion of the nanotube arms.

Use of the atomic force microscope (AFM) in quantitative force measurements inherently requires a theoretical framework enabling conversion of the observed deflection properties of the cantilever to an interaction force. In this paper, the theoretical foundations of using frequency modulation atomic force microscopy (FM-AFM) in quantitative force measurements are examined and rigorously elucidated, with consideration being given to both 'conservative' and 'dissipative' interactions. This includes a detailed discussion of the underlying assumptions involved in such quantitative force measurements, the presentation of globally valid explicit formulae for evaluation of so-called 'conservative' and 'dissipative' forces, discussion of the origin of these forces, and analysis of the applicability of FM-AFM to quantitative force measurements in liquid.